Performance and emissions of hydrogen internal combustion engine with hot EGR

The hydrogen engine combustion performance and emission characteristics were investigated based on a port fuel injection (PFI) H₂ICE test sysytem equipped with hot EGR system. Experimental results show that using hot EGR can significantly reduce the maximum cylinder pressure and temperature and slightly increase ignition delay period and combustion duration. Increasing EGR rate has no obvious effect on indicated mean effective pressure (IMEP) and working cycle variations, which means EGR has a little impact on the engine power output and ride comfort. When EGR rate is large enough at middle load, NO_x emission is reduced greatly, but only a moderate EGR rate is needed for NO_x emission control at high load, because an excessive EGR rate would lead to significant reduction in power output and fuel economy.