Enhancing outer wall temperature uniformity in a micro-combustor for micro thermophotovoltaic system via four-corner tangential inlets injection

The outer wall temperature uniformity in micro-combustors is crucial for the stability and longevity of micro thermophotovoltaic systems. This study introduces a novel corner tangential micro-combustor (CTMC) to optimize the outer wall temperature distribution. A comparative analysis with a traditional micro-combustor (TMC) demonstrates that the CTMC enhances flame stability and promotes a more uniform temperature field by leveraging the swirl effect induced by four tangential inlets injection. This advancement results in improved combustion efficiency and a more consistent temperature distribution, albeit with a modest increase in pressure loss. Specifically, at a given inlet flow rate of $3.5\times {10}^{-5}\text{kg/s}$, the average temperature on the outer wall increases by 47.93 K, the temperature standard deviation decreases by 24.15 K, and the combustion efficiency improves by 1.18 %, while the pressure loss rises by 583.19 Pa. Additionally, the influence of the inlet tangential circle diameter (d) on performance is explored. With increasing d, the flow toward the wall becomes more concentrated, resulting in a more uniform temperature field and reduced pressure loss. Notably, when d increases from 0.4 mm to 1.0 mm, pressure loss decreases by 6105.28 Pa, and the temperature standard deviation decreases by 96.04 K. Further analysis of the CTMC’s performance under varying inlet mass flow rates, revealing that higher flow rates suppress recirculation near the combustor’s front. However, excessively high flow rates lead to expulsion of unreacted fuel, reducing combustion efficiency. Temperature uniformity exhibits a non-linear trend, initially improving with increasing flow rate (from $2.5\times {\text{10}}^{\text{- 5}}\text{kg/s}$ to $3.5\times {\text{10}}^{\text{- 5}}\text{kg/s}$) before deteriorating at higher flow rates (from $3.5\times {\text{10}}^{\text{- 5}}\text{kg/s}$ to $4.5\times {\text{10}}^{\text{- 5}}\text{kg/s}$), with best case of $3.5\times {\text{10}}^{\text{- 5}}\text{kg/s}$ and corresponding TSD of 18.96 K. This research provides new insights into enhancing the temperature distribution in micro-combustors and suggests cost-effective strategies for enhancing combustor design.