Experimental Study on Engine Performance and Emissions Fuelled with CNG-Hydrogen Blends Combined with EGR

An experimental study on the performance and emissions of a spark ignition engine with natural gas-hydrogen blends combined with EGR was conducted.The results show that the engine power output decreased with the increase of exhaust gas recirculation ratio(),and hydrogen enrichment at a considerable  could improve the engine power output.Brake specific fuel consumption decreased first and then increased with the increase of ,and its value was minimum when =5%.Brake specific fuel consumption decreased with the increase of hydrogen fraction.For a specified hydrogen fraction,NOx concentration decreased with the increase of ,which was more obvious at high hydrogen fractions.HC and CO emissions increased with the increase of  and decreased with the increase of hydrogen fraction.The higher performance and the lower emissions of the engine could be obtained when φ(H2)=20% and =10%.