Evaporator for Cold Room Walk in Cooler Freezer Chiller

Evaporators for cold rooms, walk-in coolers, freezers, and chillers are important components of refrigeration systems, which play a key role in realizing the cooling function.

The evaporator is a heat exchanger of the indirect type. The low-temperature and low-pressure liquid refrigerant vaporizes and absorbs heat on one side of the heat transfer wall, so that the medium on the other side of the heat transfer wall is cooled. The cooled medium is usually water or air.

Structural Composition

It is mainly composed of five major components: a cooling heat exchange coil, an axial flow fan, a liquid distributor, a defrosting device, and a water receiving tray. The high-pressure and normal-temperature liquid refrigerant from the cold storage condenser is throttled by the thermal expansion valve and directly enters the liquid distributor of the cold storage air cooler for uniform liquid distribution, and then sent to the heat exchange coil for vaporization and heat absorption. The axial flow fan of the cold storage air cooler is responsible for forcing the convection circulation of the air inside the cold storage air cooler and the cold storage to achieve the purpose of cold storage refrigeration.

Material Selection

Common materials include copper, aluminum, and stainless steel. Copper is widely used in high-performance evaporators due to its good thermal conductivity. Stainless steel is suitable for refrigeration equipment in some special environments due to its corrosion resistance and high-temperature resistance. Aluminum is favored in some light equipment due to its light weight and good thermal conductivity.

Defrosting Method

Since the surface temperature of the evaporator is lower than 0°C, frost will form on the surface during the refrigeration process, which affects the heat transfer efficiency. Therefore, defrosting is required. Common defrosting methods include manual defrosting, refrigerant hot melt defrosting, water defrosting, and electric heating defrosting. Small refrigeration systems can use manual defrosting and electric heating defrosting, while large refrigeration systems mostly use refrigerant hot melt defrosting and water defrosting.