ENGINEERING TECHNOLOGY

Professor Qu Liangti of Tsinghua University: Create a magical “Ice Cube”!


On March 9, 2023, the new issue of High Starting Point was publishedNano Research Energy (https://www.sciopen.com/journal/2790-8119Founding editor-in-chief of Tsinghua UniversityProfessor Qu LiangtiPublished the latest research results of radiant cooling entitled “Integrated radiative and evaporative cooling beyond daytime passive cooling power limit”.

Passive cooling technologyIt is expected to replace traditional electric cooling solutions and reduce energy consumption and various types of leakage pollution. Radiant cooling is an emerging passive cooling technology that does not require additional energy consumption during cooling, developed from Planck’s law of blackbody radiation in 1900. With the rapid development of nanophotonics, new photonic crystals and metamaterials continue to appear, and radiative cooling materials that can be applied during the day have also begun to come out, avoiding the impact of daytime solar radiation on the heat dissipation of materials. However, existing daytime radiative cooling technologies are subject toPlanck’s LawLimitation, the cooling power at room temperature is difficult to exceed 150 W m–2, resulting in its cooling effect is much lower than the compressor refrigeration technology used now, which greatly affects the practical application of daytime radiant cooling technology. Therefore, there is an urgent need to develop a tool withHigh cooling powerPassive cooling technology.

Figure 1. Efficient daytime passive cooling based on radiation-evaporative cooling technology. (a) Schematic diagram of the in-situ radiative cooling and evaporative cooling processes; (b) Comparison of the performance of radiation-evaporative cooling power and traditional passive cooling technology; (c) Radiant-evaporative cooling material expandable infrared cooling effect map.

In response to the above problems, Professor Qu Liangti’s team put forwardRadiation-evaporative cooling technology solutions, established in situ interface evaporative cooling and radiant cooling, to achieve a synchronous refrigeration process. The porous polyacrylamide hydrogel acts as an evaporative cooling layer, allowing water to flow sufficiently through the entire evaporation layer, dissipating heat in the form of forced convection while having a high evaporation rate. P (VDF-TRFE) is a breathable radiantly cooled fiber layer with an average emissivity of more than 76 % in the atmospheric window and reflects 90% of visible light, achieving excellent diurnal radiative cooling. The entire material system achieves low visible light absorption, high infrared emissivity, rapid water evaporation capacity, a maximum average cooling power of 710 W m–2 during the day, and can cool water by more than 6 ºC, with an average net cooling power of 630 W m–2. In addition, functional cooling devices that can be used in the human body and equipment (Figure 1) are also established, which provides a reference for the development of new passive cooling technologies. Yao Houze, a doctoral student at Tsinghua University, is the first author of the paper.

Paper Information:

Yao H, Cheng H, Liao Q, et al. Integrated radiative and evaporative cooling beyond daytime passive cooling power limit. Nano Research Energy, 2023, https://doi.org/10.26599/NRE.2023.9120060

DOI:10.26599/NRE.2023.9120060

Nano Research Energy is a companion journal of Nano Research, (ISSN: 2791-0091; e-ISSN: 2790-8119; Official Website: https://www.sciopen.com/journal/2790-8119Founded in June 2022, Professor Qu Liangti of Tsinghua University and Professor Chunyi Zhi of City University of Hong Kong serve as editors-in-chief.Nano Research EnergyIt is an international multidisciplinary and English-based open access journal, focusing on the cutting-edge research and application of nanomaterials and nanoscience and technology in new energy-related fields, benchmarking against top international energy journals, and committed to publishing high-level original research and review papers, which has been selected2022 China Science and Technology Journals Excellence Action Plan – High Starting Point New Journal Project。 APC fees will be waived until 2025, and teachers are welcome to submit their papers.

To submit, please contact:

NanoResearchEnergy@tup.tsinghua.edu.cn

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