Experimental and Numerical Investigation of Colded Exhaust Gas Recirculation Effect on Performance and Emission of Lean Burn Spark Ignition Engine with Natural Gas and Pre-Chamber

In the present research, the performance of a single-cylinder engine with a pre-chamber and natural gas fuel designed in Urmia University has been investigated and the effect of Exhaust Gas Recirculation (EGR) on engine performance has been analyzed. The results indicate that the simultaneous use of the pre-chamber and the EGR reduces significantly nitrogen oxides emission. Also, the amount of unburned hydrocarbons (HC) decreases in the low EGR, but the amount of HC increases significantly with higher EGR. EGR increases the carbon monoxide (CO) emission but does not have a significant effect on carbon dioxide (CO2) emission. Simultaneous use of EGR and pre-chamber can reduce the amount of emission while it can maintain the engine braking. The engine power and the indicated mean effective pressures (IMEP) which are the main indicators of the engine's performance, decrease by 3 to 4 percent for every 5 percent of the EGR. The results show that the EGR reduces the velocity of the jet flames out of the pre-chamber which ultimately reduces the advance of the flame front. Analysis of the results of the experimental test and the simulated model shows that an ideal range for EGR in an engine with a pre-chamber can be defined in which the emission is minimal and the engine power is maintained. In the engine used in this research, the exhaust gas reaction is in the ideal 10% range.