1Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, I.R. IRAN
2Department of Mechanical Engineering, University of Tehran, Tehran, I.R. IRAN
Nowadays, increased attention has been focused on internal combustion engine fuels. Regarding environmental effects of internal combustion engines particularly as sources of pollution and depletion of fossil fuels, compressed natural gas has been introduced as an alternative to gasoline and diesel fuels in many applications. A high research octane number which allows combustion at higher compression ratios without knocking phenomenon and with good emission characteristics of unburned hydrocarbons and carbon monoxide are major benefits of compressed natural gas as an engine fuel. In this paper, natural gas as an alternative fuel in a spark ignition engine, has been considered. Engine performance and exhaust emissions have been experimentally studied for both natural gas and gasoline fuels in a wide range of engine operating conditions.
 Shamekhi, A., Khatibzadeh, N., Shamekhi, A.H., Performance and Emissions Characteristics Inves-tigation of a Bi-Fuel SI Engine Fuelled by CNG and Gasoline, Proceedings of ASME, Internal Com-bustion Engine Division, Paper No.ICES2006-1387 (2006).
 Lapetz, J., McCarthny, D., Greenfield, N., Czapski, R., Geftos, T., Rosson, J., Development of the Ford QVM CNG Bi-Fuel 4.9L F-Series Pickup Truck, Society of Automotive Engineers, Paper No. 960850 (1996).
 Duan, S.Y., Using Natural Gas in Engines: Laboratory Experience with the use of Natural Gas Fuel in IC Engines, IMechE Seminar Publication, pp. 39-46 (1996).
 Johansson, B. and Olsson, K., Combustion Chambers for Natural Gas SI Engines, part 1: Fluid Flow and Combustion, Society of Automotive Engineers, Paper No. 950469 (1995).
 Johansson, B. and Olsson, K., Combustion Chambers for Natural gas SI Engines, part 2: Fluid Flow and Combustion, Society of Automotive Engineers, Paper No. 950517 (1995).
 Evans, R.L., Blaszczyk, J., Fast-Burn Combustion Chamber Design for Natural Gas Engines, ASME Journal of Engineering for Gas Turbines and Power, 120 (1998).
 Swain, M.R., Yusuf, M.J., Dulger, Z. and Swain, M.N., The Effect of Hydrogen Addition on Natural Gas Engine Operation,Society of Automotive Engineers, Paper No. 932775 (1993).
 Zuo, C., Zhao, K. A., Quasi-dimensional Model of SI Natural Gas Engines with Pre-chamber, Society of Automotive Engineers, Paper No. 972994 (1997).
 Evans, R. L., Blaszczyk, J. A., Comparative Study of The Performance and Exhaust Emissions of a Spark Ignition Engine Fuelled by Natural Gas and Gasoline, Proc. Inst. Mech. Engrs., D00295 (1997).
 Manivannan, A., Tamil Porai, P., Chandrasekaran, S., Ramprabhu, R., Lean Burn Natural Gas Spark Ignition Engines-An Overview, Society of Auto-motive Engineers, Paper Series 2003-01-0638 (2003).
 Chiodi, M., Jurgen Berner, H., Baragende, M., Investigation on Mixture Formation and Combustion Process in a CNG Engine Using a Fast Response 3d cfd Simulation, Society of Automotive Engineers, Paper Series 2004-01-3004 (2004).
 Shamekhi, A. H. and Ghaffari, A., An Improved Model for SI Engines, ASME Technical Conference, ICEF-2004-818 (2004).
 Volpato, O., Theunissen, F., Mazara, R., Engine Management for Multifuel Plus Compressed Natural Gas Vehicles, Society of Automotive Engineers, Paper Series 2005-01-3777 (2005).
 Aslam, M. U., Masjuki, H. H., Kalam, M. A., Abdessalam, H., Mahlia, T.M.I, Amalina, M.A., An Experimental Investigation of CNG as an Alternative Fuel for a Retrofitted Gasoline Vehicle, Journal of fuel research, Fuel 85, p. 717 (2006).
 Matranga, Kimberly R., Myers, Alan L., Glandt, Eduardo D., Storage of Natural Gas by Adsorption on Activated Carbon, Chemical Engineering Sciences, 47 (7), p. 1569 (1992).
 Lozano-Castello, D., Alcaniz-Monge, J., Casa-Lillo, M. A., Cazorla-Amoros, D., Linares-Solano, A., Advances in the Study of Methane Storage in Porous Carbonaceous Materials, Fuel, 81(14), p. 1777 (2002).
 Pupier, O., Goetz, V., Fiscal, R., Effect of Cycling Operations on an Odsorped Natural Gas Storage, Chemical Engineering and Processing, 44 (1), p. 71 (2005).
18] Basumatary, R., Dutta, P., Prasad, M.,Srinivasan, K., Thermal Modeling of Activated Carbon Based Adsorptive Natural Gas Storage System, Carbon, 43 (3), p. 541 (2005).
 Kato, K., Igrahashi, K., Masuda, M., Otsubo, K., Yasuda, A., Takeda, K. and sato, T., Development of Engine for Natural Gas Vehicle, Society of Automotive Engineers, Paper No. 01-0574 (1999).
 Tilagone, R., Monnier, G., Chaouche, A., Baguelin, Y., Chauveron, D.S., Development of a High Efficiency, Low Emission SI-CNG Bus Engine, Society of Automotive Engineers, Paper No. 961080 (1996).
 Kubesh, J. T., Igarashi, D. J., Gugliemo, K.H. and McaCaw, D., Development of an Electronically-Controlled Natural Gas-Fueled John Deere Power Tech 8.1L Engine, Society of Automotive engineers, Paper No. 951940, p. 788 (1995).
 Goto, S., Itoh, Y., Higuchi, Y., NIGATA Ultra Lean Burn SI Gas Engines-Achieving High Efficiency and Low NOx Emissions, Society of Automotive Engineers, Paper No. 901608 (1990).
 Bhargava, S., Clark, N., Hildebrand, W., Exhaust Gas Recirculation in a Lean Burn Natural-Gas SI Engines, Society of Automotive Engineers, Paper No. 981385 (1998).
 Chi-Burn, I., Sang-Ho, K., Catalyst Technology Satisfying Low Emissions of Natural Gas Vehicle, Society of Automotive engineers, Paper No. 970744 (1997).