Measurements and predictions of the fuel consumption and emission of a spark ignition engine fuelled with hydrogen-enriched gasoline

The effect of the amount of hydrogen addition on the fuel consumption and emission of a spark ignition engine has been studied. Dynamometer test results for a wide range of engine speeds, engine loads, equivalent ratio and hydrogen enrichment under steady state operation are presented, and the engine requirements for minimum b.s.f.c. are specified. A detailed model to simulate a four-stroke cycle of a spark ignition engine fuelled with hydrogen-enriched gasoline was used to predict the optimal amount of hydrogen supplement as well as the corresponding minimum best torque (MBT) optimal throttle position and emissions levels of CO and NO_x. It has been shown that a significant reduction in the b.s.f.c, in the order of 20 per cent, is achieved with hydrogen-enriched gasoline for a hydrogen-fuel mass ratio of 6 per cent and equivalence ratio of 0.65. A very smooth operation has been observed under these conditions. The energy conversion gain is prominent at partial loads and depends only to a limited extent on the engine speed.