CO2 conversion promoted by water-cooling coupled with rotating gliding arc plasma

AN Chunguo; WANG Zongqun; ZHAO Zijiang; MIAO Jingquan; ZHANG Bin; SHI Ronggui; QU Huige; WU Angjian; ZHANG Hao

doi:10.13226/j.issn.1006-6772.24102601

Abstract：CO2 capture,utilization,and storage are widely regarded as one of the main technological pathways for carbon reduction,and an important method for China to address the challenges of its"dual carbon"goals.Rotating gliding arc plasma possesses advantages such as high energy efficiency,simple structure,short start-up and shut-down times,and low energy consumption,making it a highly promising technology for CO2 conversion and utilization.However,during the activation and decomposition of CO2,rotating gliding arc plasma experiences excessively high gas temperatures(4 000-6 000 K),which exacerbates the reverse reaction of CO2 decomposition,limiting the conversion rate.To address this,a water-cooled rotating sliding arc plasma reactor has been developed in this study.This innovative approach utilizes cooling to suppress the mechanism of the reverse reaction of CO2 decomposition,effectively enhancing CO2 conversion efficiency.The study explores the decomposition behavior of CO2 under different cooling intensities.By measuring the gas temperature downstream of the plasma,variations in the macro gas temperature under different condensation intensities and operating conditions were determined.The effects of inlet gas flow rate(2-8 L/min)and cooling intensity on CO2 decomposition conversion rate and energy efficiency within the water-cooled reactor were systematically investigated.The experimental results indicate that the introduction of water cooling significantly lowers the gas temperature in the reaction zone,suppressing the reverse reaction of CO2 caused by high temperatures,thereby increasing both CO2 conversion rates and energy efficiency.In the absence of water cooling,the gas temperature reached 461 ℃,whereas under moderate and strong water cooling conditions,it was reduced to 282 ℃ and 222 ℃,respectively.Additionally,the introduction of the water cooling system reduced the stability time of the reactor from 400 s to 150 s,enhancing the stability of the reaction.The introduction of water cooling significantly decreased the rate of the reverse reaction of CO2 decomposition.Due to the suppression of the vibration-translation relaxation process,the energy levels of vibrationally excited states were elevated,thus enhancing CO2 conversion efficiency.The optimal experimental conditions were found to be with medium cooling intensity(cooling water flow rate of 4.8 mL/s)and an inlet gas flow rate of 4-5 L/min,under which a high CO2 conversion rate(9.5％-11.5％)and energy efficiency(26.0％-29.5％)were achieved.This study demonstrates the effectiveness of water cooling in suppressing high-temperature reverse reactions of CO2 conversion and improving CO2 conversion performance,providing new insights for the further development of plasma CO2 conversion technologies.