Documents published in 2017 : Scipedia

The generation of power from a cement kiln waste gases: a case study of a plant in Kenya
S. Irungu, P. Muchiri, J. Byiringiro

Energy Science & Engineering (2017).

Abstract
The cement production process is energy intensive both in terms of the thermal energy (firing the kiln, drying and De carbonation) and electrical energy for driving the numerous drives within the process line. The average specific power consumption of the case study plant was 111 kWh/ton of cement with an average peak demand of 9.7 MW. The high cost of electric power at 0.14 USD/kWh results in very high cost of production that significantly lowers the companys profit margin and limits its competitive advantage. The generation of electrical power from waste heat recovery would reduce the electricity power bill through partially substituting the power procured from the national grid. This research evaluated the potential that the plant has for generating electrical power from the hot waste gases vented into the atmosphere and it was found that the plant has the potential to generate 3.4 MWh of electrical power. This results to a net potential to generate 2.89 MWh of electrical power after factoring in the auxiliary power consumption by Waste heat recovery plant system at 15%. This ultimately gave a reduction of 33% in the electricity power bill of the case study plant. The paper recommends the installation of a steam rankine cycle for the power generating plant. In this work the authors designed the steam boilers for the waste heat recovery plant for conversion of thermal energy to electrical energy, selected a commercial steam turbine and evaluated its economic feasibility and established that the designed plant would have a simple payback period of 2.7 years.
Abstract
The cement production process is energy intensive both in terms of the thermal energy (firing the kiln, drying and De carbonation) and electrical energy for driving the numerous [...]
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The progressive routes for carbon capture and sequestration
S. Nanda, S. Reddy, S. Mitra, J. Kozinski

Energy Science & Engineering (2017).

Abstract
The global warming is directly related to the increased greenhouse gas emissions from both natural and anthropogenic origins. There has been a drastic rise in the concentration of CO2 and other greenhouse gases since the industrial revolution primarily due to the intensifying consumption of fossil fuels. With the need to reduce carbon emissions and mitigate global warming certain strategies relating to carbon capturing and sequestration are indispensable. This paper comprehensively describes several physicochemical, biological and geological routes for carbon capture and sequestration. The trend of the increase in greenhouse gases over the years is illustrated along with the global statistics for fossil fuels usage and biofuels production. The physicochemical carbon capturing technologies discussed include absorption, adsorption, membrane separation and cryogenic distillation. The algal and bacterial systems, dedicated energy crops and coalbed methanogenesis have been vividly explained as the biological routes for carbon sequestration. The geological carbon sequestering route centers on biochar application and oceanic carbon storage. A systematic survey has been made on the origin and impact of greenhouse gases along with the potential for sequestration based on some fast-track and long-term sequestration technologies.
Abstract
The global warming is directly related to the increased greenhouse gas emissions from both natural and anthropogenic origins. There has been a drastic rise in the concentration [...]
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Study of thermal behavior of deoiled karanja seed cake biomass: thermogravimetric analysis and pyrolysis kinetics
R. Muktham, A. Ball, S. Bhargava, S. Bankupalli

Energy Science & Engineering (2017).

Abstract
Karanja is a medium sized evergreen tree which has minor economic importance in India. The nonedible seed kernel contains 27–30% oil that is used for biodiesel production, leaving the remaining nonedible seed cake as a waste product. The aim of the present work was to obtain kinetic parameters in relation to technological parameters in nonedible seed cake biomass pyrolysis conversion process to bio-oil and biochar. Effects of heating rate on karanja seed cake slow pyrolysis behavior and kinetic parameters were investigated at heating rates of 5, 10, and 20°C/min using thermogravimetric analysis (TGA). Thermogravimetric experiments showed the onset and offset temperatures of the devolatilization step shifted toward the high-temperature range, and the activation energy values increased with increasing heating rate. In the present study, isoconversional method was applied for the pyrolysis of karanja seed cake biomass by TGA and the activation energies (118–124 kJ/mol) and the pre-exponential factors obtained using progressive conversion. Proximate–ultimate analyses, energy value, surface structure, and Fourier transform infrared spectra of the biomass processed under conditions were reported. The pyrolysis resulted in upgradation of the energy value of seed cake biomass from 18.1 to 24.5 MJ/kg, importantly with high carbon and low oxygen contents. The approach represents a novel method for the upgrading of karanja seed cake that has significant commercial potential.
Abstract
Karanja is a medium sized evergreen tree which has minor economic importance in India. The nonedible seed kernel contains 27–30% oil that is used for biodiesel production, [...]
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Postcombustion CO2 capture using N-(3-trimethoxysilylpropyl)diethylenetriamine-grafted solid adsorbent
N. Mittal, A. Samanta, P. Sarkar, R. Gupta

Energy Science & Engineering (2017).

Abstract
In this work, the performance of N-(3-trimethoxysilylpropyl)diethylenetriamine (DAEAPTS)-grafted mesoporous SBA-15 adsorbent for postcombustion carbon capture was studied. Wet grafting technique was adopted to functionalize SBA-15 surface. The adsorption of CO2 on the amine-grafted sorbent was measured by the thermogravimetric method over a CO2 partial pressure range of 0–90 kPa and a temperature range of 25–105°C under atmospheric pressure. The optimal amine loaded SBA-15 adsorbent containing 40 wt% DAEAPTS exhibited capture capacity up to 2.3 mmol/g under simulated gas conditions (88.2% CO2/N2) at 75°C. The CO2 adsorption–desorption kinetics of the grafted sorbents were found to be sufficiently fast in both dry and humid CO2 streams and it was observed that the grafted adsorbent achieved 75% of the total capacity in 5 min of adsorption time in dry 8.8% CO2/N2 and in less than 3.5 min in humid 8.8% CO2/N2. It was also observed that 95% of the total desorption occurred in less than 7 min at 150°C under pure N2. The grafted sorbents showed good reversibility and multicycle stability and the drop in capacity after 100 cycles in dry and humid 8.8% CO2/N2 streams was around 7.09% and 11.65%, respectively.
Abstract
In this work, the performance of N-(3-trimethoxysilylpropyl)diethylenetriamine (DAEAPTS)-grafted mesoporous SBA-15 adsorbent for postcombustion carbon capture was studied. [...]
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The remarkable impact of renewable energy generation in Sicily onto electricity price formation in Italy
F. Meneguzzo, R. Ciriminna, L. Albanese, M. Pagliaro

Energy Science & Engineering (2017).

Abstract
During the first half of 2015, for the first time, the zonal electricity price in Sicily decreased below than the national wholesale price in Italy. Showing the unique pattern of electricity consumption in Italys largest region at different time scales, we identify the effectiveness of the impact of renewable power generation on utility-scale in Sicily upon the whole of Italys electricity market. Increasing the electrification of the energy end uses, as it is happening despite prolonged reduction in electricity demand, will lead to further benefits for power consumers throughout the whole country.
Abstract
During the first half of 2015, for the first time, the zonal electricity price in Sicily decreased below than the national wholesale price in Italy. Showing the unique pattern [...]
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The great solar boom: a global perspective into the far reaching impact of an unexpected energy revolution
F. Meneguzzo, R. Ciriminna, L. Albanese, M. Pagliaro

Energy Science & Engineering (2017).

Abstract
This study offers a unified perspective into the unexpected solar energy photovoltaic revolution, and its far reaching impact onto both energy generation and electricity markets. Practically relevant aspects, such as those related to the value of solar PV electricity, land consumption, energy return on energy invested, reliability of the technology, the structure of the global PV industry, the cost of Li ion batteries and related market trends are clarified. We identify the main barriers to overcome for solar PV to expand beyond a niche market (say,
Abstract
This study offers a unified perspective into the unexpected solar energy photovoltaic revolution, and its far reaching impact onto both energy generation and electricity markets. [...]
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Biodiesel from grease interceptor to gas tank
A. Ragauskas, Y. Pu, A. Ragauskas

Energy Science & Engineering (2017).

Abstract
The need for sustainable biofuels has initiated a global search for innovative technologies that can sustainably convert nonfood bioresources to liquid transportation fuels. While 2nd generation cellulosic ethanol has begun to address this challenge, other resources including yellow and brown grease are rapidly evolving commercial opportunities that are addressing regional biodiesel needs. This review examines the technical and environmental factors driving the collection of trap FOG (Fats, Oils, and Greases), its chemical composition and technologies currently available and future developments that facilitate the conversion of FOG into biodiesel.
Abstract
The need for sustainable biofuels has initiated a global search for innovative technologies that can sustainably convert nonfood bioresources to liquid transportation fuels. [...]
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Design, operation, and performance evaluation of a cable-drawn dual-axis solar tracker compared to a fixed-tilted system
S. Lo, F. Cheng, V. Chang, W. Liu, L. Chang, O. Adurodija, E. Chou, C. Lung, J. Liu, T. Lu, J. Su, E. Cheng

Energy Science & Engineering (2017).

Abstract
This article discusses the design, operation, and performance evaluation of a unique cable-operated 6.24 kWp commercial-size solar tracking system called iPV dual-axis tracker or iPV DAT with a position detector to gain the maximum power from the sunlight. Compared with other solar tracking systems, low cost, simplified hardware structure, and controlling algorithm are the advantages of this system. The operating method of the 6.24 kWp iPV DAT follow a simple pull and release of the steel cables connecting the corners of the PV module frame to the electric motors and directed by an electronic control system. The steel cables attached to the corners of the module frame also provide an extra stability in the event of high wind of up to 220 km/h. The accuracy of the tracking effect is managed by an astronomical algorithm that enables a full 360° azimuth rotation and altitude tilt of −40° to 40° (0 = horizontal). The controller algorithm also includes backtracking capability that allows optimization of ground cover ratio. Performance evaluation of the iPV DAT installed and operated in Taiwan for 12 months is compared with a fixed-tilt PV system. An average electricity gain of 30.1% and performance ratio of 93% are realized using iPV DAT.
Abstract
This article discusses the design, operation, and performance evaluation of a unique cable-operated 6.24 kWp commercial-size solar tracking system called iPV dual-axis tracker [...]
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Systematic study of aqueous monoethanolamine-based CO2 capture process: model development and process improvement
K. Li, A. Cousins, H. Yu, P. Feron, M. Tade, W. Luo, J. Chen

Energy Science & Engineering (2017).

Abstract
In this paper, we present improvements to postcombustion capture (PCC) processes based on aqueous monoethanolamine (MEA). First, a rigorous, rate-based model of the carbon dioxide (CO2) capture process from flue gas by aqueous MEA was developed using Aspen Plus, and validated against results from the PCC pilot plant trials located at the coal-fired Tarong power station in Queensland, Australia. The model satisfactorily predicted the comprehensive experimental results from CO2 absorption and CO2 stripping process. The model was then employed to guide the systematic study of the MEA-based CO2 capture process for the reduction in regeneration energy penalty through parameter optimization and process modification. Important process parameters such as MEA concentration, lean CO2 loading, lean temperature, and stripper pressure were optimized. The process modifications were investigated, which included the absorber intercooling, rich-split, and stripper interheating processes. The minimum regeneration energy obtained from the combined parameter optimization and process modification was 3.1 MJ/kg CO2. This study suggests that the combination of a validated rate-based model and process simulation can be used as an effective tool to guide sophisticated process plant, equipment design and process improvement.
Abstract
In this paper, we present improvements to postcombustion capture (PCC) processes based on aqueous monoethanolamine (MEA). First, a rigorous, rate-based model of the carbon [...]
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Models and experiments for energy consumption and quality of green tea drying
N. Langat, T. Thoruwa, J. Wanyoko, J. Kiplagat, B. Plourde, J. Abraham

Energy Science & Engineering (2017).

Abstract
An experimental apparatus has been developed to evaluate the drying process of green tea leaves. Tea drying is an energy-intensive process which results in the removal of leaf moisture, it is essential to the quality of the final product. In order to more efficiently use process energy, a prototype drying system has been built and tested. The prototype incorporates a rotating perforated drum which helps speed the drying process. Experiments were carried out with multiple temperatures, airflow rates, and drum rotation rates, a subset of those results is shown here. In particular, the impact of airflow rate on the process was studied. It was found that as the airflow increased, the drying rate increased, as expected. However, the efficiency of energy use, which was quantified by the Specific Energy Consumption rate, varied considerably with flow. While higher flows led to faster drying, it resulted in a lower energy efficiency. Also, a two parameter predictive model was developed that was able to accurately match the moisture removal rates for a very wide range of flows. This predictive model, which is based on thermal-fluid fundamentals, can be used to extrapolate the presented results to cases which were not considered.
Abstract
An experimental apparatus has been developed to evaluate the drying process of green tea leaves. Tea drying is an energy-intensive process which results in the removal of [...]
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Various operating methods and parameters for SO2 electrolysis
A. Krüger, H. Krieg, S. Grigoriev, D. Bessarabov

Energy Science & Engineering (2017).

Abstract
The application of PFSA-based proton exchange membranes was investigated for the production of hydrogen and sulfuric acid using a SO2-depolarized electrolyzer system. Parameters investigated included hot pressing pressure for the membrane electrode assembly (MEA) manufacturing, cell temperature, membrane thickness, catalyst loading, membrane type, and SO2 anode feed concentration. The effect of cell temperature, membrane thickness, and acid concentrations was also investigated when using a second method, where clean sulfuric acid as cathode and SO2 saturated sulfuric acid as anode were used. Electrochemical impedance spectroscopy showed that the pressure exerted in the MEA manufacturing step had a significant influence with 125 kg cm−2 yielding the highest current density. High temperatures (>80°C) and thin membranes (≈120 μm) showed the best performance while thicker membranes produced higher acid concentration when using the first system. The SO2 concentration in the anode had a significant influence with the over potential increasing with decreasing SO2 concentration. When using the second method, it was found that the SO2 solubility in sulfuric acid is important as the mass transport of the SO2 limits the overall reaction rate. From the two systems tested, the first method, that is, dry SO2 anode and liquid water cathode showed the best operational effectiveness reaching a maximum of 0.32 A cm−2 at 80°C using N115 coated with 1 mgPt cm−2 while the second system under the same conditions achieved a current density of 0.18 A cm−2 when using N117.
Abstract
The application of PFSA-based proton exchange membranes was investigated for the production of hydrogen and sulfuric acid using a SO2-depolarized electrolyzer system. Parameters [...]
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Influence of different adsorbates on the efficiency of thermochemical energy storage
T. Kohler, K. Müller

Energy Science & Engineering (2017).

