What is a phase change material?
相变材料(PCM - Phase Change Material)是指随温度变化而改变物质状态并能提供潜热的物质。转变物理性质的过程称为相变过程，这时相变材料将吸收或释放大量的潜热。例如水的相变过程（如图）：
Phase Change Material refers to a substance that changes the state of a substance with temperature changes and can provide latent heat. The process of transforming physical properties is called the phase change process. At this time, the phase change material will absorb or release a large amount of latent heat. For example, the phase change process of water (as shown in the figure):
Phase change materials have the ability to change their physical state within a certain temperature range. Take the solid-liquid phase transition for example. When heated to the melting temperature, a phase change from solid to liquid occurs. During the melting process, the phase change material absorbs and stores a large amount of latent heat; when the phase change material cools, the stored Heat must be dissipated to the environment within a certain temperature range, and the reverse phase change from liquid to solid is carried out. During these two phase transitions, the stored or released energy is called the latent heat of phase transition. When the physical state changes, the temperature of the material itself remains almost unchanged before the phase change is completed, forming a wide temperature platform. Although the temperature does not change, the latent heat absorbed or released is quite large.
Application of phase change materials
Because the temperature of outer space is extremely cold or extremely hot, the protection requirements for astronauts and spacecraft are very strict, and ordinary materials cannot adapt to harsh conditions. Therefore, special materials are required for protection. Scientists in the United States and the former Soviet Union first developed phase-change materials, which enabled astronauts’ clothing and return capsule shells to be used. The technology has always been in a monopoly position. Since my country entered the 21st century, through the continuous efforts of scientists, the key technology has been overcome and practical applications have begun.
In the field of home textile clothing, the use of phase change materials and the implantation of phase change materials into fibers can greatly change people's quality of life. Without using any energy, ordinary clothes and bedding can be turned into micro air conditioners.
Traditional refrigeration equipment, such as air conditioners, refrigerated trucks, and cold storage, all adopt compressor refrigeration technology for refrigeration, which not only consumes electricity, but is also not environmentally friendly. Using phase change technology, it can replace compressors for refrigeration, saving more than 60% of energy.
In terms of cooling of equipment boxes (rooms) such as communications and power, phase change materials can save equipment costs by more than 75%. In the communication field, it has been widely used in the computer room and battery pack room of the communication base station, so that the traditional one-year life of the equipment can be extended to 4 years or more.
Phase change energy storage building materials have the advantages of both ordinary building materials and phase change materials, and can absorb and release an appropriate amount of heat energy; they can be used simultaneously with other traditional building materials; no special knowledge and skills are required to install and use heat storage building materials; It can be produced with standard production equipment; it is economically competitive.
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