In a direct refrigeration system, which of the following would not be used as a cooling medium for building spaces being cooled?

In a direct refrigeration system, a cooling medium is used to absorb heat from the areas needing cooling and to transfer this heat away. The most common cooling mediums include water, brine solutions, and glycol, which are utilized because they can effectively carry heat away and are conducive to use in cooling applications.

R-22, however, is a refrigerant and operates within the refrigeration cycle rather than serving as a direct cooling medium in the space being cooled. Refrigerants like R-22 circulate within the closed refrigeration system, changing states from liquid to gas and back, effectively removing heat from an area without being used directly in contact with the space itself. Using R-22 as a cooling medium for building spaces doesn't apply because it is meant to function internally within the refrigeration system rather than as a fluid that cools the space directly.

In contrast, the substances that are typically used for cooling, such as glycol, brine solutions, and water, are effective heat transfer fluids that can be circulated through coils or systems to achieve the desired cooling effect in buildings.