Thermal and emission performance of CH₄ and H₂–CH₄ thermophotovoltaic micro-power generators

Micro-power generation can be pursued using various methods such as thermophotovoltaic and thermoelectric generators. In this study, the effects of operational conditions and addition of Hydrogen to methane on the thermal and pollution performance of thermophotovoltaic generators are studied using measurements and modeling in a CH₄ and H₂ thermophotovoltaic power generators. The measurements focus on key parameters including temperature, radiation efficiency, NO_x emission and flame regimes. Measurements of CH₄-air mixture show the high sensitivity of temperature to equivalence ratio were the cases with stoichiometric mixture and high combustor diameter have the highest mean wall temperature and NO_x concentration. Moreover, the highest radiation efficiency in CH₄ flames achieved in a lean mixture with equivalence ratio of 0.9 in the small diameter case. CH₄-air mixture gave three flame regimes of weak flame with inlet velocity of 0.1 m/s, asymmetric flame at inlet velocity of 0.23 m/s and steady symmetric flame at inlet velocity of 0.44 m/s. When adding H₂ to the fuel (20% H₂ and 80% CH₄), the radiation efficiency increased from 11.5 to 13.5% which is highly favorable for thermophotovoltaic applications.