Fumigation of a Diesel Engine with Low Btu Gas 850238
A 0.5 liter single-cylinder, indirect-injection diesel engine has been fumigated with producer gas, a mixture of principally H2, CO, and N2 with a heating value of about 160 Btu/ft3. Producer gas is produced by air-blown gasification of coal or biomass. Measurements of power, efficiency, cylinder pressure, and emissions were made. At each operating condition, engine load was held constant, and the gas-to-diesel fuel ratio was increased until abnormal combustion (severe efficiency loss, missfire, knock, or preignition) was encountered. This determined the maximum fraction of the input energy supplied by the gas, Emax, which was found to be dependent upon injection timing and load. At light loads, Emax was limited by severe efficiency loss and missfire, while at heavy loads it was limited by knock or preignition. The highest value of Emax that could be obtained at full load was 48% at a timing of 2 CAD BTDC, while the highest overall value of Emax, 72%, was obtained at 20% load, at a timing of 11 CAD BTDC. Fumigation generally increased ignition delay and heat release rates, but peak pressures were not strongly influenced. Efficiency was slightly decreased by fumigation as were NOx and particle emissions while CO emissions were increased.