Like its name would suggest, a refrigerant dryer cools the compressed air. This allows the water present in the compressed air to condense and be separated from the air itself, and it is a crucial air system component for applications that require compressed air dried to a low dew point. In the first stage, compressed air enters the dryer and passes through an air-to-air heat exchanger, which pre-cools the incoming air. In the second stage, compressed air passes through an air to refrigerant heat exchanger to reduce the compressed air dew point, typically to 3°C / 37°F. Water vapor that was in the air condenses into liquid, which is trapped and removed. The dry air is then warmed up in the air-to-air heat exchanger to reduce the relative humidity in the air; this will prevent condensate from forming in downstream piping.
Refrigerated air dryers are a common type of compressed air dryer used to remove moisture from compressed air systems. These dryers work by cooling the compressed air, causing the moisture to condense into liquid form, which is then separated and drained. Here's some information about refrigerated air dryers:
