Universal strategy for all-weather and all-terrain radiative cooling with non-reciprocal mid-infrared windows. (1st September 2020)

• Record Type: Journal Article
• Authors: Wei, Mingming; Wu, Wanchun; Li, Dong; Xu, Hua; Lu, Yuehui; Song, Weijie
• Is Part Of: Solar energy. Volume 207(2020)
• Page Start: 471
• Page End: 478
• Publication Date: 2020-09-01
• Subjects: High humidity -- Atmospheric transparency -- High-rise buildings -- Non-reciprocal transmission -- All-weather and all terrain; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2020.07.010
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: A non-reciprocal MIR window with pyramidal micro-structures is designed. The non-reciprocal window allows to radiate heat to outer space while suppressing the incoming heat flux. A temperature reduction limit of 110 °C is possible under a low-transparency sky. A temperature reduction of 10 °C can be preserved under an unfavourable weather and surroundings condition. Use of the non-reciprocal window promises a 45% energy savings for cooling during China's summer, around 180 TWh. Abstract: Passive radiative cooling has a potential impact on global energy consumption, while it is vulnerable to weather and surroundings, hindering its practical applications. Here, we present a facile pyramidal micro-structure that can be formed on a mid-infrared (MIR) window for achieving non-reciprocal propagation whereby the incoming heat flux from low-transparency atmosphere and/or surrounding high-rise buildings is suppressed without limiting the outgoing radiation from radiative coolers. In an ideal case without solar absorption, convective, and conductive heat losses, a temperature reduction limit of 110 °C is simulated even under a low-transparency sky. For an unfavorable weather and surrounding obstruction condition, the radiative cooler integrated with the non-reciprocal MIR window can still reach a 10 °C temperature reduction, while a standalone radiative cooler fails the sub-ambient cooling. The effects of non-reciprocal MIR windows on China's average temperatures in summer are estimated, roughly corresponding to a 45% energy savings for cooling, around 180 TWh. This universal strategy would remove the bottlenecks of putting passive radiative cooling into practice worldwide even if local weather and surrounding terrain conditions are undesirable.