Dammam, Saudi Arabia
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Al-Amri F.,Dammam College of Technology
42nd ASES National Solar Conference 2013, SOLAR 2013, Including 42nd ASES Annual Conference and 38th National Passive Solar Conference | Year: 2013

It is well known that multijunction based concentration solar cells produced highest possible electric conversion efficiency. Moreover, these modern photovoltaic (PV) cells can be operated at a relatively high temperature with reasonable system efficiency. However, at very high operating temperatures, the power coefficient of the solar cells becomes negative. This paper presents a heat transfer model, which predicts the solar cell temperature for multijunction concentrating solar cell systems. This work models solar cells made of GaInP, GaAs and Ge with active aluminum back plates and anti-reflected glass plates. Airactive cooling was used to alleviate the operating solar cell temperature. Air is forced to flow within the ducts behind the solar cell assembly, and a finite difference technique has been used to solve the governing equations. The effects of the controlling parameters on solar cell temperatures are illustrated. Results show that the interaction of surface radiation and air convection can adequately cool the solar cell at medium concentration ratios. In addition, the ultimate values of the concentration ratio at which PV solar cells can be operated with reasonable efficiency have been obtained. Copyright © (2013) by American Solar Energy Society.

Triki H.,University of Sfax | Mellouli A.,Dammam College of Technology | Hachicha W.,University of Sfax | Masmoudi F.,University of Sfax
International Journal of Computer Integrated Manufacturing | Year: 2016

The lively field of assembly line configuration and adjustment often have a significant impact on the performance of manufacturing systems. In this context, assembly line balancing problems (ALBPs) are widely cited in the literature. An ALBP consists of distributing the total product manufacturing workload among the stations along the manufacturing line. Previous research has focused on developing effective and fast solution methods for solving simple assembly line balancing problems (SALBP) and their various extensions. Each extension is motivated by several real-life applications and the need for solving precise practical problems. In this article, another interesting extension of SALBP (named in this work Task Restrictions Assembly Line Balancing Problem of type 2 (TRALBP-2)) is focused on. In this situation, the number of stations is known and the objective is to minimise cycle time where both precedence and zoning constraints between tasks must be satisfied. For the resolution of such problem, an innovative hybrid genetic algorithm (HGA) scheme hybridised with a local search procedure is implemented. This genetic algorithm consists of a new representation scheme and a special genetic operator. The effectiveness of the proposed HGA is evaluated through various sets of instances which are (1) theoretically and randomly generated, (2) collected from the literature and (3) based on a real case study of an automotive cable manufacturer. Comparison of the proposed HGA results with CPLEX software for the TRALBP-2 demonstrates that, in a reasonable time, the proposed HGA generates consistent solutions that are very close to their optimal ones. Therefore, the proposed HGA approach is very effective and competitive. © 2015 Taylor & Francis.

Gammoudi A.,Dammam College of Technology | Zinoubi J.,Institute for Engineering Studies El Manar
International Review of Mechanical Engineering | Year: 2010

The influence of the plume source temperature in the structure of a thermal plume evolving in a heated vertical canal has been studied. For that an experimental apparatus comprising a rectangular source was placed at the entrance of a vertical canal of a rectangular section open at both ends on quiet environment of uniform temperature. The thermal plume generated by a heated source is added to a thermosiphon flow that develops at the walls of the canal. A visualization by laser plane has shown that the system was fed from the bottom through by three fresh air nets, the existence of a hot envelope just above the source and also three different zones of flow as has been noted in previous work on cylindrical geometry. The study of the thermal and dynamics fields, performed by hot wire and constant current anemometry, has shown that, contrary to previous work, the blocking of the lateral extension of the plume to the sides of the canal is not observed, the existence of three areas already observed by flow visualization for all the temperatures of the source studied. Moreover, the increase of the temperature of the source allows a larger lateral transport, improves flow rate of the flow and intensifies heat transfer. © 2010 Praise Worthy Prize S.r.l. - All rights reserved.

Al-Amri F.,Dammam College of Technology | Mallick T.K.,Heriot - Watt University
World Renewable Energy Forum, WREF 2012, Including World Renewable Energy Congress XII and Colorado Renewable Energy Society (CRES) Annual Conferen | Year: 2012

It is well know that the highest possible solar cell efficiency is achieved by multijunction based concentrating solar cells. However, due to very high solar flux at the solar cell region, the operating temperature of the solar cell becomes very high which leads to negative power coefficient. In this work, a heat transfer model for mult ijunction concentrating solar cell system has been developed. The solar cell made of GaInP, GaAs and Ge with active aluminium back plate and anti-reflected glass plate was modeled in this work. To alleviate the operating solar cell temperature an active cooling was used. Water is forced to flow within the ducts behind the solar cell assembly and a finite difference technique has been used to solve the governing equations. In addition, the parametric analysis of the concentrator cell design and the effect of the concentration ratio to the operating temperature of the solar cell have been performed. Results show that maximum cell temperature is extremely dependent on water inlet velocity and channel width more than thicknesses and thermal conductivities of the solar cell holders and accessories. It is also found that the thermal conductivity and the thickness of the solar cell assembly have small effect compared to that of the fluid properties of the active cooling arrangements.

