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Aims and Scope
Editorial Board

1. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

Maher A.R. Sadiq Al-Baghdadi

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

Abstract: Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport in micro PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize the micro fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a micro proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a micro PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

Volume 5, Issue 1, 2014, pp.1-22.

2. Numerical simulation of CO₂ geological storage in saline aquifers – case study of Utsira formation

Zheming Zhang, Ramesh K. Agarwal

Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, MO 63130, USA.

Abstract: CO₂ geological storage (CGS) is one of the most promising technologies to address the issue of excessive anthropogenic CO₂ emissions in the atmosphere due to fossil fuel combustion for electricity generation. In order to fully exploit the storage potential, numerical simulations can help in determining injection strategies before the deployment of full scale sequestration in saline aquifers. This paper presents the numerical simulations of CO₂ geological storage in Utsira saline formation where the sequestration is currently underway. The effects of various hydrogeological and numerical factors on the CO₂ distribution in the topmost hydrogeological layer of Utsira are discussed. The existence of multiple pathways for upward mobility of CO₂ into the topmost layer of Utsira as well as the performance of the top seal are also investigated.

3. Modeling of reaction kinetics in bubbling fluidized bed biomass gasification reactor

R.K. Thapa¹, C. Pfeifer², B. M. Halvorsen¹

1 Telemark University College, Kjolnes ring 56, P.O. Box 203, 3901 Porsgrunn, Norway.

2 University of Natural Resources and Life Sciences, Vienna, Austria.

Abstract: Bubbling fluidized beds are widely used as biomass gasification reactors as at the biomass gasification plant in Güssing, Austria. The reactor in the plant is a dual circulating bubbling fluidized bed gasification reactor. The plant produces 2MW electricity and 4.5MW heat from the gasification of biomass. Wood chips as biomass and olivine particles as hot bed materials are fluidized with high temperature steam in the reactor. As a result, biomass undergoes endothermic chemical reaction to produce a mixture of combustible gases in addition to some carbon-dioxide (CO2). The combustible gases are mainly hydrogen (H2), carbon monoxide (CO) and methane (CH4). The gas is used to produce electricity and heat via utilization in a gas engine. Alternatively, the gas is further processed for gaseous or liquid fuels, but still on the process of development level. Composition and quality of the gas determine the efficiency of the reactor. A computational model has been developed for the study of reaction kinetics in the gasification rector. The simulation is performed using commercial software Barracuda virtual reactor, VR15. Eulerian-Lagrangian approach in coupling of gas-solid flow has been implemented. Fluid phase is treated with an Eulerian formulation. Discrete phase is treated with a Lagrangian formulation. Particle-particle and particle-wall interactions and inter-phase heat and mass transfer have been taken into account. Series of simulations have been performed to study model prediction of the gas composition. The composition is compared with data from the gasifier at the CHP plant in Güssing, Austria. The model prediction of the composition of gases has good agreements with the result of the operating plant.

4. Impact of kiln thermal energy demand and false air on cement kiln flue gas CO₂ capture

Udara S. P. R. Arachchige¹, Dinesh Kawan¹, Lars-André Tokheim¹, Morten C. Melaaen^1,2

1 Telemark University College, Porsgrunn, Norway.

2 Tel-Tek, Porsgrunn, Norway.

Abstract: The present study is focused on the effect of the specific thermal energy demand and the false air factor on carbon capture applied to cement kiln exhaust gases. The carbon capture process model was developed and implemented in Aspen Plus. The model was developed for flue gases from a typical cement clinker manufacturing plant. The specific thermal energy demand as well as the false air factor of the kiln system were varied in order to determine the effect on CO₂ capture plant performance, such as the solvent regeneration energy demand. In general, an increase in the mentioned kiln system factors increases the regeneration energy demand. The reboiler energy demand is calculated as 3270, 3428 and 3589 kJ/kg clinker for a specific thermal energy of 3000, 3400 and 3800 kJ/kg clinker, respectively. Setting the false air factor to 25, 50 or 70% gives a reboiler energy demand of 3428, 3476, 3568 kJ/kg clinker, respectively.

5. Simulation and validation of chemical-looping combustion using ASPEN plus

Ling Zhou^{1, 2}, Zheming Zhang², Ramesh K. Agarwal²

1 Research Center of Fluid Machinery Engineering & Technology, Jiangsu University, Zhenjiang 212013, China.

2 Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, MO 63130, USA.

Abstract: Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC) is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO₂ and H₂O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated.

6. On the wave energy potential along the southern coast of Brazil

Leandro Eduardo Assis, Alexandre Beluco, Luiz Emílio B. de Almeida

Inst. Pesquisas Hidráulicas, Univ. Fed Rio Grande do Sul, Porto Alegre, Brazil.

