VOLUME 2, ISSUE 4, 2011



Aims and Scope
Editorial Board

Volume 2, Issue 4, 2011, pp.i-viii. Download Full Text (PDF)

1. A CFD analysis on the effect of ambient conditions on the hygro-thermal stresses distribution in a planar ambient air-breathing PEM fuel cell

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 and 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 planar ambient air-breathing, proton exchange membrane fuel cell has been developed and used to study the effects of ambient conditions on the temperature distribution, displacement, deformation, and stresses inside the cell. The behaviour of the fuel cell during operation has been studied and investigated under real cell operating conditions. 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. The results showed that the ambient conditions (ambient temperature and relative humidity) have a strong impact on the temperature distribution and hygro-thermal stresses inside the cell.

Volume 2, Issue 4, 2011, pp.589-604.

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2. Thermal properties of the vernacular buildings envelopes: the case of the "Sassi di Matera" and "Trulli di Alberobello"

Nicola Cardinale1, Gianluca Rospi1, Pietro Stefanizzi2, Valentina Augenti2

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

2 Department of Architecture and Town Planning, Faculty of Engineering, Polytechnic of Bari, Italy.

Abstract: The stone and the clay are the basic elements of the existing architectural heritage in the Mediterranean area, both historical and monumental. The study cases taken into account are the "Sassi of Matera" and the "Trulli of Alberobello." The thermohygrometric performances of the "Tufo of Matera" (commonly denoted as calcarenite sandstone) and the "Stone of Fasano" (commonly denoted as calcareous stone), which are the base materials of the buildings "Sassi" and "Trulli", were quantified through measurements in situ, realized with nondestructive methodology and analyses in laboratory. The behavior of these constructions has finally been better described with dynamic simulations developed by the software EnergyPlus. This study demonstrated that the thermal mass of these structures mainly affect the indoor microclimate, stabilizing the inside temperatures and thus annulling the great thermal daily oscillations of the external temperature. The results of the measurements and numerical simulations confirmed that the seasonal thermal storage of these structures allows comfortable temperatures during the summer season, with values below 26 C, and stabilizes the indoor temperatures during the winter season, through the release of the heat stored during warm season.

Volume 2, Issue 4, 2011, pp.605-614. Download Full Text Article (PDF)

3. Different physical and chemical pretreatments of wheat straw for enhanced biobutanol production in simultaneous saccharification and fermentation

Chumangalah Thirmal, Yaser Dahman

Department of Chemical Engineering, Ryerson University, Toronto, Ontario, CANADA M5B 2K3.

Abstract: The objective of this study is to increase butanol product yields using wheat straw as the biomass. First this study examined different pretreatment and saccharification processes to obtain the maximum sugar concentration. Three different physical and chemical pretreatment methods for the wheat straws were examined in the present work in comparison with physical pretreatment alone as a reference. This included water, acidic, and alkaline pretreatment. For all cases, physical pretreatment represented by 1 mm size reduction of the straws was applied prior to each pretreatment. Results showed that 13.91 g/L glucose concentration was produced from saccharification with just the physical pretreatment (i.e., no chemical pretreatment). This represented ~5-20 % lower sugar release in saccharification compared to the other three pretreatment processes. Saccharification with acid pretreatment obtained the highest sugar concentrations, which were 18.77 g/L glucose and 12.19 g/L xylose. Second this study produced butanol from simultaneous saccharification and fermentation (SSF) using wheat straw hydrolysate and Clostridium beijerinckii BA101. Water pretreatment was applied to separate lignin and polysaccharides from the wheat straw. Physical pretreatment was applied prior to water pretreatment where, wheat straw was grounded into fine particles less than 1 mm size. Another experiment was conducted where physical pretreatment was applied alone prior to SSF (i.e. no chemical pretreatment was applied). Both processes converted more than 10% of wheat straw into butanol product. This was 2% higher than previous studies. The results illustrated that SSF with physical pretreatment alone obtained 2.61 g/L butanol.

