Effects of propane addition and burner scale on the combustion characteristics and working performance

In order to investigate the micro combustion characteristic, thermal performance, as well as boost the energy efficiency and extend its application, the effects of burner size and fuel properties on combustion and working performance are studied. The results indicate that 5% propane added to premixed H2/air combustion contributes to the flame relocation and flame stretch, affecting the thermal performance of burner. It also enhances the heat transfer of gas-wall and increases the radiation power at a lower fuel flow rate. Moreover, the chamber diameter and heat recirculation zone also effectively alter the working performance of the burning reactions and extend the limit of flame blow-off, and a more uniform temperature profile along the outer wall can be achieved in the tube with suitable step height or larger size. It is also found that the small tube size boosts the radiation temperature and limits the chemical input, while the heat release from burning is more difficult to be transferred to the wall in the large chamber. Subsequently, a comparison study indicated that the micro-thermophotovoltaic system with InGaAsSb photovoltaic cells and tube T5-2 is more suitable for the application and generates an electrical power output of 1.74 W when the hydrogen flow rate is 876 mL/min and the equivalence ratio is 1.0.