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Aims and Scope
Editorial Board

1. A CFD study of hygro-thermal stresses distribution in tubular-shaped ambient air-breathing PEM micro fuel cell during regular cell operation

Maher A.R. Sadiq Al-Baghdadi

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

Abstract: The need for improved lifetime of air-breathing proton exchange membrane (PEM) fuel cells for portable applications necessitates that the failure mechanisms be clearly understood and life prediction models be developed, so that new designs can be introduced to improve long-term performance. An operating air-breathing PEM fuel cell has varying local conditions of temperature, humidity. As a result of in the changes in temperature and moisture, the membrane, GDL and bipolar plates will all experience expansion and contraction. Because of the different thermal expansion and swelling coefficients between these materials, hygro-thermal stresses are introduced into the unit cell during operation. In addition, the non-uniform current and reactant flow distributions in the cell result in non-uniform temperature and moisture content of the cell which could in turn, potentially causing localized increases in the stress magnitudes, and this leads to mechanical damage, which can appear as through-the-thickness flaws or pinholes in the membrane, or delaminating between the polymer membrane and gas diffusion layers. Therefore, in order to acquire a complete understanding of these damage mechanisms in the membranes and gas diffusion layers, mechanical response under steady-state hygro-thermal stresses should be studied under real cell operation conditions. A three-dimensional, multi–phase, non-isothermal computational fluid dynamics model of a novel, tubular, ambient air-breathing, proton exchange membrane micro fuel cell has been developed and used to investigate the displacement, deformation, and stresses inside the whole cell, which developed during the cell operation due to the changes of temperature and relative humidity. The behaviour of the fuel cell during operation has been studied and investigated under real cell operating conditions. In addition to the new and complex geometry, a unique feature of the present model is to incorporate the effect of mechanical, hygro and thermal stresses into actual three-dimensional fuel cell model. The results show that the non-uniform distribution of stresses, caused by the temperature gradient in the cell, induces localized bending stresses, which can contribute to delaminating between the membrane and the gas diffusion layers. The non-uniform distribution of stresses can also contribute to delaminating between the gas diffusion layers and the current collectors. These stresses may explain the occurrence of cracks and pinholes in the fuel cells components under steady–state loading during regular cell operation, especially in the high loading conditions.

Volume 1, Issue 2, 2010, pp.183-198.

2. Electric and hydrogen consumption analysis in plug-in road vehicles

João P. Ribau, Carla M. Silva, Tiago L. Farias

IDMEC, Instituto Superior Técnico, Technical University of Lisbon,  Department of Mechanical Engineering, Av. Rovisco Pais, 1 Pav. Mecânica I, 2º andar, 1049-001 Lisboa, Portugal.

Abstract: The main goal of the present study is to analyze some of the capabilities and behavior of two types of plug-in cars: battery electric and hydrogen fuel cell hybrid electric, facing different driving styles, different road gradients, different occupation rates, different electrical loads, and different battery's initial state of charge. In order to do that, four vehicles with different power/weight (kW/kg) ratio (0.044 to 0.150) were simulated in the software ADVISOR, which gives predictions of energy consumption, and behavior of vehicle’s power train components (including energy regeneration) along specified driving cycles. The required energy, electricity and/or hydrogen, to overcome the specified driving schedules, allowed to estimate fuel life cycle's CO₂ emissions and primary energy. A vehicle with higher power/weight ratio (kW/kg) demonstrated to be less affected in operation and in variation of the energy consumption, facing the different case studies, however may have higher consumptions in some cases. The autonomy, besides depending on the fuel consumption, is directly associated with the type and capacity (kWh) of the chosen battery, plus the stored hydrogen (if fuel cell vehicles are considered, PHEV-FC). The PHEV-FC showed to have higher autonomy than the battery vehicles, but higher energy consumption which is extremely dependent on the type and ratio of energy used, hydrogen or electricity. An aggressive driving style, higher road gradient and increase of weight, required more energy and power to the vehicle and presented consumption increases near to 77%, 621%, 19% respectively. Higher electrical load and battery's initial state of charge, didn't affect directly vehicle's dynamic. The first one drained energy directly from the battery plus demanded a fraction of its power, with energy consumption maximum increasing near 71%. The second one restricted the autonomy without influence directly the energy consumption per kilometer, except for the PHEV-FC with energy consumption increasing near 28% (due to the higher fraction of hydrogen used). In order to have a different and nearer realistic viewpoint the obtained values for these plug-in vehicles, were also compared to the results of a conventional HEV and ICEV, both gasoline vehicles.

