Experimental Investigation of Performance and Emissions of a Sequential Port Injection Compressed Natural Gas Converted Engine

A single cylinder port injection gasoline engine was converted to a bi-fuel gasoline-compressed natural gas operation. The engine was run at wide open throttle and speeds ranging from 1500 to 5000 rpm. Cylinder pressure and air-fuel flow rate were recorded to calculate the indicated performance. Results show CNG operation yields higher FCE and lower ISFC. However, the indicated power, indicated torque, IMEP and volumetric efficiency of CNG were reduced due to lower charge density and slower flame speed. In terms of exhaust emissions, CNG shows significantly lower emission of HC, CO₂ and CO. The NO_x emission however shows mixed behavior.