Volume 2, Issue 4, 2011, pp.615-626. Download Full Text Article (PDF)

4. Performance characteristic of energy selective electron (ESE) heat engine with filter heat conduction

Zemin Ding, Lingen Chen, Fengrui Sun

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

Abstract: The model of an energy selective electron (ESE) heat engine with filter heat conduction via phonons is presented in this paper. The general expressions for power output and efficiency of the ESE heat engine are derived for the maximum power operation regime and the intermediate operation regime, respectively. The optimum performance and the optimal operation regions in the two different operation regimes of the ESE heat engine are analyzed by detailed numerical calculations. The influences of filter heat conduction and the temperature of hot reservoir on the optimum performance of the ESE heat engine are analyzed in detail. Furthermore, the influence of resonance width on the performance of the ESE heat engine in intermediate operation regime is also discussed. The results obtained herein have theoretical significance for understanding and improving the performance of practical electron energy conversion systems.

Volume 2, Issue 4, 2011, pp.627-640. Download Full Text Article (PDF)

5. Carbon footprint reductions via grid energy storage systems

Trevor S. Hale1,3, Kelly Weeks2, Coleman Tucker3

1 Naval Facilities Engineering Service Center, 1100 23rd Avenue. Port Hueneme, CA 93043 USA.

2 Department of Maritime Administration, Texas A&M University at Galveston, Galveston, TX 77553 USA.

3 Department of Management, Marketing, and Business Administration, University of Houston – Downtown, Houston, Texas 77002 USA.

Abstract: This effort presents a framework for reducing carbon emissions through the use of large-scale grid-energy-storage (GES) systems. The specific questions under investigation herein are as follows: Is it economically sound to invest in a GES system and is the system at least carbon footprint neutral?  This research will show the answer to both questions is in the affirmative. Scilicet, when utilized judiciously, grid energy storage systems can be both net present value positive as well as be total carbon footprint negative. The significant contribution herein is a necessary and sufficient condition for achieving carbon footprint reductions via grid energy storage systems.

Volume 2, Issue 4, 2011, pp.641-646. Download Full Text Article (PDF)

6. Characterization of biochar from hydrothermal carbonization of bamboo

Daniel Schneider1, Marina Escala1, Kawin Supawittayayothin2, Nakorn Tippayawong2

1 Institute of Natural Resource Sciences, School of Life Sciences and Facility Management, Zurich University of Applied Sciences, Waedenswil, Switzerland.

2 Department of Mechanical Engineering, Chiang Mai University, Chiang Mai, Thailand.

Abstract: This paper presents a preliminary investigation on producing biochar from bamboo using a technique of hydrothermal carbonization. Laboratory scale experimentation to produce carbonaceous materials was carried out. The suspended biomass samples in water were subjected to hydrothermal carbonization at 220 C, 2.2 MPa in a closed vessel for six hours. The resulting products were in solid and liquid phase. The coal-like biochar was found to have rough surface and porous structure. The aqueous solution was found to contain a high concentration of nutrients, especially nitrogen, phosphorus, and potassium. The study shows that bamboo is an interesting and adequate biomass for the production of biochar with several applications including carbon sequestration.

Volume 2, Issue 4, 2011, pp.647-652. Download Full Text Article (PDF)

7. A biodegradation and treatment of palm oil mill effluent (POME) using a hybrid up-flow anaerobic sludge bed (HUASB) reactor

S. A. Habeeb, AB. Aziz Abdul Latiff, Zawawi Daud,  Zulkifli Ahmad

Faculty of Civil and Environmental Engineering, University Tun Hussein Onn, Malaysia (UTHM).

