A Tentative Modeling Study Of The Effect Of Wall Reactions On oxidation Phenomena

摘要

This paper gives details of a tentative modeling study that investigates the inhibiting effect of internal reactor walls treated with acid or metal oxides on low-temperature autoignition phenomena. Reactions that depend on the type of reactor wall coating have been considered for HO_2 and RO_2 radicals and H_2O_2 with estimated rate constants. These heterogeneous reactions have been incorporated into a homogeneous comprehensive n-butane oxidation mechanism. Simulations have been performed with spatial uniformity assumed, in order to assess the effect of the wall reactions on autoignition delay times and on a pressure-ambient temperature (p-T_a) ignition diagram. Experimental comparisons show that the main trends are qualitatively captured well by the model. Simulation results show an importance of RO_2 wall reactions at temperatures below 750 K that control the minimum autoignition temperature. HO_2 radical and H_2O_2 related wall reactions have an important effect at temperatures above 650 K and influence the minimum pressure at which autoignition occurs. The minimum temperature at which reaction occurs in jet-stirred reactor simulations is also affected by considering these heterogeneous reactions. The impact of the limiting case assumption of spatial uniformity on the modeling results is discussed. The work aims to serve as a basis for future modeling efforts that may couple the kinetics with a detailed physical model.