Catalytic effects of methane/air and propane/air mixtures using a platinum catalyst in a stagnation point flow configuration

A stagnation-point flow burner facility has been developed to provide a canonical framework to study the catalytic surface reactions of premixed combustion systems. The configuration serves as an important platform to investigate the interaction between homogeneous and heterogeneous reactions with an independent control of the characteristic residence time scales. Methane/air, and propane/air mixtures were examined with or without the presence of a platinum catalyst located at the stagnation surface. The effects of oxidizer composition and nitrogen dilution were examined. Depending on the operating conditions, either a stable gas-phase flame is established between the nozzle and the stagnation surface or the unburned reactant mixture directly impinges on the heated surface. In the former case, the extinction limits of the gas-phase flame were measured for various equivalence ratios and flow conditions. In the latter case, the heat release resulting from the surface reaction was quantified by measuring the surface temperature of the stagnation plate. The results are discussed in terms of the relative contributions of the gas-phase and the surface reaction chemistry to the burner performance. Understanding gained from this study will provide insights into the role of catalytic reactions in extending the flammability of compact combustors subjected to excessive surface heat loss.