Liquid chillers are machines that remove heat from a liquid via a vapor-compression refrigeration cycle or vapor-absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool equipment.
centrifugal water-cooled chiller. Image source: Wikimedia Commons (P199)
Liquid chillers can be of two types. They are:
Shell and Tube type Chiller:
- Shell and tube type of chiller consists of a steel shell, cylindrical in shape fitted with a number of parallel tubes.
- There can be two types in the configuration in shell and tube types of chillers, when the refrigerant flows through the tubes and the liquid to be chilled (water or brine) flows in the shell, and secondly, the refrigerant flows in the shell and the liquid in the tubes.
- The latter types of chillers are called flooded-type chillers and a float valve is used as the expansion device.
- When the refrigeration flows into the shell, the level of liquid refrigerant in the shell is never full, as some clear space is required for the liquid and vapor to separate.
- In the dry expansion type chiller, the refrigerant flows through the tube and the liquid is chilled in the shell, so turbulence is caused in the liquid which improves the overall heat transfer coefficient.
- A thermostatic expansion valve is used through which the liquid refrigerant is fed into the tubes.
- Shell and tube chillers are widely used in almost all refrigeration systems as they have very high efficiency, require negligence maintenance and are adaptable to any system.
Shell and Coil type Chiller:
- Shell and coil-type chillers consist of a shell in which tube coils are fitted. the coils are spiral-shaped. Normally dry expansion-type shell and coil chillers are used. The refrigerant flows through the coils and the liquid to be chilled flows through the shell.
- The expansion device used is a thermostatic expansion valve. It is used for chilling water for drinking purposes. In the evaporator, the liquid is not recalculated and is chilled instantaneously as it passes through coils.