Abstract
The main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process conditions, for example, desorption time and desorption temperature, and the working pair (adsorbent–adsorbate). Due to constrained process requirements, for example, hours of sun shine and low desorption temperatures available from a flat plate solar collector (333–373 K), the only possibility to increase the efficiency is to change the working pair. The reference working pair water–zeolite 13X needs high desorption temperatures of 500 K and high heat inputs per mass adsorbent (1080 kJ kg−1) in the desorption process to reach the maximum efficiency of 79 % and maximum energy density of 844 kJ kg−1. Therefore, the goal is to reach efficiencies in the same range as the maximum efficiency of water–zeolite 13X for desorption temperatures lower than 500 K with the usage of different adsorbates. Four systems of alcohol as adsorbate on activated carbon are compared with the reference working pair. The usage of alcohols on activated carbon allows for highly efficient adsorptive storage even at low desorption temperatures between 360 and 450 K. The maximum efficiency is shifted to higher desorption temperatures with increasing carbon chain length of the alcohol. At low desorption temperatures, the energy density and efficiency of methanol, ethanol, and propanol are higher than the energy density of the reference system. Hence, the alcohol systems on activated carbon are viable alternative approaches for regulating these process parameters.
Abstract
The main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process [...]
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Multi angle laser light scattering evaluation of field exposed thermoplastic photovoltaic encapsulant materials
M. Kempe, D. Miller, J. Wohlgemuth, S. Kurtz, J. Moseley, D. Nobles, K. Stika, Y. Brun, S. Samuels, Q. Shah, G. Tamizhmani, K. Sakurai, M. Inoue, T. Doi, A. Masuda, C. Vanderpan

Energy Science & Engineering (2017).

Abstract
As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. To investigate the possibility of creep, modules were constructed, using several thermoplastic encapsulant materials, into thin-film mock modules and deployed in Mesa, Arizona. The materials examined included poly(ethylene)-co-vinyl acetate (EVA, including formulations both cross-linked and with no curing agent), polyethylene/polyoctene copolymer (PO), poly(dimethylsiloxane) (PDMS), polyvinyl butyral (PVB), and thermoplastic polyurethane (TPU). The absence of creep in this experiment is attributable to several factors of which the most notable one was the unexpected cross-linking of an EVA formulation without a cross-linking agent. It was also found that some materials experienced both chain scission and cross-linking reactions, sometimes with a significant dependence on location within a module. The TPU and EVA samples were found to degrade with cross-linking reactions dominating over chain scission. In contrast, the PO materials degraded with chain scission dominating over cross-linking reactions. Although we found no significant indications that viscous creep is likely to occur in fielded modules capable of passing the qualification tests, we note that one should consider how a polymer degrades, chain scission or cross-linking, in assessing the suitability of a thermoplastic polymer in terrestrial photovoltaic applications.
Abstract
As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the [...]
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Field testing of thermoplastic encapsulants in high-temperature installations
M. Kempe, D. Miller, J. Wohlgemuth, S. Kurtz, J. Moseley, Q. Shah, G. Tamizhmani, K. Sakurai, M. Inoue, T. Doi, A. Masuda, S. Samuels, C. Vanderpan

Energy Science & Engineering (2017).

Abstract
Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be mechanically stable at high temperatures in the field. Recently, this has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. We constructed eight pairs of crystalline-silicon modules and eight pairs of glass/encapsulation/glass thin-film mock modules using different encapsulant materials, of which only two were formulated to chemically crosslink. One module set was exposed outdoors with thermal insulation on the back side in Mesa, Arizona, in the summer (hot-dry), and an identical module set was exposed in environmental chambers. High-precision creep measurements (±20 μm) and electrical performance measurements indicate that despite many of these polymeric materials operating in the melt or rubbery state during outdoor deployment, no significant creep was seen because of their high viscosity, lower operating temperature at the edges, and/or the formation of chemical crosslinks in many of the encapsulants with age despite the absence of a crosslinking agent. Only an ethylene-vinyl acetate (EVA) encapsulant formulated without a peroxide crosslinking agent crept significantly. In the case of the crystalline-silicon modules, the physical restraint of the backsheet reduced creep further and was not detectable even for the EVA without peroxide. Because of the propensity of some polymeric materials to crosslink as they age, typical thermoplastic encapsulants would be unlikely to result in creep in the vast majority of installations.
Abstract
Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be [...]
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Al2O3/TiO2 double layer anti-reflection coating film for crystalline silicon solar cells formed by spray pyrolysis
H. Kanda, A. Uzum, N. Harano, S. Yoshinaga, Y. Ishikawa, Y. Uraoka, H. Fukui, T. Harada, S. Ito

Energy Science & Engineering (2017).

Abstract
An Al2O3/TiO2 double layer anti-reflection coating (ARC) film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as the nonvacuum processing method. The thickness of the Al2O3 layer and TiO2 compact layer was controlled by the volume of deposited precursor solution and confirmed by ellipsometry and scanning electron microscopy. The average photovoltaic properties of photocurrent density (Jsc), open-circuit photovoltage (Voc), fill factor (FF), and photo energy conversion efficiency (η) were 37.0 mA/cm2, 590 mV, 0.712, and 15.5%, respectively. A significant improvement on Jsc and η could be confirmed owing to the Al2O3/TiO2 ARC. The results of Fourier transform infrared (FTIR) spectroscopy and optical simulation with modeling for the reflectance properties confirmed that C-H-based organics remained after the deposition of thin films.
Abstract
An Al2O3/TiO2 double layer anti-reflection coating (ARC) film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as the nonvacuum processing [...]
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Ozone pretreatment of humid wheat straw for biofuel production
A. jibouri, G. Turcotte, J. Wu, C. Cheng

Energy Science & Engineering (2017).

Abstract
In an attempt to maximize the amount of ozone reacting with lignin inside humid wheat straw, some of the ozone-reactive lignin degradation products were washed away before a second ozonolysis delignification stage. The total contact time for the two stages was kept the same as that for a one-stage process for comparison. A significant decrease in the Acid Insoluble Lignin (AIL) content of the straw resulted: from 13.04 wt. % (after a 30-min one-stage ozonolysis) to 9.34 wt. % (after a 30-min two-stage ozonolysis, separated by a washing step). This significant improvement was accompanied by an increase in released fermentable sugars from an enzymatic hydrolysis. The yield increased from 60% theoretical sugars to 80%. A further improvement in AIL (down to 7.36 wt. %) and released sugars (up to 90% theoretical) occurred when the moisture content (MC) of the straw entering the second stage was adjusted to the optimum value of the straw entering first stage (45 wt. %, predicted from an experimental design). The authors believe this is the first time results are published for the introduction of a two-stage process separated by a washing step.
Abstract
In an attempt to maximize the amount of ozone reacting with lignin inside humid wheat straw, some of the ozone-reactive lignin degradation products were washed away before [...]
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A new era of renewable power plants?
T. Kåberger

Energy Science & Engineering (2017).
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Combining science and engineering for global health and prosperity
T. Kåberger

Energy Science & Engineering (2017).
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Energy science during industrial transformation
T. Kåberger

Energy Science & Engineering (2017).
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Capacity assessment of CO2 storage in deep saline aquifers by mineral trapping and the implications for Songliao Basin, Northeast China
C. Jin, L. Liu, Y. Li, R. Zeng

Energy Science & Engineering (2017).

Abstract
Sequestrating CO2 in deep saline aquifers is maybe the most effective option to mitigate CO2 emission. The storage capacity of CO2 is the key factor for site selection before a project is carried out. Most of the existing methods are for assessment of CO2 sequestered by stratigraphic and structural trapping, as well as residual trapping and solubility trapping. In this study, we used a new method that considers CO2 consumption through geochemical reactions with minerals of reservoir rocks, mainly sandstones. Contribution of storage capacity from carbonate mineral mainly refers to calcite is excluded. That is because lifetime of calcite (the whole time from reaction starting to calcite running out) is very short contrast with geological time-scale or it is a temporary trapping. The geochemical reactions between CO2 and feldspar minerals with thousand-year lifetime are regarded as the permanent methods for trapping CO2. CO2 consumptions by K-feldspar, albite, and anorthite are assessed with volume method based on corresponding geochemical reactions. Storage efficiency factor is also considered as one of the most important parameters in the reaction formula and it depends on specific surface area of minerals contacting with formation water and kinetics of precipitation and dissolution of minerals. We assessed the CO2 storage capacity of mineral trapping in Baokang sedimentary system, south Songliao Basin through the detailed analysis of geological data in this area. The calculated results show the total CO2 storage capacity of mineral trapping of the study area is 457.5–5114.5 Mt and the corresponding storage efficiency factor is 1%. The CO2 consumed by albite makes up more than 60% of the total storage capacity and it is about 30% for anorthite.
Abstract
Sequestrating CO2 in deep saline aquifers is maybe the most effective option to mitigate CO2 emission. The storage capacity of CO2 is the key factor for site selection before [...]
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A simplified methodology for estimating solar spectral influence on photovoltaic energy yield using average photon energy
T. Ishii, K. Otani, A. Itagaki, K. Utsunomiya

Energy Science & Engineering (2017).

Abstract
Nowadays, investors, customers, and even suppliers focus on the bankability of photovoltaic (PV) technologies. However, few studies have investigated the annual net effect of solar spectrum. In this study, we estimate the net effect of the solar spectrum on the annual energy yield of c-Si and a-Si modules by two parameters. One parameter is a direct calculation from spectral factor (SF). The other parameter uses average photon energy (APE) and a regression line or curve. The estimations by the two parameters are quite consistent, whereas there is 1.2% difference between the estimations at most. Therefore, APE would be a useful index to quantify the effect of the solar spectrum.
Abstract
Nowadays, investors, customers, and even suppliers focus on the bankability of photovoltaic (PV) technologies. However, few studies have investigated the annual net effect [...]
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University of Texas study underestimates national methane emissions at natural gas production sites due to instrument sensor failure
T. Howard

Energy Science & Engineering (2017).

Abstract
The University of Texas reported on a campaign to measure methane (CH4) emissions from United States natural gas (NG) production sites as part of an improved national inventory. Unfortunately, their study appears to have systematically underestimated emissions. They used the Bacharach Hi-Flow® Sampler (BHFS) which in previous studies has been shown to exhibit sensor failures leading to underreporting of NG emissions. The data reported by the University of Texas study suggest their measurements exhibit this sensor failure, as shown by the paucity of high-emitting observations when the wellhead gas composition was less than 91% CH4, where sensor failures are most likely, during follow-up testing, the BHFS used in that study indeed exhibited sensor failure consistent with under-reporting of these high emitters. Tracer ratio measurements made by the University of Texas at a subset of sites with low CH4 content further indicate that the BHFS measurements at these sites were too low by factors of three to five. Over 98% of the CH4 inventory calculated from their own data and 41% of their compiled national inventory may be affected by this measurement failure. Their data also indicate that this sensor failure could occur at NG compositions as high as 97% CH4, possibly affecting other BHFS measurement programs throughout the entire NG supply chain, including at transmission sites where the BHFS is used to report greenhouse gas emissions to the United States Environmental Protection Agency Greenhouse Gas Reporting Program (USEPA GHGRP, U.S. 40 CFR Part 98, Subpart W). The presence of such an obvious problem in this high profile, landmark study highlights the need for increased quality assurance in all greenhouse gas measurement programs.
Abstract
The University of Texas reported on a campaign to measure methane (CH4) emissions from United States natural gas (NG) production sites as part of an improved national inventory. [...]
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Greenhouse gas emissions from domestic hot water: heat pumps compared to most commonly used systems
B. Hong, R. Howarth

Energy Science & Engineering (2017).

Abstract
We estimate the emissions of the two most important greenhouse gasses (GHG), carbon dioxide (CO2) and methane (CH4), from the use of modern high-efficiency heat pump water heaters compared to the most commonly used domestic hot water systems: natural gas storage tanks, tankless natural gas demand heaters, electric resistance storage tanks, and tankless electric resistance heaters. We considered both natural gas-powered electric plants and coal-powered plants as the source of the electricity for the heat pumps, the thermal electric storage tanks, and the tankless electric demand heaters. The time-integrated radiative forcing associated with using a heat pump water heater was always smaller than any other means of heating water considered in this study across all time frames including at 20 and 100 years. The estimated amount of CH4 lost during its lifecycle was the most critical factor determining the relative magnitude of the climatic impact. The greatest net climatic benefit within the 20-year time frame was predicted to be achieved when a storage natural gas water heater (the most common system for domestic hot water in the United States) fueled by shale gas was replaced with a high efficiency heat pump water heater powered by coal-generated electricity, the heat pump system powered by renewable electricity would have had an even greater climatic benefit, but was not explicitly modeled in this study. Our analysis provides the first assessment of the GHG footprint associated with using a heat pump water heater, which we demonstrate to be an effective and economically viable way of reducing emissions of GHGs.
Abstract
We estimate the emissions of the two most important greenhouse gasses (GHG), carbon dioxide (CO2) and methane (CH4), from the use of modern high-efficiency heat pump water [...]
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Parametric analysis and systems design of dynamic photovoltaic shading modules
J. Hofer, A. Groenewolt, P. Jayathissa, Z. Nagy, A. Schlueter

Energy Science & Engineering (2017).

Abstract
Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading systems opens new opportunities for BIPV (building integrated photovoltaics) on façades. A key problem of such systems is mutual shading among PV modules as it can lead to electrical mismatch losses and overheating effects. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film PV modules to simulate electric energy yield of geometrically complex PV applications. The developed method is able to predict the shading pattern for individual PV modules with high spatio-temporal resolution, which is of great importance for electrical system design. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement. The analysis shows, that there is a trade-off between tracking performance and mutual shading of modules. Distance between modules is a critical parameter influencing the amount of mutual shading and hence limiting solar irradiation and electricity generation of PV shading systems using solar tracking. Planning of module string configuration, PV cell orientation, and location of bypass diodes according to partial shading conditions, reduces electrical mismatch losses and results in significantly higher electricity generation. The integration of parametric 3D and electrical modeling opens new possibilities for PV system design and dynamic control optimization. Though the analysis focuses on BIPV, the method is useful for the planning and operation of solar tracking systems in general.
Abstract
Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading [...]
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Automatized analysis of IR-images of photovoltaic modules and its use for quality control of solar cells
J. Hepp, F. Machui, H. Egelhaaf, C. Brabec, A. Vetter

Energy Science & Engineering (2017).

Abstract
It is well known that the performance of solar cells may significantly suffer from local electric defects. Accordingly, infrared thermography (i.p. lock-in thermography) has been intensely applied to identify such defects as hot spots. As an imaging method, this is a fast way of module characterization. However, imaging leads to a huge amount of data, which needs to be investigated. An automatized image analysis would be a very beneficial tool but has not been suggested so far for lock-in thermography images. In this manuscript, we describe such an automatized analysis of solar cells. We first established a robust algorithm for segmentation (or recognition) for both, the PV-module and the defects (hot spots). With this information, we then calculated a parameter from the IR-images, which could be well correlated with the maximal power (Pmpp) of the modules. The proposed automatized method serves as a very useful foundation for faster and more thorough analyses of IR-images and stimulates the further development of quality control on solar modules.
Abstract
It is well known that the performance of solar cells may significantly suffer from local electric defects. Accordingly, infrared thermography (i.p. lock-in thermography) has [...]
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MoS2 as a co-catalyst for photocatalytic hydrogen production from water
B. Han, Y. Hu

Energy Science & Engineering (2017).

Abstract
Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly active, inexpensive, and earth-abundant materials as photocatalysts. As a presentative layer-structured transition metal dichalcogenides, molybdenum disulfide (MoS2) is attracting intensive attention due to its unique electro and photo properties. In this article, we comprehensively review the recent research efforts of exploring MoS2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO2, and others. It is shown that MoS2–semiconductor composites are promising photocatalysts for hydrogen evolution from water under visible light irradiation.
Abstract
Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly [...]
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Fe-Cu metastable material as a mesoporous layer for dye-sensitized solar cells
A. Alami, J. Abed, M. Almheiri, A. Alketbi, C. Aokal

Energy Science & Engineering (2017).

