Numerical Simulations of Methanol Engine Performance for High-altitude, Non-road Applications

摘要

Ambient pressure and temperature are two main factors affecting the engine performance. As altitude increases, the air volume and air temperature entering the cylinder per cycle decrease due to the lowering of atmospheric pressure and temperature, which directly affects the engine performance. As a result, engine performance in the plateau environment degrades while the power, economy, and emission performance of the engine significantly deteriorate. This paper focuses on the simulation and parameter optimization of the combustion process of non-road methanol engines, and 1D simulation is for BSFC (Brake Specific Fuel Consumption) prediction while 3D simulation is for soot and NO_x (Nitrogen Oxides) predictions. Discusses, analyzes and predicts the feasibility of non-road methanol engines for high altitude conditions. Especially the application of high proportion of methanol in non-road methanol engines at high altitudes. It provides numerical simulations based on the Yuchai YC6M series heavy-duty direct-injection ignition engine and corresponding engine bench test data which elucidate the effects of oxygen-containing methanol fuel on engine performance. The role of methanol in the blend as well as resulting changes in engine power and emissions were investigated; results show that methanol mass fraction of about 40% yields the slowest engine power reduction rate at high altitude. The results also show that the NO_x emissions of the engine slowly decrease as altitude increases, by about 4% at altitude of 4000 m; the soot emissions increase as altitude increases.