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Spark ignition natural gas engines with prechamber, having high thermal efficiency and low exhaust emissions, have been developed due to energy resources and air pollution problems in recent ten years. A lot of significant results on experimental have been given, but the reports on combustion model were few seen so far. This paper discribles a quasidimensional combustion model for the engines with prechamber. A simulation method for calculating turbulent intensity in cylinder and a submodel for jet orifices between two chambers are put forward. It showed by testing that calculated data showed good general agreement with the corresponding experimental values.

This paper describes the development of a natural gas engine with a prechamber. The comparison between a conventional gas engine and the engine with the prechamber is given. The testing results show that the new combustion system is reliable and practical. The performance of the engine, compared to the conventional gas engine, is greatly improved due to stable ignition and quick flame propagation in the prechamber and a high burning rate and short burning period in main chamber. The analyses of the combustion processes and lean combustion potential in the engine are further discussed.

There is a worldwide interest in the research of various alternative fuels for automotive engines for the purpose of reduction of CO2 and toxically harmful exhaust emissions. Coal-bed gas, the main component of which is methane, has been considered an attractive alternative fuel for combustion engines due to its abundant resources, high hydrogen-carbon ratios and very low soot formation tendency. The composition of available coal-bed gas, however, can vary considerably, and this has made its combustion stability difficult to control in conventional spark ignition engines. To overcome the problem, a combustion system with a swirl chamber connected to the main combustion chamber through an orifice has been developed for the use of coal-bed gas in spark ignition engines, and the corresponding combustion process has been studied using a developed combustion model involving flame kernel formation and flame front propagation.

This paper presents a dual fuel system for diesel-natural gas operation for a truck diesel engine, and describes results of testing and analysis of the operating characteristics of the engine. The research results show that rates of fuel consumption and fuel efficiencies are increased with this engine design, and heat consumption decreased with increasing load on the engine. The heat consumption rates at medium-high loads are lower than at light loads. At full loads, the dual fuel engine exhibits heat release in which start combustion is reduced and the following combustion is rapid. The engine is tested with an electronically controlled method to meet the requirement of engine output torque.