ANALYSIS OF MULTIDIMENSIONAL MODELS OF MONOLITH CATALYSTS FOR HYBRID COMBUSTORS

Distributed parameter models of the single channel of a monolith combustor have been derived from progressively simplified assumptions. Simulation results are compared to assess the importance of the different physicochcmical phenomena occurring in the combustor and to identify the simplest adequate model. For typical operating conditions of the hybrid combustor (gas and wall temperature not exceeding 1,073 and 1,273 K, respectively, high flow rate and pressure, natural gas as fuel), the results show that variations of gas properties have to be considered while homogeneous combustion can be neglected. Assumption of the approximate radial profile of axial velocity with invariant parabolic shape, rather than the rigorous solution of momentum balance and the continuity equation, provides accurate results. Moreover, for simulation of ceramic monoliths, backward heat transmission by wall conduction can be neglected with a substantial saving of computational labor.