What is the primary function of a secondary coolant in an indirect refrigeration system?

In an indirect refrigeration system, the primary function of a secondary coolant is to absorb heat from the primary refrigerant. This process allows for the transfer of thermal energy without mixing the two fluids directly. The secondary coolant is typically a fluid (often water or a water-glycol mixture) that circulates through the system, absorbing heat from the primary refrigerant that has passed through the evaporator. This enables the secondary coolant to effectively carry that absorbed heat away to where it can be rejected or utilized, such as in cooling ice rinks or other applications.

By absorbing heat from the primary refrigerant, the secondary coolant helps to lower the temperature in the evaporator, allowing the refrigeration cycle to continue efficiently. This makes it a crucial component in maintaining the desired temperatures in refrigeration applications.