Study On LNG "Weathering" And The Engine Performance Influenced By It

With the oil resource shortage and the increasingly outstanding pollution of the environment in the world, it becomes an important project, studied by the international communities, to lower the fuel consume rate of the vehicle engine and the harmful compositions in the exhaust. The Natural Gas Vehicle(NGV) develops quickly for its slight emission, economic, fuel extensive and safety. The Liquified Natural Gas Vehicle(LNGV), with its characters such as safety, economic, long mileage and good environment protection function, is a new generation of NGV, and starts becoming the developing direction of NGV. Consequently, property change for new fuel brings a series of new problems to be studied. The phenomenon of LNG "weathering" is one of them.Firstly, the paper discussed the advantages of LNG as fuel for the buses and tractors, and the development and application conditions of the natural gas engine technology, analysed the development trend of LNGV; and put forward the basic concept of LNG "weathering", analysed the mechanism and the reasons of the "weathering". The calories are transfered into the LNG stored in the container for the obvious difference in temperature between the cryo-LNG and the outside environment. The infiltrating calories and the variety of LNG compositions are the base reasons for LNG "weathering"; Then the process of LNG "weathering", while using and or not, was simulated from different directions.Based on the mass experimental data, the paper still analysed the performance of the engine influenced by LNG "weathering". In the aspects of burning, the ignition time and the regulation of heat release rate are affected severely by LNG "weathering". The ignition time is postponed obviously, and heat is more concentratedly released. In the aspects of exhaust, there are slightly influences on CO, HC and NOx, and no obvious influence on carbon smoke.