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Aims and Scope
Editorial Board

1. Optimal design of PEM fuel cells to generate maximum power: A CFD study

Maher A.R. Sadiq Al-Baghdadi

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

Abstract: A full three-dimensional, multi-phase computational fluid dynamics model of a PEM fuel cell has been developed. The parametric study using this model has been performed and discussed in detail. Optimization study of a PEM fuel cell performance has been performed. The study quantifies and analyses the impact of operating, design, and material parameters on fuel cell performance and get an optimal design for PEM fuel cells to generate maximum power. To generate maximum power, the results show that the cell must be operate at higher cell operating temperature, higher cell operating pressure, higher stoichiometric flow ratio, and must have higher GDL porosity, higher GDL thermal conductivity, narrower gases channels, and thinner membrane. At these optimum conditions, the result shows that the total displacement and the degree of the deformation inside the MEA were decreased. However, the Miss stress in the membrane was increased due to higher cell operating temperature.

Volume 2, Issue 6, 2011, pp.953-962.

2. Modeling flow inside an anaerobic digester by CFD techniques

Alexandra Martínez Mendoza¹, Tatiana Montoya Martínez², Vicente Fajardo Montañana², P. Amparo López Jiménez¹

1 Departamento de Ingeniería Hidráulica y Medio Ambiente, Universitat Politècnica de València, Camino de Vera S/N 46022, Spain.

2 Grupo Aguas de Valencia. Avenida Marqués del Turia 19 46005 Valencia, Spain.

Abstract: Anaerobic processes are used to treat high strength organic wastewater as well as for the treatment of primary and secondary sludge from conventional wastewater treatment plants. In these processes, heterotrophic microorganisms convert biodegradable organic matter to methane and carbon dioxide in the absence of dissolved oxygen and nitrate. Some of the most important aspects of the design of anaerobic digesters are related to hydraulic considerations. In spite of its important role in performance, hydraulics of flow inside digesters has not been quantified or adequately characterized. In this contribution a three-dimensional steady-state computational fluid dynamics (CFD) simulation has been performed for a particular anaerobic digester, in order to visualize the flow patterns. Flow and velocities profiles have been represented inside the digester to identify possible dead zones or stratifications. The geometry of a real digester installed in Valencia Waste Water Treatment Plant (located in Quart-Benager, Valencia, Spain) has been used in order to consider the proposed methodology.

3. Endoreversible four-mass-reservoir chemical pump with diffusive mass transfer law

Dan Xia^1,2, Lingen Chen¹, Fengrui Sun¹

1 College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033, P R China

2 92957 Troops, Zhoushan 316000, P R China.

Abstract: The performance of an isothermal endoreversible four-mass-reservoir chemical pump, in which the mass transfer obeys diffusive law, is analyzed and optimized in this paper. The relation between the rate of energy pumping and the coefficient of performance of the isothermal chemical pump is derived by using finite-time thermodynamics. Moreover, the optimal operating regions and the influences of some parameters on the performance of the cycle are studied. The results obtained herein can provide some new theoretical guidelines for the optimal design of a class of apparatus such as mass exchangers, and electrochemical, photochemical, and solid-state devices, as well as fuel pumps for solar-energy conversion systems.

4. Modelling and verification of single slope solar still using ANSYS-CFX

Hitesh N Panchal¹, P. K. Shah²

1 Research Scholar, Kadi Sarvavishwavidyalaya University, Gandhinagar, India.

2 Principal, Silver Oak College of Engineering & Technology, Ahmedabad, India.

Abstract: Solar distillation method is an easy, small scale and cost effective technique for providing safe water. It requires an energy input as heat and the solar radiation can be source of energy. Solar still is a device which uses process of solar distillation. Here, a two phase, three dimensional model was made for evaporation as well as condensation process in solar still by using ANSYS CFX method to simulate the present model. Simulation results of solar still compared with actual experiment data of single basin solar still at climate conditions of Mehsana (23°12’ N, 72°30’). There is a good agreement with experimental results and simulation results of distillate output, water temperature and heat transfer coefficients.  Overall study shows the ANSYS CFX is a powerful tool for diagnostic as well as analysis of solar still.

