git Cooling gel : eutectic liquid, definition and concept

Refrigerating gel

Refrigerating liquid

A refrigerating liquid is a eutectic solution consisting of water and mineral salts. The quality and concentration of these mineral salts can vary in order to modify the water’s freezing point.
Water solidifies when it freeze at or below 0°C. A eutectic solution with a freezing point at -21°C solidies at or below -21°C.
Freezing point and released temperature are closely related : a eutectic device at -21°C releases a negative cold at -18°C while frozen pure water releases cold at +2°C.
The refrigerating liquid is contained in eutectic plates, more commonly called ‘ice packs’.


Refrigerating gel

Slimy agents are often added to the eutectic liquid, giving the liquid a more doughy consistency. This is called refrigerating gel (sometimes also called,, ice packs).
The gel allows the eutectic solution to blend better : the salts are well distributed in the liquid and the concentration is homogeneous.
Gels improve the thawing time, during which the gel absords heat, and the temperature release is more stable.

Single use refrigerating gel

eutectic plates

The viscosity of refrigerating gels (ice packs) can vary considerably. Thicker gels are generally used for single use flexible cooling packs. Viscosity brings sturdiness and dimensional stability to the flexible pack. A « pulpy » coloured ice pack is more appealing.

Reusable refrigerating gel

Reusable cold accumulators have a rigid envelope. The refrigerating gel’s viscosity therefore does not need to be as high: robustness is provided by the rigid external pack.
The shape of the envelope is designed to optimise the heat exchange surface of the cooling gel.
The plates feature bridging points to improve the heat exchange and convection power of the ice packs.