What is a Chiller?
A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool equipment, or another process stream (such as air or process water). As a necessary by-product, refrigeration creates waste heat that must be exhausted to ambience, or for greater efficiency, recovered for heating purposes.
Chilled water is used to cool and dehumidify air in mid- to large-size commercial, industrial, and institutional facilities. Water chillers can be water-cooled, air-cooled, or evaporatively cooled. Water-cooled systems can provide efficiency and environmental impact advantages over air-cooled systems.
Water Cooled Chiller means?
The Water Cooled Chiller supplies cold water to the cooling coil of fan coil units and air handlers. An overall comparison of water-cooled and air-cooled chillers shows the water-cooled type to be much more efficient. However, air-cooled chillers do not require water and are free of the complications of precipitation in the cooling circuit, thus extending the service life of the AC equipment. Furthermore, the function of air-cooled chillers is not interrupted by disruptions in the water supply.
Water-cooled chiller systems have a cooling tower, thus they feature higher efficiency than air-cooled chillers.
Water-cooled chillers are more efficient because they condense depending on the ambient temperature bulb temperature, which is lower than the ambient dry bulb temperature. The lower a chiller condenses, the more efficient it is.
This system has several essential components including:
- Cooling towers
- Condenser water pumps
- Make-up water pumps
- TES reservoirs
What are the benefits of a water-cooled chiller?
Some users may prefer these chillers because of the smaller size they occupy as compared to air-cooled chillers. These chillers also feature higher efficiency and last longer than the mentioned alternative. Those who would like the equipment to be placed indoors may find the water-cooled machine desirable.
In The Evaporator
The role of the evaporator is to produce chilled water. The device releases the water at about 6°C (42.8°F) and pushes it throughout the facility with the help of a pump.
A network of pipes passes the chilled water through every necessary section of the building. After exchanging coldness with room air, which blows across the Air Handling Units (AHU’s) and fan coil units (FCU’s), the water is now warmer at about 12°C (53.6°F). It returns to the evaporator where the refrigerant absorbs the unwanted heat and directs it to the condenser. The chilled water is cool once again and it can now continue to cool the facility. Note how this is called “chilled water” throughout no matter the temperature.
In The Condenser
A refrigerant brings unwanted heat from the evaporator and passes through the condenser. There is another loop connected to the condenser- the condenser water loop, which is between the cooling tower and the condenser.
After entering the condenser at about 27°C (80.6°F), the water leaves at 32°C (89.6°F) and heads to the cooling tower. Note that at no time do the refrigerant and the condenser contact directly. Heat exchange is only through a pipe wall. The condenser water, with the unwanted heat, goes to the cooling tower for further heat rejection.
In The Cooling Towers
This is where the unwanted heat in a facility ends up. A large fan feeds the unit with air. The air meets with the oncoming condenser water. From the direct contact, the condenser water loses heat to the air. The condenser water goes back to the condenser the cycle continues. These open-topped devices come in many designs depending on many factors. Examples are cross flow, counter flow, natural draft and mechanical draft. Stay with us for a coverage of these designs in upcoming posts.