A novel refrigerant-direct radiant cooling system: Numerical simulation-based evaluation

Split air-conditioners have deficiency in thermal comfort due to draught sensation and fan noise. The existing radiant cooling systems adopt chilled water as circulating medium, resulting in low energy efficiency because of the requirement of secondary heat exchange. To address these problems, a novel refrigerant-direct radiant cooling (RDRC) system is proposed. Experiments are conducted in a climate chamber to evaluate the thermal performance of this system. Results show that the RDRC terminal surface temperature is distributed homogenously and this system has excellent stability. The mathematical and economic models of this terminal are established and the mathematical model is validated with experimental data. The effects of different structural parameters on thermal and economic performances of the RDRC system are investigated, and then this terminal is optimized by orthogonal design method. The cooling capacity for per exterior area is considered as objective function and the initial cost less than 121.1 $ is taken as constraint condition. Results indicate that the fin height of 40.0 mm, the copper pipe diameter of 6.0 mm, the copper pipe spacing of 40.0 mm and the aspect ratio of 0.88 are recommended.