Quantitative characterization of the effect of inclination angle on flat-plate radiative cooling performance in buildings. (1st November 2022)

• Record Type: Journal Article
• Authors: Hu, Mingke; Zhao, Bin; Suhendri, ; Cao, Jingyu; Wang, Qiliang; Riffat, Saffa; Su, Yuehong; Pei, Gang
• Is Part Of: Journal of building engineering. Volume 59(2022)
• Publication Date: 2022-11-01
• Subjects: Radiative cooling -- Passive cooling -- Inclination angle -- Stagnation temperature -- Buildings; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.105124
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: The environment-friendly and energy-free nature of radiative sky cooling fosters its application in buildings where a radiative cooler is usually positioned at a tilted angle. However, though the cooling capacity of various radiative cooling materials placed horizontally is extensively explored, their performance when mounted with an inclination angle are generally unclear. Therefore, the present work carried out an outdoor experimental investigation on quantitatively uncovering the relationship between the cooling capacity of the flat-plate radiative cooler and its inclination angle. Generally, the cooling performance deteriorates at elevated inclination angles, but the deteriorating tendency is not always linearly. The inclination angle shows relatively weak influences on the cooling performance when less than 20°. The two key performance indicators, sub-ambient emitter temperature drop and net radiative cooling power, decrease by about 50% when the inclination angle increases to 70° and 73°, respectively. Both indicators drop by around 66.7% when the inclination angle increases to 90° from 0°. This study may pave the way for predicting the cooling potential of building-integrated devices such as pitched roof-mounted radiative coolers, radiative cooling-regulated smart windows, radiative cooling-assisted solar photovoltaic panels, etc. Highlights: Connection between the performance of a radiative cooler and its tilted angle. Quantitative relations have been derived for performance prediction. Inclination angle has relatively easy impact when less than 20°. Cooling capacity shrinks by 66.7% when the tilted angle increases to 90° from 0°.