Automatic operation system of HCCI engine with Gas fuel from biomass

Two types of the automatic HCCI engine control systems to use biomass gas were developed. One is to use inhomogeneity of pre-mixture, and another one is to use city gas 13A to control ignition and combustion. Ion current measurement system was applied to detect the combustion behavior for the variation of biomass gas and was also used for the closed loop control systems. From these systems, it was clarified that the maximum timing of the ion current and the rate of heat release have correspondence regardless of fuel compositions and inhomogeneity of mixture. In both control systems, setting the maximum timing of ion current to a constant value is enough to achieve higher thermal efficiency. Both systems succeeded to operate the engine for varying compositions of biomass gas, although the combustion system using city gas 13A shows better applicability than the inhomogeneity of mixture control system.