3-D modeling of monolith reactors

Dynamic behavior of a monolith catalytic reactor formed by ceramic body with the system of parallel channels with square crossection has been studied experimentally and by numerical simulation. Gaseous reaction mixture flows through channels without mass exchange among them. Inner channel surface is coated with catalyst and strongly exothermic reaction of CO oxidation takes place on the catalyst surface. Constructed experimental monolith reactor enables measurement of temperature profiles along 24 chosen channels. The used three-dimensional (3D) model considers heat conduction and accumulation in the solid phase (Fourier equation) and mass and heat balances both on the surface of the catalyst and in the gas phase. Proper discretization of concentration and temperature fields leads to a system of several tens of thousands of ODE's which are then integrated on a fast workstation. Mutual interaction of heat accumulation, heat transfer and nonlinear heat generation gives rise to propagating temperature fronts. Evolution of temperature fields for spontaneous ignition and extinction and after electric preheating of small part of the monolith are studied experimentally and by mathematical modeling.