VOLUME 3, ISSUE 4, 2012



Aims and Scope
Editorial Board

Volume 3, Issue 4, 2012, pp.i-viii. Download Full Text (PDF)

1. Prediction of deformation and hygro-thermal stresses distribution in PEM fuel cell vehicle using three-dimensional CFD model

Maher A.R. Sadiq Al-Baghdadi

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

Abstract: Durability is one of the most critical remaining issues impeding successful commercialization of broad PEM fuel cell transportation energy applications. Automotive fuel cells are likely to operate with neat hydrogen under load-following or load-levelled modes and be expected to withstand variations in environmental conditions, particularly in the context of temperature and atmospheric composition. In addition, they are also required to survive over the course of their expected operational lifetimes i.e., around 5,500 hrs, while undergoing as many as 30,000 startup/shutdown cycles. The damage mechanisms in a PEM fuel cell are accelerated by mechanical stresses arising during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running, because it consists of the materials with different thermal expansion and swelling coefficients. Therefore, in order to acquire a complete understanding of the damage mechanisms in the membrane, mechanical response under steady-state hygro-thermal stresses should be studied under real cell operating conditions and in real cell geometry (three-dimensional). In this work, full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to simulate the stresses inside the PEM fuel cell, which are occurring during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running due to the changes of temperature and relative humidity. A unique feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional fuel cell model. In addition, the temperature and humidity dependent material properties are utilize in the simulation for the membrane. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and stresses distribution that have limited experimental data. This model is used to study and analyse the effect of operating parameters on the mechanical behaviour of PEM. The analysis helped identifying critical parameters and shed insight into the physical mechanisms leading to a fuel cell durability for vehicular applications.

Volume 3, Issue 4, 2012, pp.485-504.

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2. Exergoeconomic performance optimization of an endoreversible intercooled regenerative Brayton combined heat and power plant coupled to variable-temperature heat reservoirs

Bo Yang, Lingen Chen, Fengrui Sun

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

Abstract: An endoreversible intercooled regenerative Brayton combined heat and power (CHP) plant model coupled to variable-temperature heat reservoirs is established. The exergoeconomic performance of the CHP plant is investigated using finite time thermodynamics. The analytical formulae about dimensionless profit rate and exergy efficiency of the CHP plant with the heat resistance losses in the hot-, cold- and consumer-side heat exchangers, the intercooler and the regenerator are deduced. By taking the maximum profit rate as the objective, the heat conductance allocation among the five heat exchangers and the choice of intercooling pressure ratio are optimized by numerical examples, the characteristic of the optimal dimensionless profit rate versus corresponding exergy efficiency is investigated. When the optimization is performed further with respect to the total pressure ratio, a double-maximum profit rate is obtained. The effects of the design parameters on the double-maximum dimensionless profit rate and corresponding exergy efficiency, optimal total pressure ratio and optimal intercooling pressure ratio are analyzed in detail, and it is found that there exist an optimal consumer-side temperature and an optimal thermal capacitance rate matching between the working fluid and the heat reservoir, respectively, corresponding to a thrice-maximum dimensionless profit rate.

Volume 3, Issue 4, 2012, pp.505-520. Download Full Text Article (PDF)

3. Integration of energy and environmental systems in wastewater treatment plants

Suzanna Long1, Elizabeth Cudney2

1 Department of Engineering Management and Systems Engineering, 600 W, 14th Street, 215 EMGT Building, Rolla, MO-65401, 573-341-7621, U.S.A.

2 Department of Engineering Management and Systems Engineering, 600 W, 14th Street, 217 EMGT Building, Rolla, MO-65401, 573-341-7931, U.S.A.

Abstract: Most wastewater treatment facilities were built when energy costs were not a concern; however, increasing energy demand, changing climatic conditions, and constrained energy supplies have resulted in the need to apply more energy-conscious choices in the maintenance or upgrade of existing wastewater treatment facilities. This research develops an integrated energy and environmental management systems model that creates a holistic view of both approaches and maps linkages capable of meeting high-performing energy management while meeting environmental standards. The model has been validated through a case study on the Rolla, Missouri Southeast Wastewater Treatment Plant. Results from plant performance data provide guidance to improve operational techniques. The significant factors contributing to both energy and environmental systems are identified and balanced against considerations of cost.

Volume 3, Issue 4, 2012, pp.521-530. Download Full Text Article (PDF)

4. Investigation of thermal effect on exterior wall surface of building material at urban city area

Mohd Fadhil Md Din1, Hazlini Dzinun1, M. Ponraj1, Shreeshivadasan Chelliapan1, Zainura Zainun Noor1, Dilshah Remaz2, Kenzo Iwao3

1 Institute of Environmental Water Resources and Management (IPASA), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.

