Investigations of a micro-thermo-photovoltaic system fuelled with ammonia/hydrogen under extreme operational conditions

The present study is concerned with numerical investigations on the electrical power output, and NO emissions of an ammonia/hydrogen fuelled micro-thermo-photovoltaic (MTPV) system under extreme operational conditions. For this, three critical parameters are identified and examined. They include: (1) the inlet velocity, (2) the inlet equivalence ratio, and (3) the mole blending ratio of hydrogen. Increasing the inlet velocity markedly raises the electrical power output of the MTPV system. At lower inlet velocities, a higher background temperature helps reducing NO emissions (NO emissions at 2 m/s and 200K are 5.5% higher than at 350K), whereas at higher inlet velocities, lower background temperatures are more effective in reducing NO emissions (NO emissions at 12 m/s and 350K are 6% higher than at 200K). The electrical power output of the MTPV system is maximized, when the inlet equivalence ratio is set to 0.9, yielding a total power output of 15.2W. For optimizing energy efficiencies, an inlet equivalence ratio of 0.8 is preferred, with an energy efficiency of 6.3%. Blending ammonia with hydrogen significantly increases NO emissions (NO emissions at 200K with a hydrogen blend ratio of 0.5 are 26% higher than with the blending ratio of 0.1) and provides limited improvement in the energy output of the MTPV system (energy output at 200K with a hydrogen blend ratio of 0.5 is 10% higher than that with a blending ratio of 0.1, and the energy output at 300K with a hydrogen blend ratio of 0.5 is 7% higher than that at a blending ratio of 0.1).