According to the usage of the refrigerant "inner circuit", horizontal evaporators can be divided into two types: "dry evaporator" and "full liquid evaporator". The former refrigerant boils (evaporates) inside the tube, while the air flows outside the tube, which is widely used in cold drying machines. In a full liquid evaporator, the refrigerant liquid boils (evaporates) outside the tube, and the cooled compressed air flows inside the tube; The refrigerant level will completely immerse the heat exchange copper tube. 

Full liquid evaporators are less commonly used in cold dryers because:

 ① it is not possible to increase the heat exchange area on the side with a smaller heat release coefficient by using methods such as outer sleeves to enhance the heat exchange effect; 

② Refrigerant Freon is easily soluble in refrigerant oil and difficult to remove, which can affect heat transfer efficiency and affect oil return. In severe cases, it can cause the compressor to run out of oil; 

③ Cannot set baffle plates to block or collect condensed water;

④ From the perspective of the force acting on the copper tube, the gas pressure inside the tube is higher than the evaporation pressure of the refrigerant outside the tube, and the copper tube is prone to cracking