5. Energy savings due to daylight and artificial lighting integration in office buildings in hot climate

Nagib T. Al-Ashwal¹, Ismail M. Budaiwi²

1 Sana’a University, Sana’a Yemen.

2 King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia.

Abstract: Reducing energy consumption while maintaining acceptable environmental quality in buildings has been a challenging task for building professionals. In office buildings, artificial lighting systems are a major consumer of energy and can significantly contribute to building cooling load. Furthermore, although reliable, artificial lighting does not necessarily provide the required quality of lighting. Significant improvement in lighting quality and energy consumption can be achieved by proper integration of daylight and artificial lighting. The objective of this study is to investigate the energy performance of office buildings resulting from daylight and artificial lighting integration in hot climates. A parametric analysis is conducted to find the impact of different window design parameters, including window area, height and glazing type, on building energy performance. Results have shown that as much as 35% reduction in lighting energy consumption and 13% reduction in total energy consumption can be obtained when proper daylighting and artificial lighting integration is achieved.

6. Economic metrics for wind energy projects

Wagner Sousa de Oliveira, Antonio Jorge Fernandes, Joaquim Jose Borges Gouveia

Department of Economics, Management and Industrial Engineering, University of Aveiro & Campus Universitário de Santiago, 3810-193  Aveiro, Portugal.

Abstract: This paper presents an overview of economic metrics for wind energy projects. The attractiveness of the proposed wind energy can vary considerably between evaluation of the private and public sector. The financing structure is very important influencing factor for the attractiveness of wind energy project. In many cases, the economic activities practiced by economic agents of financing the project in order to earn sufficient income to meet the investors‘ needs and other economic agents involved. They are also characterized the assessment indicators and economic-financial management of projects implemented renewable energy exclusively for onshore wind energy systems. All indicators presented should be used in economic engineering analysis to meet specific information needs for decision making in situations of investment opportunity for renewable energy projects.

7. A typical small-scale chlorine leak and dispersion simulation in industrial facilities

Li Jianfeng1, Zhang Bin1, Liu Wenmao2

1 Beijing Municipal Institute of Labor Protection, Beijing, China.

2 Institute of Education, Tsinghua University, Beijing, China.

Abstract: The liquefied chlorine release is the most frequent accident in hazardous materials ( HAZMAT) releases. A typical small-scale accidental release of chlorine was simulated using a FLUENT code (CFD software). In addition, consequences of continuous and instantaneous release scenarios were investigated here. Case studies showed that, for a continuous release scenario, buildings and eddies would slow down the chlorine dispersion and resulted in a much lower concentration behind the buildings than other zones. As for an instantaneous release scenario, chlorine was trapped in the eddy zones. Inside these zones, the presence of chlorine lasted longer. Further, cause and effect diagram was adopted here to conduct cause-consequence analysis. Also, risk reduction measures and accident prevention strategies resulted from accident causal analysis were proposed for the emergency management and regulatory circles.

8. Process evaluation and treatability study of wastewater in a textile dyeing industry

Debabrata Mazumder

Civil Engineering Department, Bengal Engineering and Science University, Shibpur, P.O. – Botanic Garden, Howrah, West Bengal – 711 103, India.

Abstract: The process was investigated in a textile dying unit and subsequently wastewater generation profile was studied for the development of a viable treatment. The dyeing unit under the study generated a considerable volume of wastewater containing inorganic chemicals and organic reactive green dye. Chemical oxygen demand (COD) resulting from all the chemically oxidizible substances and the residual color of the dye were targeted for removal. The wastewater samples were collected from different sub-processes and then characterized for the parameters viz. pH, Total solid, Suspended solid, Dissolved solid, COD and Alkalinity. A composite wastewater sample was prepared according to the measured wastewater discharge from various unit operations and used for treatability study. In the first stage, coagulation-flocculation with alum and chemical oxidation with bleaching powder were performed separately. Subsequently, adsorption study was conducted with crushed burnt coal (C.B.C.) on the composite wastewater, initially treated with 10% bleaching powder solution. After several trials, this combination was found to be effective for a C.B.C. content of 10% under a contact period of 90 minutes, which showed 100% colour and about 95% COD removal.

