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Aims and Scope
Editorial Board

1. Three-dimensional solid mechanics-CFD modeling of a PEM fuel cell stack

Maher A.R. Sadiq Al-Baghdadi

Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39, Iraq.

Abstract: PEM fuel cell stack assembly process, including clamping pressure, material properties of each component, design (component thickness and cell active area), and number of cells in the stack are important factors influencing the performance and durability of the PEM fuel cell stack. Furthermore, when temperature and relative humidity increase during operation, the membrane absorbs water and swells. Since the relative position between the top and bottom end plates is fixed, the polymer membrane is spatially confined. Thus the GDL will be further compressed under the land and the intrusion into channel becomes more significant. Assembly pressure, contact resistance, membrane swelling and operating conditions, etc., combine to yield an optimum assembly pressure. The clamping pressure is therefore a critical parameter for optimal fuel cell performance and durability. Too high, too low, or inhomogeneous compressions have negative effects on the performance and durability of the stack. In this study, full three-dimensional, non-isothermal computational fluid dynamics (CFD) detailed model of a PEM fuel cell stack has been developed and coupled with a solid mechanics model to simulate the stress distribution inside the stack, which are occurring during fuel cell assembly (bolt assembling), and membrane swelling and cell materials expansion during fuel cell running due to the changes of temperature and relative humidity. The PEM fuel cell stack model simulated includes the following all components in full details; two end-plates, two current plates, two bi-polar plates with straight flow channels for reactants and cooling serpentine water flow channel on the upper face of cathode bi-polar plate, two GDLs, two gaskets, and, an MEA (membrane plus two CLs). The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, with stress distribution inside the stack during operation on the performance and durability of the stack that have limited experimental data. Furthermore, the model is shown to be able to provide a computer-aided tool for design and optimize future fuel cell stack with much higher power density, long stack life, and lower cost.

Volume 9, Issue 1, 2018, pp.1-26.

2. Blades design for a small wind turbine to supply a rural house. Case study

Rafael Ortiz Juan, Modesto Pérez-Sánchez, P. Amparo López-Jiménez

Hydraulic and Environmental Engineering Department. Universitat Politècnica de València. Camino de Vera s.n. 46022. Valencia, Spain.

Abstract: Nowadays the global warming has caused a growing increase of sensitivity of the population to reduce the consumption of non-renewable resources. Therefore, the use of renewable energies is currently increasing and the development of studies to install small renewable generators to supply domestic uses also does. In this line, the present research develops a methodology to design the blades of a small wind turbine with horizontal axis, applying it to a real case study. To improve the design of the wind turbine, a meteorological station was installed in the study point as well as historic registered data were used. Finally, the estimated energy produced by this generator was 1453 kWh/year and the energy could be used to supply in the rural house to complement the electrical consumption, reducing the consumption of the other non-renewable resources.

3. Energy and exergy analysis of a double-effect LiBr-H₂O absorption refrigeration system

Tuğba Kovacı, Arzu Şencan Şahin

Süleyman Demirel University, Technology Faculty, 32260, Isparta, Turkey.

Abstract: An absorption refrigeration system is environmental friendly a technology with zero ozone depletion and global warming potential. The LiBr-H₂O solution in the generator is heated by any renewable source or industrial waste heat. In the present study the analysis of a parallel flow LiBr-H₂O double-effect absorption refrigeration system is performed to compute the optimum system conditions from the point of maximum exergetic efficiency and coefficient of performance (COP), minimum exergy destruction. This analysis is also provides to more develop efficiencies of an absorption driven chiller system by using avoidable exergy analysis. For this purpose of an avoidable and unavoidable exergy destruction analysis is also conducted for each of absorption chiller component. Effect of main temperature difference on the conductance (UA), COP, exergetic efficiency is lent assistance to recover absorption refrigerant system. This study also is showed that how the changing the temperature difference effects total thermal conductance, COP and exergetic efficiency.

