Exhaust emissions of a H2-enriched heavy-duty diesel engine equipped with cooled EGR and variable geometry turbocharger

► The addition of H2 to diesel engine increases substantially NO2 emissions. ► The addition of H2 to diesel engine reduces PM, CO and CO2 emissions. ► The increased NO2 emissions are due to unburned H2. ► Engine load is an important factor affecting the impact of H2 on NOx emissions.