Due to its excellent heat transfer properties, glycol is ideal for cooling and chilling applications.
The most commonly used coolant in a chiller is water or a mixture of water and another substance with appropriate heat conduction properties – such as a glycol compound. Referred to as antifreeze, glycol is an organic compound belonging to the alcohol family. Glycol has excellent heat transfer properties and is able to remove large amounts of heat quickly in a chiller.
Heat is a normal byproduct of chemical reactions and has to be removed rapidly in order to maintain the stability of the reaction. In such instances, glycol chillers are used due to their quick reaction and excellent heat transfer properties. In addition to providing excellent heat transfer parameters, glycol tends to discourage algae growth in heat transfer equipment.
Pure glycol or a mix of glycol and water has a much lower freezing point than that of pure water. The low freezing point of glycol mixtures makes them ideal for cooling items that are below the freezing point of water. Although glycol has a lower heat capacity than water, the larger temperature difference allows the glycol mixture to remove heat more quickly than pure water. Glycol also has refrigerant properties that are more suited for use in chillers expected to function in low-temperature environments.
Glycol-based coolants are either composed of ethylene glycol or propylene glycol. While these two variants have similar physical properties, they should never be mixed. Ethylene and propylene have different fluid, toxicity, and heat transfer properties that would prevent a system from working properly. Also, due to its toxicity, ethylene glycol is not approved for food processing.
The most common use for glycol in chillers is in the production of beverages for breweries, wineries, distilleries, cider mills, and dairy products, where the cooling process has to be at a specific level to ensure the quality of the final product. Using a glycol-water mix as a chiller coolant has various benefits over the use of plain water as a chiller fluid. These advantages are due to its unique physical properties, including a lower freezing point than water.