Computational study of the effects of solar and electric power on Solar-Enhanced Microwave Plasma CO₂ decomposition

The utilization of CO₂ in the synthesis of fuels and chemicals using renewable energy can help limit CO₂ emissions driving climate change. Plasmachemical CO₂ decomposition processes can be highly efficient; however, solar thermochemical approaches, given their direct use of solar energy, can be more sustainable. Solar-Enhanced Microwave Plasma (SEMP) chemical conversion is an effective approach that combines the advantages of both methods. SEMP exploits the greater absorption of solar radiation by CO₂ in thermal nonequilibrium (compared to CO₂ in Local Thermodynamic Equilibrium) to enhance CO₂ decomposition. A computational study of the effects of input solar power and input electric power on a SEMP reactor operating with Ar-CO₂ (7:1) at atmospheric pressure is presented. The 2D model describes, via a completely-coupled solution approach, fluid flow, heat transfer, plasma dynamics, chemical kinetics, electromagnetic field evolution, and radiative transport in participating media. Simulation results reveal that CO₂ conversion increases with increasing microwave and incident solar power, in good agreement with experimental results. Moreover, the results quantify the enhancement afforded by the incorporation of solar power and suggest strategies towards improved process performance.