9. Process parameters affecting the sustainability of fermentative hydrogen production: A short-review

Carlos Dinamarca, Rune Bakke

Telemark University College, Department of Process, Energy and Environmental Technology, Porsgrunn-Norway.

Abstract: Anaerobic fermentation is regarded as the least energy intensive method for H2 production. Extensive literature on experimental attempts to achieve the highest possible theoretical yield (e.g. 4 mol H2/mol glucose) is available. All published steady state, mixed culture studies show yields much lower than the theoretical maximums for the substrates applied. This article summarizes the influence of key process parameters (pH and buffer systems, temperature, H2 partial pressure, feed stock, and reactor configuration) on fermentative hydrogen production. The following three requirements for successful Bio-H2 fermentation in mixed cultures are identified: (1) Maintain environmental conditions for the formation of oxidized products; (2) Optimize the relationship between biomass and hydrogen yields; and (3) Maintain unfavorable conditions for hydrogen consuming organisms. Fulfilling these requirements has not yet been achieved in stable continuous cultures, and it may not be achievable do to some fundamental limitation.

10. Effect of turbulence in modeling the reduction of local drag forces in a computational automotive model

Sanwar A. Sunny

Department of Mechanical Engineering, School of Engineering, University of Kansas, Lawrence, KS 66045, USA.

Abstract: In this computational fluid dynamic (CFD) study on vehicle drag forces sheds light on the mathematical algorithms utilized to converge on pertinent data useful in the design and manufacture of automobiles. COSMOS Floworks™ was used to model the virtual vehicle motion involving various governing flow equations with main attention given to turbulent behavior in incompressible fluid flows. The paper highlighted Navier-Stokes considerations in the study and introduced Reynolds Decomposition methods to generate more refined models which in turn give accurate results, such as Reynolds-Averaged Navier–Stokes (RANS) Equations and Large Eddy Simulation (LES) Techniques, introduced using the Einstein Notation. Recent developments in Coherent vortex simulation methods were also briefly discussed. Example modeling and tests were conducted to show automotive design improvements that resulted in a 8.57% improvement in local drag forces (FD) at the rear wheel wells, which effectively reduces the required Horsepower (hp) of the vehicle traveling at a certain speed (7.24 %). Different 3-D Automotive Design Models were examined in the current study, where real life design considerations and design benefits applications were briefly discussed. Furthermore, the paper highlights the need for utilization of both computational and real flow analysis on the car body and future performance relationship with the car’s body weight, material and design.

11. Wave energy resource assessment and review of the technologies

Wan Nik WB¹, Sulaiman OO¹, Rosliza R², Prawoto Y³, Muzathik AM⁴

1 Maritime Technology Department, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Malaysia.

2 TATI University College, Teluk Kalong, 24000 Kemaman, Terengganu, Malaysia.

3 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM, Skudai, Johor, Malaysia.

4 Institute of Technology, University of Moratuwa, Sri Lanka.

Abstract: Increase in human population has increased the demand for more energy. Technical improvement in transport and electrical appliances gives a lot of facilities to our life nowadays. Still we need to generate or convert this energy. Energy generation based on conventional technologies is always accompanied by environmental pollution. It gives overheating and greenhouse effects that later result in biosphere degradation. Nowadays sea wave energy is being increasingly regarded in many countries as a major and promising resource. It is renewable and environmentally friendly. In this paper wave parameters related to wave energy is analyzed. Then the paper describes the development of many different types of wave-energy converters. Several topics are addressed; the characterization of the wave energy resource, range of devices and how such devices can be organized into classes.

