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Shen Jun, researcher of Institute of Physics and Chemistry Technology, Chinese Academy of Sciences

Today, I will tell you a story about temperature.

This picture is a scene that appears in many science fiction movies. A beautiful woman lies in a very beautiful coffin, and then flies for hundreds of years, and then comes out as a beautiful woman. Does anyone want to freeze themselves? If there is, come to me and I can freeze you.

Cryogenic freezing and resuscitation?

Actually, the so-called frozen person puts you in a liquid nitrogen tank. But can it really freeze people? I can tell you that it is definitely not possible now, but it is certainly possible in the future. In the future we can definitely freeze people.

This is a very hot video on the Internet, that is, put the goldfish in liquid nitrogen to freeze it, and then put it in the water and it will be resurrected immediately. Can animals really resurrect when they freeze? The answer is no.

In fact, putting a goldfish in liquid nitrogen for only a few seconds can only freeze the surface of the goldfish. The inside of the goldfish and internal organs are not frozen. If all the inside is frozen, it can never be resurrected. That is to say, So far, the resurrection of life has been a problem for humans.

I just said that the whole creature is not allowed for a long time, is it possible?

Cells, such as sperm and eggs, will be rewarmed after it is frozen, and then fertilized after rewarming. It can also produce very healthy and lively children.

That is to say, freezing at the cell level is possible, in addition to what scale can the tissue be frozen?

For example, human skin and cornea, It is also possible for relatively small organs in our body For example, for skin, freeze it at a scale of millimeters for ten or twenty years, and then take it out It still works. So now there are many medical institutions and beauty salons that say that to preserve cells, freezing can achieve their goals.

ButSo far, the human bodyAfter the officials and others freeze, it is impossible to resurrect.

There are several companies that do this kind of business. The most famous one in the United States is Alcor. There is a very well-known writer who sent his head to this company. Now anyone who wants to freeze himself can send himself to this company for freezing. It takes about 200,000 US dollars to freeze the whole body. If you want to freeze your body, it can be realized by only tens of thousands of dollars.

But I can tell you, No matter whether it is Alcor or KrioRus in Russia, it is just for the preservation of the body. You want to freeze yourself alive for twenty years and then resurrect it, and now our technology is unattainable.

Why? It is because of this large scale that about 70% of our bodies are water, including about 25% to 30% of water in bones.

Water will freeze at low temperatures, and it will produce crystals, which are ice crystals or crystals, which will pierce your cells and body tissues. In other words, this crystalline state will cause the loss and destruction of your entire organ function.

This is a picture of “Three Body”, everyone may have seen it. The author is Da Liu, Liu Cixin. I think he has done a lot of homework and he is very scientific.

He mentioned that the three-body people were suddenly dehydrated when they were at Samsung Sun. If all the water is removed, there will be no crystalline state and the organs will not be brokenBad, Da Liu’s method is very good.

But how can you dehydrate instantly? There are three suns in “Three Body”, and three suns can be dehydrated. This method of Da Liu is a very, very good method.

In reality, we are also studying various methods, such as using magnetic or other nanoparticles, using microscale to replace all the tissues and water in your body, using this method. The freezing of the human body.

At present, I want to freeze the whole person, but I still can’t reach this technology. We have made a small refrigerator with low temperature, which can be used to transport human organs or blood plasma.

Frozen people sounds dazzling, but in fact, they are put in a liquid nitrogen tank. This is just the tip of the iceberg of refrigeration. Refrigeration can do many, many things.

It can be seen that this is a thermometer. From room temperature to the lowest, it is minus 273.15 degrees, which is our absolute zero. In the entire temperature zone, our job is to customize the temperature you want. What kind of temperature do you want, we will make such a temperature for you, this is my job.

Customized life: -40℃

The refrigerators and air conditioners that are usually used are probably in a temperature zone of minus forty degrees. When it comes to air conditioning, in the summer, everyone can be indoors comfortably, rather than a very grilled situation, air conditioning may be essential. But we all know that there is a problem with air conditioners, that is, it has freon.

Freon will destroy ozone, and will also produce GWP greenhouse effect, as well as ODP emissions, etc., such bad places. The Kyoto Protocol and the Montreal Protocol tell us that in less than a decade, Freon in the world will no longer be usable by 2025. What will we do then?

The refrigerator air conditioner is no longer available, do you agree?

Now we are studying various alternative substances for new refrigeration. Our current refrigeration method is vapor compression refrigeration, there is such a liquid, the liquid circulates in it, it changes from liquid to gas, and then comes back, through this cycle, to achieve our purpose .

We are still working on a new technology—Magnetic refrigeration, which uses solids for refrigeration.

You can see the picture on the left, it is a rare earth, and in the middle is the material we used in magnetic refrigeration, it is blue iron silicon.

Freon is liquid, we don’t want liquid. We use a solid, put it in a magnetic field, and when the magnetic field is added and removed, a temperature change will occur, and then the temperature change will be circulated to form refrigeration, so that the purpose of green environmental protection can be achieved.

