Multiple Ignition, Normal and Catalytic Combustion and Quenching of Fuel/Air Mixtures

摘要

Lean combustion of propane in platinum/alumina/cordierite catalysts has been studied at atmospheric pressure, gas velocities of 10-40 m/s, C3H8 equivalence ratios of .19 to .32 and H2O concentration of 1.2 to 1.7 mol %. Measurements of substrate temperature and gas composition, pressure, and temperature inside and downstream of the catalyst have been made. The dependences of substrate temperature, gas temperature, and gas composition of inlet temperature, reference velocity, and equivalence ratio have been investigated. A two-dimensional model of the gas-phase including the effect of finite-rate chemical kinetics at the substrate surface has been developed and tested. When the experimental wall temperature is used as boundary condition for the gas-phase equations, the emission predictions are in reasonably good agreement with the measured ones. The indications obtained from the model are that propane is oxidized via a multi-step kinetic mechanism, that in the range of temperatures and equivalence ratios explored, most of the fuel is burnt at the catalytic wall rather than in the gas phase, and that wall kinetics is slower than gas diffusion transport.