Numerical analysis of hydrogen-oxygen hydrothermal combustion: Laminar counterflow diffusion flames

Hydrogen hydrothermal combustion is a promising technology in the field of energy conversion. The H₂–O₂ hydrothermal combustion is comprehensively investigated using a one-dimensional laminar counterflow diffusion flame model. The introduction of the real-fluid thermodynamic and transport properties approach corrects the temperature and location of the flame. Effects of strain rate, pressure, inlet temperature, and fuel concentration on flame structure and extinction limit are examined. The increase in strain rate and pressure reduces the maximum temperature and flame thickness, while the inlet temperature and fuel concentration have the opposite effect. The extinction strain rate ranges from 30 s⁻¹ to 5200 s⁻¹ at inlet temperatures of 773 K–973 K and fuel concentrations of 10 mol%–50 mol%, indicating that the hydrothermal flame stability is much worse than gas-phase combustion. The unity Lewis number assumption underpredicts the maximum flame temperature by nearly 100 K at any strain rate.