Abstract: Generally, anaerobic treatment has become a viable alternative in support of industrial wastewater treatment. Particularly, it is used in common to treat the palm oil mill effluent (POME). This study was carried out to assess the start-up performance of a bioreactor hybrid up-flow anaerobic sludge blanket (HUASB). Whereby, three identical reactors of 7.85-l capacity R1, R2, and R3 were operated for 57 days in order to provide two alienated comparisons. Identical operation conditions of organic loading rate (OLR) and hydraulic retention time (HRT) of 1.85 kg.m-3.day-1, and 2.6 day, respectively. R1 was operated in room temperature of 28±2°C, and packed with palm oil shell as filter medium support. R2 was set with room temperature but packed with course gravel. R3 was provided with water bath system to adjust its temperature at 37±1°C mesophilic, while its filter material had to be palm oil shell. During the whole operation period R3 was more efficient for organic materials, where a chemical oxygen demand (COD) removal efficiency of 82% was registered, while R1 and R2 were relatively less efficient of 78%, and 76%, respectively. Furthermore, TSS removal of R3 was also higher than R1, and R2 as registered 80%, 77% and 76%, respectively. On the other hand, turbidity and colour removal were not efficient and needed a post treatment. The seeded sludge was developed in each reactor as illustrated in this paper. Therefore, all reactors show favorable performance of anaerobic treatability of POME as well as good response of microbial species development.

Volume 2, Issue 4, 2011, pp.653-660. Download Full Text Article (PDF)

8. Optimization of injection timing and injection pressure of a DI diesel engine fueled with preheated rice bran oil

R. Raghu1, G. Ramadoss2

1 Department of Mechanical Engineering, Jayam College of Engineering and Technology, Dharmapuri, Tamil Nadu, India.

2 Department of Mechanical Engineering, St. Peter’s University, Chennai, Tamil Nadu, India.

Abstract: In the present study experiments were carried out in a constant speed, stationary direct injection diesel engine and the performance was investigated. Initially the engine fueled with diesel, rice bran biodiesel (methyl ester), raw rice bran oil and preheated rice bran oil with standard injection timing and injection pressures at different load conditions and the performances were compared. With the help of a heat exchanger and using the exhaust gases, the rice bran oil was preheated. It was found that the pre heated rice bran oil exhibits a closer performance as compared to rice bran biodiesel. Then the injection timing and injection were varied and the performance and emission parameters were investigated using preheated rice bran oil. It was found that the brake thermal efficiency and oxides of nitrogen were found to be higher and BSFC and smoke were found to be lower at 21° CA bTDC of injection timing and 230 bar injection pressure. From the test results the optimum injection timing and injection timing for the engine fueled with preheated rice bran oil were evaluated.

Volume 2, Issue 4, 2011, pp.661-670. Download Full Text Article (PDF)

9. Trace metals content (contaminants) as initial indicator in the quality of heat treated palm oil whole extract

Noor Akhmazillah bt Mohd Fauzi1, Mohd Roji Sarmidi2

1 Chemical and Bioprocess Department, Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), 86400 Parit Raja, Batu Pahat, Johor,Malaysia.

2 Chemical Engineering Pilot Plant, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.

Abstract: An investigation was carried out on the effect of different sterilization time on the trace metals concentration of palm oil whole extract. Palm fruits were collected, cleaned and sterilized for 0, 20, 40 and 60 minutes. The kernels were then stripped from the sterilized fruits to get the pulp and later the pulp was pressed using small scale expeller. The resulting puree was centrifuge at 4000 rpm for 20 minutes. The palm oil whole extract were then collected and trace metals analysis was conducted using Inductively Couple Plasma-Mass Spectrometry (ICP-MS). The result showed that the highest yield was obtained at 40 minutes of sterilization with 19.9 ± 0.21 % (w/w). There was no significant different (p < 0.5) in total trace metals content between the degrees of the heat treatment. Na+ was found as the highest trace metals content in the extract with mean concentration ranging from 1.05 ± 0.03 ppm to 2.36 ± 0.01 ppm. 40 minutes of heating time was predicted to have good oil quality due to higher content in trace metals that inhibit the lipase enzyme activity.

