Answer: In the precooler, saturated humid hot air will condense during the cooling process, and because the compressed air entering the precooler has a high temperature and high water content, a lot of condensate will precipitate in the precooler during the heat exchange process. Therefore, setting up an automatic drainer on the precooler to allow part of the condensate to be discharged first can reduce the heat load of the evaporator. This is especially necessary in large dryers.
