Fuel Design Concept for Robust Ignition Process in Compression Ignition Engines

Abstract

A fuel design concept for an HCCI engine to optimize a profile of heat release and achieve a robust ignition process has been proposed and applied to design the optimal methane-based blend. According to results from detailed chemical kinetic computations where ignition process chemistry of each component of the natural gas was analyzed, ethane indicates a low ignitability close to that of methane with an initial temperature below 800 K, but a higher ignitability close to those of propane, n-butane and isobutane with an initial temperature above 1100 K. And ethane indicates a higher heat release rate than those of the other components in a late stage of an ignition process. According to results from engine operating tests with a compression ratio of 28.0 : 1, a dual-component fuel of the main component of methane and the sub component of ethane demonstrates a lower COV of IMEP than those of the other dual-component fuels with the sub components of propane, n-butane and isobutane, when the timing of 10 % heat release is set at the same crank angle in the expansion stroke.