Answer: In the refrigeration device in operation, since the refrigerant and refrigeration oil will produce impurities such as moisture, solid powder, dirt, etc., in serious cases, the throttling holes of the throttling structure will be blocked, so a dry filter must be installed in front of the refrigerant liquid supply pipe. In addition, trace moisture in the refrigerant is the most harmful to the refrigeration system, and the drying treatment of the refrigerant, refrigeration oil, evaporator, and condenser is extremely important.