Research On Radiative Temperature Management Material Based On Nano Structure

The increasing economic activities of mankind have increased energy consumption year by year and aggravated the greenhouse effect.At the same time,people's pursuit of comfort in life has led to a rapid increase in energy consumption for temperature regulation.Radiation temperature control(cooling or heating)can regulate the temperature of objects within a certain range without additional energy consumption,and has become a research hotspot in recent years.High-efficiency radiative cooling or heating materials have important application prospects in many fields such as solar cells,aerospace,construction,transportation,and human body and environmental temperature control.Traditional temperature control equipment mainly uses phase-changeable substances in the process of evaporating and gasifying heat absorption/condensing and liquefying heat to adjust the ambient temperature.The operation of these devices requires energy,otherwise they cannot work normally.Obviously,in a special environment where energy cannot be provided,radiation temperature control is the only solution.Taking a step back from the perspective of energy conservation,radiation temperature control is also a green and important energy-saving method worth promoting.Radiation refrigeration uses the infrared heat radiation on the surface of the object to release heat into a cold background(such as outer space,low-temperature darkroom),thereby cooling the surface of the object;reducing the external radiation of the object will increase the temperature,and using materials with low surface emissivity can be Effectively suppress infrared radiation to achieve heat preservation and even heating.Both the radiative cooling efficiency and the radiative heating efficiency are closely related to the characteristics and the surface structure of the material itself.The application fields and places of radiation temperature control materials and structures are very wide,and the requirements for the environmental conditions are not high.However,the current large-area,easy-to-prepare radiation temperature control materials,especially radiation refrigeration materials,have various shortcomings,which directly affect their applications.How to obtain large-area,low-cost and high-efficiency radiation temperature control materials is still a major problem to be solved urgently.In this article,first,we systematically analyze the radiation temperature control mechanism to obtain various specific sub-band spectral characteristics that the radiation temperature control needs need to meet.Then,focusing on specific spectral characteristics,we innovatively design different types of thin film materials with special micro-nano structures,and use a variety of experimental methods to achieve large-area preparation.Finally,a high-efficiency,low-cost,and high-quality radiation temperature control film was obtained,and actual experimental verification was carried outIn the first chapter,the requirements and significance of radiation temperature management are introduced,and the spectral characteristics of different radiation temperature control scenarios are defined.The development and current situation of radiation temperature control are reviewed.In the second chapter,we innovatively propose to combine the scattering absorption of silicon nitride(Si₃N₄)particles and the intrinsic absorption of polydimethylsiloxane(PDMS)thin film materials to construct the selective radiation spectrum characteristics of the atmospheric window,and combine the spraying and scraping methods to prepare the stack structure of Al/Si₃N₄/PDMS three-layer thin film.The cooling temperature and cooling power of the film were analyzed by using the theory of radiation refrigeration,and verified by designing a reasonable low temperature background environment.The structure of the material is simple,and the preparation process is efficient and convenient,which provides a feasible technical scheme for the rapid preparation of large area and high quality selective radiation refrigeration of atmospheric window.In the third chapter,we innovatively combine the scattering of Ca CO₃ particles and the scattering of polypropylene layered film to construct the short wave(0.3-2.5?m)high reflection spectral characteristics,and successfully prepare the samples with polyethylene/polypropylene Ca CO₃particlemixture/polyethylene/polydimethylsiloxane multilayer film stack structure.Besides,based on the self-designed outdoor test system,we have carried out experiments in many places to verify its efficient radiation refrigeration characteristics.In the fourth chapter,we innovatively propose to use transparent conductive oxide as the infrared spectrum structure material for radiation heating,and based on the method of mica substrate retransfer,we can get polyethylene/indium doped tin oxide/transparent substrate large area visible transparent flexible radiation heating material.The radiation insulation effect is also preliminarily verified by experiments.In the fifth chapter,we design and prepare radiation insulation film materials for objects higher than ambient temperature based on polyethylene terephthalate(PET)substrate as high temperature resistant substrate.The film is composed of Polydimethylsiloxane/silver doped indium tin oxide/polyethylene terephthalate(PDMS/Ag doped ITO/PET)three-layer structure,which can achieve the highest temperature difference under the same sunlight in summer.In the sixth chapter,we summarize our work and analyze the advantages and disadvantages of experimental and theoretical analysis.The next step of this work is prospected,and how to expand and improve the current work is analyzed,so as to prepare for higher radiation temperature control effect.