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

100%

Labeckas G. , Slavinskas S. , Vilutienė V.

tom Vol. 22, No. 2

129--138

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 (CO) emissions and total unburned hydrocarbons (HC) decreased 2.1 times and by 12.3% when running with fuel blend J+D70 at speed of 2200 min–1 compared 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–1. The engine produced 34.5% more smoke from combustion of fuel blend J+D70 at the low speed of 1400 min–1, but smoke converted to be 11.3% lower when operating at a higher speed of 2200 min–1.

Analysis of combustion processes in ci engine fuelled either with diesel fuel or rape oil methyl ester and additionally with ethanol

84%

Kowalewicz A.

tom Vol. 13, No. 2

225-240

At the conference KONES’2005 combustion characteristics of CI engine fuelled with rape oil methyl ester (RME) and ethanol injected into inlet port have been presented. In this paper combustion processes in the engine fuelled with two base fuels: diesel oil (DF) or rapeseed oil methyl ester and additionally with ethanol have been analyzed and combustion parameters have been compared. Ethanol fraction has a serious influence on combustion. Addition of ethanol delays combustion in the initial stage but despite of that, combustion is completed earlier if the ethanol fraction is higher. This phenomenon takes place for both base fuels: RME and DF. However, for high speed (2200 rpm) and torque = 20 Nm (pe= 0,256 MPa) ignition delay of DF was so long, that ignition took place 15 CA deg ATDC. Nevertheless of that, combustion was completed only about 5 CA deg later than for neat DF. Combustion processes for both fuels are similar, but there are some differences in ignition delay. At low load and high speed for fuelling with DF combustion extends for exhaust stoke. On account on diesel – knock the engine can not be loaded by higher torque at high speed. Besides ethanol fraction, there is a strong influence of load and speed on combustion parameters. Generally increase of speed decreases maximum pressure and increase of load increases it, as well for RME as for DF. The highest pressure has been measured for DF and ethanol injection.