Volume 2, Issue 4, 2011, pp.671-676. Download Full Text Article (PDF)

10. Investigations on burning efficiency and exhaust emission of in-line type emulsified fuel system

Yen Kuei Tseng1, Hsien Chang Cheng2

1 Department of Mechanical Engineering, National Chinyi University of Technology, Taiwan.

2 Point Environmental Protection Technology Company Limited, Taiwan.

Abstract: In this research, the burning efficiency as well as exhaust emission of a new water-in-oil emulsified fuel system was studied. This emulsified system contains two core processes, the first one is to mix 97% water with 3% emulsifier by volume, and get the milk-like emulsified liquid, while the second one is to compound the milk-like emulsified liquid with heavy oil then obtain the emulsified fuel. In order to overcome the used demulsification problem during in reserve or in transport, this system was designed as a made and use in-line type. From the results of a series burning tests, the fuel saving can be over 8~15%. Also, from the comparison of decline for the heat value and total energy output of varies emulsified fuel, one can find that the water as the dispersed phase in the combustion process will leading a micro-explosion as well as the water gas effect, both can raise the combustion temperature and burning efficiency. By comparing the waste gas emission of different types of emulsified fuel, one can know that, the CO2 emission reduces approximately 14%, and NOx emission reduces above 46%, that means the reduction of the exhaust gas is truly effectively. From the exhaust temperature of tail pipe, the waste heat discharge also may reduce 27%, it is quite advantageous to the global warming as well as earth environmental protection.

Volume 2, Issue 4, 2011, pp.677-682. Download Full Text Article (PDF)

11. Enzymatic biodegradation of pharmaceutical wastewater

Uwadiae S. E, Yerima Y, Azike R.U

Department of Chemical Engineering, Igbinedion University, Okada, P.M.B 0006, Benin City, Edo State, Nigeria.

Abstract: The present effort is an attempt to reduce pollution caused by the discharge of untreated wastewater (effluents) to the environment by using a low cost method. The effluent was bio-remediated using yeast and amylase as the active agents. The greater the decomposable matters present in an effluent, the greater the oxygen demand; the greater the Biological Oxygen Demand (BOD) and Chemical Oxygen Demand(COD) values, the less Dissolved Oxygen(DO) values. 10g of yeast and amylase were added to 1000ml each of pharmaceutical effluent. 150 ml of the effluent (from the yeast and amylase) dosed was withdrawn weekly for analysis alongside with the effluent without enzymes for turbidity, DO, BOD and COD. After a period of six weeks the effluent dosed with yeast gave the highest performance followed by that dosed with amylase. The result shows that as time increases, the amount of oxygen demand reduces while the dissolved oxygen content of the effluent increases. This indicates that the yeast enzyme was able to aid remediation of the pharmaceutical effluent.

Volume 2, Issue 4, 2011, pp.683-690. Download Full Text Article (PDF)

12. Magnetic field effects on unsteady convective flow along a vertical porous flat surface embedded in a porous medium with constant suction and heat sink

S. S. Das1, J. Mohanty2, P. Das1

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

2 Department of Physics, ABIT, CDA, Sector-I, Bidanasi, Cuttack-753 014, (Orissa), India.

Abstract: The magnetohydrodynamic unsteady convective flow of a viscous incompressible fluid along a vertical porous plate embedded in a porous medium with constant suction and heat sink is considered. Approximate solutions for velocity, temperature, skin friction and rate of heat transfer are obtained by solving the governing equations of the flow field using multi parameter perturbation technique. The effects of various flow parameters affecting the flow field are discussed with the help of figures and table. It is observed that a growing magnetic parameter or heat sink parameter retards the transient velocity of the flow field while the Grashof number or permeability parameter reverses the effect. Further, an increase in magnetic parameter or Prandtl number or heat sink parameter decreases the transient temperature of the flow field. A growing permeability parameter enhances the magnitude of skin friction and the rate of heat transfer at the wall, while the magnetic parameter reverses the effect.

