Abstract
Adaptation of hydrogen fuel for heating applications presents several challenges, particularly thermal NO (x) production and reduced radiative heat transfer. Oxy-steam combustion in the MILD (moderate or intense low-oxygen dilution) regime addresses both challenges by removing the nitrogen from the oxidizer and introducing steam as a diluent that can increase thermal radiation. However, both steam and pure oxygen are required to achieve these conditions. This study investigates the feasibility of using hydrogen peroxide (H(2)O(2)) as an oxygen and steam carrier for hydrogen-fuelled heating applications, as when heated, H(2)O(2) decomposes into water and oxygen. Batch reactor, perfectly stirred reactor, and opposed flow laminar flamelet simulations are conducted over a range of representative conditions to investigate the combustion characteristics of this system. Reactor ignition is found to be enhanced with an increase in H(2)O(2) mass fraction within the oxidizer mixture. However, even at a high H(2)O(2) content, preheating does not allow significant decomposition of the H(2)O(2) into an appropriate radical pool to promote ignition within furnace-relevant residence times, suggesting that external preheating or cracking may be required for practical applications. Fundamentally, H(2)O(2)-steam flames without precracking show unique flame structures when compared to the equilibrium/cracked mixtures in MILD conditions, similar to those observed in conventional combustion of H(2)O(2). A double-peak structure of heat release is observed in the H(2)O(2)-steam cases, where one peak correlates with the exothermic decomposition of H(2)O(2), and the second peak corresponds to the primary combustion process with the fuel. That finding suggests that there is a significant heat addition into the flow that comes from the decomposition process that cannot be neglected in the reactor analysis, and can contribute to low temperature ignition in these conditions.