COLD STORAGE FOR APPLES AND PEARS 



25 



Table 4. — Data on sodium chloride (common salt) and calcium chloride brines 



SODIUM CHLORIDE 



Specific 

 gravity 



1.00. 

 1.02_ 

 1.04. 

 1.06. 

 1.08. 



Salt in 100 



pounds of 



brine 



Pounds 

 



2.8 

 5.5 

 8.2 

 10.9 



Freezing 

 point 



32.0 

 29.1 

 26.0 

 22.7 

 19.0 



Density 



Pounds per 

 gallon 

 8.33 

 8.50 

 8.67 

 8.84 

 9.00 



Specific 

 gravity 



Salt in 100 



pounds of 



brine 



1.10. 

 1.12. 

 1.14. 

 1.16. 

 1.18. 



Pounds 

 13.5 

 16.1 

 18.6 

 21.1 

 23.5 



Freezing 

 point 



14.9 

 10.4 

 5.4 

 -.3 



Density 



Pounds per 

 gallon 



9.17 

 9.34 

 9.50 

 9.67 

 9.84 



CALCIUM CHLORIDE 



1.00 







4.7 

 9.2 

 13.5 



32.0 



29.3 

 23.2 

 16.5 



8.33 



8.67 

 9.01 

 9.35 



1.16 



17.6 

 21.5 

 25.1 

 28.7 



7.0 



-5.8 



-21.5 



-44.3 



9.68 



1.04 



1.20 



10.01 



1.08 



1.24 



10.35 



1.12... 



1.28— 



10.68 









See American Society of Refrigerating Engineers Data Book (S). 



DRY -COIL BUNKER SYSTEM 



In the dry-coil bunker system of cooling, the ammonia coils are 

 put in a separate room or bunker and air from a large blower is passed 

 over them, then distributed through ducts to the storage room. If large 

 quantities of air are used, prompt cooling and even temperatures may 

 be obtained. The problem of accumulation of frost on the pipes re- 

 mains, although disposal of the water and frost without damage to the 

 fruit is simpler than under direct expansion. In some installations the 

 pipes are defrosted periodically by spraying with brine or warm un- 

 salted water. The blower is stopped while the defrosting is taking 

 place. In other plants defrosting is done by pumping hot ammonia 

 into the coils. Dry-coil bunkers have largely given way to brine-spray 

 systems in recent installations. 



BRINE-SPRAY SYSTEM 



In the brine-spray system of cooling, air from a large blower is 

 moved over banks of ammonia coils that are continually being sprayed 

 with a solution of salt in water. Sodium chloride (common salt) is 

 generally used in these systems. The salt prevents accumulation of 

 frost, and the fine spray, being in intimate contact with the air, cools 

 it effectively. A far smaller bank of pipes can be used than in a dry 

 bunker, and cooling can be done with a higher ammonia temperature. 

 After cooling, the air is distributed to the storage rooms. When a 

 continuous brine spray is used, it is necessary to use baffles, or elimina- 

 tors, in the air stream to prevent particles of brine from being carried 

 in the air to the storage rooms. It is also necessary to treat the brine 

 with chemicals, as recommended by equipment manufacturers, to 

 reduce its tendency to become unduly corrosive. Despite the necessity 

 for eliminators, which increase the resistance to air flow, and the 

 tendency of the brine to cause corrosion, brine-spray chambers are 

 generally displacing both direct-expansion and dry-coil bunker sys- 



669297° — 46 4 



