Experimental study on NO_x emissions of hydrogen internal combustion engine

Experimental study was carried out on the characteristics of combustion and NO_x emissions of a 2.0 L hydrogen internal combustion engine (HICE). The correlations between NO_x emissions and both equivalence ratio Φ and ignition timing were examined. Experimental results show: at Φ=0.88 the NO_x emissions reach maximum value; when Φ is below 0.88 the NO_x emissions increase with Φ increasing and when Φ is in the range of 0.88 to 1.2 the NO_x emissions decrease quickly with Φ increasing. For lean mixture the effect of ignition timing on NO_x formation is relatively small. The achievements are useful to development of HICE lean combustion technique to reduce effectively its NO_x emissions.