4. Self-cleaning and self-cooling photovoltaic system with feedback control

Issameddin Abdullah¹, Ali Akayleh², Mohammed Al-Soud², Salah Abdallah³

1 Department of Industrial Engineering, Business and Technology University, Jeda, Saudi Arabia.

2 Department of Electrical Engineering, Tafila Technical University, P.O.Box-66, Tafila 66110, Jordan.

3 Department of Mechanical & Industrial Engineering, Applied Science University, Amman 11931-166, Jordan.

Abstract: One of the most important problems in using photovoltaic systems (PV) is the low power production due to increasing the ambient temperature, and the accumulation of dust on PV panels surfaces. In this work, self-cleaning and self-cooling PV system with feedback control was designed, constructed and operated .The programming method of control of water pumping system is achieved by means of programmable logic controller (PLC)and frequency inverter (FI). The control system consists of two subsystems based upon the same electromechanical system .One system for controlling the cooling of PV system by using temperature sensor and feedback system, and the other system for controlling the cleaning of PV system by using huge pressure of water to push away the accumulated dust on the PV surface. An experimental study was performed to investigate the effect of using self-cleaning and self-cooling system on the electrical power generation at the output of PV system. The electrical power generation at the output of PV modules with self-cleaning and self-cooling system has increased by 34 % and the efficiency by 26 %.

5. Feasibility study of using 2kWp residential PV system comparing with 2.5kVA gasoline generator (Case study: Baghdad city)

Hasan Noaman Muslim¹, Afaneen Alkhazraji¹, Mohammed Ahmed Salih²

1 Department of Electrical and Electronic Engineering, University of Technology, Baghdad, Iraq.

2 Planning and Studies Department, Ministry of Electricity, Baghdad, Iraq.

Abstract: The economic analysis is the most important parameter in the engineering projects. The current research aims to propose economic and financial analysis in order to assess the feasibility for a 2kWp designed PV system with a battery capacity of 500Ah for each residential consumer of Baghdad city in Iraq comparing with a 2.5kVA gasoline generator and thus calculating the total expected revenue from the use of PV system against using conventional electricity generation sources (gasoline generator). The economical evaluations in this work clarified that the life cycle cost of the conventional source (gasoline generator) is approximately doubled the life cycle cost of the PV system for a 2kWp system capacity. This result indicates that the using of PV system for residential sector in Baghdad city is feasible when compared with conventional electricity source.

6. Experimental study of the hydraulic performance of piano key weir

Abdul-Hassan K. Al-Shukur, Ghufraan H. Al-Khafaji

Department of Civil Engineering, College of Engineering, University of Babylon, Iraq.

Abstract: In this study, laboratory experiments were performed to evaluate the effects of the weir geometry of a Piano Key Weir (PKW) type B on the discharge coefficient under free flow conditions. Experiments were conducted in a 15 m long, 0.3 m wide and 0.45 m deep rectangular glass-walled flume. The experimental work includes testing of sixteen PKW models which results 172 tests to cover the effects of weir length and height, up-and downstream key widths, upstream apex overhangs length, dam height and height difference between up and downstream on the weir flow discharge coefficient. Experimental results showed that the most influential parameters for the tested PKW models are the relative length L/W and height difference between up and downstream Pi/Po, both increasing the discharge capacity by 42%. Also the energy dispassion was estimated from the parameter B/P by considering the effect of slope (B the base and P the height) on distance of hydraulic jump formation. Then, the PKW angle which makes it an energy dissipater itself has been selected. Experimental data were used to develop empirical formula based on dimensional analysis technique and the statistical software SPSS. This formula, having a coefficient of determination of (R2=0.984), is used to find the discharge coefficient during free flow condition.

7. Catalytic deoxygenation of benzaldehyde on cobalt and cooper tungstates

Rafael Oliveira Paes de Lima, Marcelo da Silva Batista

Chemical Engineering Department, Federal University of São João Del Rei, Campus Alto Paraopeba, Rodovia MG 443, Km 5, Pobox 131, Cep 36420-000, Ouro Branco MG, Brazil.

