bio-hydrogen and bio-ethanol as alternative fuels compared with gasoline from the viewpoints of performance and emissions

the strict environmental laws, the cost of oil and its limited resources, have made the engine manufacturers to think of other energy resources rather than oil and its products. in this study the effect of exhaust gas recirculation (egr) on performance and emission characteristics of a si engine fueled separately with gasoline, bio-hydrogen and bio-ethanol have been compared and discussed. in order to do that the engine has been simulated with a three dimensional computational fluid dynamics (cfd) code. the validation results prove that the code has the ability to evaluate performance and emission characteristics of this engine. the results show that in the identical condition as the egr rate raised, although emission levels plummeted, but due to substantial fall in flame speed, a significant decrease in indicated mean effective pressure (imep) levels occurs. bio-hydrogen even though, because of its high heating value shows the least imep decrease in comparison with the other fuels.