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 NO_x 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 (m_N), and fuel flow rates (V_f). The results indicate that m_N 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 m_N = 15 %. Block insertion alters flame characteristics and enhances gas-wall heat transfer, and the combustor with thinner blocks at higher m_N and thicker blocks at lower m_N 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 L_b = 7 mm based on V_f. The maximum electrical power of 3.7 W is achieved with a burner length of 28 mm for the system using InGaAsSb cells at V_f = 1200 mL/min.