PCM (Phase Change Material) and gel packs are both used as cold chain packaging solutions, but they differ in their composition, mechanism of action, and specific applications. Here are the key differences between PCM and gel packs:

1. Composition: PCM is a material that undergoes a phase change from solid to liquid or vice versa at a specific temperature. Common PCM materials include paraffin wax, salt hydrates, and organic compounds. Gel packs, on the other hand, are typically composed of a gel-like substance encased in a plastic or fabric pouch. The gel is usually made from water mixed with polymers or other substances to create a semi-solid consistency.
   
   
2.  Temperature Range: PCM and gel packs have different temperature ranges at which they provide cooling. PCM materials are designed to undergo phase change at specific temperatures, and as such have wider segments- such as 0°C (32°F), -20°C (-4°F), or -70°C (-94°F). They absorb or release thermal energy during the phase change, providing temperature regulation within a narrow range. Gel packs, on the other hand, are primarily used for refrigeration and typically provide cooling within a range of 0°C to 8°C
   
   
3. Mechanism of Action: PCM utilizes the latent heat of fusion to absorb or release thermal energy during the phase change. When the PCM is transitioning between solid and liquid states, it absorbs heat from the surroundings (during melting) or releases heat to the surroundings (during solidification), maintaining a constant temperature within its phase change range. Gel packs, on the other hand, provide cooling through the use of a gel-like substance that absorbs heat from the surroundings and keeps the temperature of the contents lower than the ambient temperature.
   
   
4. Reusability: PCM materials can be reusable, as they can go through multiple cycles of phase change without significantly degrading their performance. Gel packs, on the other hand, are often considered single-use or limited-use items. They may lose their cooling efficiency over time or may not be designed for repeated use.
   
   
5. Flexibility: Gel packs are typically more flexible and adaptable compared to PCM materials. The gel-like substance allows them to conform to the shape of the packaged items and provide more even cooling. PCM materials, on the other hand, are often solid and rigid, which may limit their suitability for certain packaging configurations.
   
   
6. Application: PCM materials are used in applications where precise temperature control within a narrow range is critical. Gel packs, on the other hand, are widely used in various refrigeration applications, such as keeping perishable food items, beverages, or medical samples cool during transportation. Costing is therefore a major factor to be considered when choosing one over the other