Dual behavior of hydrogen peroxide in gaseous detonations

Abstract

The paper describes the dual behavior observed for hydrogen peroxide when added to hydrogen-air detonating mixtures. The effect of the addition of hydrogen peroxide on \(\text {NO}_{x}\) emissions and critical detonation parameters was evaluated for \(\text {H}_{2}\) air mixtures using one-dimensional ZND calculations. Hydrogen peroxide acts as an ignition promoter and is shown to significantly enhance the detonation chemistry when added in small concentrations. It alters the ignition chemistry of an underlying detonation wave without affecting the bulk thermodynamic properties. The main objective of the present study is to evaluate the ignition promotion and \(\text {NO}_{x}\) mitigation effects of hydrogen peroxide in gaseous detonations when it is added to hydrogen-air mixtures in small and large concentrations. In the current work, the diminishing sensitizing potential of hydrogen peroxide when added in large amounts (up to 10%) is also reported. The results show a visible effect on ignition promotion up to 20,000 ppm. At concentrations higher than 20,000 ppm of \(\text {H}_{2}\text {O}_{2}\), further reduction in the induction length was found to be minimal. The \(\text {NO}_{x}\) emissions were found to decrease for stoichiometric and fuel-lean \(\text {H}_{2}\)-air mixtures, whereas the \(\text {NO}_{x}\) concentration was found to increase for fuel-rich mixtures with the addition of hydrogen peroxide. Thus, the dual behavior exhibited by \(\text {H}_{2}\text {O}_{2}\) is shown to be advantageous as it could potentially mitigate \(\text {NO}_{x}\) emissions at high temperatures for fuel-lean and stoichiometric hydrogen-air mixtures and, at the same time, could sensitize the given mixture for applications in detonation-based combustors.