Making the most of heat: the Pang Ya Ka effect of combining cold and warm

“Make the best use of heat” - as the name suggests, it means exploring feasible methods to improve the comprehensive utilization efficiency of thermal energy.

Recently, the author discovered that the Ponjac effect in plastic crystal materials can be used as a new type of refrigeration material. This material can not only achieve zero-carbon refrigeration and eliminate environmental hazards in the refrigeration field, but also realize the collection and reuse of waste heat, thereby reducing carbon emissions and improving energy utilization.

Part 1

What is heat?

Heat is a form of energy that can be characterized by temperature. The higher the temperature, the more heat energy it contains.

Heat can be seen and touched. If we take the image of the Long March 5 rocket launch as an example, we can judge that the flame temperature at the tail end of the rocket is very high, because its heat radiation is very high, so we can tell its temperature by its color. At the same time, heat can also be touched. If you touch a hot object with your hand, you will feel that it is hot.

Long March 5 rocket launch

(Photo source: People's Daily Online)

From a microscopic perspective, thermal energy reflects the intensity of the microscopic movement of the atoms or molecules that make up a substance. The stronger the intensity of the movement, the more thermal energy the material contains and the higher its temperature.

Heat has a characteristic that, like water, it always moves to lower places, which is determined by the second law of thermodynamics. Clausius, the founder of thermodynamics and creator of the concept of "entropy", once pointed out that heat spontaneously transfers from high-temperature objects to low-temperature objects, and they will eventually reach equilibrium at the intermediate temperature.

Heat plays an indispensable role in our lives. If our target temperature is lower than the ambient temperature, it is cooling; if our target temperature is higher than the ambient temperature, it is heating.

Part 2

The past and present of refrigeration

As you can imagine, if we want to freeze something, we have to take the heat out of it to achieve refrigeration.

During the Warring States Period in my country, a bronze vessel called "Ice Mirror" was invented. This bronze vessel has a layer inside, which is used to hold ice. It is the most primitive "refrigerator" discovered so far. But strictly speaking, it is not a refrigerator, because it requires ice to use, which is not active refrigeration.

Active refrigeration in the true sense came after the First Industrial Revolution, when the steam engine was invented, giving humans power for the first time. The steam engine power was used to create a vacuum, thereby accelerating the volatilization process of volatile substances such as ether, and the purpose of refrigeration was achieved by using the principle of volatilization absorbing heat.

This was the first time that humans were able to achieve refrigeration in an active way, and refrigerators in our modern sense were not invented until 1927!

(Photo source: Veer Gallery)

Part 3

Heating - a witness to human development history

Compared with cooling, heating can better reflect the development history of our entire human race. From the ancient times when our ancestors drilled wood to make fire, to the large-scale use of coal before and after the First Industrial Revolution, steam power greatly promoted human progress, and in recent years, the large-scale use of oil and natural gas, "heating" has a huge impact on modern life.

(Photo source: Veer Gallery)

In the current basic pattern of thermal energy utilization, about 31% of our primary energy is used to generate heat, while at the same time 28% of energy is lost in the form of heat in other industrial sectors. Thermal energy production accounts for about 30% of the total carbon emissions of the whole society.

(Photo source: Veer Gallery)

This brings up a very interesting problem, called the thermal energy paradox - if the heat energy lost in the energy utilization process is utilized to make up for thermal energy production, it not only saves energy but also reduces carbon emissions generated in the thermal energy production process.

So, is there any way to realize this fantastic idea?

Part 4

What is the Ponzi effect?

The author discovered a new material property called the Pomjerka effect. When talking about the Pomjerka effect, we need to first explain what plastic crystal materials are. This is a very special solid material composed of high-speed rotating, disordered organic molecules.

This material is very soft, and only a small pressure is needed to suppress the high energy state of these organic molecules, and the material changes to a low energy state, thereby releasing a large amount of heat. Li Bing named this phenomenon of significant phase change cooling effect induced by small pressure the Pangyaka effect. Using the Pangyaka effect, the author led the team to design the first prototype of the Yika refrigeration machine.

Compared with traditional gas compression refrigeration technology, Pangyaka refrigeration technology uses a solid material during the entire refrigeration process. No gas is involved in this process, so there will obviously be no carbon emissions and ozone depletion issues that we are concerned about.

While researching refrigeration technology, the author was also thinking about how to efficiently recycle and utilize the heat energy generated, so as to realize the fantastic ideas mentioned above.

Through experiments, the author found that a type of plastic crystal material begins to store heat and become a plastic crystal state at around 80 degrees Celsius. In a room temperature environment, applying a tiny pressure of about 6 MPa (equivalent to the force we use to pinch an object with our hands) can induce the plastic crystal state to transform into a conventional crystal state. A large amount of stored heat can be released in a very short time, and the temperature can rise by 48 degrees Celsius within 20 seconds.

This is a complete process of heat absorption and release of plastic crystal materials - heating to absorb heat, cooling to lock heat, and pressurizing to release heat.

As we all know, various industrial processes and large data centers consume a lot of energy. At the same time, the heat generated needs to be dissipated or cooled, which in itself is a huge waste of energy and will also bring a lot of carbon emissions.

Based on this type of technology, if we can achieve the absorption, storage, and reuse of thermal energy such as waste heat from industrial processes, waste heat from large data centers, geothermal resources, and solar resources, and then achieve orderly regulation of thermal energy, this will be of great significance to carbon neutrality and even the protection of the earth's environment.

Produced by: Science Popularization China

Author: Li Bing (Institute of Metal Research, Chinese Academy of Sciences)

Producer: China Science Expo

Editor: Sun Chenyu

The article only represents the author's views and does not represent the position of China Science Expo

This article was first published in China Science Expo (kepubolan)

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