What defines a direct expansion air conditioning system?

A direct expansion air conditioning system is defined by its method of cooling air through the direct evaporation of refrigerant within the system's coils. This process involves the refrigerant changing from a liquid to a gas as it absorbs heat from the air that is being cooled. The refrigerant then cycles back to a compressor, where it is condensed back into a liquid and the cycle repeats. This refrigerant-to-air interaction allows for efficient and effective cooling, as the air is cooled directly at the point of use.

The other options describe different aspects of air conditioning systems or different types of systems altogether. The use of chilled water in a coil instead describes a chilled water system commonly found in larger commercial setups, which uses water as a medium for heat exchange rather than refrigerant. Multiple fans for air distribution may pertain to different configurations or enhancements in air handling but do not define a direct expansion system. An outside air intake system is related to ventilation and air quality but is not a characteristic that identifies a direct expansion air conditioning system specifically.