What does glass that regulates sunlight look like?

2022-07-11 0 By

Glass has appeared in our human society for thousands of years, but for quite a long time, glass is actually a luxury, almost with gold and silver jewelry is a level.For example, Jia Rong in a Dream of Red Mansions borrowed a glass kang screen from Wang Xifeng to show off her wealth.At the beginning of the 20th century, glass began to enter the home of ordinary people because of technological breakthroughs.The most remarkable feature of glass is that it has strong light transmission, so people can enjoy the sunlight in the room and also see the scenery outside.But this property of glass has its drawbacks, too.Every summer, the sun shines through the glass and heats the room.In winter, heat is lost through the glass and the temperature drops.Current research shows that China’s energy consumption through the loss of Windows and doors glass has accounted for about one-fifth of the total energy consumption of our entire society.This is a very surprising number, and one we rarely pay attention to.So how does glass waste energy?According to the basic principles of thermodynamics, we know that there are three main forms of heat transfer: convection, conduction and radiation.Thermal convection refers to the phenomenon of heat transfer caused by the flow of gas or liquid.For example, if you close a window, you can reduce energy consumption by blocking air convection between inside and outside.Heat conduction is the transfer of heat from a place with a higher temperature to a place with a lower temperature.From the point of view of heat transfer, to get good energy-saving glass, we can make the glass thicker, or we can make the glass in two layers, and leave a hollow in the middle, or even further, vacuum the hollow area, which is now common double glass.Thermal radiation refers to the phenomenon that an object radiates electromagnetic waves because of its temperature.From this point of view, the situation is slightly more complicated.The purpose of our glass is to see the outside world.At the same time, the room receives radiation from the sun through the glass to raise its internal temperature, while the heater in the room radiates electromagnetic waves through the glass to cool the room.So, really good energy-saving glass will not only let the sun radiation in, but also let the radiation that raises the temperature of the room not easily run out, all the radiation is controlled.And a large amount of thermal radiation overflow, is the key way of glass waste energy.For example, in winter, the main sources of indoor heat are solar radiation and heater radiation.Solar radiation will enter the room through the glass, and the indoor temperature is usually higher than the outdoor, coupled with radiators, heaters and other types of heating equipment will emit middle and far infrared radiation at room temperature, radiation hit the glass, so that the glass absorbs the heat of radiation heating up.The glass then gives that energy to the ice outside, causing a lot of energy to be lost.Let’s say that we can have a way in which more solar radiation comes in and less radiation comes out of the heating equipment.Such energy consumption could then be greatly reduced.Different kinds of radiation pass through ordinary glass. Now scientists have developed a new material.When it is applied to glass, it has the ability to control sunlight, making it a new type of energy-saving glass.So what is this new material?How does it make glass energy efficient?Compared with the traditional energy-saving glass, what are the advantages?Just listen to me slowly.The biggest difference between solar and indoor thermal radiation lies in their different wavebands.Therefore, if we set the waveband access conditions on the glass, we can artificially regulate their arrival and departure.With this in mind, researchers at the Institute of Engineering Thermophysics, Chinese Academy of Sciences, have designed a metamaterial (artificial material with special properties) that can regulate radiation by combining a highly transparent polymer with a nanocomponent unit with a specific structure.Ordinary glass can be turned into a new energy-saving glass by applying this artificial material on it.In this metamaterial, a highly transparent polymer allows visible light to pass through, while the nanounit screens for radiation — it is activated and releases energy when exposed to short-wavelength solar radiation.The long-wavelength thermal radiation emitted by a room-temperature object, on the other hand, forms a “net” that reflects it back.This metamaterial combined with glass can make glass keep good light transmittance while selectively passing through heat radiation, thus achieving the purpose of heat preservation in winter and heat resistance in summer.Metamaterials absorb solar heat radiation and prevent indoor heat radiation from spilling out.The researchers carried out an experiment: two models of glass houses, one made of ordinary glass and the other of energy-efficient glass.The initial temperature in both models is 21 degrees Celsius. Turn on the sun simulator and expose them to direct sunlight