Numerical investigations on hydrogen-fueled micro-cylindrical combustors with cavity for micro-thermophotovoltaic applications

In order to enhance the thermal performance of micro-cylindrical combustors for micro-thermophotovoltaic applications, a micro-cylindrical combustor with cavity is designed. Extensive numerical investigations on micro-cylindrical combustors with and without cavity are implemented under different inlet velocities, hydrogen/air equivalence ratios and solid wall materials by ANSYS Fluent 16.0 with 9-species-19-reactions mechanism. It is found that the thermal performance of micro-cylindrical combustors with cavity is much better than that of micro-cylindrical combustors without cavity. This is attributed to that the cavity makes the burned gas closer to the back part of solid walls. Then, effects of cavity length and depth are analyzed and discussed. The optimal cavity length and outlet diameter of cavity is 6 mm and 2 mm, respectively. The mean outer wall temperature reaches 1306.88 K. Meanwhile, the mean nonuniformity of outer wall temperature is relatively low. All in all, the micro-cylindrical combustor with cavity has better potentiality for applications in micro-TPV system compared with the micro-cylindrical combustor without cavity. [Display omitted] •A micro-cylindrical combustor with cavity is developed.•Thermal performance enhancement mechanism of the designed micro combustor is revealed.•Thermal performance enhancement under different conditions is obtained.•The optimal cavity length and outlet diameter of cavity is determined.