3. An experimental investigation on hydrogen fuel injection in intake port and manifold with different EGR rates

N.Saravanan¹, G.Nagarajan²

1 Manager, ERC Engines, Tata Motors Ltd., Pimpri, Pune-411019, India.

2 Department of Mechanical Engineering, College of Engineering, Guindy, Anna University Chennai, Chennai 600025, India.

Abstract: In the present investigation hydrogen was used in a diesel engine in the dual fuel mode using diesel as an ignition source. In order to have a precise control of hydrogen flow and to avoid the backfire and pre-ignition problems hydrogen was injected into the intake system. Experiments were conducted to determine the optimized injection timing, injection duration and injection quantity of the fuel in manifold and port injected hydrogen-operated engine using diesel as ignition source for hydrogen operation. From the results it was observed that in manifold injection technique the optimized condition was start of injection at gas exchange top dead centre (GTDC) with injection duration of 30^o crank angle (CA) with hydrogen flow rate of 7.5 litres/min. In port injection technique, the optimized condition was start of injection at 5^o before gas exchange top dead centre (5^o BGTDC) with injection duration of 30^o CA with hydrogen flow rate of 7.5 litres/min. With the above optimized timings of port and manifold injection it was observed that brake thermal efficiency in port injection increases by 13 % and 16 % in manifold injection at 75 % load. However at full load the brake thermal efficiency decreases by 1 % in port injection and 8 % in manifold injection. A reduction in NOX emission by 4 times is observed in port injection and 7 times in manifold injection at full load. At 75 % load the NOX emission reduces by 3 times in both port injection and manifold injection. Smoke emission increases with increase in EGR percentage. The smoke increases by 36 % at full load in port injection and by 44 % in manifold injection. At 75 % load the smoke emission reduces by 13 % in port injection and 9 % in manifold injection. In both the port injection and manifold injection ignition delay was 12^o or 1.33 ms while for diesel it was 11^o or 1.22 ms. Port injection system with diesel as ignition source operates smoothly and shows improved performance and emit lesser pollution than diesel.

4. Pressured liquid chlorine leakage accident simulation in highway tunnel

LI Jianfeng^1,2, LIU Mao², WANG Wei²

1 Department of Environmental Science and Engineering, Tsinghua University, Beijing, China.

2 College of Environmental Science and Engineering, Nankai University, Tianjin, China.

Abstract: With the national economic development, China's transportation infrastructure has also made great progress, particularly in the highway. How to reduce the accident consequence that occurred in the highway tunnel has been the tropical topic in China. The liquid Chlorine accidental leakage in highway tunnel was exemplified for the poisonous gas dispersion consequence analysis using computational fluid dynamics. First, the GAMBIT code was used to create geometrical models and generate meshes. Second, by using the FLUENT code, the Chlorine gas dispersion in the highway tunnel was simulated and the scenarios with different leak sources were discussed. Case study shows that the FLUENT code was useful on the simulation of gas dispersion in highway tunnel that serves the prerequisite for the further research.

5. Estimation of luminous efficacy of daylight and illuminance for composite climate

M. Jamil Ahmad, G.N. Tiwari

Center for Energy Studies, Indian Institute of Technology, Hauz Khas, New Delhi-16, India.

Abstract: This Daylighting is one of the basic components of passive solar building design and its estimation is essential. In India there are a few available data of measured illuminance as in many regions of the world. The Indian climate is generally clear with overcast conditions prevailing through the months of July to September, which provides good potential to daylighting in buildings. Therefore, an analytical model that would encompass the weather conditions of New Delhi was selected. Hourly exterior horizontal and slope daylight availability has been estimated for New Delhi using daylight modeling techniques based on solar radiation data. A model to estimate interior illuminance was investigated and validated using experimental hourly inside illuminance data of an existing skylight integrated vault roof mud house in composite climate of New Delhi. The interior illuminance model was found in good agreement with experimental value of interior illuminance.

