Alternative fuel engines have widely been developed in the world due to the decrease of oil resources and the strictness of exhaust regulation. This paper introduces the main processes of designing the diesel engine fuelled with coal-bed gas and ignited by spark plug, and analyzes a number of problems considered in processes of designing the engine. As an example, the characteristics of a coal-bed gas engine converted from a S195 diesel engine are introduced, and the performances of the prototype engine are discussed based on the results of engine testing. And some significant conclusions were got.

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. The combustion model includes two sub-models with the first dealing with the calculation of turbulence intensity history, and the second modeling a jet flow through the orifice of the swirl chamber. Emissions of NOX, HC and CO have been predicted using the combustion model based on an extended Zeldovich mechanism, wall quenching and incomplete oxidation simulations. The effects of various components in coal-bed gas on the engine combustion process and emissions are also investigated. Validation of the combustion model has been performed through comparing simulation data with the experimental result obtained from a relevant single cylinder research engine, and a satisfactory agreement between them has been achieved in terms of combustion parameters and exhaust emissions.

Woody biomass was liquefied by water in an autoclave in the reaction temperature range of 280-420℃with sodium carbonate as the catalyst. The experimental results show that the yield of the main liquefaction product (heavy oil) was significantly influenced by the process conditions. The maximum yield of heavy oil was obtained at reaction temperature 380℃. The heavy oils obtained at different reaction temperature were analyzed by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS). The analytical results show the heavy oil is complex compound that contain hydrocarbon, aldehyde, ketone, hydroxybenzene and ester.

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.

Natural gas engines have widely been developed in the world because of the decrease of oil resources and strictness of the exhaust regulations. This paper introduces the main processes of designing diesel engines fuelled with natural gas and ignited by spark plugs. Secondly, it analyzes a number of problems considered during the process of designing. As an example, authors introduce the characteristic of a natural gas engine converted from a 4125 diesel engine and discuss the performances of the prototype engine according to results of the engine bed testing .The result is satisfying.