Investigation of the cold-start engine performance at a low temperature for an engine fuelled with alternative fuel

Abstract

With the stringent emissions regulations for spark ignition engines, attention has always been paid to the cold-start emissions of hydrocarbons and carbon monoxide. The engine speed is an external parameter that can reflect the combustion quality. In this paper, a four-cylinder spark ignition engine fuelled with gasoline and methanol–gasoline blends with methanol fractions of 10%, 30% and 85% is studied; the cold-start transient performances are investigated at ambient temperature of 15 °C, −7 °C, −15 °C and −25 °C respectively. The engine speed curves indicate the existence of misfire cycles and incomplete combustion cycles, which are proved by the measured in-cylinder temperatures and the data on the indicated mean effective pressure. The experimental results show that the addition of methanol increases the starting time at low temperatures, which improves the combustion, however. The engine started successfully for all the blending ratios and ambient temperatures except for the 85% methanol–gasoline blend at −25 °C. During the cold-start process, the peak speed and the transient period increase with increasing methanol fraction, while the speed fluctuations decrease. Thus the addition of methanol improves the cold-start performance of the engine.