Reduced Research On Reaction Mechanism Of CH₄under O₂/CO₂Atmosphere

As greenhouse effect is more and more serious, people gradually get the attention of O2/CO2combustion technology which is a way to effectively reduce CO2emissions. Compared with the traditional combustion, O2/CO2combustion technology use O2/CO2instead of O2/N2. Because of the presence of CO2and different chemical and physical properties of CO2and N2, making the important component and main reaction change when fuels is burned in O2/CO2atmosphere, this make fuel’s reaction mechanism change. The reduced mechanism is conducive to numerical simulation. Therefore, this article mainly study the reaction mechanism of CH4when burned in O2/CO2atmosphere.First, this article use the global and local sensitivity analysis to study the process of combustion in four kinds of the reactor(PREMIX reactor, PSR reactor,0-D reactor and PFR reactor). The results show that the highly reactive free radicals H, O and OH played a significant role in four kinds of the reactor; The reaction R38、R52and R119play a major role on temperature and component concentration in the whole process of combustion when burned in PREMIX reactor; In the PSR reactor, R33, R35, R38plays a main role on the combustion temperature, and the R98plays a main role on the component concentration; In the0-D closed reactor, R38, R155, R156and R158plays a main role; R32, R155, R156and R158plays a main role, and R38play a secondary role in PFR reactor.Second, we use direct relationship graph method to analysis the coupling relationship of species in GRI-Mech3.0detail mechanism. Deleting redundant species and reactions, we construct a reduced reaction mechanism which is consists of24species and126elementary reaction. In order to verify the reduced reaction mechanism, we use reduced reaction mechanism and detail mechanism to calculate temperature, mass concentration of important species, flame propagation speed and ignition delay time in the four types of reactor model. The results show that the reduced reaction mechanism and the detail mechanism is identical, and average error is less than5%.Third, in order to reduce system’s stiffness, we use quasi-steady-state-assumption to reduced reaction mechanism for further simplification. In the end, we construct a14-steps global reaction mechanism and a10-steps global reaction mechanism. In order to verify global reaction mechanism, we use global reaction mechanism and detail mechanism to calculate temperature and mass concentration of important species in the four types of reactor model. The results show that the14-steps global reaction mechanism and10-steps global reaction mechanism can better describe the change of temperature and mass concentration of species, and the use of14-steps global reaction mechanism and10-steps global reaction mechanism is reliable when describe the combustion of CH4in O2/CO2atmosphere...