25/02/2016
Description of the Technology
Commercial Refrigeration System
presents the basic components of a commercial refrigeration system.
Heat is removed from the product display cases and discharged to the outdoors.
The basic steps of the v***r compression cycle and it's primary components are:
Ev***rator: A heat exchanger inside the display case in the sales area. Heat removed from the conditioned space within the case causes the liquid refrigerant to boil away at a very low temperature, producing a low-temperature, low-pressure gas.
Compressor: This unit pulls the refrigerant gas from the ev***rator through refrigerant piping and compresses, or pumps it up, to a much higher pressure. Compression also results in a much higher temperature for the gas. Compressors are usually centrally located in a machine room at the back of the store.
Condenser: Typically located outside, this is a heat exchanger which transfers the heat from the refrigerant to the outdoors. High-pressure refrigerant gas from the compressor is converted back into a liquid (i.e., condensed) as it is cooled inside the condenser. All the refrigerant v***r changes back into a liquid, but it is still at the same pressure as when it entered the condenser. A high-pressure, medium-temperature liquid refrigerant is now moving out of the condenser.
Receiver: A vessel which stores the liquid refrigerant leaving the condenser until it is needed at the ev***rators.
Expansion Valve: This valve, also located in the refrigerated display case, releases the high-pressure liquid in a controlled fashion. When the pressure is removed from the liquid, it rapidly be becomes a v***r that is much colder than the liquid. Now a mixture of cold liquid and v***r is coming out of the expansion device, getting ready to enter the ev***rator and start the cycle over.
Refrigerants: Commercial refrigeration systems have traditionally used R-12, R-22, and R-502 as refrigerants. These are all chlorofluorocarbon (CFC) refrigerants and as of January 1, 1997, R-12 and R-502 are no longer being produced for U.S. consumption. The cost of existing quantities has risen sharply and their future availability is uncertain. Some stores are converting from R-502 to HFC-404A. New stores or major remodels are using HFC-404A for the low-temperature systems and HFC-134A for the medium-temperature systems. Another solution is to stay with R-22 designs until firm recommendations are available from chemical suppliers and compressor manufacturers.
