Experimental and numerical investigations on NH3/H2 fueled combustion in the combustor with block for improved micro power generation

To advance the application of zero-carbon fuels in micro combustion, enhance energy conversion, and reduce NOx emissions in NH3/H2-fueled micro power generators, a micro-combustor with an inserted block is proposed and tested under various chamber configurations and operational conditions. Experimental and numerical tests are conducted in micro-combustors with varied block settings, burner dimensions, NH3 blended ratios (mN), and fuel flow rates (Vf). The results indicate that mN significantly impacts the generation and consumption of H, O, and OH radicals, as well as NO, affecting flame regime and heat transfer. Specifically, adding 5∼15 % NH3 improves the operating performance of the burner, with the highest mean temperature achieved in combustor #24C3-0.4 at mN = 15 %. Block insertion alters flame characteristics and enhances gas-wall heat transfer, and the combustor with thinner blocks at higher mN and thicker blocks at lower mN contributes to better thermal performance. Furthermore, combustors with thinner blocks exhibit lower NO emissions. The working performance of the micro-thermophotovoltaic system can be enhanced by selecting the appropriate burner length with block thickness W = 0.4 mm and position Lb = 7 mm based on Vf. The maximum electrical power of 3.7 W is achieved with a burner length of 28 mm for the system using InGaAsSb cells at Vf = 1200 mL/min.