Study On Numerical Simulation And Optimization Of Aging Characteristic For Three-Way Catalytic Converter

The automobile exhaust pollution poses a grave threat to human environment. Automotive three-way catalytic converter is an effective device of controlling exhaust pollution. Fresh catalytic converter's conversion efficiency can reach ninety-five percent. Three-way catalytic converter often ages because of the long-term working in a severe condition and its conversion efficiency drops at the same time. Therefore, it is absolutely important to study the aging characteristic of three-way catalytic converter to ensure long-term steady and effective operation of three-way catalytic converter.Aging mechanism of three-way catalytic converter including the catalyst deactivation mechanism is studied. Thermal aging and poisoning are emphasized. Aging is studied from aspects of sinter rate and reaction rate. Considering dropping of catalytic reaction activation and growing of Pt particles, the aging characteristic model including aging process of catalytic converter is created by combining aging characteristic parameters and fresh converter reaction model. This model compensates for the deficiency of old reaction model which neglects aging effects.Based on the model, numerical simulation of temperature and oxygen fields is simulated using FLUENT. Aging characteristic parameters are calculated by MATLAB. In aging process, Pt particles'mean diameter is enlarged. But Pt particles'growing is impressed in the front of monolith because of poisoning effect. While in the middle and back of monolith, Pt particles are growing for thermal sinter. Reaction activation drops after aging. Reaction deactivation factor decreases and is minimal in the front of monolith. Also exhaust conversion efficiency drops observably. It shows that the sinter and poisoning of catalyst are the major factors of converter's aging. The impacts of inlet diffuser, inlet temperature and aging mileage on aging characteristics of three-way catalytic converter are studied. This supplies certain foundation for the structure optimization and performance improvement of three-way catalytic converter.At last, anti-aging measures are put forward from the aspects of petroleum quality, composition and distribution of catalyst. These measures provide some referable ways for the development of three-way catalytic converter which can meet increasingly stringent durability requirement.