III. HIGH-PRESSURE COMPRESSORS.
B. High-duty Apparatus.-
5. Compressors refriqerated by Injection of Water in the Cylinder. -This system is better than the foregoing, because the air becomes more perfectly saturated with watery vapor.
The compressing cylinder of the Windhausen machine (see REFRIGERATING MACHINERY
) is of this class, and is represented in Fig. 152. The cylinder
has a doable envelope in which cold water circulates. In order
to augment the surface exposed to the action of the water, grooves
are made close together on the outside of the interior shell.
Four valves, placed in each end of the cylinder, are contained
in the covers, which form chambers, and are connected by horizontal
tubes, whence lead the air-ducts. The two inlet-valves placed
at the upper part of the cover are guided by stems whichcarry
small pistons moving in closed cylinders, in which the air forms
an elastic cushion. A lever, actuated by traverse-guides on the
piston-rod, moves these stems so as completely to close the inlet-valves
when the piston reaches the end of its stroke. The two delivery-valves
at the lower part of the cylinder are composed each of a cylinder
of bronze closed by a lightly concave bottom. This cylinder travels
in another closed cylinder in which the air-spring tends to maintain
the valve upon its seat. These valves are also guided by stems
terminated by a projection with which a lever comes in contact
so as to lift the traverse guide of the piston at the end, of
each aspirating stroke. The cooling of the air is directly effected
in the cylinder by a jet of cold water which enters at the upper
portion of each end of the cylinder through an aperture made between
the two inlet-valves. This injection is produced by small pumps
placed laterally at each end of the cylinder, the pistons of which
are actuated by the air compressed in the cylinder, so that the
intensity of the jet increases with the degree of compression
of the air. Dimensions and data: Absolute air-pressure, 5 atmospheres;
vol. ume of air per minute furnished at this pressure, 371 cubic
feet. Motor, sin.-le horizontal cylinder communicating with compressor;
compressor horizontal, double-acting. Diameter of piston, 43.6
inches ; stroke, 41 inches; useful volume of cylinder, 37.1 cubic
feet ; revolutions per minute, 25 ; theoretic volume at this velocity,
1,858.5 cubic feet.