How Do Commercial Chillers Work?

by Contributing Writer; Updated September 26, 2017
Chiller for building cooling

Overview of Commercial Chillers

A commercial chiller is a device that removes heat from liquid using vapor-compression technology. Commercial chillers reduce the temperature of liquids (often water though other liquids can also be cooled by chillers) for industrial applications. Commercial chillers utilize four main components: a compressor, an evaporator, a condenser and a metering device. Commercial chillers operate with a closed-loop system, which means that the coolant remains in the chiller and is recycled across many uses. Closed-loop commercial chillers contain a separate tank that filters and cleans the coolant before returning it to the main storage area for re-use.

Mechanics of Commercial Chillers

Commercial chillers use a chemical refrigerant to absorb heat and remove it from the liquid being chilled. There are numerous different types of refrigerants, although Freon is the most popular. The refrigerant mixes with the liquid in a chamber inside the chiller, where it interacts with the liquid to remove the heat. The rate at which the refrigerant and the liquid enter the chamber is controlled by the chiller's metering device. After the refrigerant has absorbed the heat, it is sucked out of the chamber and sent to the chiller's compressor. The compressor evaporates the heat from the refrigerant and pumps the refrigerant back into the recycling tank, which contains a condenser. The condenser filters the refrigerant and cools it before returning it to the main storage tank for re-use. The heat that remains in the compressor mixes with air to form vapor, which the compressor pumps into the atmosphere through a vent. Some commercial chillers contain large cooling towers attached to the compressor to provide additional cooling power. The cooling towers improve the commercial chiller's effectiveness by accelerating the evaporation of the heat from the refrigerant.

Vapor-Compression Technology

Vapor-compression is the method by which a commercial chiller's compressor evaporates heat from the refrigerant. There are four main types of compressors that utilize vapor-compression technology: reciprocating compressors, scrolling compressors, centrifugal compressors and rotary screw compressors. Reciprocating compressors are the most widely used because they are the simplest and the easiest to maintain. Reciprocating compressors use pistons to compress the refrigerant and the liquid, which causes heat evaporation in the piston chamber. Scrolling compressors use orbiting disks to suck refrigerant into a sealed chamber, where it interacts with the liquid to evaporate heat. Centrifugal compressors use an impeller wheel to exert force on the refrigerant inside of a chamber. The force compresses the refrigerant into the liquid, accelerating evaporation. Rotary screw compressors are similar to scrolling compressors in that they use two helical rotors to suck refrigerant into the chamber and force the mixing of the refrigerant with the liquid.

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