Formation and evolution characteristics of hydrothermal flames inside a transpiring wall reactor: A transient numerical investigation


Transpiring-wall reactors with hydrothermal flames are effective in preventing corrosion and salt deposition in supercritical water oxidation systems. To uncover the not-well-understood evolution characteristics of the hydrothermal flame surrounded by a transpiring water film, a 2-D unsteady simulation is firstly conducted in this study. The transient results show that the variations of flow fields and flame shapes are attributed to the competition between inertial forces and buoyant forces. And the quasi-steady results present that high feed concentration may damage transpiring wall and delay the evolution of hydrothermal flames. In addition, a low feed temperature or a big flow area of jet can lead to open hydrothermal flames, which adversely affect the reactor. Furthermore, Froude Number, Fr, shows effectiveness in predicting quasi-steady flame shapes. For large-Fr conditions, the inertial force outweighs the buoyant force and hence closed flames are developed; while for low-Fr cases, open flames are developed.

The Journal of Supercritical Fluids