The effect of aviation fuel jp-8 and diesel fuel blends on engine performance and exhaust emissions

The article presents bench test results of a four-stroke, four-cylinder, naturally aspirated, DI diesel engine operating with neat JP-8 fuel (J) and its blends with Diesel fuel (D) in following proportions by volume: 90/10 (J+10D), 70/30 (J+D30), 50/ 50 (J+D50), 30/70 (J+D70), and 100% diesel fuel (DF). The purpose of the research was to analyse and compare changes occurred in the autoignition delay, combustion events, engine performance efficiency, emissions, and smoke of the exhaust when running on JP-8 fuel, jet-diesel fuel blends, and diesel fuel at a full (100%) engine load and speed of 1400 min-1 at which maximum torque occurs and rated speed of 2200 min-1. It was found that the start of injection (SOI) and the start of combustion (SOC) occurred earlier in an engine cycle and the autoignition delay decreased by 9.0% and 12.7% due to replacement of aviation JP-8 fuel with diesel fuel at a full load and the latter speeds. Maximum in-cylinder pressure was 6.8% and 4.0% higher when operating with diesel fuel, whereas brake thermal efficiency was 3.3% and 7.7% higher, and brake specific fuel consumption 2.8% and 7.0% lower when using fuel blend J+D50 compared with the respective values measured with neat JP-8 fuel. Emissions of nitric oxide (NO) and nitrogen oxides (NOx) were 13.3% and 13.1% higher from a straight diesel running at speed of 1400 min-1, and 19.0% and 19.5% higher at a higher speed of 2200 min-1. The carbon monoxide emissions and total unburned hydrocarbons decreased 2.1 times and by 12.3% when running with fuel blend J+D70 at speed of 2200 min-1compared with those values measured with jet fuel. Smoke of the exhaust was 53.1% and 1.9% higher when using fuel blend J+D10 than that of 46.9% and 70.0% measured with jet fuel at speeds of 1400 and 2200 min-1Generolo Jono Žemaičio Lietuvos karo akademijaVytauto Didžiojo universitetasŽemės ūkio akademij