Coil Room Systems.
—The overhead bunker system as described under “Construction” in this work details the application of the United States practice.
Accepting the use of the coil room system and of still storage the question arises as to the application. A visit of inspection to the various packing plants throughout America will impress one with the fact of the existence of a wide variation of opinion and practice with regard to the methods of applying refrigeration for packing house purposes. There are two principal applications—direct expansion, wherein the ammonia gas is circulated through the coils throughout the premises, and brine circulation, open or closed, where chilled brine is circulated throughout the works.
Brine Chilling.
—The two types of brine chilling, open and closed, produce the same result, except as to the actual brine cooler, of which there are several, namely:
(1) Brine tank in which are submerged ammonia expansion coils.
(2) Double or triple pipe coolers in which brine and ammonia are circulated in annular spaces between pipes.
(3) Shell type coolers in which the brine is passed through tubes within a shell similar to an ordinary flue boiler.
For a close brine system, which is the term applied to a system where brine is circulated through pipes and not exposed to the atmosphere so as to absorb moisture, the shell type cooler is a convenient and economical means of chilling brine. It is so readily applicable to the use of a balanced system, thereby lessening the power requirement for pumping.
Double pipe coolers can be used in the same method, but are not quite so favorably considered owing to the aggregate quantity of joints.