6. Biogas technology dissemination in Ghana: history, current status, future prospects, and policy significance

Edem Cudjoe Bensah¹, Abeeku Brew-Hammond²

1 Chemical Engineering Department, Kumasi Polytechnic, Box 854, Kumasi, Ghana.

2 Faculty of Mechanical and Agricultural Engineering, Kwame Nkrumah University of Science and Technology (KNUST), Private Mail Bag, Kumasi, Ghana.

Abstract: Despite numerous benefits derived from biogas technology, Ghana is yet to develop a major programme that will promote the dissemination of biogas plants on a larger scale. This paper reviews biogas installations in Ghana and investigates challenges facing the design, construction, and operation of biogas plants. It further captures the current status and functions of biogas plants as well as the impact of these plants on the people who use them. The study was done by surveying fifty (50) biogas installations, and conducting interviews with both plant users and service providers. From the survey, twenty-nine (58 %) installations were institutional, fourteen (28 %) were household units, and the remaining seven (14 %) were community plants. Fixed-dome and water-jacket floating-drum digesters represented 82 % and 8 % of installations surveyed, respectively. It was revealed that sanitation was the main motivational reason for people using biogas plants. Of the 50 plants, 22 (44 %) were functioning satisfactorily, 10 (20 %) were functioning partially, 14 (28 %) were not functioning, 2 (4 %) were abandoned, and the remaining 2 (4 %) were under construction. Reasons for non-functioning include non-availability of dung, breakdown of balloon gasholders, absence of maintenance services, lack of operational knowledge, and gas leakages and bad odour in toilet chambers of biolatrines. This paper recommends the development of a national biogas programme focussing on three major areas – sanitation, energy, and agricultural fertilizer production; it further supports the development of standardized digester models. The founding of a national body or the establishment of a dedicated unit within an existing organization with the sole aim of coordinating and managing biogas dissemination in Ghana is proposed.

7. Effect of biodiesel structural configuration on its ignition quality

A. Gopinath¹, Sukumar Puhan², G. Nagarajan³

1 Product Development, Ashok Leyland Technical Centre, Chennai, Tamilnadu, India.

2 Department of Mechanical Engineering, Veltech Engineering College, Chennai, Tamilnadu, India.

3 Internal Combustion Engineering Division, Department of Mechanical Engineering,    College of Engineering, Anna University Chennai, Tamilnadu, India.

Abstract: Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. Cetane number is one of the most significant properties to specify the ignition quality of any fuel. The cetane number of biodiesel fuels is considerably influenced by their fatty acid methyl ester composition. The objective of this work is to investigate the influence of fatty acid methyl ester composition on cetane number of biodiesel fuels. In the present work, 15 various biodiesel fuels were prepared and their cetane number was measured experimentally. A wide literature review was made and the measured cetane numbers were compared with the reported values. The dependence of cetane number of biodiesel fuels on their fatty acid ester composition investigated. It was found from the investigation that the unsaturation percentage can significantly affect the cetane number.

8. The cold air machine

Barış Bağcı

TÜV Rheinland Hong Kong Ltd., Emperor International Square, 10/F, 7 Wang Tai Road, Kowloon Bay, Hong Kong.

Abstract: This study focuses on the human behaviour in regards of air-conditioning usage in indoor environment. A mid-sized, carpet floored office (600 sqm) with 120 employees in Hong Kong was chosen as the experiment field due to two reasons. The first reason is that the office buildings in Hong Kong are the coldest office buildings worldwide. And the building where the office is located doesn’t provide a central air-conditioning system, which means that the human behaviour is very crucial to save energy in such offices. The second reason is that the largest portion of electricity consumption in Hong Kong belongs to the air-conditioning systems in buildings (25% of total electricity consumption in Hong Kong). Development and usage of energy efficient technologies are no doubt very crucial in emission reduction and environmental protection. But, the best energy efficient equipment is not much worth and waste of money if the behaviour of the persons using that equipment does not change. In this study we searched for the reasons behind the persistent behaviour of wrongly using the air conditioning systems and making Hong Kong probably the city with the largest energy consumption for cooling per square meter.

