Effect of Jet A-1/Ethanol Fuel Blend on HCCI Combustion and Exhaust Emissions

This paper deals with the effects of adding Jet A-1 fuel to ethanol (E) in proportions of 20/80 vol% in biofuel homogeneous charge compression ignition (HCCI) combustion. Experiments were performed with a four-stroke direct injection (DI) diesel engine, the first cylinder of which was converted to operate in HCCI mode with various air/ethanol and air/Jet20E80mixtures characterized by relative air:fuel ratios of =3.01-2.02 and 3.84-1.90 and externally prepared in the intake manifold at the inlet air temperature of 100 degrees C. We studied the effects of Jet20E80 fuel blends on start of combustion (SOC), maximum heat release rate, burn angle mass burn fraction (MBF) 50, combustion duration, maximum in-cylinder pressure, and temperature indicated mean effective pressure (IMEP), thermal efficiency, coefficient of variation (COV) of maximum in-cylinder pressure and IMEP, as well as smoke and exhaust emissions. The air/Jet20E80mixture improved HCCI combustion-phasing control, suggesting higher engine efficiency and ecological benefits. The start of combustion (SOC) occurred 2.2 crank angle degrees (CAD) later in the cycle, which enhanced the maximum heat release rate and the peak in-cylinder pressure by 37.2 and 23.1% and IMEP and thermal efficiency by 49.0 and 16.0%, respectively. The IMEP coefficient of variation decreased to its lowest level, 3.73%, when running with the richest air/Jet20E80mixture, =1.90, at a constant speed of 1,400rpm. The production of NOx and total unburned hydrocarbon (THC) emissions decreased 2.8 and 1.3 times, while smoke and CO emissions were 2.5 and 1.6 times higher than the amounts that HCCI combustion of neat ethanol produces under these conditions.