Volume 2, Issue 4, 2011, pp.691-700. Download Full Text Article (PDF)

13. Heat transfer characteristics of R410A during its evaporation inside horizontal tube

M. Fatouh, A.B. Helali, M.A.M. Hassan, A. Abdala

Mechanical Power Engineering Department, Faculty of Engineering at El-Mattaria, Helwan University, Cairo, Egypt.

Abstract: Evaporative local heat transfer coefficients of R22 and R410A are determined in electrically heated a smooth horizontal copper tube with inner diameter of 9.525 mm and length of 1000 mm. Experiments are carried out varying: the vapor quality (0.1:1), the heat fluxes (10:29) kW/m2 and the evaporation temperatures (-5:5ºC) at mass flux of 100 kg/m2s. Effect of the above operating parameters on heat transfer coefficients are investigated and reported in graphical forms. Experimental results showed that the heat transfer coefficients of R410A are better than those of R22, by about 17%  and 14% during the lower and higher value of evaporating pressures and heat flux, respectively. The modified Kattan model  results were found to be in much better agreement with the experimental results than the correlations from Gungor [12], Shah [20] and other correlations.

Volume 2, Issue 4, 2011, pp.701-716. Download Full Text Article (PDF)

14. Spatial and temporal changes of density and chemical composition of heavy oils of Eurasia

Y.M. Polishchuk, I.G. Yashchenko

Institute of Petroleum Chemistry, Siberian Branch of Russian Academy of Sciences, 3 Akademichesky Ave., 634021, Tomsk, Russia.

Abstract: Paper is devoted to analytical review of regularities of spatial and temporal changes of chemical composition and density of heavy oils of Eurasia, which are envisaged as main reserve of world’s oil production industry for future years. The contents of sulfur, paraffin, resin, asphaltene and light fraction in heavy oils and their density were analysed statistically with use the global database on petrochemistry created by Institute of petroleum chemistry. The database includes above 3,660 samples of heavy oils from 62 principal oil-bearing basins in Eurasia. The basic regularities of regional distribution of heavy oils are considered. It is shown that the heaviest oils of Eurasia are in oil-bearing basins of Southern Europe and Southern Asia. The regularities of heavy oil density changes depending on occurrence depth are given. It is shown oil density decreases with depth growth. Maximum values of density of heavy oils are observed in Cenozoic rocks and their minimum values are in Proterozoic rocks. In average, heavy oils are sulfur, high resin, high asphaltenes ones containing small paraffin and small light fractions.

Volume 2, Issue 4, 2011, pp.717-722. Download Full Text Article (PDF)

15. Optimizations of a model external combustion engine for maximum work output with generalized radiative heat transfer law

Kang Ma1,2, Lingen Chen1, Fengrui Sun1

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

2 First Proving Ground, Naval Test Base, Huludao 125001, P. R. China.

Abstract: The generalized radiative heat transfer law is introduced into a model external combustion engine with a movable piston, and effects of heat transfer laws on the optimizations of the engine for maximum work output are investigated in this paper. Numerical examples for the optimizations with linear phenomenological (n=-1), Newton’s (n=1), square (n=2), cubic (n=3) and radiative (n=4) heat transfer laws are provided, respectively, and the obtained results are compared with each other. The results show that work output and efficiency of the optimal fully cyclic operation and optimal semi-cyclic operation decrease with the increase of heat conductance, and the work output, compression ratio and efficiency of the optimal semi-cyclic operation are larger than those of optimal fully cyclic operation. Although all of the curves of volume versus time of the optimal fully cyclic operation and the Euler-Lagrange (E-L) arcs of the optimal semi-cyclic operation are nearly sinusoidal and consist of three stages with the five heat transfer laws, the curves with different heat transfer laws are different.

