Comparative analysis of the thermal performance of step, cavity and rib micro-burners using the field synergy principle

This study applies the field synergy principle to numerically investigate the performance of three micro-burner configurations, namely Step, Cavity, and Rib, using hydrogen as the fuel. Results show that Step and Cavity burners, with larger combustion chambers, enhanced combustion efficiency but compromise heat transfer. Conversely, the Rib burner, with its narrow flow channel, limits combustion efficiency while significantly improves heat transfer performance via enhanced impingement. All three configurations can generate thermal recirculation zones, thus ensuring flame stability. Across the configurations, combustion efficiency, average outlet temperature, and outer wall temperature uniformity decrease sequentially, whereas heat transfer efficiency increases progressively. An optimal micro-burner design should feature a wide-front to promote combustion and ensure flame stability, coupled with a narrow-rear to enhance heat transfer. Revised designs in this study increased the maximum effective heat transfer efficiency from 37.4 % to 52.2 % for the Rib-5mm burner.