Experimental investigation on night sky radiant cooling performance of duct-type heat exchanger

Night sky radiant cooling is one of such promising natural techniques that can be worth a high recommendation. In this study, a novel design of night sky radiation heat exchanger is proposed, and its influencing factors were evaluated by the experimental investigations. The night sky radiant cooling performance of duct-type heat exchanger under different surface material and weather conditions were conducted by case study. The results show that the temperature differences between the inlet and outlet air of the duct-type heat exchanger under the heat exchanger surface painted and unpainted conditions were about 6.8 and 2.3 degrees C, respectively. The temperature differences between the inlet and outlet air under the weather conditions of clear sky, cloudy sky and overcast sky were averagely 6.8, 4.9 and 4.4 degrees C, respectively. It can be concluded that the surface material emissivity plays an essential role on the cooling performance of night sky radiation heat exchanger.