Abstract

This paper investigates the effects of LPG injection during air inlet period on emissions and performance characteristics. The engine has been modified to determine the best LPG composition for dual operation in order to improve the emissions quality while maintaining high thermal efficiency in comparison to a conventional diesel engine. An electronic controlled LPG injection system has been developed for this purpose. LPG injection rate were selected as 5, 10, 15 and 25% on a mass base. Minimum SFC and maximum brake efficiency obtained with 15% LPG between 1400 and 1800 rpm engine speeds. Optimum injection rates is found at 5% LPG in terms of exhausts emissions and performance. At this injection rate, SFC, NOx and smoke emissions decreased by 9, 27.6 and 20% at the test speed of 1600 rpm, respectively.

Key words: Diesel engine, dual fuel, LPG, emissions, performance.