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Performance and combustion characteristics of a diesel-pilot gas injection engine Gunawan, Hardi

Abstract

High pressure injection of natural gas with diesel liquid pilot fuel has been investigated in a single-cylinder two-stroke diesel engine of low compression ratio. The thermal efficiency and emissions of NOx, CO and HC were determined at 1200RPM as a function of load. Variations of the pilot-diesel energy to total heat energy ratio (in the range 15 -25%) strongly affected efficiency and emissions rate. Gas injection pressure was also shown to be an important variable. The thermal efficiency of the gas-diesel engine was shown to exceed that of the conventional diesel at full load, and is less at low load in the present configuration. The combustion rate analysis has been used to determine the pressure rise (ignition time) delay and combustion duration as well as the characteristic burning pattern. At low load late burning high cyclic variations, and incomplete combustion are associated with peak compression temperature lower than 900 K.

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