9. Numerical modeling of oxides of nitrogen based on density of biodiesel fuels

A. Gopinath¹, Sukumar Puhan², G. Nagarajan³

1 Product Development, Ashok Leyland Technical Centre, Chennai, Tamilnadu, India.

2 Department of Mechanical Engineering, Veltech Engineering College, Chennai, Tamilnadu, India.

3 Internal Combustion Engineering Division, Department of Mechanical Engineering,    College of Engineering, Anna University Chennai, Tamilnadu, India.

Abstract: Biodiesel is an alternative fuel derived from vegetable oils or animal fats. Research has shown that biodiesel fueled engines produce lesser carbon monoxide, unburned hydrocarbon, and particulate emissions compared to mineral based diesel fuel but emit higher oxides of nitrogen (NOx) emissions. NOx could be strongly correlated with density or cetane number of a fuel. The objective of the present work is to predict the NOx concentration of a neat biodiesel fueled compression ignition engine from the density of biodiesel fuels using regression model. Experiments were conducted at different engine loads and the results were given as inputs to develop the regression model. A single cylinder, four stroke, constant speed, air cooled, direct injection diesel engine was used for the experiments. Five different biodiesel fuels were used and NOx were measured at different engine loads. The NOx concentration was taken as response (dependent) variable and the density values were taken as explanatory (independent) variables. The regression model has yielded R2 values between 0.918 and 0.995. The maximum prediction error was found to be 3.01 %.

10. Business sustainability in Brazil and Germany: case study of the automotive industry

K. R. A. Nunes¹, A R. Valle¹, J. A. A. Peixoto²

1 Federal University of Rio de Janeiro (UFRJ), COPPE, Industrial Engineering Program, P.O. Box 68.507 CEP 21.945-970, Rio de Janeiro, RJ, Brazil.

2 Federal Centre of Technological Education Celso Suckow da Fonseca (CEFET-RJ), Program of Master’s Degree in Technology, Av. Maracanã, 229 Bloco E, Room 505.3, Maracanã, 20271-110, Rio de Janeiro, RJ, Brazil.

Abstract: A significant number of German companies are installed in Brazil, many of them in the automotive or automotive supplier sectors. Information about the economic, environmental and social performance of major companies in these sectors is easily obtainable from sustainability reports, available as printed reports distributed by the head offices or as files for downloading in corporate websites. This paper gives a brief review about corporate sustainability and the results of a study carried out on sustainability reports of three companies with head offices (or, in one case, a relatively independent subsidiary) in Germany and subsidiaries in Brazil. The results show that, although the sustainability reports of the analyzed companies contain relevant information, they do not allow any sustainability benchmarking that could distinguish better and worse environmental and social performances. They also do not help an environmental and social performance comparison between plants in the European Union (e.g. Germany) and Mercosur (e.g. Brazil). Nevertheless, they give some evidence of efforts aligned with the principles of the Global Compact.

11. Effective efficiency prediction for discrete type of ribs used in solar air heaters

Muneesh Sethi¹, Mridul Sharma², Varun²

¹ Mechanical Engineering Department, IEET Baddi – 173205, India.

² Department of Mechanical Engineering, National Institute of Technology Hamirpur - 177005, India.

Abstract: The use of an artificial roughness on a surface is an effective technique to enhance the heat transfer from the collector plate to the air in a solar air heater duct. However, artificial roughness leads to even more fluid pressure thereby increasing the pumping power. Number of geometries of roughness elements has been investigated on the heat transfer and friction characteristics of solar air heater ducts. This paper presents a comparison of effective efficiency of solar air heaters having different types of geometry of roughness elements (discrete ribs) on the absorber plate. The effective efficiency has been computed by using the correlations for heat transfer and friction factor developed by various investigators within the investigated range of operating and system parameters.

12. Effect of engine parameters on NOx emissions with Jatropha biodiesel as fuel

S. Jindal

Mechanical Engineering Department, College of Technology and Engineering, Udaipur 313001 India.

