Anatural draft cooling tower is very tall because: (a) possibility of drift losses of water (b) large quantities of packing are needed to compensate for the low air velocities achieved by the tower. (c) possibility of spreading legionnaire's disease is minimized (d) the amount of draft provided for pulling air through the tower is proportional to the tower height.

The catalogue for a refrigerant 22, four-cylinder, hermetic compressor operating at 29 r/s. a condensing temperature of 40°c and an evaporating temperature of -4°c shows a refrigeration capacity of 115 kw. at this operating point, the motor (its efficiency is 90 percent) draws 34.5 kw. the bore of the cylinders is 87 mm and the piston stroke is 70 mm. the performance data are based on 8°c of sub-cooling of the liquid leaving the condenser. compute (a) the actual volumetric efficiency and (b) the compression efficiency.