Local thermal environment and thermal comfort of a novel low-temperature radiant structure using CFD simulation

Abstract

A novel low-temperature radiant structure (LTRS) has been developed to create local thermal environment and thermal comfort. This design incorporates an air layer that separates the air-contact surface from the radiant cooling surface, which enables low-temperature radiant cooling, increases cooling capacity and reduces condensation risk. The study addresses the concern of whether the LTRS with low-temperature radiant cooling would degrade thermal comfort. Heat transfer models of the LTRS were developed, and agreed well with the experimental results with difference within ±0.3 °C. Four cases with radiant surface temperatures of 27.9, 15, 10 and 5 °C were investigated, and in all cases a consistent operative temperature was maintained. This study evaluated various parameters, including the air temperature and velocity distributions, mean radiant temperature, operative temperature, and thermal comfort indices. Results indicated that the application of the LTRS increased the supply air temperature by 1.6 °C, suggesting significant energy-saving potential ranging in 28.4 %–52.7 % compared to traditional all-air cooling systems. Moreover, both general and local thermal comfort under the regulation of the LTRS satisfied the criteria in the ASHRAE Standard 55. These findings demonstrate that the novel LTRS has the capability of improving energy efficiency while maintaining satisfactory levels of thermal comfort. This study provides valuable insights and serves as a reference for promoting the use of personalized radiant cooling systems and enhancing building energy efficiency.