What distinguishes a two-stage evaporative cooler from a single-stage evaporative cooler?

A two-stage evaporative cooler is characterized by its use of two heat exchangers, typically one that is dry and one that is wet. This design allows it to achieve greater efficiency in cooling and humidity control compared to a single-stage evaporative cooler. The dry heat exchanger cools the air through direct contact with the outside air, while the wet heat exchanger further cools and humidifies the air, enhancing the overall cooling effect. This dual-stage process helps to deliver cooler air with a more comfortable humidity level, making the cooling system more effective for various applications.

The other aspects, such as producing more humidity or requiring mechanical energy, do not specifically define the distinction between single-stage and two-stage coolers. Additionally, while both types can be used indoors or outdoors, the main differentiator lies in the two distinct heat exchangers which optimize the cooling process.