Abstract
This study investigates the performance of dye-sensitized solar cells constructed with a Fe-Cu metastable material as the mesoporous layer on which a natural organic dye is applied. The synthesis of the Fe-Cu material is done via a high throughput process that produces nanosized particles from elemental metallic powders. Xanthophyll is singled out as the organic natural dye of choice among other dyes that were extracted, as it exhibited wider spectral absorptivity in terms of wavelength range and magnitude. Two compact solar cells were constructed and tested, one is a reference cell with a TiO2 working electrode and the other with a Fe-Cu working electrode. The results show a better power conversion efficiency for the Fe-Cu-based solar cell 0.943% compared to 0.638% for the TiO2, and the number of carriers in the former is found to be orders of magnitude higher than the latter (1019 vs. 1032, respectively). A thorough optical, electrical, and thermal analysis of the Fe-Cu material is conducted and used to explain the obtained results.
Abstract
This study investigates the performance of dye-sensitized solar cells constructed with a Fe-Cu metastable material as the mesoporous layer on which a natural organic dye is [...]
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Review of passive heating/cooling systems of buildings
N. Gupta, G. Tiwari

Energy Science & Engineering (2017).

Abstract
In this review, an attempt has been made to analyze passive solar heating and cooling concepts along with their effects on performance of a buildings thermal management. The concepts of Trombe wall, solarium, evaporative cooling, ventilation, radiative cooling, wind tower, earth air heat exchanger, roof pond, solar shading for buildings, and building-integrated photovoltaic thermal (BiPVT) systems are extensively covered in this review. Comparison of results by various heating and cooling concepts has been made. It has been observed that direct heating through double-glazed window saves maximum conventional fuel for thermal heating during winter months. Further, an evaporative cooling is one of the best cooling concepts which is economical too in summer period.
Abstract
In this review, an attempt has been made to analyze passive solar heating and cooling concepts along with their effects on performance of a buildings thermal management. The [...]
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Offshore wind energy potential estimation using UPSCALE climate data
M. Gross, V. Magar

Energy Science & Engineering (2017).

Abstract
Offshore and near-shore wind energy is one of the major renewable energy resources, which already make a substantial contribution to the energy supply in Europe. Nevertheless, development is still in the start-up phase, with new projects being planned and implemented continuously. This development needs to be informed, to enable deployment at the most suitable/ideal locations. However, in order to predict the potential energy yield, forecasts have to be made. In this paper the authors present a scoping study. This study uses high-resolution climate data to predict wind speeds at various heights, and various locations along the coast of Mexico. Several techniques for wind extrapolation are explored, alongside a new method based on data analysis. The results show clearly a strong sensitivity to the method chosen, and results have to be interpreted accordingly. Also, the impact of water vapor is shown, using a method that predicts the moist air density at the hub height. The paper indicates that valuable information can be gained from the analyses undertaken, prior to embarking on detailed, targeted studies. The paper concludes with recommendations for further work.
Abstract
Offshore and near-shore wind energy is one of the major renewable energy resources, which already make a substantial contribution to the energy supply in Europe. Nevertheless, [...]
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Influence of different SSF conditions on ethanol production from corn stover at high solids loadings
A. Gladis, P. Bondesson, M. Galbe, G. Zacchi

Energy Science & Engineering (2017).

Abstract
In this study, three different kinds of simultaneous saccharification and fermentation (SSF) of washed pretreated corn stover with water-insoluble solids (WIS) content of 20% were investigated to find which one resulted in highest ethanol yield at high-solids loadings. The different methods were batch SSF, prehydrolysis followed by batch SSF and fed-batch SSF. Batch-SSF resulted in an ethanol yield of 75–76% and an ethanol concentration of 53 g/L. Prehydrolysis prior to batch SSF did not improve the ethanol yield compared with batch SSF. Fed-batch SSF, on the other hand, increased the yield, independent of the feeding conditions used (79–81%, 57–60 g/L). If the initial amount of solids during fed-batch SSF was lowered, the yield could be improved to some extent. When decreasing the enzyme dosage, the greatest decrease in yield was seen in the fed-batch mode (75%), while lower or the same yield was seen in batch mode with and without prehydrolysis (73%). This resulted in similar ethanol yields in all methods. However, the residence time to achieve the final ethanol yield was shorter using fed-batch. This shows that fed-batch can be a better alternative also at a lower enzyme loading.
Abstract
In this study, three different kinds of simultaneous saccharification and fermentation (SSF) of washed pretreated corn stover with water-insoluble solids (WIS) content of [...]
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High efficiency thin-film amorphous silicon solar cells
A. Ghahremani, A. Fathy

Energy Science & Engineering (2017).

Abstract
Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping techniques such as utilizing textured back reflectors for pronounced light scattering within the cell thus achieving higher absorption. It is believed that embedding metallic nanoparticles (MNPs) inside the structure could increase light scattering. However, embedding MNPs can also cause significant structure defects and pronounced efficiency drop as well – it has been indicated by many experiments that disproved this belief. In search of ways to improve efficiency, we have investigated the impact of MNPs size, and location within the solar cell, in addition to the effect of defects, and doping levels on the overall efficiency. On the basis of our 3D multiphysics (optical-electric) modeling, we developed a design guideline for embedding these MNPs and reducing the impact of defects created in the embedding process. The results of simulations were compared to relevant measured data, and it showed a good agreement. Subsequently, models were used to predict performance, and over 30% improvement in solar cell efficiency (~13% is predicted), which is beyond the state of the art. This was predicted by optimizing the size and location of the MNPs and tailoring the doping levels to have better forward light trapping and absorption.
Abstract
Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping [...]
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A three-dimensional multiphysics modeling of thin-film amorphous silicon solar cells
A. Ghahremani, A. Fathy

Energy Science & Engineering (2017).

Abstract
A 3D multiphysics simulation toolbox for thin-film amorphous silicon solar cells has been developed. The simulation is rigorous and is based on developing three modules: first to analyze light propagation using electromagnetic techniques, second to account for charge generation and transportation based on the physics of the semiconductor device, and third including electrode modeling by applying electrostatic techniques. Published results of a P-I-N thin-film amorphous silicon solar cell fabricated on a thick glass and experimentally evaluated was used as a vehicle to validate our 3D multiphysics toolbox and demonstrate its capabilities. The toolbox utilizes COMSOL for solving the partial differential equations describing the three modules, and MATLAB to input data, control the solver, and provides the coupling between the three modules. The developed toolbox was used to investigate both the effect of embedding Metallic Nanoparticles (MNPs) and the impact of defects on the external quantum efficiency. The simulator, besides being rigorous, is suitable to model various types of solar cells (organic, inorganic, thick film, thin film, heterojunction, or plasmonic) as well.
Abstract
A 3D multiphysics simulation toolbox for thin-film amorphous silicon solar cells has been developed. The simulation is rigorous and is based on developing three modules: first [...]
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Reservoir modeling for Wabamun lake sequestration project
S. Ghaderi, Y. Leonenko

Energy Science & Engineering (2017).

Abstract
A study, entitled “Wabamun Lake Sequestration Project” or “WASP, ” was performed to evaluate large-scale CO2 storage opportunities in the Wabamun area including potential risks. The project examined the feasibility of storing 20 megatons (Mt) of CO2 per year over 50 years. This scale is one order of magnitude larger than the typical benchmark (1 Mt/year) used in academic research and commercial projects that are currently in place or under review. The study was conducted by a group of researchers from several universities as well as industry consultants. This study presents an overview of the reservoir modeling part of this study, which the authors were responsible for. The main objectives of the reservoir modeling for WASP project were as follows: (1) estimation of storage capacity (traditionally, this value is projected based on the available pore space, but we have an additional practical consideration: the maximum amount one can inject within short period of time [~50 years] and within a localized injection area [~30 km × 90 km]), (2) investigation of CO2 plume movement and pressure distribution during and after injection including the effect of formation dip angle on the plume shape and its migration, (3) investigation of the long-term fate of injection associated with free phase CO2 (risks of leakage) and aquifer pressurization (possible geomechanical changes and related phenomena), (4) investigation of the phase behavior of H2S initially available and dissolved in brine during CO2 sequestration process. The WASP reservoir modeling study mentioned above led to a few important findings. The most important one is that, when CO2 is being injected into a sour aquifer, initially dissolved H2S will release into the expanding CO2 plume and accumulate at the leading edge of the plume. Also, the large-scale injection scheme (20 Mt/year), which requires multi well injectors, provides very different pressure response compared to a one well (1 Mt/year) scenario.
Abstract
A study, entitled “Wabamun Lake Sequestration Project” or “WASP, ” was performed to evaluate large-scale CO2 storage opportunities in the Wabamun area including potential [...]
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Liquinert quartz crucible for the growth of multicrystalline Si ingots
K. Fujiwara, Y. Horioka, S. Sakuragi

Energy Science & Engineering (2017).

Abstract
The growth of a multicrystalline silicon (mc-Si) ingot for solar cell applications was attempted using a Liquinert quartz crucible. A mc-Si ingot was also grown in a quartz crucible coated with Si3N4 powder for comparison with that from the Liquinert quartz crucible. The mc-Si ingot grown in the Liquinert quartz crucible had a shinier surface which has few impurity particles and higher minority carrier lifetime than the mc-Si ingot grown in a quartz crucible coated with Si3N4 powder. These results indicate that contamination with impurities was reduced with the Liquinert quartz crucible, therefore, this crucible has the potential to be a powerful tool for the production of high-quality mc-Si ingots for solar cell applications.
Abstract
The growth of a multicrystalline silicon (mc-Si) ingot for solar cell applications was attempted using a Liquinert quartz crucible. A mc-Si ingot was also grown in a quartz [...]
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Cyclical hydrogen storage and retention in polyaniline
R. Ebrahim, A. Zomorrodian, N. Attia, K. Geckeler, A. Ignatiev

Energy Science & Engineering (2017).

Abstract
Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric analysis were used to investigate the cyclical hydrogen adsorption in PANI. A hydrogen storage capacity of up to 3 wt % was obtained by charging the polymers at up to 3.0 × 106 Pa hydrogen at elevated temperature. Multiple charge and discharge cycles have been shown, with good retention beyond 106 sec.
Abstract
Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric [...]
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Renewable energy auctions in South Africa outshine feed-in tariffs
A. Eberhard, T. Kåberger

Energy Science & Engineering (2017).

Abstract
South Africas Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private investment, and electricity prices of wind power falling by 46% and solar PV electricity prices by 71%, in nominal terms. Competitive tenders were introduced after an unsuccessful attempt to implement feed-in tariffs. The tenders incorporated standard, nonnegotiable contract documents, including 20-year Power Purchase Agreements and an Implementation Agreement whereby the Government of South Africa back-stops IPP payments by the national utility, Eskom. All of these projects have reached financial close to date and some are already delivering power to the grid. The financing success has been due in part to the requirements for commercial banks to undertake a thorough due diligence of projects prior to bids being offered. The details of the policy package described may be useful for other policy makers in countries developing policies for renewable energy deployment.
Abstract
South Africas Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private [...]
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Comprehensive study of performance degradation of field-mounted photovoltaic modules in India
R. Dubey, S. Chattopadhyay, V. Kuthanazhi, A. Kottantharayil, C. Solanki, B. Arora, K. Narasimhan, J. Vasi, B. Bora, Y. Singh, O. Sastry

Energy Science & Engineering (2017).

Abstract
The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules including current-voltage, infrared and electroluminescence imaging, visual inspection, insulation resistance test and interconnect breakage test. More than a thousand modules were inspected in the field and the main results of the survey are presented in this paper. The average Pmax degradation rate for the so-called ‘good’ modules (Group X) is 1.33%/year which is higher than that commonly projected by manufacturers, and widely employed in financial calculations. Modules falling in the ‘not-so-good’ category (Group Y) show even higher degradation rates, and it is at least partly due to higher number of micro-cracks in the modules, and increased degradation of the packaging materials like encapsulant, backsheet, etc. Modules in ‘Hot’ climates degrade faster than modules in the ‘Non-Hot’ climates. Degradation in fill factor is the primary cause for performance degradation in the young modules (ages
Abstract
The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules [...]
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Performance analysis of a tower solar collector-aided coal-fired power generation system
L. Duan, X. Yu, S. Jia, B. Wang, J. Zhang

Energy Science & Engineering (2017).

Abstract
In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. The integration scheme of tower solar collector and conventional coal-fired power plant is proposed. Based on the simulation platform TRNSYS, the TSCACPG system model is established and the dynamic performance of the TSCACPG system with the operating mode of coal saving is studied. The TSCACPG system performances of 1 day and 1 year are all discussed by using the DNI data of typical year in Chinese typical city of Dunhuang. Then, the sensitivity analysis of the TSCACPG system is carried out by changing the heliostat field scale (the size of the molten salt tower also changes accordingly). The annual performance of the TSCACPG system is also acquired. In consideration of the economic costs, the heliostat field area with the maximum annual solar-to-electric efficiency is selected as the optimal value. The results show that, for the case studied, the optimal heliostat field area is 101, 400 m2, and the maximum annual solar-to-electric efficiency is 16.74%. And under the optimal situation, the standard coal consumption rate of the original coal-fired power plant is reduced from 301.5 g/kWh to 294.5 g/kWh.
Abstract
In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. [...]
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Design and experimental execution of a microcontroller (μC)-based smart dual-axis automatic solar tracking system
S. Das, S. Chakraborty, P. Sadhu, O. Sastry

Energy Science & Engineering (2017).

Abstract
Detail analysis of microcontroller (μC)-based smart dual-axis automatic solar tracking system utilizable for different purpose is presented in this paper. Working of the proposed smart tracking system is based on the automatic rotation of photovoltaic (PV) panel depending on the intensity of sun light. It will help in maintaining the alignment of PV panels with the Sunlight to obtain maximum solar power at any instance. Intensity of sunlight on a particular alignment of solar PV panel varies throughout the day. As the intensity of light on PV panel decreases the proposed smart tracking system has the intelligence to automatically redirect the panel alignment to get maximum intensity of light. Four Light Dependent Resistor (LDR) sensors are placed on the surface of the PV panel to detect the intensity of light. Two servomotors are employed in the back side of PV panel system to align the panel with maximum luminous intensity. Design and construction of the proposed tracking system is presented to measure the efficiency over the fixed PV panel. Experimental results indicate that the power output of the PV system, using the proposed tracking system is increased up to 19.73% compare to the traditional fixed PV panel. The efficiency of the proposed design is considerably higher and comparable to the existing design which has the average efficiency around 12–15%.
Abstract
Detail analysis of microcontroller (μC)-based smart dual-axis automatic solar tracking system utilizable for different purpose is presented in this paper. Working of the [...]
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Estimating the specific chemical exergy of municipal solid waste
F. Eboh, P. Ahlström, T. Richards

Energy Science & Engineering (2017).