at the same time.The results showed that after an hour, the temperature of the ordinary glass room rose to 27.3 degrees Celsius, and that of the energy-efficient glass room rose to 43 degrees Celsius.The temperature of the two model rooms was increased by 6.3 degrees Celsius and 22 degrees Celsius, respectively, compared with the initial temperature.In other words, the energy-efficient glass room is 15.7 degrees Celsius higher than ordinary glass room.The heating test results of the radiation-controlled glass room and the ordinary glass room show that the high-efficiency energy-saving glass has a better passing rate of solar heat radiation, and has a better blocking effect on the indoor heat radiation spillover.It turns out that energy-efficient glass can help us make better use of solar energy and also help us save energy better.What are the advantages of efficient energy-saving glass?Compared with the existing energy-saving glass, the advantages of new energy-saving glass mainly have three points: the first is high efficiency.Use of new energy-saving glass, can ensure indoor energy saving at the same time, as far as possible to let more solar radiation in, so the indoor temperature control has a better effect.Research shows that the existing energy-saving glass visible light transmittance is relatively low, generally 30% ~ 70%, but the new energy-saving glass can reach more than 85%, so that more light in.The second advantage is the ease of production, transportation and use.Conventional energy-saving glass is produced by evaporation of various coatings in vacuum, a process that is costly to produce and inconvenient to transport.In addition, because the inside of conventional energy-saving glass is vacuum, the replacement of the whole replacement.And for the new energy-saving glass, whether it is traditional glass, or a certain energy-saving performance of the glass, as long as it has been shaped, do not need to remove or do other changes, only coated with this material, or affixed by the material made of the film can be used.The third advantage is flexibility.This metamaterial is a flexible material that can be applied to different scenarios.In the past, for example, it was difficult to apply low-radiation glass to tents.Because low radiation glass needs to use double, very thick glass to protect the functional layer inside, lack of flexibility.Now, with this new technology, metamaterials can be made into a film, or they can be made into a coating and sprayed onto the tent.Although energy-efficient glass has performed well in the laboratory, its universality has yet to be proven as more extensive testing of its environmental resistance, such as in areas with severe cold and strong salt fog, has not been carried out.Before a new technology can be applied to life, rigorous research, experiments and analysis are needed.But that doesn’t stop us from looking forward to future applications of this technology, which, by its very nature, gives us a lot of hope.What are the application prospects of high efficiency energy-saving glass?The flexibility of energy-efficient glass has led scientists to see many applications.For example, we need to plant out-of-season vegetables in agricultural greenhouses, but in some areas, due to the overall high latitude, insufficient sunlight and low temperature in the sheds, the planting effect is not ideal.If the metamaterial is applied to a shed, it can raise and maintain the temperature of the shed, which is equivalent to an enhanced plastic greenhouse 2.0.Some scientists even have the imagination to use metamaterials to better harness the sun’s energy if humans grow vegetables on Mars.The metamaterial could also be used to make boxes more insulated, for example.In the future, transparent boxes with metamaterial coatings for better insulation may allow us to taste more delicious food, and help the delivery guy.Energy-efficient glass offers even more technological imagination.The core of it is actually selective radiation through light.If scientists can selectively pass through light, can they also selectively pass through all electromagnetic waves in the light range?We sometimes don’t get very good cell phone reception indoors because the electromagnetic wave from the base station outside the house can’t reach inside the house.If we can update the current technology, can we selectively get the electromagnetic wave we want, excluding other clutter?Can we even keep harmful electromagnetic waves from entering the room?Perhaps in the near future, scientists will be able to solve the problem and give us a glimpse of the truth.References: 1. Perspective of New Science and Technology 20210417 Glass to control sunlight _CCTV-program official website -CCTV-10_ CCTV.comBeijing cityscape outside the glass windowDefinitions and differences of Heat conduction, Heat convection and Heat radiationHow to solve the problem of planting light in modern Vegetable greenhouse Construction (11467.com)5.Why are so many people trying to do it when delivery is so hard?Chen Lin (Institute of Engineering Thermophysics, Chinese Academy of Sciences), Chen Jintao (Beijing University of Aeronautics and Astronautics)