Experimental NO profiles in H2/O2/NH3 stagnation point flames over platinum substrates are obtained with laser-induced fluorescence for a range of flame equivalence ratios and substrate temperatures. This study generates baseline data against which comprehensive gas-phase and surface chemical models of NO destruction can be compared. The experimental profiles are compared with the predictions of a one-dimensional stagnation flow model that includes full gas-phase chemistry, multicomponent transport, and detailed surface chemistry. A baseline surface chemistry mechanism, assembled by using conventional H/O heterogeneous chemistry and NO adsorption and dissociation followed by N2 desorption, provides good agreement with the experimental results for only a limited range of operating conditions. At low temperatures (425 K), the mechanism underpredicts NO removal, while at high temperatures (940 K) and fuel-lean conditions (Φ = 0.7) the mechanism overpredicts NO destruction. Addition of NH2 and N2O production to the surface mechanism does not improve the level of agreement. However, consideration of the reconstruction of the platinum surface at high temperatures tends to shift the predicted profiles closer to those observed in the experiment for the high temperature cases.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)