Abstract
A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented, the model is based on the content of carbon, hydrogen, oxygen, nitrogen, sulfur, and chlorine on a dry ash-free basis (daf). The proposed model was obtained from estimations of the higher heating value (HHV) and standard entropy of MSW using statistical analysis. The ultimate analysis of 56 different parts of MSW was used for the derivation of the HHV expression. In addition, 30 extra parts were used for validation. One hundred and seventeen relevant organic substances that represented the main constituents in MSW were used for derivation of the standard entropy of solid waste. The substances were divided into different waste fractions, and the standard entropies of each waste fraction and for the complete mixture were calculated. The specific chemical exergy of inorganic matter in the waste was also investigated by considering the inorganic compounds in the ash. However, as a result of the extremely low value calculated, the exergy of inorganic matter was ignored. The results obtained from the HHV model show a good correlation with the measured values and are comparable with other recent and previous models. The correlation of the standard entropy of the complete waste mixture is less accurate than the correlations of each individual waste fraction. However, the correlations give similar results for the specific chemical exergy, indicating that HHV has a greater impact when estimating the specific exergy of solid waste than entropy.
Abstract
A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented, the model is based on the content of carbon, hydrogen, oxygen, nitrogen, [...]
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Technical mapping of solar PV for ISM-an approach toward green campus
S. Chakraborty, P. Sadhu, N. Pal

Energy Science & Engineering (2017).

Abstract
This paper aims toward the first step for green campus approach for Indian School of Mines (ISM) campus. Comparative study of the performances for nine different commercialized solar panels made of Maxeon Cell Technology, HIT (Heterojunction with Intrinsic Thin layer), monocrystalline silicon (Mono C-Si), polycrystalline silicon (Poly C-Si), Micromorph, SCHOTT, amorphous silicon (a-Si), CIGS, CdTe technologies in the environmental condition of ISM are presented in this paper. This system suggests to supply the daytime electricity demand of ISM campus as well as efficient use of the huge roof areas of different buildings to setting up the photovoltaic plant. This system ensures a daily mean reduction of 8 MWh electricity consumption from grid. The outcome of this study is that a superior performance is noted for modules made of amorphous silicon technology under the typical temperature variant and dry environmental condition of ISM campus.
Abstract
This paper aims toward the first step for green campus approach for Indian School of Mines (ISM) campus. Comparative study of the performances for nine different commercialized [...]
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Developing new perspectives on the energy trilemma
A. Carrick

Energy Science & Engineering (2017).

Abstract
The energy group of SCI (Society of Chemical Industry) was host for an event on 28th March 2017 at SCI Headquarters in London (UK) with a meeting on the important topic of the energy trilemma (sustainable, affordable and secure supply of energy). Alexandra Carrick gives an overview of the event.
Abstract
The energy group of SCI (Society of Chemical Industry) was host for an event on 28th March 2017 at SCI Headquarters in London (UK) with a meeting on the important topic of [...]
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Heterogeneous and homogenous catalysts for hydrogen generation by hydrolysis of aqueous sodium borohydride (NaBH4) solutions
P. Brack, S. Dann, K. Wijayantha

Energy Science & Engineering (2017).

Abstract
It is clear that in order to satisfy global energy demands whilst maintaining sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. Due to its high chemical energy density and the benign by-product of its combustion reactions, hydrogen is one of the most promising of these. However, methods of hydrogen storage such as gas compression or liquefaction are not suitable for portable or automotive applications due to their low hydrogen storage densities. Accordingly, much research activity has been focused on finding higher density hydrogen storage methods. One such method is to generate hydrogen via the hydrolysis of aqueous sodium borohydride (NaBH4) solutions, and this has been heavily studied since the turn of the century due to its high theoretical hydrogen storage capacity (10.8 wt%) and relatively safe operation in comparison to other chemical hydrides. This makes it very attractive for use as a hydrogen generator, in particular for portable applications. Major factors affecting the hydrolysis reaction of aqueous NaBH4 include the performance of the catalyst, reaction temperature, NaBH4 concentration, stabilizer concentration, and the volume of the reaction solution. Catalysts based on noble metals, in particular ruthenium (Ru) and platinum (Pt), have been shown to be particularly efficient at rapid generation of hydrogen from aqueous NaBH4 solutions. However, given the scarcity and expense of such metals, a transition metal-based catalyst would be a desirable alternative, and thus much work has been conducted using cobalt (Co) and nickel (Ni)-based materials to attempt to source a practical option. “Metal free” NaBH4 hydrolysis can also be achieved by the addition of aqueous acids such as hydrochloric acid (HCl) to solid NaBH4. This review summarizes the various catalysts which have been reported in the literature for the hydrolysis of NaBH4.
Abstract
It is clear that in order to satisfy global energy demands whilst maintaining sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. [...]
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An old solution to a new problem? Hydrogen generation by the reaction of ferrosilicon with aqueous sodium hydroxide solutions
P. Brack, S. Dann, K. Wijayantha, P. Adcock, S. Foster

Energy Science & Engineering (2017).

Abstract
The chemical hydrogen storage properties of ferrosilicon were investigated. A hydrogen yield of ~4.75 wt.% (with respect to the mass of ferrosilicon) was estimated by the reaction of varying quantities of ferrosilicon with 5 mL of 40 wt.% sodium hydroxide solution. The reaction of ferrosilicon with aqueous sodium hydroxide solution to form hydrogen was found to have an activation energy of 90.5 kJ mol−1 by means of an Arrhenius plot. It was observed that the induction period of the hydrogen generation reaction varies exponentially with temperature. Although this combination of high activation energy and a lengthy induction period at low temperatures reduces the attractiveness of ferrosilicon for portable hydrogen storage applications unless methods can be developed to accelerate the onset and rate of hydrogen generation, its low cost and widespread availability make it attractive for further studies focused on higher temperature stationary applications.
Abstract
The chemical hydrogen storage properties of ferrosilicon were investigated. A hydrogen yield of ~4.75 wt.% (with respect to the mass of ferrosilicon) was estimated by the [...]
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Numerical computation of a large-scale jet fire of high-pressure hydrogen in process plant
C. Jang, S. Jung

Energy Science & Engineering (2017).

Abstract
Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents at process plants in the past, it is clear that fire accidents occur with the highest frequency, leading this study to consider accidental fire scenarios at process plants. For the scenario of an incident, a jet fire involving a massive amount of hydrogen gas to be processed or delivered at the process plant has been selected. The analysis of incident outcome resulting from the hydrogen jet fire has been implemented through the computational fluid dynamics simulation methodology Kameleon FireEx. Based on the outcome of this simulation, the consequences of a jet fire with high temperature and heat radiation are analyzed and evaluated. In addition, the results from Phast ver. 7.11 simulation for the same scenario are presented for comparison and further validation.
Abstract
Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents [...]
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Energy harvesting for assistive and mobile applications
V. Bhatnagar, P. Owende

Energy Science & Engineering (2017).

Abstract
Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements to milliwatts and microwatt range. Consequently, many complex electronic systems and devices such as wearable medical and autonomous devices consume power in the range less than 200 μW, and wireless sensor networks in the range μW to 100 mW are operated on battery power. Due to the salient limitations of battery power, such as longevity of charge and where applicable, the requirement for periodic recharging, possibilities for utilization of autonomous energy sources is critical for operation of such devices. Ambient energy sources, such as vibrations (1 μW to 20 mW), motion (wide range in power outputs), temperature gradient (0.5–10 mW), radiofrequency waves (>180 μW/cm2), light (100 μW/cm2 to 100 mW/cm2), acoustics (0.003–0.11 μW/cm2), and many other, have the potential to directly power the electronic device. Ambient energy harvesting, when used separately or in conjunction with batteries, will enhance the longevity of equipment operations requiring portable or autonomous power supply. This paper reviews the state of the art in energy-harvesting techniques, power conversion, and characterization of mini- and microscale self-sustaining power generation systems in the range 600 μW to 5 W, specifically focusing on low-power system applications, for personal assistive and mobile technology devices.
Abstract
Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements [...]
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Potential induced degradation of n-type crystalline silicon solar cells with p front junction
S. Bae, W. Oh, K. Lee, S. Kim, H. Kim, N. Park, S. Chan, S. Park, Y. Kang, H. Lee, D. Kim

Energy Science & Engineering (2017).

Abstract
N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type silicon solar cells, and there are few studies on potential induced degradation (PID) in n-type solar cells. In this study, we investigated PID in n-type silicon solar cells with a front p+ emitter. Further, the PID characteristics of n-type solar cells are compared with those of p-type solar cells. The electrical properties of PID in solar cells are observed with the light I-V, quantum efficiency (QE), and electroluminescence (EL). The possible causes for the change in the external quantum efficiency (EQE) after PID are interpreted using PC1D and are discussed by comparing the experimental results with the simulation results.
Abstract
N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type [...]
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Response surface methodology for optimization of bio-lubricant basestock synthesis from high free fatty acids castor oil
V. Borugadda, V. Goud

Energy Science & Engineering (2017).

Abstract
In this paper, an eco-friendly single-step process for the synthesis of biolubricant basestock from high free fatty acid (FFA) castor oil (CO) via epoxidation reaction was investigated. Influence of various process parameters on the structural modification of CO and their interaction with the maximum oxirane oxygen content (OOC) was optimized. Central composite design (CCD) as one of the tools in response surface methodology (RSM) was used to evaluate the effects of process variables on maximum OOC. Iodine value (IV) and OOC was used to monitor the progress of epoxidation. From the RSM study, the optimal condition inferred was H2O2, 1.65 mol, catalyst loading, 15.14 wt%, temperature, 52.81°C, and reaction time, 2.81 h. At this optimum condition, OOC was found to be 3.85 mass%. Further, the epoxide product was confirmed by 1H, 13C NMR spectral technique and OOC was determined by the standard HBr method. Finally, the significant physico-chemical properties for the prepared epoxide were determined and compared with the castor oil.
Abstract
In this paper, an eco-friendly single-step process for the synthesis of biolubricant basestock from high free fatty acid (FFA) castor oil (CO) via epoxidation reaction was [...]
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Spectral response measurements of multijunction solar cells with low shunt resistance and breakdown voltages
J. Babaro, K. West, B. Hamadani

Energy Science & Engineering (2017).

Abstract
Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias-dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage. The analysis revealed that both low shunt resistance and low breakdown voltages in two of the three junctions influenced the measured quantum efficiency of all three junctions. The data and the modeling suggest that combination of current-voltage measurements under various light bias sources can reveal important information about the spectral response behavior in multijunction solar cells.
Abstract
Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions [...]
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Comparison of the indoor performance of 12 commercial PV products by a simple model
G. Apostolou, A. Reinders, M. Verwaal

Energy Science & Engineering (2017).

Abstract
This article presents a simple comparative model which has been developed for the estimation of the performance of photovoltaic (PV) products' cells in indoor environments. The model predicts the performance of PV solar cells, as a function of the distance from a spectrum of artificial (fluorescent light, halogen light, and light-emitting diodes) and natural light. It intends to support designers, while creating PV-integrated products for indoor use. For the models validation, PV cells of 12 commercially available PV-powered products with power ranging from 0.8 to 4 mWp were tested indoors under artificial illumination and natural light. The model is based on the physical measurements of natural and artificial irradiance indoors, along with literature data of PV technologies under low irradiance conditions. The input data of the model are the surface of the solar cell (in m2), the wavelength-dependent spectral response (SR) of the PV cell, the spectral irradiance indoors, and solar cells distance from light sources. The model calculates solar cells' efficiency and power produced under the specific indoor conditions. If using the measured SR of a PV cell and the irradiance as measured indoors, the model can predict the performance of a PV product under mixed indoor light with a typical inaccuracy of around 25%, which is sufficient for a design process. Measurements revealed that under mixed indoor lighting of around 20 W/m2, the efficiency of solar cells in 12 commercially available PV products ranges between 5% and 6% for amorphous silicon (a-Si) cells, 4–6% for multicrystalline silicon (mc-Si) cells, and 5–7% for the monocrystalline silicon (c-Si) cells.
Abstract
This article presents a simple comparative model which has been developed for the estimation of the performance of photovoltaic (PV) products' cells in indoor environments. [...]
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Hydrotreating reactions of tall oils over commercial NiMo catalyst
J. Anthonykutty, J. Linnekoski, A. Harlin, J. Lehtonen

Energy Science & Engineering (2017).

Abstract
Catalytic hydrotreating is an attractive method for upgrading bio-derived oils into renewable feedstocks with less oxygen content, suitable for producing valuable hydrocarbons through various petro-refinery processes. This study evaluates the catalytic activity of a commercial alumina (Al2O3) supported NiMo catalyst for hydrotreating tall oil feeds such as crude tall oil (CTO), distilled tall oil (DTO), and tall oil fatty acid (TOFA). Catalytic experiments carried out in a bench-scale fixed bed reactor set-up at different process conditions [space velocity (1–3 h−1), temperature (325–450°C), and H2 pressure (5 MPa)] produced a wide-range of products from tall oil feeds. Hydrotreating of TOFA produced highest yield of n-alkanes (>80 wt%) compared to DTO and CTO hydrotreating. A high conversion of fatty acids and resin acids was obtained in DTO hydrotreating. In CTO hydrotreating, a drop in conversion of fatty acids and resin acids was observed especially at the lowest temperature tested (325°C). The study revealed that there are various deoxygenation pathways preferential at different hydrotreating temperatures. As an example for TOFA, the decarboxylation route is dominant over the hydrodeoxygenation route at high temperatures (>400°C).
Abstract
Catalytic hydrotreating is an attractive method for upgrading bio-derived oils into renewable feedstocks with less oxygen content, suitable for producing valuable hydrocarbons [...]
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Performance testing of thermal and photovoltaic thermal solar collectors
J. Allan, Z. Dehouche, S. Stankovic, L. Mauricette

Energy Science & Engineering (2017).

Abstract
This work details a methodology to characterize the performance of solar thermal and photovoltaic thermal (PVT) collectors using an indoor solar simulator. In this study, several cases have been compared to show that the methodology can be used to extract fundamental performance characteristics from a solar collector. In the first case, a serpentine collector was compared against a header riser collector using the same mass flow rate. It was found that the header riser was less efficient, with a 34% increase in the overall loss coefficient. The experimental results were compared with commonly used empirical models and showed a close agreement. In the second case, the impact on performance of using a polycarbonate cover is presented. The results show that the optical efficiency of the collector is reduced by 12% when using a cover, however, because the loss coefficient is reduced by 53%, the covered collector performs better when there is a large temperature difference between the absorber and the ambient. The third case investigates the combined performance of a PVT collector, that produces both heat and electricity from a single device. By placing photovoltaic (PV) laminates on top of the serpentine absorber, the thermal efficiency is reduced by 15%. When electricity is generated by laminates, the thermal efficiency is reduced by a further 3.5%, this drop in thermal efficiency is a result of the incident radiation producing electricity before reaching the thermal absorber. The combined efficiency of the PVT collectors was compared at controlled inlet temperatures. The serpentine design had the highest combined efficiency of 61% with 8% electricity at the lowest inlet temperature (21°C). The dominant form of loss in the PVT system is temperature driven, as the thermal efficiency decreases, electricity generation makes up a larger percentage of the combined output. This study highlights the potential for manufacturers of bespoke thermal absorbers and PV devices to combine their products into a single PVT device that could achieve improved efficiency over a given roof area.
Abstract
This work details a methodology to characterize the performance of solar thermal and photovoltaic thermal (PVT) collectors using an indoor solar simulator. In this study, [...]
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Energy efficient inactivation of Saccharomyces cerevisiae via controlled hydrodynamic cavitation
L. Albanese, R. Ciriminna, F. Meneguzzo, M. Pagliaro

Energy Science & Engineering (2017).

