College of Engineering

Flame stabilization is a common problem in small-scale combustion systems. However, the fuel-air mixture flow pattern, including any recirculation, is critical to achieving flame stability. In the present study, numerical simulations are conducted to understand the mechanisms of flame stabilization in heat-recirculating continuous flow reactors. The essential factors affecting combustion characteristics and flame stability are determined in order to obtain design insights. The results indicate that the wall thermal conductivity, flow velocity, equivalence ratio, and exterior heat losses are important factors in determining the energy efficiency of the reactor. There is an optimum wall thermal conductivity in terms of flame stability. The system with a moderate wall thermal conductivity will be most robust against the surrounding conditions. Excess enthalpy combustion can occur in an efficient and rapid manner, resulting from the injection of free radicals and heat produced by the catalytic reaction. The design incorporates the best features of both catalytic combustion and thermal flame methods. The system is essentially free of mass transfer limitations. Stable operation of the system is limited to a relatively wide flow regime, and the flow velocity is critical to achieving flame stability. Blowout shifts homogeneous combustion downstream significantly without substantially reducing the reaction rate. Both chemical and thermal environments are improved with the catalytically stabilized combustion method and the heat-recirculating structure.