An Investigation of Effect of Fuel Temperature on Engine Performance and NO Emissions in a Spark Ignition Engine Running on LPG

Abstract

LPG is the second most commonly used fuel in the world in spark-ignition engines after gasoline. It has a wider operating range than gasoline and less harmful exhaust emissions are produced. However, when LPG is used as fuel instead of gasoline, the engine output power reduces approximately 5-10%. This is because, LPG occupies 15-20% a larger volume (compared to gasoline) in intake manifold. Since this lowers the energy density of the fuel-air mixture, power output of the engine reduces in parallel to the reduction in the amount of energy drawn into the cylinder at each cycle. Another parameter that reduces energy density hence the volumetric efficiency is the increase of the charge temperature of fuel-air mixture. Increase in the temperature of mixture causes decrease in the energy density in intake manifold and thus causes reduction in engine performance. In this study, an experimental system has been established to investigate the effect of LPG fuel temperature on engine performance and exhaust emissions. Experiments carried out in high speed under high load shown that, with increase in the LPG fuel temperature at regulator outlet; engine output power reduced by nearly 1.85% while NO emission increased by 7%.