Numerical and Experimental Investigation of High-Pressure Stoichiometric Hydrogen-Oxygen Combustion In a Steam Atmosphere

Abstract

The present work deals with the numerical and experimental investigation of a novel combustion system for the generation of superheated steam. This combustion system is based on the stoichiometric combustion of pure oxygen and hydrogen in an atmosphere of high-pressure, low-temperature steam (“Oxy-H2 in steam” combustion). For successful steam superheating, it is important that only small quantities of unreacted hydrogen and oxygen remain in the steam. A two-stage design is therefore envisaged, in which the first stage serves mainly the purpose of combustion of hydrogen and oxygen, whereas the second stage is used to provide sufficient time for mixing and for chemistry to reach chemical equilibrium. The total amount of steam is split between these two stages. In the first stage, only a small fraction is added as a diluent to limit the combustion temperature. The bulk of the steam is added in a second stage. The detailed investigation of the first stage, i.e., the burner, is the main focus of the present work. Based on computational fluid dynamics, the combustion process and the conditions in the reaction zone are simulated numerically. Emphasis is given on an analysis of the flame structure and the mixing of the reactants with the dilution steam. For validation, measurement data for the OH* chemiluminescence are collected in high-pressure experiments at 10 bar in an optically accessible combustion chamber. The comparison to experimental data shows that the numerical simulation can reproduce key aspects of the combustion accurately.