Study of cycle-by-cycle variations of a spark ignition engine fueled with natural gas/hydrogen blends was investigated. Natural gas/hydrogen blends with hydrogen volumetric fraction in the fuel blends of 0%, 12%, 23%, 30% and 40% were experimentally studied. The effect of hydrogen addition on the cycle-by-cycle variations of the natural gas engine operation was analyzed. The results showed that the maximum pressure rise, the maximum rate of pressure rise and the indicated mean effective pressure increased and their corresponding cycle-by-cycle variations decreased with the increase of hydrogen fraction in the blends under lean mixture condition. The above parameters and their corresponding crank angles show the higher inter-dependency with the increase of hydrogen fraction at lean mixture operation. The coefficient of variation of the indicated mean effective pressure (COVimep) maintained at the low level under stoichiometric and relatively rich mixture operation while it decreased with the increase of hydrogen fraction under lean mixture operation. The corresponding excessive air ratio at COVimep = 10% would extend to the leaner mixture with the increase of hydrogen fraction and this indicated that the stable lean limit of natural gas engine could be extended with hydrogen addition.
|Number of pages||7|
|Journal||Neiranji Xuebao/Transactions of CSICE (Chinese Society for Internal Combustion Engines)|
|Publication status||Published - 1 Jan 2009|