PERFORMANCE AND EMISSION CHARACTERISTICS OF DIESEL ENGINES FUELED BY VEGETABLE OILS

The aim of the present study is to clarify how utilization methods of vegetable oils influence engine performance and emissions. In the experiment two types of small single cylinder DI diesel engines were employed: Engine A, equipped with a bowl in the piston, is designed for use in fishing boats. Engine B has a toroidal type combustion chamber and is designed for agricultural use. The experiments used BDF (biodiesel fuel) and rape-seed oil as the base fuel: BDF was emulsified with water and rape-seed oil was blended with several kinds of alcohol. The engine performance and emission characteristics were compared with gas oil operation. The emulsified BDF reduced NOx and smoke emissions significantly although the specific energy consumption (BSEC) increased slightly depending on the engine type and operating conditions. Performance tests also showed that with up to 40% (vol.) alcohol addition, the blended fuels with 1-propanol or 1-butanol in rape-seed oil realize stable combustion similar to gas oil operation. The smoke emissions with alcohol blended fuels were somewhat lower than with gas oil while the BSEC was slightly higher with the alcohols. ç