Research On Temperature Control Strategy And Carbon Emission Control Based On Passive Radiation Cooling/Photothermal

At present,more than half of the energy consumption is on the amount of cold and heat,and with global warming weather and a series of factors,such as population increase in the temperature control energy consumption will increase year by year,the cooling is the main demand,at the same time,the massive combustion of fossil fuels increased greenhouse effect,formed the negative feedback,caused a serious impact on the environment.Therefore,achieving the high energy efficiency of buildings with minimum carbon footprint has become an important goal of sustainable development.Among them,passive Radiative cooling technology requires no energy input and can partially replace traditional cooling systems.The existing Radiative cooling technology has high cost and limited application scenarios,so a low cost,large-scale production,flexible to adapt to various scenarios of the material is needed to achieve the purpose of Radiative cooling.At the same time,the ambient temperature changes at any time with the time and season,and a single cooling function can greatly not meet the building temperature demand throughout the whole year,and may even increase energy consumption because of excessive cooling,so a single Radiative cooling can only meet part of the demand.Given the above problems,this study designed an effective and economical Radiative cooling material to ensure the cooling effect all day and all year round.Meanwhile,the film combined the photothermal heating and Radiative cooling and carried out function switches inappropriate scenarios to adapt to the annual temperature change.The current research results are as follows:Firstly,the radiation cooling film was prepared by electrostatic spinning technology,and the thermal radiation of atmospheric window was realized by using the principle that different molecular bonds vibrate differently in the infrared band,and the influence of materials with different molecular structures on the thermal radiation of atmospheric window was explored.Based on Mie theory and FDTD simulation,the effects of films with different physical structures on sunlight reflection were investigated.At the same time,the ability of different structures of radiative cooling film to resist atmospheric heat radiation and environmental heat exchange was investigated.It was found that the molecular structure vibrated in the infrared region of 1250～769cm^-1 showed the best radiative cooling ability.The microcosmic size of the radiation cooling film is controlled at about 400 nm,and the diffuse reflection of sunlight is the strongest.It can be known that different molecular structure and microstructure of radiation cooling film have different cooling ability.The radiation cooling power of PAN fiber membrane was 129.60W·m^-2,and that of PVDF fiber membrane was 62.67 W·m^-2.At the same time,the radiation cooling effect of inorganic material silicon dioxide was investigated.The results show that the radiation cooling power of silicon dioxide is 163.24 W·m^-2.Janus fiber films were prepared by continuous spinning,which combined the functions of photothermal heating and radiative cooling to meet different temperature requirements.By refractive index change of switch function,choose the right solution and the refractive index matching with the spinning fiber film of reach from the state optical reflection to the through the state,choose to switch from the refractive index of ethanol solution,due to large refractive index difference of air and fiber film,and present a reflective,ethanol after fiber film space position,the refractive index matching,In the transmission state,the light can reach the photothermal film through the Radiative cooling film for photothermal heating mode.Through the alternating occupation of ethanol solution and air on the fiber gap to switch different functions,the reflectivity of photothermal heating and Radiative cooling in the sunlight part is 90%and 5%,respectively.After multiple switching cycles,the performance is not affected,with good durability.In the outdoor test,the temperature changes in 24 hours and the temperature differences in static conditions were measured respectively.There were obvious temperature differences between Radiative cooling and photothermal heating and the environment.To explore the degree of carbon emission reduction by Janus fiber membrane,software was used to conduct a simulation test on a building in Harbin.During the one-year simulation test,the annual energy saving was 44206.3 KW·h,and the carbon dioxide saving was 44073.68 kg.Therefore,the Janus fiber membrane prepared in this design can achieve the effect of energy-saving and has certainly helped to carbon emission reduction.