The cold storage evaporator is a heat exchanger that allows the low-temperature liquid refrigerant to exchange heat energy with the medium requiring refrigeration.

The evaporator is composed of one or several sets of coils: when low-temperature liquid refrigerant enters the evaporator coil to flow. After the tube wall draws on the heat of the medium (air or water) around the coil, the most boiling liquid turns into a gas (evaporates), so that the temperature of the medium around the coil is reduced or maintained at a certain low temperature, thus achieving the goal of refrigeration. Because of this, the evaporator coil should be placed in the space medium that requires cooling. The evaporator of the cold storage is placed in the refrigerator and the freezer; the evaporator of the room air conditioner is placed inside the wall of the air-conditioned room. And as an air cooler, the evaporator coil of the water chiller that produces low water (called cold water in engineering) is placed in the shell box where cold food water is grown.