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In this paper, a simplified prediction model for aiming to design an engine control system of Homogeneous Charge Compression Ignition (HCCI) engine has been developed. Developed HCCI engine model is for rebreathing concept and employs the discretized cycle concept to realize fast calculation speed. The ignition timings are predicted by Livengood-Wu integration combined with a function of ignition delay and the combustion durations are predicted from supplied fuel mass quantity. Maximum pressure and its phase are compared to experiments. In addition, for designing an HCCI engine, the models to predict appropriate operation conditions are considered.

This study aims to develop a small size gas engine system with biomass gas by modifying the control system of a conventional spark ignition engine. In this paper, combustion characteristics of typical biomass gas assuming the wood chip pyrolysis gas, whose lower heating value was about 1/6 of the city gas in Japan, were investigated. Engine control system for biomass gas was also examined. It was confirmed that simulated biomass gas could achieve high thermal efficiency and stable combustion for wide range equivalence ratio without knocking and at low emissions. Automatic engine operation with real time in-cylinder gas pressure analysis was also tried under fuel composition change.