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DRY AIR REFRIGERATING MACHINE.


A large number of scientific and other gentlemen interested in
mechanical refrigeration lately visited the works of Messrs. J. & E.
Hall, of Dartford, to inspect the working of one of their improved
horizontal dry air refrigerators!

The machine, which is illustrated below, is designed to deliver about
10,000 cubic feet of cold air per hour, when running at the rate of 100
revolutions per minute, and is capable of reducing the temperature of
the air from 90 deg. above, to about 50 deg. below zero, Fah., with an
initial temperature of cooling water of 90 deg. to 95 deg. Fah. It can,
however, be run at as high a speed as 140 revolutions per minute.
The air is compressed in a water-jacketed, double-acting compression
cylinder, to about 55 lb. per square inch --more or less according to
the temperature of the cooling water--the inlet valve being worked from
a cam on the crank shaft, to insure a full cylinder of air at each
stroke, and the outlet valves being self acting, specially constructed
to avoid noise in working and breakages, which have given rise to so
much annoyance in other cold air machines. The compressed air, still at
a high temperature, is then passed through a series of tubular coolers,
where it parts with a great deal of its heat, and is reduced to within
4 deg. or 5 deg. of the initial temperature of the cooling water. Here