There are major two heat exchangers that are currently working in the market. One is that converts the air to air and the other one is used to convert the air to the refrigeration. In addition to these two systems of heat exchange, there is one more system that has both the functions embedded in the system as TRISAB. The compressors used in the both or mixed kind of heat dryers are usually of the most common gas used as R-410a and R-134a with a hermetic type of system especially in the case of an air dryer that is small up to 100 cfm. An older and larger dryer still keeps a different form of gas that is R-22 and R-404a refrigerants. The main goal of the system with two heat exchangers embedded in it is to get the cool outgoing air cooling down the hot air that is coming inside and this reduces the size of the compressor that is required. An increase in temperature at the same time of outgoing air is able to prevent the re-condensation from happening. There are some manufacturers that produce cycling dryers. This kind of dryers has the cold mass that is sufficient enough to cool the air in the beginning when one has turned off the compressor.
At the time of compressor running the large mass takes a little longer to produce the results of cooling, so the compressor works longer and has to stay OFF longer. This kind of units operates at the lower points of dew basically 35-40 f range. When a person is selecting the optional cold coalescing filter, the units can deliver the air with compression with lower dew points.
The non-cycling dryers choose to the use of a hot gas through gas pass valve in order to prevent the dryers from icing up. There are some manufacturers that produce “cold coalescing filters” with a position inside the air dryer with the lowest possible air temperature.
Compressors can be built in refrigeration dryers with a mixed acceptance that they get in the market.