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 en-gines after gasoline. It has a wider operating range than gasoline and less harmful exhaust emissions are pro-duced. However, when LPG is used as fuel instead of gasoline, the engine output power reduces approxi-mately 5-10%. This is be-cause, LPG occupies 15-20% a larger volume (compared to gasoline) in intake mani-fold. 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 pa-rameter that reduces energy density hence the volumet-ric efficiency is the increase of the charge temperature of fuel-air mixture. Increase in the temperature of mix-ture causes decrease in the energy density in intake manifold and thus causes reduction in engine perfor-mance. In this study, an experimental system has been established to investi-gate the effect of LPG fuel temperature on engine per-formance and exhaust emissions. Experiments carried out in high speed under high load shown that, with increase in the LPG fuel temperature at regula-tor outlet; engine output power reduced by nearly 1.85% while NO emission increased by 7%.