A novel hybrid low-temperature thermal catalysis and radiative sky cooling system for day and night air purification and cooling

Thermal catalytic oxidation is an air purification technology that can efficiently and stably degrade volatile organic compounds. However, using thermal catalysis to purify indoor air in the summer can cause problems of indoor overheating. Radiative sky cooling is a passive cooling method that dissipates heat through reflection and radiation, which can provide sub-ambient cooling during day and night. In this study, a novel hybrid low-temperature thermal catalysis and radiative sky cooling system for day and night air purification and cooling was proposed, which combined thermal catalysis with radiative sky cooling, and used low-temperature driven thermal catalysts to solve the problem of indoor overheating in summer. A numerical model of the hybrid system was established to simulate the formaldehyde degradation and cooling performance of the system under different operating conditions. The results show that under summer conditions with an average daily temperature of 35 °C and humidity levels between 70 % and 80 %, the system produced a total of 665.29 m³/m² of clean air after running for an entire day. The average single-pass conversion rate of formaldehyde was 0.46, and the maximum temperature difference between indoor and outdoor air was 5 °C. This provides guidance for the integration of the hybrid system with buildings.