Abstract: Hydrodeoxygenation reaction (HDO) has been used to remove oxygen of substances in bio-oil and improve the quality of this biofuel. In this work were prepared copper and cobalt tungstates to be evaluated as catalysts for HDO of benzaldehyde. The benzaldehyde was used as model of bio-oil in HDO. Copper and cobalt tungstates (Cu1-xCoxWO4 where x=0; 0.5; 1) were prepared by co-precipitation method and characterized by XRD and H2-TPR. The XRD results showed presence of tungstates (CuWO4, CoWO4, Cu0.5Co0.5WO4) and also copper oxide. The H2-TPR profile showed that copper and cobalt in tungstate and copper oxide were reduced at temperature different. CoWO4 showed the highest catalytic activity and the high selective to toluene and benzyl alcohol. CuWO4 and Cu0.5Co0.5WO4 showed lower selectivity to benzyl alcohol, and consequently, the highest selective to HDO.

8. A new prediction of the fatigue limit based on Brinell hardness and ultimate strength for high strength steels

Azzam D. Hassan

University of Basrah, Materials engineering department, Iraq.

Abstract: Estimation of the fatigue limit based on the S-N curve means required many experimental tests; furthermore this required more time and high costs. In this study, several high strength materials of steels with their chemical composition, uniaxial mechanical properties, and fatigue limit are listed from previous studies. It was found that Brinell hardness numbers and mechanical uniaxial properties show a linear behaviour in relation to the fatigue limit of the materials were estimated. Correlations between fatigue limit and uniaxial properties were then investigated. Validity of the proposed correlation is examined and compared with other materials proposed and studied by the ASM international. Empirical correlations are founded that enable the evaluation of fatigue limits from the uniaxial properties. The proposed correlation was shown to provide a good reasonable approximations of the materials fatigue limit prediction for the selected materials.

9. Acoustical noise reduction technique

Kadim Karim Mohsen Alturshan

Mechanical Engineering Department, College of engineering / Thi-Qar University, Iraq.

Abstract: The noise reduction analysis are studied for different models such as noise reduction for two rooms separated by a brick wall containing single and companied pane of glass , non-distorting wall and infinite flexible wall. The transmitted sound through infinite partition depends on the relative speed and free flexural wave in partition and the incident Plane wave. This paper presents acoustical noise reduction analysis for the transmission of noise through partitions. The models investigates the reduction in sound pressure level required in two rooms separated by a brick wall containing a single pane of glass and a compound pane of glass also study the noise transmitted and reflected at normal incident through a non-distorting wall simulated as spring and damper mass system and study the analysis of noise transmission through infinite flexible wall and discuss the merits of the various methods that could be used to achieve the reduction. The analytic model and the analysis in the present work give some insight to the behavior of the structures under noise problem showing the different parameters that related with the transmission of noise, such as power transmitted through the panel, power incident through the panel sound reduction index (transmission loss), octave band center frequency, sound power level, reverberation time, deformation, propagation and non-propagation of noise. A life predication model is presented to control the optimum design and to find a proper combination of noise and life.

10. A suggested analytical solution for dynamic behavior of a cracked pipe conveying fluid

Muhsin J. Jweeg¹, Emad Q. Hussein², Karrar Ibrahim Mohammed³

1 University of Telafer, College of Engineering, Iraq.

2 University of Kerbala, Faculty of Engineering, Oil and Petrochemicals Engineering Department, Iraq.

3 University of Kerbala, Faculty of Engineering, Mechanical Engineering Department, Iraq.

Abstract: This research investigates the effect of cracks into a simply supported pipe conveying fluid on the frequency and the response of the pipe. A plastic pipe with modulus of elasticity 800 N/mm2 and dimensions of 1m length, 2cm internal diameter and 3cm external diameter used as models. A laminar flow established according to Reynold's number calculation between 500 to 1500 with a flow velocity 1 m/sec. to achieve the objectives, two techniques are used I- Analytically using the derived equation of motion for the pipe conveying fluid and the crack model is included in the stiffness of the pipe. Matlab R2016 language, a computer program has been used to solve the derived equations to predict the vibration response and to embrace the theoretical work. II-Numerical investigation is employed using the finite element method (FEM) adopting COMSOL 5.2 program to verify the analytical results. The research conveys the variation of depth and the crack positions (0.25L, 0.375L and 0.5L) where L is the pope length. It was found that the value of frequency of the pipe transmitted fluid with crack is decreased more and more when increasing the size of crack with a maximum discrepancy of (5.53%). Also, it was found that the frequency value becomes smaller when the crack position gets closer to the middle section.