Volume 2, Issue 4, 2011, pp.723-738. Download Full Text Article (PDF)

16. Numerical parametric investigation of a gasoline fuelled partially-premixed compression-ignition engine

Arash Nemati1, Shahram Khalilarya2, Samad Jafarmadar2, Hassan Khatamnejhad2, Vahid Fathi3

1 Islamic Azad University, Miyaneh Branch, Miyaneh, Iran.

2 Department of Mechanical Engineering, Urmia University, Urmia, Iran.

3 Islamic Azad University, Ajabshir Branch, Ajabshir, Iran.

Abstract: Parametric studies of a heavy duty direct injection (DI) gasoline fueled compression ignition (CI) engine combustion are presented. Gasoline because of its higher ignition delay has much lower soot emission in comparison with diesel fuel. Using double injection strategy reduces the maximum heat release rate that leads to nitrogen oxides (NOx) emission reduction. A three dimensional computational fluid dynamics (CFD) code was employed and compared with experimental data. The model results show a good agreement with experimental data. The effect of injection characteristics such as, injection duration, main SOI timing, and nozzle hole size investigated on combustion and emissions.

Volume 2, Issue 4, 2011, pp.739-748. Download Full Text Article (PDF)

17. Energy management key practices: A proposed list for Malaysian universities

Choong Weng Wai, Abdul Hakim Mohammed, Low Sheau Ting

Centre for Real Estate Studies, Faculty of Geoinformation and Real Estate, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.

Abstract: This study embarks to propose a list of energy management key practices for Malaysian Universities. Energy management is beneficial for Malaysian university that confront expensive energy bill, for it have large build up areas, comprehensive facilities as well as large numbers of building users. The proposed list of energy management key practices is a complement to their existing practices and, to guide them in achieving energy sustainability. A non-experimental, quantitative, and survey research design was used. Questionnaire survey was performed in Malaysian public and private universities to obtain energy coordinators’ perspective on the importance of proposed energy management key practices. This study suggests a total of 47 key practices are vital to manage energy in university, they were grouped into three major phases: “Planning”, “Implementing”, and “Monitoring and Evaluation”. The results show that key practices pertain to involvement, measurement and verification, budget allocation, energy goals and objectives were considered very important by university energy coordinators. Although technology approach seems impressive, result shows it is not their prior choice. Also, some of the soft energy management key practices, such as “develop education plan” and “advice on energy matters” are not considered important by the energy coordinators. The paper confirms the importance of the proposed list of energy management key practices, the list would be applicable to university to monitor and measure their energy performance.

Volume 2, Issue 4, 2011, pp.749-760. Download Full Text Article (PDF)

18. MPFI gasoline engine combustion, performance and emission characteristics with LPG injection

Shankar K. S1, Mohanan P2

1 Department of Mechanical Engineering, P. A. College of Engineering, Mangalore, Karnataka – 574153, India.

2 Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal, Karnataka -575025, India.

Abstract: The present work is aimed at the study of a four cylinder multipoint port fuel injection gasoline engine combustion, performance and emission characteristics which is retrofitted to run with LPG injection. The findings of the experiments suggest that higher thermal efficiency and therefore improved fuel economy can be obtained from SI engines running on LPG as opposed to gasoline. The cycle-by-cycle variation of IMEP with LPG combustion can be reduced by advancing the idle ignition timing. The results of the study at wide open throttle opening conditions indicate that there is an increase in the brake thermal efficiency with LPG use in the engine at higher operating speeds when compared to gasoline at the factory set idle ignition timing of 5o bTDC. The exhaust emissions of CO and HC have reduced considerably. But the NOX emission has increased considerably at elevated engine speeds with LPG fuel when compared to gasoline fuel operation. The results of LPG fuel operation at various idle ignition timings indicate that advancing the timing from 5o bTDC to 6o bTDC has resulted in increased brake thermal efficiency, and reduced emissions of CO and HC, compared to retarding the idle ignition timing to 4o bTDC and 3o bTDC. However advanced idle ignition timing has an adverse effect on NOX emissions as it increases further.

Volume 2, Issue 4, 2011, pp.761-770. Download Full Text Article (PDF)