This is a magnetic refrigerator developed by our laboratory, which is currently not available on the market. Because we still have problems with materials, low heat exchange efficiency of regenerators, the cooling capacity of the system and so on. But we are gradually solving these problems, and within a few years, I believe you can see them in the market.

There are also some prototypes, and the magnetic refrigerators we make are prototypes. This is a prototype of General Motors of the United States. This magnetic refrigerator can cool the beer in front. At the London Olympics, there was also such an application. Putting beer into it for a while will be cold. This is a magnetic refrigerator.

The one on the right is the magnetic refrigeration wine cabinet made by Haier Company at the 2015 CES Consumer Exhibition in the United States-a wine cabinet made with magnetic refrigeration technology. In fact, the machine in Haier was made by a company in the United States. So far, our country’s independent intellectual property rights magnetic refrigeration technology is what we are doing.

Cross customization: -80℃

Why is it called cross customization? Because doing temperature and cooling can also serve many other disciplines. For example, chemistry. From the Institute of Chemistry, the first chairman of the Youth Promotion Association for the synthesis of chemical materials, Luo Sanzhong, came to me to ask if they could make a low-temperature refrigeration for their high-temperature chemical synthesis.

Later, we built a reactor for chemical synthesis at low temperature. They used this reactor to synthesize many, very valuable new materials.

This is a photo of my astronomical observatory in Lijiang, Chinese Academy of Sciences. They specifically invited me to solve the problem for them.

Lijiang Yunnan is a remote area and wants liquid nitrogen, but Kunming Yunnan’s main station does not give it, so this observatory cannot be tested. So I said that you can directly make a liquid nitrogen machine for them, collect nitrogen from the air, and then liquefy this nitrogen into liquid nitrogen, you can do experiments.

Industry customization: -196℃

We can now make a liquid nitrogen machine that produces 10 to 1,000 liters of liquid nitrogen per day, to provide users with some scientific experiments and so on. In fact, the temperature of liquid nitrogen is already minus 196 degrees Celsius, which is what we call 77K of liquid nitrogen. What other applications does it have?

First, it is used in the collection of green and clean energy natural gas.

About ten years ago, when I went to Tuqa, Xinjiang, I saw many torches that burned natural gas.

Why? Because they want to extract oil and coal underneath, but the gas field above it may not be that big, only enough to extract five or ten years. And they burned all the smaller gas fields like this. So every year our country burns about 20 billion yuan!

It’s all money. Can you say it’s burning? Of course, it cannot continue to waste. What should I do? One method is to liquefy natural gas.

But it is necessary to build a station and a factory, and the cost of this factory may be very, very high. For example, this gas field, after five years and ten years of mining, what should we do if it is gone?

Later, there is a method of laying pipelines. The cost of laying pipelines is also very high, so pipelines are generally laid for such large gas field transmissions internationally.

We later came up with a way to make a small LNG plant. Similar to this, like the size of a container.

We use a very good process design, making it very compact throughout. It’s like having a main base in the game. The equipment extracts gas at this place and then liquefies it. The volume of natural gas before liquefaction is 600 times that of compressed gas. To another placebr>

Extreme customization: -273℃

There are also superconducting maglev trains in Shanghai that require low-temperature refrigeration. The lowest temperature is minus 273.15 degrees, and we need such a low temperature in space.

On the left is a magnetic refrigeration device made in the United States. It can reach 50 mK, that is to say, a temperature of 50 mK below 1K, which can be used on space telescopes.

Cooling customized full temperature zone

Heat dissipation is another expression of cooling. The picture below shows the Tesla factory. There are no workers in it, all are machines. We also want to build such a factory. What are we going to do?

For example, the cutting and welding of automobile steel plates. There are also aircraft welding. There are countless rivets on the wings of the aircraft, and replacing these rivets with laser welding can reduce the weight of the fuselage and reduce the overall cost. After the fuselage loses weight, more passengers can sit on the same plane.

The laser produced by the semiconductor encountered a problem. The picture above shows the skin of Airbus A380. Their one-kilowatt laser can’t weld this skin, it must be three kilowatts, five kilowatts, and it must be emitted from a laser chip with an area of ​​about one square millimeter.

But one square millimeter is about 1/100 of a human fingernail. In such a small area, it is necessary to have an ultra-high heat flux density, so that it can generate a strong enough laser to weld and melt.

So in the Tesla factory we just mentioned, the heat flux density of welding cars and airplanes should reach the heat flux density of the surface of the sun: roughly 10^7 watts per square meter. This is very, very difficult.

Therefore, to cool it very quickly in a very small area, we have designed a new laser heat sink structure and its cooling system.

Later, we solved this problem not only for the semiconductor institute, but also for our country. The new generation of semiconductor lasers made by semiconductors will be used in the country’s future advanced manufacturing 2025, which means that we will be the Tesla plant in China.

So, temperature customization exists in every aspect around us, including refrigerators, air conditioners, military, aerospace, etc.

We are here to customize the temperature you want. If you want to freeze yourself, you can come to me. Thank you!