Chiller Barrel Evaporator – A chiller evaporator barrel exchanges heat between one refrigerant and another. Usually, the primary refrigerant is R-22, R-134A, or some other blend or alternative HFC. The secondary refrigerant is water. This water is circulated throughout the building where it passes through piping and coils. This is generally in most cases a forced air coil where the heat is removed from the air by a heat exchange process with the water and the coil. The cooler air is then forced through duct work and into the space to be conditioned.
The water is then pumped back through the chiller barrel evaporator so that the heat absorbed can be removed in the chiller barrel evaporator where another heat exchange process is done. The heat in the water is absorbed into the refrigerant and the water makes another trip to the building to absorb more heat. The refrigerant is then pumped to the compressor where it is compressed and then it travels through a condenser coil or a condenser barrel where the heat it absorbed from the water is rejected. This is the basic process for a chilled water system. There are many different types of chilled water systems which use different refrigerants but that is the basics of a chilled water system operation. These systems range from small residential units to very large multi-tonnage systems which serve very large buildings and process refrigeration in industry.
Smaller chillers are typically air cooled while larger systems use a cooling tower. If the heat in the condenser is rejected via air then the chiller will have several fans that will pull air through the condenser coils and the heat is rejected into the atmosphere allowing the refrigerant in the condenser coils to cool and then return to the metering device and the evaporator barrel. If the chiller uses a condenser then the heat is rejected into water that is circulated through the same condenser where the refrigerant is located. Heat is exchanged from the refrigerant to the water. The water is then pumped to a cooling tower where the cooling tower rejects the heat from the water into the atmosphere using the heat exchange process of evaporation.
There are a few other methods but this is by far the way chilled water for chilled water systems are produced for all applications of air conditioning including process cooling, commercial cooling, and residential cooling. If you work in a large building, a data center, or a business where it necessary to have large scale cooling systems then it is very likely that the place where you work is cooled by a chilled water system.