In some special industries, it is not only necessary to use compressed air with a low pressure dew point (i.e., water content), but also requires that the temperature of the compressed air be very low, that is, to use a freeze dryer as a "dehydration and cooling fan". 

The measures taken at this time are: 

① Cancel the precooler (air air heat exchanger), so that the compressed air after forced cooling by the evaporator cannot be heated back; 

② At the same time, conduct an accounting of the refrigeration system, and if necessary, increase the power of the compressor and the heat exchange area of the evaporator and condenser. (In practice, a simple method commonly used is to use a larger size refrigeration dryer without a precooler to process small flow of gas.).