Abstract: With global warming and frequent abnormal high temperatures, radiation cooling technology, as an environmentally friendly cooling technology, has shown great potential in regulating thermal comfort. The human body in a specific environment can be regarded as an open system composed of human body, clothing and environment, and radiation plays an indispensable role in human heat dissipation. According to Kirchhoff's law of thermal radiation, radiation heat dissipation can be accelerated by regulating the optical properties of clothing materials and then regulating the heat radiation exchange between the human body and clothing. In the indoor environment, the selection and design of materials enable clothing fabrics to possess high mid-infrared transmission, allowing heat radiation emitted by the human body to dissipate into the environment almost unobstructed through the clothing to the environment. In the outdoor environment, where a single infrared transparent material cannot block the entry of external mid-infrared radiation, the emissivity of the outer surface of the clothing material is regulated to endow the fabric with high mid-infrared emissivity. This allows the fabric to absorb heat and convert it into radiant energy to dissipate heat into the environment.
The regulation of infrared radiation or solar radiation in the concept of radiation cooling technology is combined with personal thermal management technology, and a variety of radiation cooling textile materials are derived to regulate human thermal comfort. High transmission cooling materials are led by membrane composite materials, sub-band response cooling materials, cooling materials with cooling/thermal insulation dual function materials and cooling materials with unidirectional moisture conduction characteristics. In order to obtain mass production textile materials with high radiation cooling ability and ideal wearing comfort, researchers have prepared various fibrous materials with high radiation properties through phase separation, particle doping and other methods around the high transmission and high emission cooling mechanism, such as high-permeability fabrics, outdoor high-emission/high-reflection fabrics and all-weather selective emission/high-reflection fabrics.
The review found that the development of radiation-cooling materials still faces many challenges. At present, most of the developed membrane materials have problems such as poor air permeability, washable repeatability and wearability, so it is difficult for them to be applied in clothing development. The performance evaluation of radiation-cooling materials mainly includes three methods: spectral measurement, thermal measurement comparison and real person evaluation. Most studies are still in the laboratory stage, the testing of cooling characteristics has not been standardized and unified, and the overall application evaluation of clothing is lacking, so further research and improvement is needed. Currently, most of the radiation-cooled fiber material processes are still relatively complex, and it is difficult to achieve high industrialization and rapid preparation. In order to realize the commercialization goal of materials in the field of textile and garment, continuous optimization of material preparation processes should be conducted in the future in terms of improving the cooling efficiency of materials, enhancing wearability, simplifying preparation processes, optimizing overall clothing evaluation methods, and broadening the practical functions of materials.

Key words: functional clothing, infrared radiation, radiation cooling, ergonomics, high emission, high transmission

摘要： 辐射降温作为一种无源输入的降温技术，可实现零能耗、零污染的自发降温，为应对环境变化和调控人体热舒提供了创新的能源解决方案。文章聚焦于辐射降温技术在服装领域的应用与性能评价，介绍了基于人体热交换模型及Kirchhoff热辐射定律的高透射和高发射降温机制；综述了以膜态复合材料以及纤维态织物为代表的辐射降温材料的材料选择与制备工艺；讨论了光谱分析、织物热测量对比和服装真人试验3种性能评价方式。综述发现，辐射降温技术在服装领域大有可为，未来在材料的降温效率、改善服用性能、简化制备工艺、优化服装整体评价方法等方面持续优化材料的制备工艺与评价体系，以及拓宽材料的实用功能如吸湿、抗菌等，将助力推动实现辐射降温服用材料的产业化发展。

关键词: 功能性服装, 红外辐射, 辐射降温, 人体工学, 高发射, 高透射