A water chiller is a term describing an overall package which includes refrigeration plant, water chiller, and air or water-cooled condenser. This name infers that the compressor, condenser, and chiller with internal piping and controls are combined into a single unit. Water chiller plant may vary in size from small reciprocating compressor units or condensers up to large units incorporating centrifugal or screw compressors. Few of the basic components required for mechanical refrigeration are the evaporator,  condenser, thermostatic expansion valve and compressor. These so-called chillers are largely used for air conditioning, which includes comfort and controlled process applications. Typical comfort air conditioning applications are in larger buildings where the capacities are bigger such as office buildings, shopping centers, hospitals, universities, and schools say.  Wisdom. Process air conditioning is where close control of temperature and humidity is required.  These sometimes require simultaneous cooling and reheat and include laboratories, computer rooms, operating theaters, and critical manufacturing environments.  Process cooling applications also include any manufacturing process where heat generated needs to be rejected.  These typically include plastics, food  and many other manufacturing processes.

Primary System Components

Water-cooled chillers are typically installed indoors.

Chiller evaporator

The evaporator section of a water chiller is a refrigerant-to water heat exchange. Depending upon the chiller’s design, either the refrigerant or the water is contained within the tubes.

• In a flooded shell-and-tube evaporator, cool, liquid refrigerant at a low pressure enters the distribution system through the shell and moves uniformly over the tubes, absorbing heat from warmer water that flows through the tubes.

• In a direct-expansion (DX) shell-and-tube evaporator warmer water is filled in the shell while the cool, lower-pressure liquid refrigerant flows through the tubes.

Water-cooled condenser

To cool a building or apartment, the transferred heat must ultimately be rejected outdoors. The total amount of heat rejected includes the sum of the evaporator load, the compressor work. In a hermetic chiller that is where the motor and compressor are in the same housing, these loads are all rejected through the condenser.

In an open chiller where the motor is kept separate from the compressor and is connected by a shaft, the motor heat is rejected directly to the surrounding air. The evaporator load and the compressor work are blown out through the condenser and the motor heat is taken care of by the equipment room’s air-conditioning system.

Air-cooled condenser

Air-cooled chillers reject their heat by passing ambient air across refrigerant-to-air heat exchanges. Air-cooled chillers can also be split apart. One of the most important technique is to use an indoor remote evaporator with a packaged air-cooled condensing unit outdoors. One more interesting technique is to locate the compressor and the evaporator indoors (also known as a condenser less chiller) with an air-cooled condenser outdoors. It is also possible for having an indoor air-cooled condenser.

It is vital to have a clear understanding of chilled-water system concepts and their application. There is nothing particularly complex about the principles involved. A myriad of choices are available for the design and operation of chilled-water systems. These choices include flow rates, temperatures, system configurations, and control options. After determining the needs and wants of the building owner and chiller plant operator, judicious use of these choices allows designers to provide solutions that add real value.