A Model for the Transient Behavior of Catalytic Combustors

Abstract

Abstract Abstract-A transient tridimensional model has been developed which accounts for both the heterogeneous and homogeneous reactions occurring in the combustor, as well as for the axial heat conduction in the solid and radial heat losses. The heterogeneous global kinetics used here has been obtained earlier, experimentally, for the catalytic combustion of propane on a mixed transition metal oxide catalyst (3.38 percent CraOa, 1.13 percent CoaOj by weight deposited on alumina washcoated monolith). At short times, the transient behavior depends on the reactions occurring on the surface, on the heat capacity of the solid and on the advection of heat downstream by the flowing gas. The temperature of the solid near the entrance exceeds that of the gas, the latter being heated by the heat convected from the solid. At locations further downstream, the fuel concentration is low and the solid temperature falls below that of the gas, the former being heated by the latter. As the combustor heats up, the peaks i...