and condensed on the outer surfaces of the tubes (fig.
The condenser is constructed with a tube sheet
brazed to each end of a shell. Copper-nickel tubes are
inserted through drilled openings in the tube sheet and
are expanded or rolled into the tube sheet to make a
gastight seal. Headers, or water boxes, are bolted to the
tube sheet to complete the waterside of the condenser.
Zinc-wasting bars are installed in the water boxes to
minimize electrolytic corrosion of the condenser parts.
A purge connection with a valve is at the topside of
the condenser shell to allow manual release of any
accumulated air in the refrigerant circuit.
The capacity of the water-cooled condenser is
affected by the temperature of the water, quantity of
water circulated, and the temperature of the refrigerant
gas. The capacity of the condenser varies whenever
the temperature difference between the refrigerant gas
and the water is changed. An increased temperature
difference or greater flow of water increases the
capacity of the condenser. The use of colder water can
cause the temperature difference to increase.
E V A P O R A T I V E C O N D E N S E R S .An
evaporative condenser operates on the principle that
heat can be removed from condensing coils by
spraying them with water or letting water drip onto
them and then forcing air through the coils by a fan.
This evaporation of the water cools the coils and
condenses the refrigerant within.
A liquid receiver as shown at position (5) on figure
6-14, serves to accumulate the reserve liquid
refrigerant, to provide a storage for off-peak operation,
and to permit pumping down of the system. The
receiver also serves as a seal against the entrance of
gaseous refrigerant into the liquid line. When stop
valves are provided at each side of the receiver for
confinement of the liquid refrigerant, a pressure relief
valve is generally installed between the valves in the
receiver and condenser equalizing line to protect the
receiver against any excessive hydraulic pressure
being built up.
The evaporator is a bank or coil of tubing placed
inside the refrigeration space. The refrigerant is at a
low-pressure and low-temperature liquid, as it enters
As the refrigerant circulates through the
evaporator tubes, it absorbs its heat of vaporization
from the surrounding space and substances. The
absorption of this heat causes the refrigerant to boil.
As the temperature of the surrounding space (and
Figure 6-21.Water-cooled condenser.