12. Investigation of the treatment of colored water using efficient locally available adsorbent

Hossam Altaher, Emad ElQada

Chemical Engineering Technology Department, Yanbu Industrial College P.O. Box 30436, Saudi Arabia.

Abstract: In this study, the effectiveness of local agricultural waste in removing methylene blue dye from aqueous solution (date stones) was investigated. Both batch kinetics and isotherm experiments were conducted in order to determine the sorption behavior of the examined dye. The effects of initial dye concentration, initial pH, adsorbent particle size, and adsorbent dose were studied. The results indicate that the adsorption process follows pseudo second order kinetic models. The particle sizes of the adsorbent and pH had a significant effect on the adsorption process. In addition, a clear correlation was found between augmentation of the initial dye concentration and a subsequent increase of adsorption capacity. The results obtained are consistent with the Freundlich model.

13. Influence of organic waste and inorganic nitrogen source on biomass productivity of Scenedesmus and Chlorococcum sp.

M. Arumugam¹, A. Agarwal¹, M.C. Arya¹, Z. Ahmed²

1 Defence Institute of Bio-Energy Research,Defence R&D Organization, Min of Defence, Govt. of India,Field Station Pithoragarh- 262501, Uttarakhand, India.

2 Defence Institute of Bio-Energy Research, Defence R&D Organization, Min of Defence, Govt. of India, Haldwani- 263 139, Uttarakhand, India.

Abstract: Algae gaining the more attention in the recent years in order to supplement the futuristic demand of fuel requirement because of its unique feature like high productivity, short duration and higher fatty acids content. However algal culturing for large-scale production is limited due to many technical and engineering challenges. One of the main constraints for large-scale biomass production is the non-availability of cost effective and affordable growth medium for open pond condition. In order to overcome this lacuna, the present study was carried out to find out the suitable cost effective growth medium using locally available resources. Farm Yard Manure an easily available organic waste yet, rich in nutrients and used for agriculture over the generations. FYM coupled with inorganic nitrogen source like urea was found to be better alternative to the synthetic growth medium, which may make wider acceptability at farmers’ field for large-scale algal mass production. The present study reveals that FYM extract of 50% supplemented with 0.1% Urea was performing better for algal biomass growth in outdoor open pond condition.

14. Performance analysis and optimization for an endoreversible Carnot heat pump cycle with finite speed of the piston

Bo Yang, Lingen Chen, Fengrui Sun

College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033, P. R. China.

Abstract: Performance of an endoreversible Carnot heat pump cycle with finite speed of the piston is investigated by using finite time thermodynamics. The analytical formulae between the optimal heating load and the coefficient of performance (COP), as well as between the optimal heating load and speed ratio of the piston are derived. It is found that the heating load versus COP characteristics are parabolic-like, and there exist a maximum heating load and the corresponding COP. These are different from the monotonically decreasing characteristic of the endoreversible Carnot heat pump without consideration of the finite speed of the piston. At the same time, the effects of reservoir temperature ratio on the optimal relations are analyzed by numerical examples. In the analysis and optimization, two cases with and without limit of cycle period are included.

15. Effect of single double bond in the fatty acid profile of biodiesel on its properties as a CI engine fuel

S. Saravanan1, G. Nagarajan2

1 Department of Automobile Engineering, Sri Venkateswara College of Engineering, India.

2 Department of Mechanical Engineering, College of Engineering, Anna University, India.

Abstract: Fatty acid profile of the vegetable oil and animal fats plays a major role in determining the properties of biodiesel derived from them. Eventhough the type of fatty acids in vegetable oils are similar, their distribution is different. The percentage distribution of fatty acids differs by a significant magnitude with respect to the type of vegetable oil. In the present investigation the effect of single double bond fatty acids in the vegetable oil on its physical and chemical properties are investigated. Different vegetable oils based on the type and geography were selected and the properties of biodiesel derived from it were analysed with respect to its fatty acid of single double bond. From the results of the investigation it is inferred that the fatty acids with single bond plays an important role in determining the properties of biodiesel as a CI engine fuel.