What is a fluid called that is cooled by direct refrigeration to transfer cooling elsewhere?

The correct answer is that the fluid referred to in the question is called a secondary refrigerant. In refrigeration systems, a secondary refrigerant is utilized to transfer cooling effects from the primary refrigerant to the area that needs to be cooled. The primary refrigerant is the fluid that is directly cooled by refrigeration processes and operates within the evaporator and compressor. In contrast, the secondary refrigerant circulates through the system to absorb and deliver cooling to various locations.

Secondary refrigerants may include substances such as water, brine, or other fluids that can flow through pipes to carry thermal energy away from a location and release it elsewhere. They enable more efficient heat transfer and can be safer than using primary refrigerants directly in certain applications.

Understanding this distinction is key in refrigeration technology, as it allows for the optimization and control of cooling processes in various settings, such as in commercial refrigeration, HVAC systems, and industrial cooling applications.