2 Faculty of Built Environment, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.

3 Nagoya Institute of Technology, Nagoya, Japan.

Abstract: This paper describes the investigation of heat impact on the vertical surfaces of buildings based on their thermal behavior. The study was performed based on four building materials that is commonly used in Malaysia; brick, concrete, granite and white concrete tiles. The thermal performances on the building materials were investigated using a surface temperature sensor, data logging system and infrared thermography. Results showed that the brick had the capability to absorb and store heat greater than other materials during the investigation period. The normalized heat (total heat/solar radiation) of the brick was 0.093 and produces high heat (51% compared to granite), confirming a substantial amount of heat being released into the atmosphere through radiation and convection. The most sensitive material that absorbs and stores heat was in the following order: brick > concrete > granite > white concrete tiles. It was concluded that the type of exterior wall material used in buildings had significant impact to the environment.

Volume 3, Issue 4, 2012, pp.531-540. Download Full Text Article (PDF)

5. Life cycle assessment (LCA) of an energy recovery plant in the olive oil industries

Francesca Intini1, Silvana Kühtz1, Gianluca Rospi2

1 Dep. Engineering and Environmental Physics, Faculty of Engineering, University of Basilicata, Italy.

2 Dep. Engineering and Environmental Physics, Faculty of Architecture, University of Basilicata, Italy.

Abstract: To reduce the GHG emissions in the UE and to increase the produced energy it is important to spread out decentralized technologies for renewable energy production. In this paper a power plant fed with biomass is studied, in particular the biomass considered is the waste of the olive oil industries. This study focuses on the possibility of using the de-oiled pomace and waste wood as fuel. A life cycle assessment (LCA) of a biomass power plant located in the South of Italy was performed. The global warming potential has been calculated and compared with that of a plant for energy production that uses refuse derived fuel (RDF) and that of one that uses coal. The LCA shows the important environmental advantages of biomass utilization in terms of greenhouse gas emissions reduction. An improved impact assessment methodology may better underline the advantages due to the biomass utilization.

Volume 3, Issue 4, 2012, pp.541-552. Download Full Text Article (PDF)

6. An overview of the EU Member States support schemes for the promotion of renewable energy sources

Andreas Poullikkas, George Kourtis, Ioannis Hadjipaschalis

Electricity Authority of Cyprus, P.O. Box 24506, 1399 Nicosia, Cyprus.

Abstract: In this work, an overview of the European Union (EU) Member States support schemes for the promotion of renewable energy sources (RES) is provided. In particular, the status of the electricity generation capacity as well as the RES mixture in the Member States is described. Moreover, the different support schemes such as, investment support, feed-in tariffs (FiTs), tradable green certificates, and fiscal and financial measures which the Member States have adopted for the promotion of RES technologies are discussed in detail. Some Member States are implementing a single support scheme for the promotion of RES for power generation (RES-E), e.g., seven Member States use FiTs, or implement a hybrid support scheme by combining all or some of the four categories of the RES-E supporting schemes. Although, these support schemes have increased the penetration of the RES-E technologies in the Member States, still there is a long way in order to achieve the 2020 target. The reason for this may be that the way these schemes have been used so far, i.e., either as single support schemes or in combination of FiTs or tradable green certificates with investment support and fiscal and financial measures, has been ineffective. A more effective combination could be a hybrid scheme consisting of FiTs with tradable green certificates measures, as in the case of Italy and United Kingdom, that will increase the RES-E penetration and eliminate the possible technical problems which will arise from this increased penetration and have an effect in the stability of the power system.

Volume 3, Issue 4, 2012, pp.553-566. Download Full Text Article (PDF)

7. Protecting water resources from pollution in the Lake Badovc

Sabri Avdullahi, Islam Fejza, Ahmet Tmava

Faculty of Geosciences and Technology, University of Prishtina, Str. Parku Industrial, 40000 Mitrovic, Republic of Kosova.

Abstract: In recent years, the international community has witnessed incidence of climate variability and human activities. The objective of this paper is protecting water resources from pollution in the catchments area of Lake Badovc. The catchments area of the Lake Badovc has a size of 109 km² and the active storage volume of the lake is assessed to 26.4 Mill.m3. Around 28% of the total population of Municipality of Prishtina supply with drinking water from Lake Badovc. The hydrologic modelling system used, is HEC-HMS developed by the Hydrologic Engineering Centre of the US Corps of Engineers. The model is designed to simulate the rainfall-runoff processes of catchments areas and is applicable to a wide range of geographic areas.Water samples are taken from two streams reach Lake Badovc and from the lake in three different depths (5m, 10m and 15m) at different locations. Concerning the environment impact more than 140 interviews were conducted and questionnaires filled in the period October-November for Mramor area, concentrating on the most important issues: building, water supply, wastewater disposal and west disposal.

