Effect of mixing CO2 with natural gas-hydrogen blends on combustion in heavy-duty spark ignition engine

► Performance and emission characteristics of an engine fueled natural gas-hydrogen blends for each CO2 content were examined. ► The thermal efficiency decreased as the content of CO2 increased. ► The increased heat capacity of mixture reduced the combustion temperature and NOx emissions. ► THC emissions and the methane portion of them were increased with the introduction of CO2.