Numerical Simulation Of Catalytic Combustion And Its Application To HCCI Engines

With the development of global economy, the problems of energy crisis and environment pollution become more and more serious, renovations in the traditional energy technology are being focused. Because of its advantages, such as flammability, low-pollution, high-efficiency and extended ignition limits, catalytic combustion has received comprehensive attentions from academic and industrial realms. As a main representative of traditional combustion and one of the main energy consumers and the main emission source of pollution, the automotive engine faces double stresses as energy saving and environmental protection. Due to its high efficiency, very low nitrogen oxide (NO_X) and particulate matter emissions, the homogeneous charge compression ignition (HCCI) engine has recently become the focus of engine research. However, the HCCI engine still fronts some challenges including control of ignition timing, limited operating range and higher hydrocarbon (HC) and carbon monoxide (CO) emissions. On the other hand, catalytic combustion has some combustion characteristics different from the traditional combustion mode, thus it is feasible to apply catalytic combustion to the HCCI engine to overcome the above mentioned problems. Firstly, this thesis is concerning a numerical study of catalytic combustion process. Then, an approximate analytic solution and a bifurcation analysis of this process are presented. Finally, basic applications of catalytic combustion to the HCCI engine are numerical studied. The principal aim of this work is to develop simulation tools for studying applications of catalytic combustion to the HCCI engine based on a sufficient understand of the catalytic combustion mechanism.Firstly, catalytic combustion in the micro-channel is numerical simulated detailedly.1. A mathematical model (boundary-layed model) is built through comparative analyzing several different models used in the numerical simulation of catalytic combustion in micro-channel. Numerical simulations of catalytic combustion of methane in micro-channel whose surface has been coated with platinum or rhodium catalyst are conducted at low intake gas pressures. The influences of the channel diameter, the kind of catalysts and the gas intake flow speed, intake temperature, and intake equivakence ratio on catalytic combustion process are discussed. The results indicate that the conversion of reactant and the selectivity of resultant are affected by the specifications and initial conditions of the micro-channel. Through comparing the simulation result with experimental data, the detailed surface reaction mechanisms of methane on platinum and rhodium catalysts and the presented mathematical...