Volume 3, Issue 4, 2012, pp.567-576. Download Full Text Article (PDF)

8. Fuel economy improvement based on a many-gear shifting strategy

B. Mashadi1, R. Baghaei Lakeh2

1 School of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran.

2 Department of Mechanical Engineering, Southern Illinois University, Edwardsville, USA.

Abstract: Considering the engine operating condition in terms of engine load and engine speed, a fuzzy decision making system has been developed. The objective was to controlling the engine operating point in the engine torque-rpm map, in order to enhance fuel economy. The main idea stems from the approach of tracking the defined target curve in the engine map similar to the CVT control criteria. To provide resemblance between a traditional geared transmission and a CVT, a many-gear transmission concept was introduced. A Fuzzy control was utilized by defining proper membership functions for the inputs and output. The efficient fuel consumption curve in the engine map was taken as the target of controller. The effect of engine output power on fuel consumption has also been taken into consideration. Making use of ADVISOR software, vehicle simulations was performed for the many-gear base case and a very good consistency was found with the CVT case. As a result the fuel consumption was found to become considerably less than existing values. The developed strategy was then applied to other cases including conventional manual and automatic transmissions and improvements in the fuel economy was observed.

Volume 3, Issue 4, 2012, pp.577-590. Download Full Text Article (PDF)

9. Combined natural convection and mass transfer effects on unsteady flow past an infinite vertical porous plate embedded in a porous medium with heat source

S. S. Das1, R. K. Tripathy2, R. K. Padhy3, M. Sahu4

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

2 Department of Physics, D R Nayapalli College, Bhubaneswar-751 012 (Orissa), India.

3 Department of Physics, D A V Public School, Chandrasekharpur, Bhubaneswar-751 021 (Orissa), India.

4 Department of Physics, Jupiter +2 Women’s Science College, IRC Village, Bhubaneswar-751 015 (Orissa), India.

Abstract: This paper theoretically investigates the combined natural convection and mass transfer effects on unsteady flow of a viscous incompressible fluid past an infinite vertical porous plate embedded in a porous medium with heat source. The governing equations of the flow field are solved analytically for velocity, temperature, concentration distribution, skin friction and the rate of heat transfer using multi parameter perturbation technique and the effects of the flow parameters such as permeability parameter Kp, Grashof number for heat and mass transfer Gr, Gc; heat source parameter S, Schmidt number Sc, Prandtl number Pr etc. on the flow field are analyzed and discussed with the help of figures and tables. The permeability parameter Kp is reported to accelerate the transient velocity of the flow field at all points for small values of Kp (£1) and for higher values the effect reverses. The effect of increasing Grashof numbers for heat and mass transfer or heat source parameter is to enhance the transient velocity of the flow field at all points while a growing Schmidt number retards its effect at all points. A growing permeability parameter or heat source parameter increases the transient temperature of the flow field at all points, while a growing Prandtl number shows reverse effect. The effect of increasing Schmidt number is to decrease the concentration boundary layer thickness of the flow field at all points. Further, a growing permeability parameter enhances the skin friction at the wall and a growing Prandtl number shows reverse effect. The effect of increasing Prandtl number or permeability parameter leads to increase the magnitude of the rate of heat transfer at the wall.

Volume 3, Issue 4, 2012, pp.591-604. Download Full Text Article (PDF)

10. Hybrid wind-PV grid connected power station case study: Al Tafila, Jordan

Yousif El-Tous1, Saleh Al-Battat2, Sandro Abdel Hafith3

1 Department of Electrical Engineering / Faculity of Engineering Technology/ Al-Balqa’ Applied University, Amman, P.O.Box (15008), Marka Ashamalia, Jordan.

