Experimental study on performance and emission of hydrogen internal combustion engine using hot EGR

The combustion products of hydrogen internal combustion engine (HICE) are different from those of the traditional engines. The mechanism of exhaust gas recirculation (EGR) applied on HICE is also different from traditional engines. To explore the effect of hot EGR on the performance and emissions, an experimental research was carried out in a 4 cylinder, 2.0 L HICE. The combustion characteristic was analyzed to study the EGR mechanism in HICE. The experimental results showed that, when cyclic hydrogen remains constant, mixture equivalence ratio can be adjusted by the change of EGR rate. EGR has a little effect on torque under the conditions of mixture equivalence ratio less than unity. However, the torque decreases linearly with the increase of EGR rate under the conditions of equivalence ratio larger than unity. NO_x emission deteriorates as temperature in cylinder is increased by hot EGR at partial load. Engine operating on mixture equivalence ratio slightly than the stoichiometric mixture combined with hot EGR at full load can get low NO_x emission behind the three-way catalyst with the acceptable torque decrease.