화학공학소재연구정보센터
Fuel, Vol.97, 157-165, 2012
Experimental investigation of the behavior of non-esterified rapeseed oil in a diesel engine mechanical fuel injection system
The study investigates the effects of non-esterified rapeseed oil, a commonly used liquid first-generation renewable bio-fuel utilized in existing compression ignition engines, on the behavior of the fuel in the high-pressure diesel fuel injection system with a traditional mechanically controlled fuel injection pump. The experiments were carried on a Zetor tractor engine powered by diesel fuel, biodiesel and heated fuel-grade rapeseed oil, instrumented with direct and low-cost indirect fuel injection line pressure sensors. The order-of-magnitude higher viscosity, higher bulk modulus, and higher density of rapeseed oil compared to diesel fuel were found to have measurable effects on the fuel delivery timing, fuel pressure, load on the fuel injection pump, and maximum fuel delivery rates. The low-cost clamp-on pressure sensors provided a good quantitative information about the injection timing but only a qualitative information about the absolute pressure. With rapeseed oil, the load on the fuel injection pump was slightly increased, and the rapeseed oil was delivered earlier and at higher pressures, counteracting the poorer atomization and increased combustion delay, with differences between heated rapeseed oil and diesel fuel decreasing with increasing fuel temperature, but subject to diminishing returns. The fuel temperatures at the injector were markedly higher than at the injection pump inlet at higher engine load, and lower at lower loads. Looping fuel return line to the fuel filter inlet accelerated the warm-up of the fuel. Heating of the fuel past about 55 degrees C and additional electric heating of the high-pressure injection lines had no marked effects on combustion timing or exhaust emissions. (C) 2012 Elsevier Ltd. All rights reserved.