Arezki M.,Blida University | Benallal A.,Dammam College of Technology | Meyrueis P.,University of Strasbourg | Berkani D.,0 Avenue Pasteur B.P. 182
Engineering Letters | Year: 2010

In this paper, we propose a new algorithm M-SMFTF for adaptive filtering with fast convergence and low complexity. It is the result of a simplified FTF type algorithm, where the adaptation gain is obtained only from the forward prediction variables and using a new recursive method to compute the likelihood variable. The computational complexity was reduced from 7L to 6L, where L is the finite impulse response filter length. Furthermore, this computational complexity can be significantly reduced to (2L+4P) when used with a reduced P-size forward predictor. This algorithm presents a certain interest, for the adaptation of very long filters, like those used in the problems of echo acoustic cancellation, due to its reduced complexity, its numerical stability and its convergence in the presence of the speech signal. The proposed algorithm outperforms the classical adaptive algorithms because of its convergence speed which approaches that of the RLS algorithm and its computational complexity which is slightly greater than the one of the normalized LMS algorithm.

Olabi A.G.,Dublin City University | Alsinani F.O.,Dammam College of Technology | Alabdulkarim A.A.,Dammam College of Technology | Ruggiero A.,Polytechnic of Bari | And 2 more authors.
Optics and Lasers in Engineering | Year: 2013

A dissimilar full-depth laser-butt welding of low carbon steel and austenitic steel AISI316 was investigated using CW 1.5 kW CO2 laser. The effect of laser power, welding speed and focal point position on mechanical properties (i.e., ultimate tensile strength, UTS and impact strength, IS) and on the operating cost C was investigated using response surface methodology (RSM). The experimental plan was based on Box-Behnken design; linear and quadratic polynomial equations for predicting the mechanical properties were developed. The results indicate that the proposed models predict the responses adequately within the limits of welding parameters being used. The optimum welding conditions were found. © 2013 Elsevier Ltd.

Kameli S.,Universiti Sains Islam Malaysia | Mustapha G.,University Putra Malaysia | Alyami S.,Dammam College of Technology
International Journal of Applied Linguistics and English Literature | Year: 2013

The present study explored the association among vocabulary breadth/size, depth/quality of vocabulary knowledge, and reading comprehension in English as a foreign language. The main intention of this research was to explore the association of vocabulary knowledge depth/quality and reading comprehension performance. This study was also intended to find out which aspects of vocabulary knowledge, breadth/size or depth/quality, has more significant association with determining EFL learners’ reading comprehension performance. The Vocabulary Level Test (VLT), Word Associates Test (WAT), and Reading Comprehension test (IELTS) have been administered among all the respondents. The participants were 220 adult male and female EFL learners who were learning English in advanced level in BAHAR institute, Shiraz, Iran. The findings revealed that 1) test scores on vocabulary size/ breadth, depth/ quality of vocabulary knowledge, and reading comprehension were positively correlated, 2) vocabulary size/ breadth was a stronger predictor of reading comprehension than depth/ Quality of vocabulary knowledge. © Australian International Academic Centre, Australia.

Al-Amri F.,Dammam College of Technology
JP Journal of Heat and Mass Transfer | Year: 2015

A numerical solution for fully developed forced convection in a channel bounded by one isothermal and one adiabatic plate that takes surface radiation into account is presented. The solution is bounded by two pure forced convection solutions: that corresponding to the case of one isothermally heated wall and one adiabatic wall and that corresponding to two isothermal walls. The effects of the radiation number on the fluid, mixed-mean, and adiabatic wall temperatures as well as the Nusselt numbers of the isothermal and externally adiabatic walls are investigated. The radiation number at which symmetric heating appears due to surface radiation to produce a maximum Nusselt number and mixed-mean temperature is determined. In addition, it is shown that the maximum contribution from radiation to the total heat transfer does not exceed 50%. The sill value of the radiation number at which the radiation effect can be neglected is presented. © 2015 Pushpa Publishing House, Allahabad, India

Al-Amri F.,Dammam College of Technology | Mallick T.K.,University of Exeter
International Journal of Photoenergy | Year: 2014

A numerical heat transfer model was developed to investigate the temperature of a triple junction solar cell and the thermal characteristics of the airflow in a channel behind the solar cell assembly using nonuniform incident illumination. The effects of nonuniformity parameters, emissivity of the two channel walls, and Reynolds number were studied. The maximum solar cell temperature sharply increased in the presence of nonuniform light profiles, causing a drastic reduction in overall efficiency. This resulted in two possible solutions for solar cells to operate in optimum efficiency level: (i) adding new receiver plate with higher surface area or (ii) using forced cooling techniques to reduce the solar cell temperature. Thus, surface radiation exchanges inside the duct and Re significantly reduced the maximum solar cell temperature, but a conventional plain channel cooling system was inefficient for cooling the solar cell at medium concentrations when the system was subjected to a nonuniform light distribution. Nonuniformity of the incident light and surface radiation in the duct had negligible effects on the collected thermal energy. © 2014 Fahad Al-Amri and Tapas Kumar Mallick.

Al-Amri F.,Dammam College of Technology | Mallick T.K.,University of Exeter
Applied Thermal Engineering | Year: 2013

In the present paper, a heat transfer model for a multi-junction concentrating solar cell system has been developed. The model presented in this work includes the GaInP/GaAs/Ge triple-junction solar cell with a ventilation system in which air is forced to flow within a duct behind the solar cell assembly and its holders and accessories (anti-reflective glass cover, adhesive material, and aluminum back plate). A mathematical model for the entire system is presented and the finite difference technique has been used to solve the governing equations. Results showed that the interaction of surface radiation and air convection could adequately cool the solar cell at medium concentration ratios. For high concentration ratios, the channel width would need to be narrowed to micro-meter values to maintain the required efficiency of cooling. The conjugation effect has been shown to be significant and has a noticeable effect on the maximum solar cell temperature. Furthermore, the air inlet velocity and channel width were also found to have major effects on the cell temperature. © 2013 Elsevier Ltd. All rights reserved.

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