Improvement of Exhaust Emissions and Thermal Efficiency by High Compression Ratio Combustion in a DI Diesel Engine

Abstract

In order to reduce exhaust emissions and increase the brake thermal efficiency in a direct injection (DI) diesel engine, we pursued the multi-stage fuel injection characteristics and combustion chamber under the common rail fuel injection system and high compression ratio. As a result, the following conclusions were obtained. (1) The high compression ratio combustion was effective to improve exhaust emissions and the break thermal efficiency. (2) The relations between the combustion chamber and gas flow characteristics, the fuel injection characteristics and combustion characteristics were clarified. (3) For the high compression ratio combustion, the after injection was effective to reduce smoke emission.