Abstract
We investigate hydrodynamic cavitation to inactivate commonly employed Saccharomyces cerevisiae yeast strains in an aqueous solution using different reactors and hydraulic circuit selected to demonstrate the process feasibility on the industrial scale. The target to achieve an useful lethality of the yeast at lower temperature when compared with standard thermal and even with other cavitation processes was achieved, with 90% yeast strains lethality at lower temperature (6.3–9.5°C), and about 20% lower energy input. A separate model simulating the combined thermal and cavitational effects on yeast lethality allows to accommodate the data into a comprehensive framework providing a tool to design further targeted experiments and to predict results when changing the process parameters.
Abstract
We investigate hydrodynamic cavitation to inactivate commonly employed Saccharomyces cerevisiae yeast strains in an aqueous solution using different reactors and hydraulic [...]
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The impact of electric vehicles on the power market
L. Albanese, R. Ciriminna, F. Meneguzzo, M. Pagliaro

Energy Science & Engineering (2017).

Abstract
We investigate the impact of massive electric vehicle (EV) adoption onto the power market, both in the presence and in the absence of significant photovoltaic (PV) generation. Although results are derived taking into consideration Italys power market, results are of relevance also to other industrialized countries. One of the most important outcomes of the analysis, that is, the synergistic and beneficial effect on the overall energy bill of the concomitant expansion of EVs utilization and the growth of the renewable energy generation, particularly solar photovoltaics. The Conclusions provide arguments for policymakers for further support to sustainable mobility in their regions.
Abstract
We investigate the impact of massive electric vehicle (EV) adoption onto the power market, both in the presence and in the absence of significant photovoltaic (PV) generation. [...]
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Effects of temperature and equivalence ratio on mass balance and energy analysis in loblolly pine oxygen gasification
N. Abdoulmoumine, A. Kulkarni, S. Adhikari

Energy Science & Engineering (2017).

Abstract
The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H2, CH4, CO2), gas phase contaminants (tar, NH3, HCN, H2S, HCl), char, carbon, and inorganics), and energy flows on an oxygen-blown bubbling fluidized bed gasifier system using loblolly pine. The goal and value of this study was to provide quantitative and qualitative performance analysis and data for process engineering and optimization of these fledgling biomass conversion systems. As temperature and ER increased, mass balance closures also increased from 94.73% to 96.72% for temperature and 89.82–96.93% for ER. In addition, the carbon closures ranged from 80.77% to 92.29% and from 79.09% to 87.13% as temperature and ER increased, respectively. Carbon conversion efficiency to gas product ranged from 72.26% to 84.32% as temperature increased and from 72.26% to 84.66% as ER increased. Carbon flow analysis showed that the char product streams retained 10.26–6.94% and 8.82–2.13% of the carbon fed to the gasifier as temperature and ER increased, respectively. The carbon content in the liquid condensate was minimal compared to the carbon in other product streams and accounted for less than 0.1% of the carbon input to the gasifier at all conditions. The cold and hot gas efficiencies increased from 56.12% to 67.45% and from 67.51% to 83.83% as temperature increased due to higher production of CO and hydrogen (H2). In contrast, cold and hot gas efficiencies decreased from 63.85% to 52.84% and from 78.06% to 73.00% as ER increased, respectively, due to enhanced oxidation of gas products resulting in a net decrease in heating value.
Abstract
The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H2, [...]
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Time domain simulation of coupled sloshing-seakeeping problems by coupling PFEM-2 and SeaFEM
J. García-Espinosa, S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into one coupled tool to take advantage of their characteristics. The Particle Finite Element Method is a versatile framework for the analysis of fluid-structure interaction problems. The latest development within the framework of the PFEM is the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme. It is a semi-implicit scheme built over a Semi-Lagrangian (SL) formulation. This new scheme was named PFEM-2 and will be used in this work to solve the fluid dynamics (sloshing) inside the tanks. The PFEM-2 will be coupled in the time domain with SeaFEM, a solver developed for seakeeping problems. SeaFEM solves the second-order diffraction-radiation equations by using the Finite Element Method (FEM) and will be used in this work to simulate the interaction between waves and a floating body. The coupling of the two tools will be accomplished by using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. This new tool has been validated against experimental benchmarks carried out in a model basin at model scale.
Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into [...]
- 0
- read
Time domain simulation of coupled sloshing-seakeeping problems by coupling PFEM-2 and SeaFEM
J. García-Espinosa, S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into one coupled tool to take advantage of their characteristics. The Particle Finite Element Method is a versatile framework for the analysis of fluid-structure interaction problems. The latest development within the framework of the PFEM is the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme. It is a semi-implicit scheme built over a Semi-Lagrangian (SL) formulation. This new scheme was named PFEM-2 and will be used in this work to solve the fluid dynamics (sloshing) inside the tanks. The PFEM-2 will be coupled in the time domain with SeaFEM, a solver developed for seakeeping problems. SeaFEM solves the second-order diffraction-radiation equations by using the Finite Element Method (FEM) and will be used in this work to simulate the interaction between waves and a floating body. The coupling of the two tools will be accomplished by using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. This new tool has been validated against experimental benchmarks carried out in a model basin at model scale.
Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into [...]
- 0
- read
Time domain simulation of coupled sloshing-seakeeping problems by coupling PFEM-2 and SeaFEM
J. García-Espinosa, S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into one coupled tool to take advantage of their characteristics. The Particle Finite Element Method is a versatile framework for the analysis of fluid-structure interaction problems. The latest development within the framework of the PFEM is the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme. It is a semi-implicit scheme built over a Semi-Lagrangian (SL) formulation. This new scheme was named PFEM-2 and will be used in this work to solve the fluid dynamics (sloshing) inside the tanks. The PFEM-2 will be coupled in the time domain with SeaFEM, a solver developed for seakeeping problems. SeaFEM solves the second-order diffraction-radiation equations by using the Finite Element Method (FEM) and will be used in this work to simulate the interaction between waves and a floating body. The coupling of the two tools will be accomplished by using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. This new tool has been validated against experimental benchmarks carried out in a model basin at model scale.
Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into [...]
- 0
- read
Time domain simulation of coupled sloshing-seakeeping
S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into one coupled tool to take advantage of their characteristics. The Particle Finite Element Method is a versatile framework for the analysis of fluid-structure interaction problems. The latest development within the framework of the PFEM is the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme. It is a semi-implicit scheme built over a Semi-Lagrangian (SL) formulation. This new scheme was named PFEM-2 and will be used in this work to solve the fluid dynamics (sloshing) inside the tanks. The PFEM-2 will be coupled in the time domain with SeaFEM, a solver developed for seakeeping problems. SeaFEM solves the second-order diffraction-radiation equations by using the Finite Element Method (FEM) and will be used in this work to simulate the interaction between waves and a floating body. The coupling of the two tools will be accomplished by using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. This new tool has been validated against experimental benchmarks carried out in a model basin at model scale.
Abstract
The aim of this work is to be able to cope with complex sloshing-seakeeping problems in an effective manner. For this purpose, two different solvers will be integrated into [...]
- 0
- read
Time domain simulation of SeaFEM
S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must be assessed as it can be extremely important when estimating the viability of certain operations or the risks associated to specific load conditions during navigation. These operations and/or navigation conditions can be crucial in some sectors of the maritime industry where fluid-dynamic effects can improve the global dynamic response, such as anti-roll tanks used in the oil&gas industry, or can prove to be a big problem when, for example, sloshing effects appears in the transport of Liquefied Natural Gas (LNG). This presentation has two main parts. First, the recent work of the MARINE group of CIMNE in the development and application of seakeeping analysis tools will be presented. Here, we will introduce SeaFEM (see http://www.compassis.com/seafem), a second-order diffraction-radiation solver for multi-body seakeeping problems based on the Finite Element Method [1, 2]. Then, we will focus on the development and application of solutions for the coupled analysis of seakeeping problems considering internal flows in tanks, and in particular the sloshing phenomena. To estimate these critical effects, two different solvers are integrated into one coupled tool using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. Two different approaches have been implemented and validated: a) The internal flow part of the coupled problem is solved using the Smoothed Particle Hydrodynamics Method [3] (SPH) using the AQUAgpusph code developed at CEHINAV. While the interaction between waves and the floating body is solved using SeaFEM. b) The fluid dynamics part of the coupled problem is solved using the Particle Finite Element Method [4, 5] known as PFEM-2 that incorporates the X-IVAS scheme and the seakeeping problem is again solved using SeaFEM.
Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must [...]
- 0
- read
Time domain simulation of PFEM-2
S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must be assessed as it can be extremely important when estimating the viability of certain operations or the risks associated to specific load conditions during navigation. These operations and/or navigation conditions can be crucial in some sectors of the maritime industry where fluid-dynamic effects can improve the global dynamic response, such as anti-roll tanks used in the oil&gas industry, or can prove to be a big problem when, for example, sloshing effects appears in the transport of Liquefied Natural Gas (LNG). This presentation has two main parts. First, the recent work of the MARINE group of CIMNE in the development and application of seakeeping analysis tools will be presented. Here, we will introduce SeaFEM (see http://www.compassis.com/seafem), a second-order diffraction-radiation solver for multi-body seakeeping problems based on the Finite Element Method [1, 2]. Then, we will focus on the development and application of solutions for the coupled analysis of seakeeping problems considering internal flows in tanks, and in particular the sloshing phenomena. To estimate these critical effects, two different solvers are integrated into one coupled tool using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. Two different approaches have been implemented and validated: a) The internal flow part of the coupled problem is solved using the Smoothed Particle Hydrodynamics Method [3] (SPH) using the AQUAgpusph code developed at CEHINAV. While the interaction between waves and the floating body is solved using SeaFEM. b) The fluid dynamics part of the coupled problem is solved using the Particle Finite Element Method [4, 5] known as PFEM-2 that incorporates the X-IVAS scheme and the seakeeping problem is again solved using SeaFEM.
Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must [...]
- 0
- read
Time domain simulation of PFEM-2 and SeaFEM
S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must be assessed as it can be extremely important when estimating the viability of certain operations or the risks associated to specific load conditions during navigation. These operations and/or navigation conditions can be crucial in some sectors of the maritime industry where fluid-dynamic effects can improve the global dynamic response, such as anti-roll tanks used in the oil&gas industry, or can prove to be a big problem when, for example, sloshing effects appears in the transport of Liquefied Natural Gas (LNG). This presentation has two main parts. First, the recent work of the MARINE group of CIMNE in the development and application of seakeeping analysis tools will be presented. Here, we will introduce SeaFEM (see http://www.compassis.com/seafem), a second-order diffraction-radiation solver for multi-body seakeeping problems based on the Finite Element Method [1, 2]. Then, we will focus on the development and application of solutions for the coupled analysis of seakeeping problems considering internal flows in tanks, and in particular the sloshing phenomena. To estimate these critical effects, two different solvers are integrated into one coupled tool using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. Two different approaches have been implemented and validated: a) The internal flow part of the coupled problem is solved using the Smoothed Particle Hydrodynamics Method [3] (SPH) using the AQUAgpusph code developed at CEHINAV. While the interaction between waves and the floating body is solved using SeaFEM. b) The fluid dynamics part of the coupled problem is solved using the Particle Finite Element Method [4, 5] known as PFEM-2 that incorporates the X-IVAS scheme and the seakeeping problem is again solved using SeaFEM.
Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must [...]
- 0
- read
Time domain simulation of coupled sloshing-seakeeping problems by coupling PFEM-2 and SeaFEM
S. Guides

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017) (2017).

Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must be assessed as it can be extremely important when estimating the viability of certain operations or the risks associated to specific load conditions during navigation. These operations and/or navigation conditions can be crucial in some sectors of the maritime industry where fluid-dynamic effects can improve the global dynamic response, such as anti-roll tanks used in the oil&gas industry, or can prove to be a big problem when, for example, sloshing effects appears in the transport of Liquefied Natural Gas (LNG). This presentation has two main parts. First, the recent work of the MARINE group of CIMNE in the development and application of seakeeping analysis tools will be presented. Here, we will introduce SeaFEM (see http://www.compassis.com/seafem), a second-order diffraction-radiation solver for multi-body seakeeping problems based on the Finite Element Method [1, 2]. Then, we will focus on the development and application of solutions for the coupled analysis of seakeeping problems considering internal flows in tanks, and in particular the sloshing phenomena. To estimate these critical effects, two different solvers are integrated into one coupled tool using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. Two different approaches have been implemented and validated: a) The internal flow part of the coupled problem is solved using the Smoothed Particle Hydrodynamics Method [3] (SPH) using the AQUAgpusph code developed at CEHINAV. While the interaction between waves and the floating body is solved using SeaFEM. b) The fluid dynamics part of the coupled problem is solved using the Particle Finite Element Method [4, 5] known as PFEM-2 that incorporates the X-IVAS scheme and the seakeeping problem is again solved using SeaFEM.
Abstract
There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must [...]
- 0
- read
MODELO DE FUERZAS INTERATÓMICAS PARA EL GRAFENO A PARTIR DEL POTENCIAL AIREBO
M. Ariza, C. Ventura, M. Ortiz

Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería (2017). Vol. 33, (1)

Abstract
Dado que las propiedades eléctricas y térmicas del grafeno están influenciadas por la presencia de defectos topológicos en el material y que éstos condicionan así las futuras aplicaciones del grafeno como material base de componentes nanoelectrónicos, es necesario disponer de un modelo de comportamiento del grafeno que permita incluir dichos defectos. En este trabajo se ha obtenido un modelo de fuerzas interatómicas a partir del potencial AIREBO (Adaptive Intermolecular Reactive Empirical Bond-Order), desarrollado por Stuart et al. [1], que incluye interacciones atómicas hasta vecinos de orden cuarto. Se presentan, tanto expresiones explícitas de las derivadas del potencial, como los valores de las constantes de fuerza. Hemos verificado que el modelo de fuerzas cumple con las simetrías del cristal y las curvas de dispersión de fonones del correspondiente modelo dinámico presentan un buen acuerdo con las obtenidas por otros autores. Además, hemos verificado que las interacciones con vecinos terceros y cuartos no modifican, ni la estructura del campo de desplazamientos alrededor de los núcleos de dislcocación, ni sus correspondientes energías de formación que se predicen a partir de la teoría discreta de dislocaciones de Ariza y Ortiz [2]. Summary In view of the influence that topological defects have on the thermal and electrical properties of graphene, and given the pivotal role that such properties play in potential applications of graphene as a building block for nano-electronic components, models of graphene behavior that allow for the consideration of such defects are of the essence. In the present work, we have obtained an atomic force-constant model from the AIREBO potential (Adaptive Intermolecular Reactive Empirical Bond-Order), of Stuart et al. [1], that accounts for interatomic interactions up to fourth neighbors. We present explicit expressions of the potential derivatives as well as the force-constant values. We have verified that the force-constant model is invariant under the crystal symmetries and that the phonondispersion curves of the corresponding dynamic model are in good agreement with those obtained by other authors. In addition, we have verified that the thirdand fourth-neighbor interactions affect neither the displacement field in the vicinity of dislocation cores nor the corresponding formation energies predicted by the theory of discrete dislocations of Ariza and Ortiz [2].
Abstract
Dado que las propiedades eléctricas y térmicas del grafeno están influenciadas por la presencia de defectos topológicos en el material y que éstos condicionan así las [...]
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PUMI: UN CÓDIGO EXPLÍCITO NO ESTRUCTURADO PARA RESOLVER LAS ECUACIONES DE EULER
R. Flores, E. Ortega, E. Oñate

Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería (2017). Vol. 33, (1)

Abstract
El código PUMI se ha desarrollado en CIMNE para resolver rápidamente problemas de flujo compresible alrededor de geometrías complejas. En la actualidad se llevan a cabo de manera rutinaria cálculos con mallas que contienen decenas de millones de elementos. PUMI fue diseñado específicamente para tratar problemas de esta escala usando hardware modesto; por tanto la eficiencia del código ha sido uno de los objetivos fundamentales durante su diseño. Se buscó una utilización mínima de memoria, excelente comportamiento en entornos de ejecución secuencial y escalado satisfactorio hasta un número moderado de procesos (para su uso eficiente en estaciones de trabajo multiprocesador). Para facilitar en lo posible las tareas de generación de mallas se eligió una formulación no estucturada basada en elementos finitos. El presente artículo describe los fundamentos teóricos del algoritmo así como detalles de implementación que mejoran la robustez y eficiencia del código. Summary The PUMI flow solver has been developed at CIMNE in order to address the need for fast solutions of the flow field around complex geometries. Nowadays calculations involving a number of cells on the order of tens of millions are performed routinely. PUMI was created to deal with this kind of large-scale problem using modest hardware, therefore special emphasis was placed on the computational efficiency of the code. Design guidelines where minimum memory requirement, very fast single-threaded performance as well as satisfactory parallel scaling up to a moderate number of threads (as found on current entry-level SMP workstations). In order to simplify the mesh generation activities an unstructured finite element formulation was selected. This paper describes the theoretical basis of the algorithm as well as details of the implementation that increase the robustness and efficiency of the code.
Abstract
El código PUMI se ha desarrollado en CIMNE para resolver rápidamente problemas de flujo compresible alrededor de geometrías complejas. En la actualidad se llevan a cabo [...]
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Left atrial geometry and pump function in ischemic cardiomyopathy
M. Abdelzaher, W. Atteia

Collection of IJC Heart & Vasculature (2017).

Abstract
Many of the factors that are known to alter left atrial (LA) contractility are present in patients with ischemic cardiomyopathy (ICM). Nevertheless, preservation of LA contractile function in this group of patients was reported in previous studies. The aim of this study was to assess the changes in LA size, geometry and contractile function in ICM. 60 subjects (age: 49 ± 12 years, 53% males) in sinus rhythm undergoing coronary angiography (CA), were enrolled in this study, 15 subjects as a control group, 30 patients with reduced ejection fraction (EF) and significant coronary artery disease, as the ICM group, and 15 with reduced EF and normal CA, as the dilated cardiomyopathy (DCM) group. LA dimensions, volume, active emptying fraction (ACTEF) and eccentricity index (LAEi) as well as late diastolic velocities of the mitral annulus (a′) and LA free wall (A3) were measured. Compared with the control group, ICM patients had larger LA volume and reduced ACTEF, a′ and A3, with no significant difference between patients with ICM and DCM in any of these parameters. LA eccentricity was, non-significantly, higher in both cardiomyopathy groups than in the control group. Patients with ICM have increased LA volume and reduced LA contractile function in comparison with normal controls. LA enlargement, LA contractile dysfunction and LA geometric changes in ICM are similar to that occurring in DCM. LA size, contractile function and eccentricity may not be reliable in differentiating ischemic from idiopathic dilated cardiomyopathy.
Abstract
Many of the factors that are known to alter left atrial (LA) contractility are present in patients with ischemic cardiomyopathy (ICM). Nevertheless, preservation of LA contractile [...]
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A study of the impact of environmental loads that penetrate a passive skylight roofing system in Malaysian buildings
K. Al-Obaidi, M. Ismail, A. Rahman

Test journal 33 (2017).

Abstract
A passive skylight system is a significant building design element that provides an ideal condition for interior spaces. However, the use of this system is limited to specific climatic regions because of its considerable effect on the indoor environment. Malaysia is a tropical country that has favorable natural benefits, such as solar geometry and natural light, which can brighten building interiors throughout the year. However, harnessing this benefit affects spaces, especially those in single-story buildings, because of excessive natural loads. This study reviews a concept to understand the passive behavior of solar radiation in the form of light and heat that falls on, interacts with, and is emitted from a skylight system in a single-story building. The study method is theoretically based on descriptive analysis to assess design requirements. The review shows that designs grounded on the physical aspects of climate (influenced variables), materials (design variables), and human comfort (affected variables) in one process (ESI) can develop the architectural way of thinking rather than estimate the condition based on a limited perspective. This assumption indicates that the adoption of this concept in the preliminary design stage will enable designers to balance the building environment effectively.
Abstract
A passive skylight system is a significant building design element that provides an ideal condition for interior spaces. However, the use of this system is limited to specific [...]
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Passive cooling techniques through reflective and radiative roofs in tropical houses in Southeast Asia: A literature review
K. Al-Obaidi, M. Ismail, A. Rahman

Test journal 33 (2017).

Abstract
Cooling is one of the major concerns in building tropical houses. This problem is exacerbated by the heat gain of the roof, which constitutes 70% of the total heat gain. The passive cooling technique is one of the innovative practices and technologies that provide buildings with comfortable conditions through natural means. Reflective and radiative processes are the methods used to decrease heat gain by facilitating the elimination of excess heat in a building׳s interior to maintain a comfortable environment. Given that the potential of these techniques vary from region to region, their application in the tropics should be examined. Exploring these approaches in detail allows us to rethink how to effectively adapt these techniques to overcome the build-up of heat in modern tropical houses in Southeast Asia. This study reviews the physical characteristics of these approaches to guide architects and building designers. Results indicate a great reduction in operational cost. However, the significant differences in the performance of colour and material properties should be considered, given that the selected approach strongly affects the required thermal conditions of a building.
Abstract
Cooling is one of the major concerns in building tropical houses. This problem is exacerbated by the heat gain of the roof, which constitutes 70% of the total heat gain. The [...]
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Local and global approaches to Friction Stir Welding processes
. testests, V. Nogué, T. Test1, . test

Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería (2017). Vol. 33, (1)

Abstract
This paper deals with the numerical simulation of Friction Stir Welding (FSW) processes. FSW techniques are used in many industrial applications and particularly in the aeronautic and aerospace industries, where the quality of the joining is of essential importance. The analysis is focused either at global level, considering the full component to be jointed, or locally, studying more in detail the heat affected zone (HAZ). The analysis at global (structural component) level is performed defining the problem in the Lagrangian setting while, at local level, an apropos kinematic framework which makes use of an efficient combination of Lagrangian (pin), Eulerian (metal sheet) and ALE (stirring zone) descriptions for the different computational sub-domains is introduced for the numerical modeling. As a result, the analysis can deal with complex (non-cylindrical) pin-shapes and the extremely large deformation of the material at the HAZ without requiring any remeshing or remapping tools. A fully coupled thermo-mechanical framework is proposed for the computational modeling of the FSW processes proposed both at local and global level. A staggered algorithm based on an isothermal fractional step method is introduced. To account for the isochoric behavior of the material when the temperature range is close to the melting point or due to the predominant deviatoric deformations induced by the visco-plastic response, a mixed finite element technology is introduced. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear/linear P1/P1 interpolations for displacement (or velocity, ALE/Eulerian formulation) and pressure fields, respectively. The same stabilization strategy is adopted to tackle the instabilities of the temperature field, inherent characteristic of convective dominated problems (thermal analysis in ALE/Eulerian kinematic framework). At global level, the material behavior is characterized by a thermo-elasto- viscoplastic constitutive model. The analysis at local level is characterized by a rigid thermo-visco-plastic constitutive model. Different thermally coupled (non-Newtonian) fluid-like models as Norton-Hoff, Carreau or Sheppard-Wright, among others are tested. To better understand the material flow pattern in the stirring zone, a (Lagrangian based) particle tracing is carried out while post-processing FSW results. A coupling strategy between the analysis of the process zone nearby the pin-tool (local level analysis) and the simulation carried out for the entire structure to be welded (global level analysis) is implemented to accurately predict the temperature histories and, thereby, the residual stresses in FSW.
Abstract
This paper deals with the numerical simulation of Friction Stir Welding (FSW) processes. FSW techniques are used in many industrial applications and particularly in the aeronautic [...]
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Chemically reacting micropolar fluid flow and heat transfer between expanding or contracting walls with ion slip, Soret and Dufour effects
O. Ojjela, N. Kumar

Collection of Alexandria Engineering Journal (2017).

Abstract
The aim of the present study is to investigate the Hall and ion slip currents on an incompressible free convective flow, heat and mass transfer of a micropolar fluid in a porous medium between expanding or contracting walls with chemical reaction, Soret and Dufour effects. Assume that the walls are moving with a time dependent rate of the distance and the fluid is injecting or sucking with an absolute velocity. The walls are maintained at constant but different temperatures and concentrations. The governing partial differential equations are reduced into nonlinear ordinary differential equations by similarity transformations and then the resultant equations are solved numerically by quasilinearization technique. The results are analyzed for velocity components, microrotation, temperature and concentration with respect to different fluid and geometric parameters and presented in the form of graphs. It is noticed that with the increase in chemical reaction, Hall and ion slip parameters the temperature of the fluid is enhanced whereas the concentration is decreased. Also for the Newtonian fluid, the numerical values of axial velocity are compared with the existing literature and are found to be in good agreement.
Abstract
The aim of the present study is to investigate the Hall and ion slip currents on an incompressible free convective flow, heat and mass transfer of a micropolar fluid in a [...]
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MHD flow over a permeable stretching/shrinking sheet of a nanofluid with suction/injection
S. Naramgari, C. Sulochana

Collection of Alexandria Engineering Journal (2017).

Abstract
In this study we analyzed the influence of thermal radiation and chemical reaction on two dimensional steady magnetohydrodynamic flow of a nanofluid past a permeable stretching/shrinking sheet in the presence of suction/injection. We considered nanofluid volume fraction on the boundary is submissive controlled, which makes the present study entirely different from earlier studies and physically more realistic. The equations governing the flow are solved numerically. Effects of non-dimensional governing parameters on velocity, temperature and concentration profiles are discussed and presented through graphs. Also, coefficient of skin friction and local Nusselt number is investigated for stretching/shrinking and suction/injection cases separately and presented through tables. Comparisons with existed results are presented. Present results have an excellent agreement with the existed studies under some special assumptions. Results indicate that the enhancement in Brownian motion and thermophoresis parameters depreciates the nanoparticle concentration and increases the mass transfer rate. Dual solutions exist only for certain range of stretching/shrinking and suction/injection parameters.
Abstract
In this study we analyzed the influence of thermal radiation and chemical reaction on two dimensional steady magnetohydrodynamic flow of a nanofluid past a permeable stretching/shrinking [...]
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CFD investigations of data centers’ thermal performance for different configurations of CRACs units and aisles separation
S. Nada, M. Said, M. Rady

Collection of Alexandria Engineering Journal (2017).

Abstract
The thermal performance of data centers is numerically studied for different configurations of computer room air conditioning (CRAC) units and physical separations of cold and hot aisles. Temperature distribution, air flow characteristics and thermal management of data centers racks array are predicted and evaluated for the different arrangements. Measureable performance indices: supply/return heat index (SHI/RHI), return temperature index (RTI) and return cooling index (RCI) are used to measure the thermal management effectiveness of data center racks. The results showed that: (i) hot air recirculation, cold air bypass and the measurable performance indices of the racks strongly depend on the racks location in the racks array, (ii) the CRACs units layout affects the thermal managements of the racks array especially the sides and middle racks in the array, and (iii) using cold aisle containments enhances the thermal performance of the data center.
Abstract
The thermal performance of data centers is numerically studied for different configurations of computer room air conditioning (CRAC) units and physical separations of cold [...]
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Subdivision depth for triangular surfaces
G. Mustafa, M. Hashmi, F. Khan

Collection of Alexandria Engineering Journal (2017).

Abstract
The aim of this attempt was to present an efficient algorithm for the evaluation of error bound of triangular subdivision surfaces. The error estimation technique is based on first order difference and this process is independent of parametrization. This technique can be easily generalized to higher arity triangular surfaces. The estimated error bound is expressed in-terms of initial control point sequence and constants. Here, we efficiently estimate error bound between triangular surface and its control polygon after k-fold subdivision and further extended to evaluate subdivision depth of the scheme.
Abstract
The aim of this attempt was to present an efficient algorithm for the evaluation of error bound of triangular subdivision surfaces. The error estimation technique is based [...]
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Numerical study of double diffusive buoyancy forces induced natural convection in a trapezoidal enclosure partially heated from the right sidewall
M. Gholizadeh, R. Nikbakhti, J. Khodakhah, A. Ghasemi

Collection of Alexandria Engineering Journal (2017).

Abstract
A study of double-diffusive natural convection in a trapezoidal enclosure with a partial heated active right sidewall has been conducted numerically using the finite difference method. The length of the heated active part is equal to half of the inclined wall. Uniform different temperatures and concentrations are imposed along the active parts of the enclosure. The top and bottom boundaries of the enclosure, as well as inactive part of the right sidewall, are being insulated and impermeable. The species diffusivity of the fluid is considered to be constant, but the density varies linearly with the temperature and concentration. Double-diffusive convection for laminar two-dimensional incompressible flow with negligible radiation is expressed in terms of vorticity, temperature or energy, concentration and stream function. A Partial Differential Equation (PDE) technique is adopted to generate regular grid distribution in the physical space. The numerical results are reported for the effect of different heating cases, thermal Grashof numbers, and inclination angles on the contours of streamline, temperature, and concentration. Also, the relevant results for the average Nusselt and Sherwood numbers are demonstrated for several parameters including thermal Grashof number (103⩽GrT⩽106)103⩽GrT⩽106), Lewis number (0.5⩽Le⩽10)0.5⩽Le⩽10), Prandtl number (0.7⩽Pr⩽10)0.7⩽Pr⩽10) at a fixed aspect ratio Ar=1Ar=1 and buoyancy ratio N=-0.2N=-0.2.
Abstract
A study of double-diffusive natural convection in a trapezoidal enclosure with a partial heated active right sidewall has been conducted numerically using the finite difference [...]
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New homotopy perturbation method for system of Burgers equations
M. Mirzazadeh, Z. Ayati

Collection of Alexandria Engineering Journal (2017).

