Effect of advanced injection timing on the performance of rapeseed oil in diesel engines

被引:147
作者
Nwafor, OMI [1 ]
Rice, G [1 ]
Ogbonna, AI [1 ]
机构
[1] Fed Univ Technol, Dept Mech Engn, Owerri, Imo, Nigeria
关键词
advanced period; brake specific fuel consumption; brake thermal efficiency; exhaust and cylinder wall temperatures; ignition delay; mechanical efficiency; hydrocarbon emissions;
D O I
10.1016/S0960-1481(00)00037-9
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Combustion studies on both diesel fuel and vegetable oil fuels, with the standard and advanced injection timing, were carried out using the same engine and test procedures so that comparative assessments may be made. The diesel engine principle demands self-ignition of the fuel as it is injected at some degrees before top dead centre (BTDC) into the hot compressed cylinder gas. Longer delays between injection and ignition lead to unacceptable rates of pressure rise with the result of diesel knock because too much fuel is ready to take part in premixed combustion. Alternative fuels have been noted to exhibit longer delay periods and slower burning rate especially at low load operating conditions hence resulting in late combustion in the expansion stroke. Advanced injection timing is expected to compensate these effects. The engine has standard injection timing of 30 degrees C BTDC. The injection was first advanced by 5.5 degrees C given injection timing of 35.5 degrees C BTDC. The engine performance was very erratic on this timing. The injection was then advanced by 3.5 degrees C and the effects are presented in this paper. The engine performance was smooth especially at low load levels. The ignition delay was reduced through advanced injection but tended to incur a slight increase in fuel consumption. Moderate advanced injection timing is recommended for low speed operations. (C) 2000 Elsevier Science Ltd. All rights reserved.
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页码:433 / 444
页数:12
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