Answer: Horizontal evaporators can be divided into two types: "dry evaporators" and "full-liquid evaporators". In the former, the refrigerant boils (evaporates) inside the tube and the air flows outside the tube. It is widely used in cold dryers. In a full-liquid evaporator, the refrigerant liquid boils (evaporates) outside the tube and the cooled compressed air flows inside the tube; the refrigerant liquid level completely immerses the heat exchange copper tube. Full-liquid evaporators are rarely 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 jacket plates to enhance the heat exchange effect.
(2) The refrigerant Freon is easily soluble in refrigeration oil and is not easy to remove, which will affect the heat transfer effect and oil return. In severe cases, it will cause the compressor to run without oil.
(3) It is not possible to set a baffle to block and gather condensed water.
(4) From the perspective of the force 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.
