The advancement of microscale combustion-based energy and power generation systems presents a compelling alternative to traditional batteries, primarily attributed to the superior energy density of hydrogen and hydrocarbon fuels. Nevertheless, the primary hurdle lies in stabilizing flames within micro-combustors, owing to their significant surface area-to-volume ratio, which leads to substantial heat loss. To bolster the energy efficiency of micro thermo photovoltaic systems and facilitate the practical adoption of carbon-free fuels, we are optimizing the structure of the micro combustor, investigating the potential of utilizing ammonia as a fuel source, and exploring the efficiency of the power generation system. Firstly, a numerical analysis of the first and second Law efficiency of counterflow double-channel micro-combustors is presented. A parametric analysis investigates the influence of 1) the inlet velocity, 2) chamber geometry, and 3) fuel composition. The double-channel combustor significantly improves wall temperature uniformity compared that with the one single channel, with oval-shaped thread configurations resulting in the highest wall temperature and uniformity.

Secondly, we propose and test a double-channel design featuring Y-shaped internal fins to further the thermal performance of the micro combustor. we investigate three key parameters in the thermal performance of a micro-combustor: 1) the inlet velocity, 2) the inlet equivalence ratio, and 3) the combustor wall material. Further, we develop a new method to calculate the efficiency and exergy of the micro-combustor by considering the entropy generation and exhaust gas.

Thirdly, a Micro-Thermal Photovoltaic system with a Tesla-shaped micro combustor is proposed to reduce acoustic levels and improve thermal performance, electrical power output, energy efficiency, and acoustic performance while considering three key parameters: 1) inlet velocity, 2) inlet equivalence ratio, and 3) combustion channel dimensions. The reverse direct flow configuration yields better electrical power and energy efficiency compared to the direct flow configuration. The acoustic performance under reverse flow is notably superior to that under direct flow, particularly at high inlet frequencies and low inlet frequencies.

Fourthly, we investigate a double-channel counter-flow micro-combustor fueled by premixed ammonia/hydrogen/oxygen parametrically to investigate both NO emissions and thermal performance. The model is used to examine the effects of 1) inlet velocity, 2) inlet equivalence ratio. We find more fuel-rich ammonia combustion can lead to lower NO emission and better thermal performances and mixing ammonia with more hydrogen can stabilize micro-combustion and increase the temperature in the combustion field slightly.

fifthly, to enhance ammonia's flammability in atmospheric micro-combustion, hydrogen is blended in the fuel. First, a simplified chemical reaction mechanism of ammonia consisting of 44-step reactions and 19 species specifically for ammonia is developed and validated using experimental data to reduce computational cost and time. Then, we proposed a heat-recirculating micro-combustor fueled by premixed hydrogen/ammonia/air. Five key parameters are identical to numerically studying the thermal performance, entropy generation, and NO emissions. We find that hydrogen blending having a small effect on the performance but effectively reduces NO emissions. Furthermore, changing the material from steel to Corundum enhances power output by approximately 6% maximum.

Finally, blending ammonia with methane has emerged as a viable strategy to improve the laminar burning velocity of ammonia. We propose a mechanism for methane/ammonia combustion, comprising 19 species and 131 chemical reaction steps, and investigate the emissions of CO and NO, along with electrical power output and energy efficiency of a micro-thermal photovoltaic system fueled by premixed ammonia/methane/oxygen. Three key parameters are identified as: 1) the inlet mixture flow velocity, 2) the methane mole fraction blended ratio, and 3) the material of the micro-combustor.