Refrigerating Systems. Liquid coolers
Shell-and-tube heat exchangers type (Fig. 3.20) are the most common form evaporating apparatus for cooling water and cooling applications. These forms are used for cooling of liquids that can be used as a secondary refrigerant or for cooling the finished product directly. In practice, these types of heat exchangers are known as liquid coolers or chillers.
Some examples of applications in the food and refrigeration industry are:
Cooling of drinking water,
The cooling water for air conditioning coils,
Cool the milk after pasteurization and
The cooling process.
Chilled water systems can be used with flooded evaporation or direct expansion evaporator, which is usually a shell-and-tube heat exchangers. In the flooded evaporator refrigerant filled shell side of the heat exchanger and controlled valve. The water cooled passes through the tubes. On the contrary, in direct expansion evaporator, water is carried in the shell and the refrigerant is cooked inside the tubes. The speed of the flow of refrigerant do not have resources to ensure that only REFRIGERANT gas outlet of the evaporator.
Copper tubes are mounted in a carbon steel shell is the most common structure used for chilled water vaporizers.
It is important to note that if the refrigerant evaporates on the outer surface of pipes of the flooded evaporator cooler; if it vaporizes inside the tubes evaporator dry cooler (note that in this more General type, a mixture of liquid and vapor completely evaporated, as a rule, with some degree of overheating (Hewitt et al., 1994). In a flooded water cooler or in brine is distributed through pipes, which, as a rule, finned, to ensure the growth of the heat transfer rate and a decrease in the evaporator size. In a dry cooler liquid refrigerant contained in the pipes, and water, or in brine distributed through the shell of the cooler, which serves as an evaporator. Flooded coolers are often specified for applications where the shell side of the evaporation of the coolant other liquids, preferably. Due to a rapid boil in a shell, in order to obtain high purity pair, separation vessel often welded to the main shell. Flooded refrigerators, especially those in several compressor units.