Experimental study on the solar heating and night sky radiative cooling properties of biochar

IF 6.4 2区工程技术 Q1 THERMODYNAMICS Case Studies in Thermal Engineering Pub Date : 2025-03-01 Epub Date: 2025-02-03 DOI:10.1016/j.csite.2025.105832

Haiwei Xie, Jianyun Luo, Yan Zhang, Jiajuan Yan, Yuhao Qing

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Abstract

Daytime solar heating and nighttime radiative cooling are of great significance to global energy conservation and carbon neutrality because of their low cost, zero energy consumption and environmentally friendly characteristics. In this study, a new radiation material, walnut shell biochar (WBS), was proposed and its performance in daytime solar heating and nighttime radiative cooling was studied. The experimental results indicate that WBS exhibits a maximum absorption rate of 95.93 % within the solar radiation spectrum, along with an average emissivity of 92.45 % in the atmospheric transmission window. When utilizing a low-density polyethylene film cover plate with a thickness of 10 μm and employing 50 mesh of WBS, the combined effect of daytime solar heating and nighttime radiative cooling is optimized. Under conditions where the solar radiation intensity reaches 750 W/m², the surface temperature of WBS is observed to be 63.3 °C higher than that of the ambient temperature. Conversely, on clear nights, this surface temperature drops to be 15.5 °C lower than that of its surroundings. This research provides valuable technical support for developing integrated processes that leverage both daytime heating and nighttime radiative cooling.

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生物炭的太阳加热和夜空辐射冷却特性实验研究

白天太阳能供暖和夜间辐射制冷因其低成本、零能耗和环境友好的特点，对全球节能和碳中和具有重要意义。本研究提出了一种新型辐射材料——核桃壳生物炭（WBS），并对其在日间太阳能加热和夜间辐射制冷中的性能进行了研究。实验结果表明，WBS在太阳辐射光谱内的最大吸收率为95.93%，在大气透射窗内的平均发射率为92.45%。采用厚度为10 μm的低密度聚乙烯薄膜盖板，采用50目WBS，优化了白天太阳能加热和夜间辐射冷却的组合效果。当太阳辐射强度达到750 W/m2时，观测到WBS表面温度比环境温度高63.3℃。相反，在晴朗的夜晚，海面的温度比周围的温度低15.5℃。这项研究为开发白天加热和夜间辐射冷却的综合工艺提供了宝贵的技术支持。

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来源期刊

Case Studies in Thermal Engineering Chemical Engineering-Fluid Flow and Transfer Processes

CiteScore

8.60

自引率

11.80%

发文量

812

审稿时长

76 days

期刊介绍： Case Studies in Thermal Engineering provides a forum for the rapid publication of short, structured Case Studies in Thermal Engineering and related Short Communications. It provides an essential compendium of case studies for researchers and practitioners in the field of thermal engineering and others who are interested in aspects of thermal engineering cases that could affect other engineering processes. The journal not only publishes new and novel case studies, but also provides a forum for the publication of high quality descriptions of classic thermal engineering problems. The scope of the journal includes case studies of thermal engineering problems in components, devices and systems using existing experimental and numerical techniques in the areas of mechanical, aerospace, chemical, medical, thermal management for electronics, heat exchangers, regeneration, solar thermal energy, thermal storage, building energy conservation, and power generation. Case studies of thermal problems in other areas will also be considered.