Simulation has been done for HCNG blends used in an unmodified engine i.e. engine calibrated for CNG operation.
18% HCNG blend (without CO2) has higher CO, NO and CH4 emissions as compared to CNG and WOT power at full load increase by 3%.
NO and CH4 emissions can be decreased by controlling the formation of CO2 in 18% HCNG using compact reforming process.
Thermal efficiency of the light duty engine using 6% CO2 in 18% HCNG increases by 4–5%.
18% HCNG having 5–6% CO2 is optimum for Indian light duty CNG vehicles as it doesn't require any vehicular modifications.