Enhanced CO₂ Decomposition by Plasma-Cold Gas Counter Flow

The reverse reaction of carbon dioxide (e.g., O + CO + M → CO₂ + M and CO + O₂ → CO₂ + O) is a key factor limiting the conversion and energy efficiency of plasma decomposition of CO₂. This study innovatively proposes the use of a counterflow plasma reactor to construct a highly efficient plasma-cold fluid quenching system. The system investigated the effects of counterflow gas flow ratio, counterflow distance, and external magnetic field on plasma discharge characteristics and CO₂ decomposition performance. The study revealed the dual mechanism of counterflow cooling rate on the CO₂ conversion process: increasing the cooling rate can effectively inhibit the CO₂ composite reverse reaction, thereby improving CO₂ conversion performance; however, excessive cooling can interfere with plasma discharge stability and arc dynamics, which has a negative effect on the conversion process. Under optimized conditions of a counterflow gas flow ratio of 2.5 and a counterflow distance of 30 mm, the CO₂ conversion and energy efficiency were improved by 207.3% and 203.6%, respectively, compared with the conventional gliding arc benchmark conditions. Further combining magnetic acceleration gliding arc plasma discharge (MAGD) to enhance arc motion stability using a magnetic field, a conversion of 23.6% and energy efficiency of 25.1% were achieved under conditions of 4 slm gas flow and 792 W power, realizing synergistic improvement. This work provides new ideas for efficient CO₂ conversion under atmospheric pressure.