Abstract
In this paper, new homotopy perturbation method (NHPM) (Biazar et al., 2007) is applied to obtain solutions of system of Burgers equations. In this method, the solution is considered as an infinite series expansion where it converges rapidly to the exact solution. In order to show the ability and reliability of the method some examples are provided. The results reveal that the method is very effective and simple. The modified method accelerates the rapid convergence of the series solution and reduces the size of work.
Abstract
In this paper, new homotopy perturbation method (NHPM) (Biazar et al., 2007) is applied to obtain solutions of system of Burgers equations. In this method, the solution is [...]
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Large amplitude free vibration of axially loaded beams resting on variable elastic foundation
A. Mirzabeigy, R. Madoliat

Collection of Alexandria Engineering Journal (2017).

Abstract
In the present study, large amplitude free vibration of beams resting on variable elastic foundation is investigated. The Euler–Bernoulli hypothesis and the Winkler model have been applied for beam and elastic foundation, respectively. The beam is axially loaded and is restrained by immovable boundary conditions, which yields stretching during vibrations. The energy method and Hamilton’s principle are used to derive equation of motion, where after decomposition an ordinary differential equation with cubic nonlinear term is obtained. The second order homotopy perturbation method is applied to solve nonlinear equation of motion. An explicit amplitude-frequency relation is achieved from solution with relative error less than 0.07% for all amplitudes. This solution is applied to study effects of variable elastic foundation, amplitude of vibration and axial load on nonlinear frequency of beams with simply supported and fully clamped boundary conditions. Proposed formulation is capable to dealing with any arbitrary distribution of elastic foundation.
Abstract
In the present study, large amplitude free vibration of beams resting on variable elastic foundation is investigated. The Euler–Bernoulli hypothesis and the Winkler model [...]
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New approach method for solving Duffing-type nonlinear oscillator
H. Mirgolbabaee, S. Ledari, D. Ganji

Collection of Alexandria Engineering Journal (2017).

Abstract
In this paper attempts have been done to solve nonlinear oscillator by using Akbari–Ganji’s Method (AGM). Solving nonlinear equation is difficult due to its high nonlinearity. This new approach is emerged after comparing the achieved solutions with numerical method and exact solution. Results are presented for different values of amplitude vibration of the problem parameters which would certainly illustrate that this method (AGM) is efficient and has enough accuracy in comparison with other semi analytical and numerical methods. Moreover, results demonstrate that AGM could be applicable through other methods in nonlinear problems with high nonlinearity. Furthermore, convergence problems for solving nonlinear equations by using AGM appear small.
Abstract
In this paper attempts have been done to solve nonlinear oscillator by using Akbari–Ganji’s Method (AGM). Solving nonlinear equation is difficult due to its high nonlinearity. [...]
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LBM simulation of natural convection in an inclined triangular cavity filled with water
I. Mejri, A. Mahmoudi, M. Abbassi, A. Omri

Collection of Alexandria Engineering Journal (2017).

Abstract
This paper presents a numerical study of natural convection in a triangular cavity filled with water. The horizontal wall is hot, the vertical wall is cold and the inclined wall is insulated. Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature fields. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number varied from Ra = 103 to 106 and the inclination angle between Φ=0°Φ=0° and 315°315°. The effects of Rayleigh numbers and inclination angle on the streamlines, isotherms, Nusselt number are investigated. Results show that the heat transfer rate increases with the increase of Rayleigh number. In addition it is observed that the lower heat transfer rate is obtained for Φ=135°Φ=135°, however, the highest heat transfer is achieved at Φ=0°Φ=0°. The inclination angle greatly influences the heat transfer rate depending on the Rayleigh number.
Abstract
This paper presents a numerical study of natural convection in a triangular cavity filled with water. The horizontal wall is hot, the vertical wall is cold and the inclined [...]
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Buoyancy driven heat transfer in nanofluids due to wall mounted heat source
S. Malik, A. Nayak

Collection of Alexandria Engineering Journal (2017).

Abstract
This work is focussed on the numerical modeling of mixed convection heat transfer effects in a lid-driven cavity filled with a copper–water nanofluid. A heated wall mounted block with constant heat flux is attached along the vertical wall. The left vertical wall is maintained at higher temperature compared to the right vertical wall and the other (top and bottom) walls are insulated. A finite volume based numerical approach with QUICK scheme is used for the solution of nonlinear governing equations. A computational visualization technique is used to represent the two dimensional results of streamlines, isotherms, average Nusselt number and bulk-average temperature for a wide range of physical parameters, namely Reynolds number, Rayleigh number and solid volume fraction. The effective fluid flow and heat transfer variation are analyzed by placing the heated mounted block first along the left vertical wall (Case-I) and then along the right vertical wall (Case-II) to test the maximum heat transfer effects. The changes in main characteristics of the flow due to variation of Reynolds number and Rayleigh number are elaborated. The effect of various flow parameters on the thermal conductivity behavior for both cases is discussed based on average Nusselt number and bulk-average temperature and found that Case-I shows higher heat transfer rate compared to Case-II, for higher Re, Ra and ϕϕ.
Abstract
This work is focussed on the numerical modeling of mixed convection heat transfer effects in a lid-driven cavity filled with a copper–water nanofluid. A heated wall mounted [...]
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Heat transfer analysis of boundary layer flow over hyperbolic stretching cylinder
A. Majeed, T. Javed, I. Mustafa

Collection of Alexandria Engineering Journal (2017).

Abstract
In the present study heat transfer and entropy generation analysis of boundary layer flow of an incompressible viscous fluid over hyperbolic stretching cylinder are taken into account. The governing nonlinear partial differential equations are normalized by using suitable transformations. The numerical results are obtained for the partial differential equations by a finite difference scheme known as Keller box method. The influence of emerging parameters namely curvature parameter and Prandtl number on velocity and temperature profiles, skin friction coefficient and the Nusselt number is presented through graphs. A comparison for the flat plate case is given and developed code is validated. It is seen that curvature parameter has dominant effect on the flow and heat transfer characteristics. The increment in the curvature of the hyperbolic stretching cylinder increases both the momentum and thermal boundary layers. Also skin friction coefficient at the surface of cylinder decreases but Nusselt number shows opposite results. Temperature distribution is decreasing by increasing Prandtl number. Moreover, the effects of different physical parameters on entropy generation number and Bejan number are shown graphically.
Abstract
In the present study heat transfer and entropy generation analysis of boundary layer flow of an incompressible viscous fluid over hyperbolic stretching cylinder are taken [...]
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Adsorption of rhodamine B and methylene blue dyes using waste of seeds of Aleurites Moluccana, a low cost adsorbent
D. Postai, C. Demarchi, F. Zanatta, D. Melo, C. Rodrigues

Collection of Alexandria Engineering Journal (2017).

Abstract
Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds Aleurites moluccana (WAM) was studied in a batch system. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), point of zero charge measurement, and the Boehm titration method. The effects of contact time and pH were investigated for the removal of cationic dyes. An increase in pH from 3 to 9 was accompanied by an approximately three-fold increase in the amount of dye adsorbed. The adsorptions equilibrium values were obtained and analyzed using the Langmuir, Freundlich, Sips, and Redlich–Peterson equations, the Sips isotherm being the one that showed the best correlation with the experimental values. The maximum adsorption capacities of the dyes were 178 mg/g for the MB and 117 mg/g for the RhB. The kinetic sorption was evaluated by the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, where it was observed that sorption follows the pseudo-second-order kinetic model. The study of thermodynamics showed that the adsorption is a spontaneous and endothermic process. The results indicate that waste seeds of A. moluccana could be used as a low cost material for the removal of cationic dyes from wastewater.
Abstract
Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds Aleurites moluccana (WAM) was studied in a batch system. The adsorbent was characterized [...]
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Soft sensing of product quality in the debutanizer column with principal component analysis and feed-forward artificial neural network
A. Pani, K. Amin, H. Mohanta

Collection of Alexandria Engineering Journal (2017).

Abstract
In this work, data-driven soft sensors are developed for the debutanizer column for online monitoring of butane content in the debutanizer column bottom product. The data set consists of data for seven process inputs and one process output. The total process data were equally divided into a training set and a validation set using the Kennard–Stone maximal intra distance criterion. The training set was used to develop multiple linear regression, principal component regression and back propagation neural network models for the debutanizer column. Performances of the developed models were assessed by simulation with the validation data set. Results show that the neural network model designed using Levenberg–Marquardt algorithm is capable of estimating the product quality with nearly 95% accuracy. The performance of the neural network model reported in this article is found to be better than the performances of least square support vector regression and standard support vector regression models reported in the literature earlier.
Abstract
In this work, data-driven soft sensors are developed for the debutanizer column for online monitoring of butane content in the debutanizer column bottom product. The data [...]
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Nonlinear peristaltic motion of a Johnson–Segalman fluid in a tapered asymmetric channel
M. Kothandapani, J. Prakash, V. Pushparaj

Collection of Alexandria Engineering Journal (2017).

Abstract
The peristaltic flow analysis in a tapered asymmetric channel has been made for a Johnson–Segalman fluid. The tapered asymmetric channel is assumed to be formed due to a peristaltic wave train on the non-uniform walls having different amplitudes and phase. Two-dimensional equations of a Johnson–Segalman fluid have been simplified by treating a long wavelength and low Reynolds number approximations. The reduced equations are then solved for the stream function, axial velocity and axial pressure gradient using a regular perturbation technique. The expressions for the pressure rise, axial velocity and stream function are sketched and the reasons for the variations observed in various physical parameters are interpreted with valid theory. It has been noticed that peristaltic pumping region and free pumping decrease with an increase in non-uniform parameter and the situation is quite complimentary to the case of augmented pumping. It has also been observed that the size of the tapped bolus decreases with an increase in Weissenberg number.
Abstract
The peristaltic flow analysis in a tapered asymmetric channel has been made for a Johnson–Segalman fluid. The tapered asymmetric channel is assumed to be formed due to a [...]
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Three dimensional analysis of natural convection and entropy generation in a sharp edged finned cavity
L. Kolsi, H. Oztop, N. Abu-Hamdeh, A. Alghamdi, M. Borjini

Collection of Alexandria Engineering Journal (2017).

Abstract
A computational study has been performed to make a computational analysis of natural convection and entropy generation in a sharp edged finned cavity. Three dimensional analysis has been done by solving governing equations with a written computational code in Fortran. The study is performed for fin inclination angles from −60° to 60°, Ra = 105, Pr = 0.7, Rc (conductivities ratio) changes from 0.01 to 100 and irreversibility coefficient is taken as φ=10-5φ=10-5. It is observed that higher values of thermal conductivity ratio (Rc ⩾ 1) do not affect entropy generation due to heat transfer and Bejan number.
Abstract
A computational study has been performed to make a computational analysis of natural convection and entropy generation in a sharp edged finned cavity. Three dimensional analysis [...]
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Nonlinear throughflow and internal heating effects on vibrating porous medium
P. Kiran

Collection of Alexandria Engineering Journal (2017).

Abstract
The effect of vertical throughflow and internal heating effects on fluid saturated porous medium under gravity modulation is investigated. The amplitude of modulation is considered to be very small and the disturbances are expanded in terms of power series of amplitude of convection. A weakly nonlinear stability analysis is proposed to study stationary convection. The Nusselt number is obtained numerically to present the results of heat transfer while using Ginzburg–Landau equation. The vertical throughflow has dual effect either to destabilize or to stabilize the system for downward or upward directions. The effect of internal heat source enhances or sink diminishes heat transfer in the system. The amplitude and frequency of modulation have the effects of increasing or diminishing heat transport. For linear model Venezian approach suggested that throughflow and internal heating have both destabilizing and stabilizing effects for suitable ranges of . Further, the study establishes that heat transport can be controlled effectively by a mechanism that is external to the system throughflow and gravity modulation.
Abstract
The effect of vertical throughflow and internal heating effects on fluid saturated porous medium under gravity modulation is investigated. The amplitude of modulation is considered [...]
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Flexural performance of RC beams strengthened with near surface mounted CFRP strips
A. Khalifa

Collection of Alexandria Engineering Journal (2017).

Abstract
The near surface mounted (NSM) fiber reinforced polymer (FRP) reinforcement is emerging as a promising alternative strengthening technique to externally bonded reinforcement (EBR) for increasing the load carrying capacity of reinforced concrete (RC) members. NSM FRP technique has several advantages, in comparison with the EBR method, such as reducing the risk of debonding, and a better protection from the external sources of damage. In this research, the performance and effectiveness of the NSM and EBR techniques for the flexural strengthening of RC beams are compared. In order to achieve this objective, six full-scale, RC beams were strengthened with different carbon FRP (CFRP) schemes and tested. Such beams were designed to fail in a flexural mode. Test results indicated that if the same amount of CFRP is used, beams strengthened with NSM strips achieved higher ultimate load than those strengthened with EBR. Such increase in the ultimate load ratio ranged between 12% and 18%. Furthermore, a design approach for computing the moment capacity of RC flexural members strengthened with NSM CFRP strips is developed and presented in this paper.
Abstract
The near surface mounted (NSM) fiber reinforced polymer (FRP) reinforcement is emerging as a promising alternative strengthening technique to externally bonded reinforcement [...]
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Second law analysis for hydromagnetic couple stress fluid flow through a porous channel
S. Kareem, S. Adesanya, U. Vincent

Collection of Alexandria Engineering Journal (2017).

Abstract
In this work, the combined effects of magnetic field and ohmic heating on the entropy generation rate in the flow of couple stress fluid through a porous channel are investigated. The equations governing the fluid flow are formulated, non-dimensionalised and solved using a rapidly convergent semi-analytical Adomian decomposition method (ADM). The result of the computation shows a significant dependence of fluid’s thermophysical parameters on Joule’s dissipation as well as decline in the rate of change of fluid momentum due to the interplay between Lorentz and viscous forces. Moreover, the rate of entropy generation in the flow system drops as the magnitude of the magnetic field increases.
Abstract
In this work, the combined effects of magnetic field and ohmic heating on the entropy generation rate in the flow of couple stress fluid through a porous channel are investigated. [...]
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Three-dimensional unsteady natural convection and entropy generation in an inclined cubical trapezoidal cavity with an isothermal bottom wall
A. Hussein, K. Lioua, R. Chand, S. Sivasankaran, R. Nikbakhti, D. Li, B. Naceur, B. Habib

Collection of Alexandria Engineering Journal (2017).

