Which secondary coolant is commonly used for effective refrigerant properties?

Propylene glycol is widely utilized as a secondary coolant in refrigeration systems, particularly in ice rinks and other cooling applications. Its effectiveness stems from its ability to lower the freezing point of water when mixed with it, allowing for more efficient heat transfer and preventing ice from forming in the cooling system's pipes.

This makes propylene glycol an ideal choice as it provides a balance of low-viscosity characteristics for easy flow and excellent thermal conductivity properties, which are essential for effective cooling. Additionally, propylene glycol is non-toxic, which is a significant advantage when compared to other materials that could pose safety risks.

In contrast, while water is a common coolant, it lacks the necessary freezing point depression required for optimal cooling performance in many applications. Calcium carbonate and chlorine do not serve as secondary coolants and would not be suitable in this context. Calcium carbonate is primarily used in water treatment processes, and chlorine is commonly associated with disinfection rather than as a coolant. Thus, propylene glycol is recognized as the most effective secondary coolant for refrigeration systems.