Abstract: The ocean wave energy resource is a real alternative to supply part of the energy demand in various countries, since some locations have a remarkable capacity to generate electricity. The objective of this study is to evaluate the energy resource of ocean waves in the coast of Rio Grande do Sul, the southern state of Brazil. This note presents the first results. The wave data used were collected in the sea area near the Port of Rio Grande during the years 1996 to 1999, amounting to sixteen months of monitoring. The data set was treated and grouped resulting information monthly, seasonal and annual basis. The annual average was found to be 8.6 kW per meter of wave front, reaching 14.0 kW per meter for the month of May and 4.0 kW per meter for the month of January. The results indicate good perspectives in obtaining power supplies.

7. Advances in modeling plastic waste pyrolysis processes

Y. Safadi¹, J. Zeaiter²

1 Department of Mechanical Engineering, American University of Beirut, PO Box 11-0236, Beirut, Lebanon.

2 Chemical Engineering Program, American University of Beirut, PO Box 11-0236, Beirut, Lebanon.

Abstract: The tertiary recycling of plastics via pyrolysis is recently gaining momentum due to promising economic returns from the generated products that can be used as a chemical feedstock or fuel. The need for prediction models to simulate such processes is essential in understanding in depth the mechanisms that take place during the thermal or catalytic degradation of the waste polymer. This paper presents key different models used successfully in literature so far. Three modeling schemes are identified: Power-Law, Lumped-Empirical, and Population-Balance based equations. The categorization is based mainly on the level of detail and prediction capability from each modeling scheme. The data shows that the reliability of these modeling approaches vary with the degree of details the experimental work and product analysis are trying to achieve.

8. Neural network based global solar radiation estimation using limited meteorological data for Baghdad, Iraq

Rasheed H. AL-Naimi¹, Ali M. AL-Salihi¹, Dher I. Bakr²

1 Department of Atmospheric Sciences, College of Science, Al-Mustansiriyah University, Baghdad, Iraq.

2 Department of Physics, College of Science, Diyala University, Diyala, Iraq.

Abstract: In present paper, an artificial neural network (ANN) model is developed for estimating monthly mean daily global solar radiation of Baghdad city, Iraq. The results of the ANN models have been compared with measured data on the basis of root mean square error (RMSE), mean absolute error (MAE) and determination coefficient (R2). It is found that the solar radiation estimations by ANN are in good agreement with the measured values .Results obtained indicate that the ANN model can successfully be used for the estimation of monthly mean daily global solar radiation for Baghdad city. These results testify the generalization capability of the ANN model and its ability to produce accurate estimates in Baghdad.

9. Finite element modelling and simulation of free convection heat transfer in solar oven

Sobamowo M.G., Ogunmola B.Y., Ayerin A. M.

Department of Mechanical Engineering, University of Lagos, Akoka, Lagos, Nigeria.

Abstract: The use of solar energy for baking, heating or drying represents a sustainable way of solar energy applications with negligible negative effects. Solar oven is an alternative to conventional oven that rely heavily on coal and wood or Electric oven that uses the power from the National grid of which the end users have little or no control. Since the Solar oven uses no fuel and it costs nothing to run, it uses are widely promoted especially in situations where minimum fuel consumption or fire risks are considered highly important. As useful as the Solar Oven proved, it major setback in the area of applications has been its future sustainability. For the use of Solar Oven/Cookers to be sustained in the future, the design and development of solar oven must rely on sound analytical tools. Therefore, this work focused on the design and development of the solar oven. To test the performance of the Small Solar Oven a 5000cm3 beaker of water was put into the Oven and the temperature of the water was found to reach 810C after about 3hrs under an average ambient temperature of 300C. On no load test, the oven reached a maximum temperature of 112oC in 6hrs. In order to carry out the parametric studies and improve the performance of the Solar Oven, Mathematical models were developed and solved by using Characteristics-Based Split (CBS) Finite Element Method. The Model results were compared with the Experimental results and a good agreement was found between the two results.

10. A parametric FE modeling of brake for non-linear analysis

Ibrahim Ahmed¹, Yasser Fatouh1, Wael Aly²

1 Automotive and Tractors Technology Department, Faculty of Industrial Education, Helwan University, Cairo, Egypt.

2 Refrigeration and Air-Conditioning Technology Department, Faculty of Industrial Education, Helwan University, Cairo, Egypt.