Abstract: Depleting petroleum reserves on the earth and increasing concerns about the environment leads to the quest for fuels which are eco-friendly and safe for human beings. It is now well established that lower blends of biodiesel and diesel works well in the existing engines without any modifications. Use of the higher blends is restricted due to loss of efficiency and long term problems in the engine. For using higher blends of biodiesel, the engine operating parameters must be changed for recovery of power and efficiency. But these changes may affect the emissions. This study targets on investigating the effects of the engine operating parameters viz. compression ratio, fuel injection pressure, injection timing and engine speed on emissions of NOx with pure biodiesel as fuel in a small diesel engine commonly used in agricultural applications. It is found that the combined increase of compression ratio and injection pressure and retarding injection results in lower emissions of NOx as compared to the diesel fuel.

13. Influence of ventilation on energy consumption and carbon emissions in high occupant density building

Wang J., Zhang X.

Institute of HVAC & GAS Engineering, College of Mechanical Engineering, Tongji University, Shanghai 200092, China.

Abstract: Reasonable determination of outdoor airflow for building ventilation is very useful for indoor air quality improvement and building energy conservation. Variation characteristics of outdoor airflow requirement, building energy consumption and carbon emission for ventilation with indoor occupant density and ventilation time were analyzed for high occupant density building space, according to the indoor air pollutants mass-balance mechanism and outdoor airflow calculation principle in GB50019-2003 and ASHRAE Standard 62.1-2007. Advices for building energy conservation and reducing carbon emissions were given based on the variation characteristics for controlling indoor air pollution.

14. PV-solar / wind hybrid energy system for GSM/CDMA type mobile telephony base station

Pragya Nema¹, R.K. Nema², Saroj Rangnekar¹

1 Energy Engineering Department, Maulana Azad National Institute of Technology , Bhopal-462007 M.P., India.

2 Electrical Engineering Department, , Maulana Azad National Institute of Technology , Bhopal-462007 M.P., India.

Abstract: This paper gives the design idea of optimized PV-Solar and Wind Hybrid Energy System for GSM/CDMA type mobile base station over conventional diesel generator for a particular site in central India (Bhopal) . For this hybrid system ,the meteorological data of Solar Insolation, hourly wind speed, are taken for Bhopal-Central India (Longitude 77^o.23'and Latitude 23^o.21' ) and the pattern of load consumption of mobile base station are studied and suitably modeled for optimization of the hybrid energy system using HOMER software. The simulation and optimization result gives the best optimized sizing of wind turbine and solar array with diesel generator for particular GSM/CDMA type mobile telephony base station. This system is more cost effective and environmental friendly over the conventional diesel generator. It should reduced approximate 70%-80% fuel cost over conventional diesel generator and also reduced the emission of CO₂ and other harmful gasses in environments. It is expected that the newly developed and installed system will provide very good opportunities for telecom sector in near future.

15. Solar energy estimation using REST2 model

M. Rizwan¹, Majid Jamil¹, D. P. Kothari²

1 Jamia Millia Islamia, New Delhi-110025, India.

2 VIT University Vellore, Tamilnadu- 632 014, India.

Abstract: The network of solar energy measuring stations is relatively rare through out the world. In India, only IMD (India Meteorological Department) Pune provides data for quite few stations, which is considered as the base data for research purposes. However, hourly data of measured energy is not available, even for those stations where measurement has already been done. Due to lack of hourly measured data, the estimation of solar energy at the earth’s surface is required. In the proposed study, hourly solar energy is estimated at four important Indian stations namely New Delhi, Mumbai, Pune and Jaipur keeping in mind their different climatic conditions. For this study, REST2 (Reference Evaluation of Solar Transmittance, 2 bands), a high performance parametric model for the estimation of solar energy is used. REST2 derivation uses the two-band scheme as used in the CPCR2 (Code for Physical Computation of Radiation, 2 bands) but CPCR2 does not include NO₂ absorption, which is an important parameter for estimating solar energy. In this study, using ground measurements during 1986-2000 as reference, a MATLAB program is written to evaluate the performance of REST2 model at four proposed stations. The solar energy at four stations throughout the year is estimated and compared with CPCR2. The results obtained from REST2 model show the good agreement against the measured data on horizontal surface. The study reveals that REST2 models performs better and evaluate the best results as compared to the other existing models under cloudless sky for Indian climatic conditions.