O. Badr et al., A PARAMETRIC STUDY ON THE LEAN MISFIRING AND KNOCKING LIMITS OF GAS-FUELED SPARK-IGNITION ENGINES, Applied thermal engineering, 18(7), 1998, pp. 579-594
Increasing emphasis on gaseous fuels as clean, economical and abundant
fuels encourages the search for optimum operating conditions of gas-f
ueled internal combustion engines. In this context, this paper present
s the experimental results of a parametric study on the lean operation
al limits of a Ricardo E6 engine using propane and liquefied petroleum
gas (LPG) as fuels. Three different criteria for defining the engine
lean limit are used. The first is associated with the first detectable
misfire on leaning the mixture, the second is the first detectable fi
ring under motoring conditions when the mixture is being enriched slow
ly, while the third is when the torque reaches zero on leaning the mix
ture. In addition, the lean knocking limit for some experiments is pre
sented. The effects of speed, spark timing, compression ratio, intake
temperature, intake pressure (supercharging), and relative humidity of
intake air on the engine operational limits are presented and discuss
ed in relation to chemical reaction rates, ignition delay, amount of r
esidual gases, turbulence, and heat transfer. (C) 1998 Published by El
sevier Science Ltd. All rights reserved.