PRINCIPLES OF NAVAL ENGINEERING 



CONDENSER 

 WATER IN 



CONDENSER 

 WATER OUT 



• FLOAT 



■ FLOAT 



35°T0 45°F 



47.110 



Figure 19-17.— Chilled water circulating system with two-stage centrifugal compressor. 



wheel, where it is compressed and discharged 

 to the condenser. 



Between the condenser and the cooler, the 

 liquid refrigerant passes through an economizer. 

 A float in the upper chamber of the economizer 

 allo\<'s the passage of refrigerant into the lower 

 chamber. By connecting the economizer to the 

 second stage of the compressor, the pressure 

 in the lower chamber is greatly reduced. The 

 reduced pressure causes some of the liquid 

 refrigerant to flash into vapor, thus cooling the 

 remainder of the refrigerant. Thus the econo- 

 mizer acts as an interstage flash cooler and 

 increases the efficiency of the plant. A float in 

 the lower chamber of the economizer allows 

 the passage of the refrigerant into the cooler. 

 In the cooler, the liquid refrigerant absorbs 

 heat from the water and changes from a liquid 

 to a vapor. 



Self-Contained Air Conditioners 



Self-contained air conditioners are installed 

 on some ships that were originally built without 



mechanical cooling systems. A self-contained 

 air conditioner is built with the entire unit in 

 one metal cabinet. The compressing element in 

 the unit is usually of the hermetically sealed 

 type, with the motor and the compressor con- 

 tained in a welded steel shell. Some self- 

 contained air conditioners utilize a thermostatic 

 expansion valve similar to the type used in large 

 refrigeration plants; others utilize capillary 

 tubes to ensure an even flow of refrigerant 

 through the cooling coil. 



HEATING AND VENTILATION 



Aboard ship, heating is accomplished by 

 means of steam heaters installed in the ventila- 

 tion ducts and by means of space heaters. On 

 steam-driven ships, the steam for the heaters 

 is supplied at reduced pressure from an auxiliary 

 steam system. Ondiesel-driven ships, the steam 

 is supplied by an auxiliary boiler. Some electric 

 heaters are also used aboard ship; these are 

 used primarily for heating spaces which are 

 located at a considerable distance from the steam 

 piping system. i 



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