Hydrogen enrichment effects on flame dynamics and energy conversion efficiency in DME and ethane-fueled micro-thermophotovoltaic systems

Hydrogen enrichment is a promising strategy to enhance combustion stability and radiative output in micro-thermophotovoltaic (MTPV) systems. This study numerically investigates the effects of hydrogen blending on flame structure and efficiency in ethane or dimethyl ether (DME)-fueled micro-TPV combustors. Results reveal that hydrogen addition shifts flame fronts upstream and improves wall temperature. Compared with pure fuel, the oxidation process of DME is fundamentally restructured from a multiple-stage to a direct reaction with the introduced hydrogen, whereas for ethane, hydrogen blending enhances the chain branching chemistry. Additionally, both fuels exhibit optimal carbon conversion at high hydrogen volumetric fractions, around 75% for ethane and 50% for DME, owing to the competition between the reaction of H₂ + OH and the reaction of CO + OH, beyond which excessive hydrogen suppresses CO oxidation. System efficiency peaks at 85% H₂ (ethane) and 75% H₂ (DME), offering guidance for optimizing fuel composition and hydrogen usage in high-efficiency micro-TPV systems.