Abstract
Numerical computation of unsteady laminar three-dimensional natural convection and entropy generation in an inclined cubical trapezoidal air-filled cavity is performed for the first time in this work. The vertical right and left sidewalls of the cavity are maintained at constant cold temperatures. The lower wall is subjected to a constant hot temperature, while the upper one is considered insulated. Computations are performed for Rayleigh numbers varied as 103 ⩽ Ra ⩽ 105, while the trapezoidal cavity inclination angle is varied as 0° ⩽ Φ ⩽ 180°. Prandtl number is considered constant at Pr = 0.71. Second law of thermodynamics is applied to obtain thermodynamic losses inside the cavity due to both heat transfer and fluid friction irreversibilities. The variation of local and average Nusselt numbers is presented and discussed, while, streamlines, isotherms and entropy contours are presented in both two and three-dimensional pattern. The results show that when the Rayleigh number increases, the flow patterns are changed especially in three-dimensional results and the flow circulation increases. Also, the inclination angle effect on the total entropy generation becomes insignificant when the Rayleigh number is low. Moreover, when the Rayleigh number increases the average Nusselt number increases.
Abstract
Numerical computation of unsteady laminar three-dimensional natural convection and entropy generation in an inclined cubical trapezoidal air-filled cavity is performed for [...]
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Study on the effect of alumina nano-fluid on sharp-edge orifice flow characteristics in both cavitations and non-cavitations turbulent flow regimes
A. Kabeel, M. Abdelgaied

Collection of Alexandria Engineering Journal (2017).

Abstract
In the present study, the effects of alumina nano-fluid concentration on sharp-edge orifice flow characteristics in both cavitations and non-cavitations turbulent flow regimes are numerically investigated. At different concentration of AL2O3 nonmetallic particles (2%, 4%, 6%, 8%, and 10%) volume fractions in pure liquid water as a base fluid. A single-hole orifice pipe is with a small diameter ratio 0.297 and the orifice plate thickness 14 mm. The effects of alumina nano-fluid concentration on sharp-edge orifice flow characteristics have been investigated based on the turbulent kinetic energy, turbulent intensity, turbulent viscosity, and volume fraction of vapor. The results show that for increasing the nonmetallic particle volume fraction from 0.0 to 10%, the turbulent kinetic energy decreases by 20.87% in average downstream the orifice in the whole region, the turbulent intensity decreases by 11.11% in average downstream the orifice in the whole region, the turbulent intensity decreases by 11% in average in the whole region, and the volume fraction of vapor increases by 16.9%. Also, in the separation region downstream the orifice the turbulent kinetic energy increases by 160% in average and the turbulent intensity increases by 74% in average for increasing the nano-fluid concentration from 0.0% to 2%. These are mainly because for using the alumina nano-fluid the separation phenomena decrease due to the increase of the viscosity of the nano-fluid, the total losses in the sharp-edge orifice increase for the increase of the viscosity of the nano-fluid and this causes the increase of the rate of vaporization. In the orifice pipe the total-stress criterion predicts larger cavitating regions in the flow field. However using the nano-fluid with high concentration accelerates the cavitations at the orifice pipe.
Abstract
In the present study, the effects of alumina nano-fluid concentration on sharp-edge orifice flow characteristics in both cavitations and non-cavitations turbulent flow regimes [...]
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Steady fully developed natural convection flow in a vertical annular microchannel having temperature dependent viscosity: An exact solution
B. Jha, B. Aina, Z. Rilwanu

Collection of Alexandria Engineering Journal (2017).

Abstract
This study is devoted to investigate the steady fully developed natural convection flow in a vertical annular micro-channel having temperature dependent viscosity in the presence of velocity slip and temperature jump at the annular micro-channel surfaces. The governing equations of the motion are a set of ordinary differential equations and their analytical solutions in dimensionless form have been obtained for the temperature field and velocity field. The effect of various flow parameters entering into the problem is discussed with the aid of line graphs. During the course of numerical investigation, it is found that increase in viscosity variation parameter enhances the fluid velocity and velocity slip. Furthermore, an increase in viscosity variation parameter leads to increase in the volume flow rate and skin friction.
Abstract
This study is devoted to investigate the steady fully developed natural convection flow in a vertical annular micro-channel having temperature dependent viscosity in the presence [...]
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A new solution for nonlinear Dual Phase Lagging heat conduction problem
M. Noroozi, S. Saedodin, D. Ganji

Collection of Alexandria Engineering Journal (2017).

Abstract
The application of new methods to solution of non-Fourier heat transfer problems has always been one of the interesting topics among thermal science researchers. In this paper, the effect of laser, as a heat source, on a thin film was studied. The Dual Phase Lagging (DPL) non-Fourier heat conduction model was used for thermal analysis. The thermal conductivity was assumed temperature-dependent which resulted in a nonlinear equation. The obtained equations were solved using the approximate-analytical Adomian Decomposition Method (ADM). It was concluded that the nonlinear analysis is important in non-Fourier heat conduction problems. Significant differences were observed between the Fourier and non-Fourier solutions which stress the importance of non-Fourier solutions in the similar problems.
Abstract
The application of new methods to solution of non-Fourier heat transfer problems has always been one of the interesting topics among thermal science researchers. In this paper, [...]
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An empirical investigation on Cu/Ethylene Glycol nanofluid through a concentric annular tube and proposing a correlation for predicting Nusselt number
A. Jafarimoghaddam, S. Aberoumand

Collection of Alexandria Engineering Journal (2017).

Abstract
The investigation indicates an experimental study on the convective heat transfer of Cu/Ethylene Glycol nanofluid flow inside a concentric annular tube with constant heat flux boundary condition and proposes a novel correlation for the prediction of Nusselt number. For extending the previous study by Jafarimoghaddam et al., we selected the nanoparticles with the average size of 20 nm and also other conditions of the experiment are based on Jafarimoghaddam et al. (2016) [1]. The applied nanofluid was prepared by Electrical Explosion of Wire technique with no accumulation during the experiment. The tube was heated using an electrical heating coil covered it. The effects of different parameters such as flow Reynolds number and nanofluid particle concentration on heat transfer coefficient are studied. The acquired experimental data were used to establish a correlation for predicting Nusselt number of nanofluid flow inside the annular tube. This correlation has been presented by using the exponential regression analysis and least square method. Correlation is valid for Cu/Base Ethylene Glycol nanofluid flow with the volume concentrations between 0.011 and 0.171 in the hydrodynamically fully developed laminar flow regime with Re < 160 which is most applicable in micro heat sinks.
Abstract
The investigation indicates an experimental study on the convective heat transfer of Cu/Ethylene Glycol nanofluid flow inside a concentric annular tube with constant heat [...]
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Protection of DFIG wind turbine using fuzzy logic control
M. Ismail, A. Bendary

Collection of Alexandria Engineering Journal (2017).

Abstract
In the last 15 years, Double Fed Induction Generator (DFIG) had been widely used as a wind turbine generator, due its various advantages especially low generation cost so it becomes the most important and promising sources of renewable energy. This work focuses on studying of using DFIG as a wind turbine connected to a grid subjected to various types of fault. Crowbar is a kind of protection used for wind turbine generator protection. ANFIS controller is used for protection of DFIG during faults. The fault current under symmetric and asymmetric fault is presented as well as a way to control the increase in rotor current which leads to voltage increase in DC link between wind generator and the grid. ANFIS is used for solving such problem as it is one of the most commonly AI used techniques. Also the current response of DFIG during fault is improved by adapting the parameters of PI controllers of the voltage regulator using fuzzy logics. ANFIS also in this paper is used for detecting and clearing the short circuit on the DC capacitor link during the operation. A simulation study is illustrated using MATLAB/Simulink depending on currents and voltages measurement only for online detection of the faults. The proposed technique shows promising results using the simulation model.
Abstract
In the last 15 years, Double Fed Induction Generator (DFIG) had been widely used as a wind turbine generator, due its various advantages especially low generation cost so [...]
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Experimental and numerical simulation of scour at bridge abutment provided with different arrangements of collars
T. Nasr-Allah, Y. Moussa, G. Abdel-Aal, A. Awad

Collection of Alexandria Engineering Journal (2017).

Abstract
In this paper, the effects of different widths and lengths of collar around bridge abutment on local scour depth are studied numerically and experimentally. Numerical simulation of scour hole evolution at bridge abutment is more convenient than the experimental modeling, because the computational cost and time have significantly decreased. The numerical model solves 3-D Navier–Stokes equations and bed load conservation equation. The k–ε turbulence model is used to solve the Reynolds-stress term. The simulated results are verified using the laboratory experiments. In addition, the multiple linear regressions are applied to correlate the maximum local scour depth with the other independent parameters. It was found that the relative length of collar 0.73 around bridge abutment reduces the maximum scour depth by 69% compared to no-collar case. Moreover, the results of 3-D numerical model and regression models agree well with the experimental data.
Abstract
In this paper, the effects of different widths and lengths of collar around bridge abutment on local scour depth are studied numerically and experimentally. Numerical simulation [...]
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Differential Transformation Method for Newtonian and non-Newtonian nanofluids flow analysis: Compared to numerical solution
M. Hatami, D. Jing

Collection of Alexandria Engineering Journal (2017).

Abstract
In this study, a simple and high accurate series-based method called Differential Transformation Method (DTM) is used for solving the coupled nonlinear differential equations in fluids mechanic problems. The concept of the DTM is briefly introduced, and its application on two different cases, natural convection of a non-Newtonian nanofluid between two vertical plates and Newtonian nanofluid flow between two horizontal plates, has been studied. DTM results are compared with those obtained by a numerical solution (Fourth-order Runge–Kutta) to show the accuracy of the proposed method. Results reveal that DTM is very effective and convenient which can achieve more reliable results compared to other analytical methods in solving some engineering and sciences problems.
Abstract
In this study, a simple and high accurate series-based method called Differential Transformation Method (DTM) is used for solving the coupled nonlinear differential equations [...]
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Exact solutions to the (3+1)-dimensional coupled Klein–Gordon–Zakharov equation using exp(−Φ(ξ))-expansion method
M. Hafez

Collection of Alexandria Engineering Journal (2017).

Abstract
In this article, the exp(-Φ(ξ))exp(-Φ(ξ))-expansion method is modified for (3+1)-dimensional space–time coordinate system and successfully implemented to construct the new exact traveling wave solutions of the (3+1)-dimensional coupled Klein–Gordon–Zakharov equation. The solutions of this equation are expressed in terms of hyperbolic, trigonometric, exponential and rational functions. The results illustrate its effectiveness for solving nonlinear coupled partial differential equations arises in mathematical physics and engineering. The annihilation phenomena of the wave propagation in the xx–yy plane are also investigated. Furthermore, the three-dimensional surface plots due to the obtained solutions are also given to make the dynamics of the equation visible.
Abstract
In this article, the exp(-Φ(ξ))exp(-Φ(ξ))-expansion method is modified for (3+1)-dimensional space–time coordinate system and successfully implemented to construct the [...]
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An investigation into sound transmission loss by polypropylene needle-punched nonwovens
K. Ghorbani, H. Hasani, M. Zarrebini, R. Saghafi

Collection of Alexandria Engineering Journal (2017).

Abstract
In this work, the effects of variables such as initial carded web mass, needle penetration depth, punch density, and the frequency of incident sound wave on transmission of sound through polypropylene needle-punched nonwovens were investigated. Fibrous carded webs using commercially available 17 dtex, 90 mm staple length polypropylene fibers were prepared with different mass per unit area using carding machine. Samples were needled at various punch-densities and needle penetration depths were produced. Design points of experiments were set up using Taguchi experimental design method. Sound transmission loss (STL) of needled samples was measured using an impedance tube equipped with four microphones. Minitab software was used to analyze the sound transmission ability of the samples. Results indicated that all of the considered controllable factor have significant effects on STL values determined for the needled nonwovens. Also, initial carded web mass was found to be the most influential factor affecting sound transmission through the samples. It was concluded that an increase in thickness of the samples as well as mass per unit area of nonwovens results in higher sound transmission loss by the samples.
Abstract
In this work, the effects of variables such as initial carded web mass, needle penetration depth, punch density, and the frequency of incident sound wave on transmission of [...]
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Efficient design of exhaust gas cooler in cold EGR equipped diesel engine
N. Ghassembaglou, L. Torkaman

Collection of Alexandria Engineering Journal (2017).

Abstract
Using cold EGR method with variable venturi and turbocharger has very significant effect, simultaneously on the reduction of NOX and grime simultaneously. EGR cooler is one of the most important parts in the cold EGR circuit. In this paper optimum design of cooler for working in different percentages of EGR, besides determination of optimum temperature of exhausted gases, efficiency growth, weight reduction, dimension and expenditures reduction, sediment reduction, and optimum performance by using gasoil which has significant amounts of brimstone, is investigated and optimized.
Abstract
Using cold EGR method with variable venturi and turbocharger has very significant effect, simultaneously on the reduction of NOX and grime simultaneously. EGR cooler is one [...]
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Delay compensation using Smith predictor for wireless network control system
M. Gamal, N. Sadek, M. Rizk, A. Abou-elSaoud

Collection of Alexandria Engineering Journal (2017).

Abstract
Wireless Sensor Network (WSN) is widely used in the industrial Network Control System (NCS). It relies on the IEEE 802.15.4 MAC protocol to transfer data at low rate. Experimental and theoretical studies proved that the wireless channel produces a time delay. In the NCS, this delay may cause system instability and performance degradation. Delay compensation schemes are used to reduce the delay effects. In this paper, a delay compensation scheme using classical and adaptive Smith predictor is applied to wireless NCS. The Markov model is proposed to compute the estimated network delay used in the classical predictor. In the adaptive predictor, the channel delay statistics using shift register is proposed to update the estimated delay. To evaluate the proposed schemes, a DC-motor controller system based on IEEE 802.15.4 is built using True Time Matlab software. The system performance with and without the proposed delay compensation scheme is studied. It is also compared to other delay compensation schemes. The results show that the proposed scheme improves the NCS performance significantly and reduces the effect of the delay on the system.
Abstract
Wireless Sensor Network (WSN) is widely used in the industrial Network Control System (NCS). It relies on the IEEE 802.15.4 MAC protocol to transfer data at low rate. Experimental [...]
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Electrospun polymethylacrylate nanofibers membranes for quasi-solid-state dye sensitized solar cells
M. Fathy, A. Kashyout, J. Nady, S. Ebrahim, M. Soliman

Collection of Alexandria Engineering Journal (2017).

Abstract
Polymethylacrylate (PMA) nanofibers membranes are fabricated by electrospinning technique and applied to the polymer matrix in quasi-solid-state electrolytes for dye sensitized solar cells (DSSCs). There is no previous studies reporting the production of PMA nanofibers. The electrospinning parameters such as polymer concentration, applied voltage, feed rate, tip to collector distance and solvent were optimized. Electrospun PMA fibrous membrane with average fiber diameter of 350 nm was prepared from a 10 wt% solution of PMA in a mixture of acetone/N, N-dimethylacetamide (6:4 v/v) at an applied voltage of 20 kV. It was then activated by immersing it in 0.5 M LiI, 0.05 M I2, and 0.5 M 4-tert-butylpyridine in 3-methoxyproponitrile to obtain the corresponding membrane electrolyte with an ionic conductivity of 2.4 × 10−3 S cm−1 at 25 °C. Dye sensitized solar cells (DSSCs) employing the quasi solid-state electrolyte have an open-circuit voltage (Voc) of 0.65 V and a short circuit current (Jsc) of 6.5 mA cm−2 and photoelectric energy conversion efficiency (η) of 1.4% at an incident light intensity of 100 mW cm−2.
Abstract
Polymethylacrylate (PMA) nanofibers membranes are fabricated by electrospinning technique and applied to the polymer matrix in quasi-solid-state electrolytes for dye sensitized [...]
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