Numerical study on a multiple-channel micro combustor for a micro-thermophotovoltaic system

Highlights: • A multiple-channel micro combustor is presented and numerically investigated. • Outer wall temperature of multiple-channel combustor is more uniform and higher. • Radiation energy and efficiency of multiple-channel combustor are higher. • Assigning equivalence ratio can improve temperature uniformity further. - Abstract: As a key component, the design of a micro combustor is critical when determining the performance of a micro-thermophotovoltaic (TPV) system. This study proposes a multiple-channel micro combustor for a micro-TPV system. A three-dimensional computational fluid dynamics (CFD) model with a skeletal reaction mechanism embedded is established for premixed hydrogen/air combustion in the micro combustors. The numerical simulation results indicate that the temperature distribution along the outer wall of the multiple-channel micro combustor is more uniform and higher than that of the traditional single-channel micro combustor, which is highly beneficial for the micro-TPV system. Moreover, the radiation energy and radiation efficiency of the multiple-channel combustor are higher than those of the single-channel combustor at the same volume flow rate. When the flow rate is 100 cm³/s and H₂/air equivalence ratio is 0.8, the mean temperature and the wall temperature difference on the cross-sectional direction for the multiple-channel combustor are 1294.9 and 86.6 K, respectively, whereas those for the single-channel combustor are 1256.0 and 107.6 K, respectively. The radiation energy and radiation efficiency are 53.57 W and 18.84% for the multiple-channel combustor, respectively, and 47.40 W and 16.67% for the single-channel combustor, respectively. Moreover, the high equivalence ratio assignment for the side channels can further improve the temperature uniformity of the multiple-channel combustor. Results show that the wall temperature difference on the cross-sectional direction can decrease from 86.6 K to 68.8 K.