Abstract: A parametric modeling of a drum brake based on 3-D Finite Element Methods (FEM) for non-contact analysis is presented. Many parameters are examined during this study such as the effect of drum-lining interface stiffness, coefficient of friction, and line pressure on the interface contact. Firstly, the modal analysis of the drum brake is also studied to get the natural frequency and instability of the drum to facilitate transforming the modal elements to non-contact elements. It is shown that the Unsymmetric solver of the modal analysis is efficient enough to solve this linear problem after transforming the non-linear behavior of the contact between the drum and the lining to a linear behavior. A SOLID45 which is a linear element is used in the modal analysis and then transferred to non-linear elements which are Targe170 and Conta173 that represent the drum and lining for contact analysis study. The contact analysis problems are highly non-linear and require significant computer resources to solve it, however, the contact problem give two significant difficulties. Firstly, the region of contact is not known based on the boundary conditions such as line pressure, and drum and friction material specs. Secondly, these contact problems need to take the friction into consideration. Finally, it showed a good distribution of the nodal reaction forces on the slotted lining contact surface and existing of the slot in the middle of the lining can help in wear removal due to the friction between the lining and the drum. Accurate contact stiffness can give a good representation for the pressure distribution between the lining and the drum. However, a full contact of the front part of the slotted lining could occur in case of 20, 40, 60 and 80 bar of piston pressure and a partially contact between the drum and lining can occur in the rear part of the slotted lining.

11. Anaerobic expanded granular sludge bed (EGSB) reactor for the removal of sulphide by autotrophic denitrification

Carlos Dinamarca

Department of Process, Energy and Environment; Faculty of Technology; Telemark University College Kjølnes ring 56, 3918 Porsgrunn, Norway.

Abstract: The Removal efficiency, load and N/S molar ratio, of an EGSB reactor for autotrophic sulphide denitrification operated for 96 days, were studied. The reactor was operated at high inlet sulphide concentrations between 0.25 to 3.00 g HS--S/L equivalents to loads between 5 to 250 g HS--S/m3∙h. Sulphide removals higher than 99 % were achieved. At a N/S molar ratio of 0.3 and 12 hours HRT the process was stable even during transition periods of influent sulphide concentration and pH (9.0-12.1). At N/S molar ratio of 1.3, granules lost some of their sedimentation properties and appeared to disintegrate. On average 94 ± 4 % of the equivalent inlet sulphur ended as elemental sulphur.

12. Physicochemical and rheological characteristics of charcoal slurry fuel

K. E. Ugwu, S. I. Eze

National Center for Energy Research and Development, University of Nigeria, Nsukka, Nigeria.

Abstract: Charcoal slurry fuel (CCF) was prepared from a mixture of charcoal, water and a surfactant. Some properties of the slurry were examined and evaluated. The rheological characteristics which were evaluated from the measurement of the viscosity of the slurry at varying solid concentrations showed it to be a Newtonian and non-Newtonian fluid depending on the solid concentrations. The slurry was stable at below 40% solid concentration. This research results provided data that may be useful in the consideration of charcoal slurry as a potential substitute for the conventional petroleum-based diesel oil.

13. Finite difference analysis of hydromagnetic mixed convective mass diffusion boundary layer flow past an accelerated vertical porous plate through a porous medium with suction

S. S. Das¹, M. R. Saran², S. Mohanty³, R. K. Padhy⁴

1 Department of Physics, K.B.D.A.V. College, Nirakarpur, Khordha-752 019 (Odisha), India.

2 Department of Physics, Maharishi College of Natural Law, Sahid Nagar, Bhubaneswar-751 007 (Odisha), India.

3 Department of Chemistry, Christ College, Mission Road, Cuttack-753 001 (Odisha), India.

4 Department of Physics, ODM Public School, Shishu Vihar, Patia, Bhubaneswar-751 024 (Odisha), India.

Abstract: This paper focuses on the unsteady hydromagnetic mixed convective heat and mass transfer boundary layer flow of a viscous incompressible electrically conducting fluid past an accelerated infinite vertical porous flat plate in a porous medium with suction in presence of foreign species such as H₂, He, H₂O vapour and NH3. The governing equations are solved both analytically and numerically using error function and finite difference scheme. The flow phenomenon has been characterized with the help of flow parameters such as magnetic parameter (M), suction parameter (a), permeability parameter (Kp), Grashof number for heat and mass transfer (Gr, Gc), Schmidt number (Sc) and Prandtl number (Pr). The effects of the above parameters on the fluid velocity, temperature, concentration distribution, skin friction and heat flux have been analyzed and the results are presented graphically and discussed quantitatively for Grashof number Gr>0 corresponding to cooling of the plate. It is observed that a growing magnetic parameter (M) retards the velocity of the flow field at all points and a greater suction leads to a faster reduction in the velocity of the flow field. Further, as we increase the permeability parameter (Kp) and the Grashof numbers for heat and mass transfer (Gr, Gc) the velocity of the flow field enhances at all points, while a greater suction/Prandtl number leads to a faster cooling of the plate. It is also observed that a more diffusive species has a significant decrease in the concentration boundary layer of the flow field and a growing suction parameter enhances both skin friction (T') and heat flux (Nu) at the wall corresponding to cooling of the plate (Gr>0).