Ammonia Evaporator Air Cooler
Evaporator is an important component together with other major components in a refrigeration system such as compressor, condenser and expansion device. The reason for refrigeration is to remove heat from air, water or other substance.
It is here that the liquid refrigerant is expanded and evaporated. It acts as a heat exchanger that transfers heat from the substance being cooled to a boiling temperature.
There are two types of evap.:
Forced Convection Type uses a fan or pump to force the liquid being cooled over the evap.
Natural Convection Type has the liquid being cooled flows naturally to the evap. due to the density differences of the chilled and warm liquid.
Evaporator Construction Types
There are three types of evap. construction that are commonly being used today:
Bare-Tube and Plate Surface construction have the entire surface in contact with the evaporating refrigerant inside.
Finned construction are bare-tube coils upon which fins(metal plates usually Aluminium) are being installed. A more detailed discussion on this type of design will be provided here.
The fins are added to the bare-tube to increase the heat transfer capability. They act as heat collector that pick up heat from the surrounding air and conduct it to the refrigerant inside the tube hence improving the efficiency in cooling the air of the surrounding. They are best used in the air-cooling space where the temperature is around 34°F.
Having fins mean the surface area for heat transfer has been extended. This means that the finned coils can have more compact in design compared to the bare-tube type of similar capacity.