2 Department of substation maintenance and protection, National Electric Power Company (NEPCO), Amman, Jordan.

3 Department of technical support and project supervision / Integrated power systems co. / Amman, Jordan.

Abstract: In this paper, we are providing an attempt to highlight the importance of renewable energy, more specifically, the one produced from a wind-solar hybrid system. This purpose will be achieved through providing a detailed case study for such system that would be applied in Al-Tafila\Jordan. First and foremost site assessment has been conducted based on an intensive literature review for the data available regarding the availability of wind and solar energy in Jordan and resulted in the selection of Al-Tafila 2 district as the best option among all. Then, the components of the power station and its size have been selected based on specific criteria that make the station as much efficient and competitive as possible. To obtain the output of the different components with respect to the demand for a period of 25 years, a system model was built using HOMER. Finally, the total capital cost of the system was calculated and resulted to be (63400168) $ and with a cost of energy of (0.053) $/kWh which is a very competitive and feasible cost compared to similar international projects and to the conventional energy price.

Volume 3, Issue 4, 2012, pp.605-616. Download Full Text Article (PDF)

11. Effect of flow field on open channel flow properties using numerical investigation and experimental comparison

I. Khazaee1, M. Mohammadiun2

1 Department of Mechanical Engineering, Torbat-e- jam branch, Islamic Azad University, Torbat-e- jam, Iran.

2 Department of Mechanical Engineering, Shahrood branch, Islamic Azad University, Shahrood, Iran.

Abstract: In this paper a complete three-dimensional and two phase CFD model for flow distribution in an open channel investigated. The finite volume method (FVM) with a dynamic Sub grid-scale was carried out for seven cases of different aspect ratios, different inclination angles or slopes and convergence-divergence condition. The volume of fluid (VOF) method was used to allow the free-surface to deform freely with the underlying turbulence. The discharge through open channel flow is often evaluated by velocity-area integration method from the measurement of velocity at discrete locations in the measuring section. The variation of velocity along horizontal and vertical directions is thus very important to decide the location of the sensors. The aspect ratio of the channel, slope of the channel and divergence- convergence of the channel have investigated and the results show that the depth of water at the end of the channel is higher at AR=0.8 against the AR=0.4 and AR=1.2. Also it is clear that by increasing the inclination angle or slope of the channel in case1, case4 and case5 the depth of the water increases. Also it is clear that the outlet mass flow rate is at a minimum value at a range of inclination angle of the channel.

Volume 3, Issue 4, 2012, pp.617-628. Download Full Text Article (PDF)

12. Performance and emission characteristics of diesel engine with COME-Triacetin additive blends as fuel

P. Venkateswara Rao1, B. V. Appa Rao2

1 Dept. of Mechanical Engineering, K I T S, Warangal- 506015, A. P., India.

2 Dept. of Marine Engineering, Andhra University, Visakhapatnam-530003, A. P., India.

Abstract: The Triacetin [C9H14O6] additive is used an anti-knocking agent along with the bio-diesel in DI- diesel engine. In the usage of diesel fuel and neat bio-diesel knocking can be detected to some extent. The T- additive usage in the engine suppressed knocking, improved the performance and reduced tail pipe emissions. Comparative study is conducted using petro-diesel, bio-diesel, and with various additive blends of bio-diesel on DI- diesel engine. Coconut oil methyl ester (COME) is used with additive Triacetin (T) at various percentages by volume for all loads (No load, 25%, 50%, 75% and full load). The performance of engine is compared with neat diesel in respect of engine efficiency, exhaust emissions and combustion knock. Of the five Triacetin- biodiesel blends tried, 10% Triacetin combination with biodiesel proved encouraging in all respects of performance of the engine.

Volume 3, Issue 4, 2012, pp.629-638. Download Full Text Article (PDF)

13. Transformerless microinverter for photovoltaic systems

Tarak Salmi1, Mounir Bouzguenda2, Adel Gastli2, Ahmed Masmoudi1

1 Research Unit on Renewable Energies and Electric Vehicles, National Engineering School of Sfax, P.O.Box: W, 3038 Sfax, Tunisia.

2 Department of Electrical and Computer Engineering, College of Engineering, Sultan Qaboos University, P.O. Box 33, P.C. 123, Al-Khoudh, Sultanate of Oman.

Abstract: When a galvanic connection between the grid and the PV array is made, a common-mode voltage exists that generates common-mode currents. These common-mode currents may produce electromagnetic interferences, grid current distortion and additional losses in the system. Therefore, to avoid the leakage currents that would penalize the transformerless power chains, it is worth focusing on topologies that do not generate common-mode currents. Some topologies available in the market touch more or less such a crucial requirement. However, some drawbacks generated by the non-utilization of the transformer still exist. These drawbacks maybe reduced or totally eliminated using suitable topologies as well as control strategies. In this paper, a new topology has been developed. Its control strategy has been simulated and experimentally validated. Accordingly, high conversion efficiency and low leakage current level have been demonstrated.

Volume 3, Issue 4, 2012, pp.639-650. Download Full Text Article (PDF)