COMBUSTION, PERFORMANCE AND EXHAUST EMISSIONS OF THE DIESEL ENGINE OPERATING ON JET FUEL

Abstract

The article focuses on bench testing results of a four-stroke, four-cylinder, direct-injection, naturally aspirated diesel engine operating on the normal 95vol% (class C) diesel fuel + 5vol% RME (DF), F-34 jet fuel (JF) and jet fuel F-34 treated with the cetane improver (JF+0.12vol%). The purpose of the research is to investigate the availability to use of military F-34 jet fuel for land-based direct injection diesel engine powering and examine the effect of F-34 fuel and F-34 fuel treated with 0.12vol% 2-ethylhexyl nitrate on the autoignition delay, combustion, engine performance, emissions and smoke opacity of the exhausts. The peak in-cylinder gas pressure generated from JF and JF+0.12vol% is lower by 4.3% and 2.8% at 1400 min –1 speed, and 2.5% and 5.7% at 2200 min –1 speed compared to that 86.6 MPa and 82.5 MPa of the normal diesel. At rated 2200 min –1 speed, the use of treated jet fuel leads to smoother engine performance under all loads and the maximum cylinder pressure gradient lowers by 9.4% as against that 15.9 bar/deg of base diesel. The minimum brake specific fuel consumption (bsfc) for F-34 and treated F-34 fuels decreases by 4.8% and 3.5% at 1400 min –1 speed and increases by 2.7% and 3.7% at 2200 min –1 speed compared to 249.5 g/kWh and 251.8 g/kWh values of base diesel. Maximum NO emissions produced from fuels JF and JF+0.12vol% decrease by 11.5% and 7.0% at 1400 min –1 , and 17.1% and 17.3% at 2200 min –1 speed compared to 1705 ppm and 1389 ppm emanating from the normal diesel. Maximum CO emissions produced from jet fuel JF and JF+0.12vol% decrease by 39.3% and 16.8% compared to that 4988 ppm produced from base diesel running at 1400 min –1 speed. At 2200 min -1 speed, the ecological effect of using fuel F-34 fuel decreases and the CO sustains over the whole load range at the same level and increases by 2.5% and 3.0% with regard to the normal diesel operating under high load. The HC emission also is lower by 78.3% and 58.8% for low and high loads compared to 230 ppm and 1820 ppm of the normal diesel running at 1400 min –1 speed. The smoke opacity generated from fuels JF and JF+0.12vol% sustains at lower levels over the all load range with the maximum values decreased by 14.6% and 8.1% with regard to 94.9% of the normal diesel operating at 1400 min –1 speed. The test results show that military F-34 fuel is a cleaner-burning replacement of diesel fuel and suggests fuel economy with reduced all harmful species, including NO, NO 2, NO x, CO, HC, and smoke opacity of the exhausts.