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The wonderful transformation of ice and water: Why is water the best phase change material?
Water, the most common substance in our daily lives, has an amazing ability: it can easily change forms under different temperatures and pressures. From ice to water to water vapor, the scientific principles behind these changes make water an ideal phase change material (PCM), which has demonstrated its unique advantages in various applications.
Phase change material is a substance that releases or absorbs a large amount of energy during phase change. The phase change process of water provides latent heat up to 333.55 J/g, which is much higher than ordinary sensible heat energy storage.
Phase change materials can usually be divided into two categories: organic materials and inorganic materials. Organic materials mainly come from plants or petroleum, while inorganic materials include salt hydrates, etc. Water is characterized as a phase change material by its high latent heat capacity and ability to store energy when transitioning between solid and liquid, making it an important material in construction, cooling systems, and medical applications.
Latent heat of water and its applications
During the phase change of water, when ice melts into water, the heat absorbed can be as high as 333.55 J/g, which allows water to store a large amount of energy under relatively small temperature changes. Compared to other materials, water can release or absorb large amounts of heat as it changes state, making it excellent for energy storage.
PCMs have "Latent Heat Storage" (LHS) capabilities, which means they can store and release large amounts of energy near their phase change temperature.
This characteristic of water makes it widely used in buildings, especially where cooling is required in summer and heating is required in winter. By storing cold air in the winter, water can be released in the summer, balancing energy demand and supply.
Classification of phase change materials
There are many classifications of phase change materials, among which water is a solid-liquid phase change material. In addition to water, many organic phase change materials such as fatty acids and paraffins have also been widely studied. The characteristic of these materials is that they can achieve effective energy storage in a small temperature range.
Although organic PCMs are technically efficient, they often have low thermal conductivity, which means their thermal management properties need to be improved for faster energy transfer.
Inorganic PCMs, such as salt hydrates, offer higher storage density and better thermal conductivity, but they can encounter challenges with uneven melting and delamination during repeated use.
Microencapsulation technology
In certain applications, especially when phase change materials need to be applied to textiles, microencapsulation technology is introduced. This method allows the material to remain in a solid state. When the internal phase change material melts, the structure of the capsule can still retain the shape of the material, avoiding the problem of liquid leakage.
Microencapsulated phase change materials can better integrate the materials into building materials, concrete, etc., and provide convenient heat storage systems.
The introduction of this technology not only enhances the stability of phase change materials, but also improves their ability to adapt to different environments, further expanding their application scope.
The future of water
As concerns about energy efficiency and sustainability increase, the potential market for phase change materials is growing rapidly. As a representative of phase change materials, water is not only a recycled resource, but also a perfect buffer between demand and supply, whether in home construction or public facilities.
In the future, as technology advances, water phase change technology may play a more important role in more applications, such as in solar storage systems and high-efficiency air conditioning facilities. The use of water heralds more efficient and an environmentally friendly future. As the conflict between energy demand and supply continues to intensify, how will the role of water help solve this problem?
