About Phase Change Materials

Phase Change Materials (PCMs) are special thermal energy storage materials being extensively used as a reliable source of energy to maintain required temperatures in various industries. They use chemical bonds to store and release heat. The thermal energy transfer occurs when a material changes from a solid to a liquid or from a liquid to a solid. This is called a change in state or "phase".

Ice/water as good illustration of a Phase Change Material:
Ice as made from pure water provides a very good illustration of what phase change materials are. In its solid phase, water exists as "ice" at sub-zero temperatures. When exposed to heat, the temperature of ice starts rising in correlation to its specific heat capacity, until at 0°C, it starts liquefying. This is the phase change temperature for ice, and two very important observations are noteworthy during its phase change;

The temperature remains constantly at 0°C for a long time: This is regardless of the variation in temperature outside. The ice cubes continue absorbing the heat; however, till all of ice converts into water, the temperature is constant.

The latent heat capacity: The energy absorbed at 0°C by ice to turn liquid is higher than energy absorbed at any other temperature. The jargon associated with this phenomenon is latent heat capacity, because the energy absorbed by ice remains "latent" or "hidden" and does not show as temperature change in the ice temperature.
As a result, if the requirement for a given application is to maintain temperatures invariablyat 0°C, ice can be an excellent choice of energy storage. For example, for maintaining temperature of perishable sea-food over long journeys at ambient temperatures, the product can be kept in contact with sufficient amount of ice, which would absorb the ambient heat and maintain the temperature quite efficiently.

Phase Change Materials (PCM), Ice for every temperature: While it is always convenient to use ice for cold storage, an important point to note is that it absorbs large amounts of energy only at 0°C and would not be the most efficient solution at any other temperature requirement. This is where PCMs come in use. Phase Change Materials can be tailored for use at melt/freeze point. In other words, one can have an ice- type thermal storage at whatever temperatures they require, or as we like to call it, an ice for every temperature.

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