Modeling And Emulation For Decompressor Of CNGV

In recent years, governments of countries of the whole world have been seeking for a solution to the dilemma between the air pollution resulted from repaid growth of vehicle possessive quantity and the change of vehicle fuel structure, for which natural-gas-driven vehicle is being encouraged greatly in most countries. Natural-gas-driven vehicle is generally abbreviated as NGV (namely such vehicle is driven by purely compressed natural gas– CNG, liquefied natural gas—LHG). For its better emission performance, NGV is good for reforming current vehicle fuel structure with lower running cost, ripe technology and stable function, so that it has been accepted as the best choice for substitute to gasoline-driven vehicle.Decompressor is a most important component in the fuel supply system of CNGV, whose major function is level by level to decompress the highly compressed NG to a degree for gas fuel pressure degree that is acceptable for the engine. However, as to the decompressor structure design in China, it is rare to analyze the effect of decompressor's structure parameter on its performance in the viewpoint of mathematics modeling, rather than determine and regulate the decompressor's specific structural parameter through practical tryout. In order to understand the effect of the decompressor's structural parameter on its actual working performance, this dissertation applies the method of combining theory and modeling analysis to the study, sets up physical and mathematic models respectively for the transformation of inner gas and the movable parts of valves in the decompressor, and through using the MATLAB mathematic analysis emulation software and taking such performance index requirement as for evaluating the systematic stability and the velocity's influence capability of systematic control principle into consideration, makes pressure variation curve emulation and structure parameter performance analysis for the effect from changing the decompressor's structure parameter in the models, then based on the models established, recommends a reasonable range for the option of parameter. The conclusion of the study in a way can serve as a reference for optimizing the structural parameter and improving work efficiency of the decompressor in future design.