Chapter 19. -REFRIGERATION AND AIR CONDITIONING PLANTS 



Both types of chilled water circulating sys- 

 tems operate on the same general principle. 

 The secondary refrigerant (chilled water) is 

 circulated to the various cooling coils. Heat 

 from the spaces being cooled is absorbed by 

 the chilled water and is removed from the 

 water by the primary refrigerant in a water 

 chiller. 



Figure 19-16 illustrates the flow of primary 

 refrigerant, secondary refrigerant, and con- 

 denser water in an R-11 chilled water circulat- 

 ing system which has a single-stage centrifugal 

 compressor. The primary refrigerant vapor 

 goes from the evaporator to the compressor, 

 where it is compressed. It is then discharged 

 to the condenser. In the condenser, the primary 

 refrigerant vapor condenses, giving up its 

 superheat, its latent heat of vaporization, and 

 its heat of compression to the cooling water 

 that flows through the condenser tubes. The 

 liquid primary refrigerant then passes through 

 a high pressure float valve to the cooler. 



The secondary refrigerant picks up heat in 

 the coils of the air conditioned space and car- 

 ries this heat to the cooler. The function of the 

 cooler is to transfer the heat from the secondary 

 refrigerant to the primary refrigerant which 

 surrounds the tubes of the cooler. As this heat 

 is transferred, the liquid primary refrigerant 

 absorbs its latent heat of vaporization, boils, 

 and vaporizes. The quantity of liquid refrig- 

 erant thus evaporated varies directly with the 

 amount of heat picked up by the secondary 

 refrigerant. The vaporized primary refrigerant 

 goes to the compressor, and the same sequence 

 of events is repeated in a cyclical manner. 



Figure 19-17 illustrates an R-11 chilled 

 water circulating system with a two-state cen- 

 trifugal compressor. The refrigerant vapor 

 coming from the cooler goes into an opening 

 around the hub of the first wheel of the centrifu- 

 gal compressor. The blades in the rapidly 

 rotating wheel impart velocity to the vapor. The 

 vapor is then directed to the hub of the second 



(W 



-AIR CONDITIONING SYSTEM 

 COOLING COILS 



I S REFRIGERANT 



SECONDARY REFRIGERANT 

 CONDENSER WATER 



COMPRESSOR 



147.120 



Figure 19-16.— Flow diagram, chilled water circulating system with 

 single-stage centrifugal compressor. 



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