The Evaporator Coil
Evaporator Coil – the evaporator coil is responsible for absorbing heat into the coils and the refrigerant. The evaporator coil is an essential component of vapor compression refrigeration. This is usually done as result of passing air or water over the evaporator coil where a heat exchange process takes place. Heat leaves the air or water (whatever medium is used) and is absorbed into the coil and the liquid refrigerant. As more and more heat is absorbed by the evaporator coil and the refrigerant again changes state from a liquid to a refrigerant vapor. By the time the refrigerant leaves the evaporator coil the refrigerant should be all vapor and ready to be received again by the refrigeration compressor.
A new evaporator coil replacing an old leaking coil
The evaporator coil is typically inside the air handling unit or it can be installed in the duct work near the air handling unit. When the air handler blower turns on and the condenser is running refrigerant flows from the compressor through the condenser coils and then through the metering device. and into the evaporator coil. The refrigerant changes state in the evaporator coil and again in the condensing unit. In the evaporator coil the change of state is from a liquid to a vapor while in the condenser the change of state is from a vapor to a liquid. This is all necessary for the process of refrigeration to work properly. The typical evaporator coil is constructed of copper with aluminum fins surrounding the copper coils. The aluminum adds surface area to the copper coils and enhances the heat exchange rate making the coils more efficient.
Components of Vapor Compression Refrigeration – The Evaporator Coil
Cooling towers use the process of evaporation to cool or removes heat from the condenser water that was transferred to the water in the chiller condenser barrel. The heat is absorbed at the load in this case in a data center on a data center floor. The servers and electrical equipment produce a massive amount of sensible heat. The heat is absorbed by computer room air conditioners or computer room 
This large HVAC condenser pump serves a new chiller located in a data center. This pump pumps condenser water through the condenser chiller barrel and to a cooling to reject the heat absorbed in the chillers evaporator barrel. The pump works to move the water from the chiller to the cooling and then back through the chiller again. The water is diluted with a glycol solution to prevent freezing in the winter time when the chiller needs to run at low ambient temperatures. 
This Trane HVAC chiller serves four different apartments. Chilled water systems offer a great way for multi-zone 
