Chillers play a pivotal role in air conditioning, refrigeration and industrial cooling systems. The main operating component within each chiller is the compressor, which condenses gaseous refrigerant within the system so that it is able to extract more heat during the cooling process. Different types of chillers are typically distinguished from one another based on the compressor technology they employ. Choose the right type of chiller to maximize energy efficiency, balance cooling costs, and stay cool on hot summer days.
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Reciprocating chillers utilize an internal piston contained within a cylindrical compartment. As gaseous refrigerant enters the compressor, the piston compresses the refrigerant to increase pressure. Once pressure levels have risen to a high enough point, an exhaust valve releases the compressed refrigerant so it can re-enter the cooling system and claim more heat energy from the building. According to the U.S. Department of Energy, reciprocating chillers can accommodate cooling loads between 30 and 150 tons. They represent one of the most affordable and widely used forms of chillers, but are the least efficient of all chiller technologies, according to Energy Star.
Rotary chillers can handle loads as high as 300 tons, according to Energy Star, making them appropriate for large residential and most commercial applications. These units feature an internal roller that rotates within a steel cylinder. As refrigerant enters the cylinder through an intake valve, the rotating roller compresses it between the roller and the wall of the cylinder. As the roller continues to rotate, it forces the compressed refrigerant out through an exhaust valve to complete the cooling cycle. These units are one of the most efficient types of chillers on the market, and also feature quiet operation, according to Nanomagnetics.
Scroll compressors feature the smallest capacity of all chiller models, and can handle loads between 30 and 60 tons, according to the U.S. Department of Energy. They use two interlocking coils, with one stationary and one rotating. As refrigerant enter the compressor, it gets caught between the walls of the coils and compressed down into the center of the two coils, where it exits through an exhaust port. These small compressors are used in automobile air conditioners as well as small industrial cooling systems.
Centrifugal chillers use an impeller to rapidly accelerate refrigerant from an intake port to the walls of a cylinder. The centrifugal force causes the gas to collect along the walls, then directs it to an exhaust port to continue to the cycle. Many commercial systems use multiple impellers to compress large quantities of refrigerant simultaneously. According to Energy Star, these systems have the largest capacity of all chillers, and are often used on applications requiring 300 tons of cooling capacity or greater.