result in a distilled water supply temperature to the
electronics of approximately 104°F. Type II (SW/DW,
CW/DW) systems are used in installations that cannot
accept a DW temperature higher than 90°F. Type III
(CW/DW) systems are used in installations where the
temperature range is critical. They require close
regulation of the DW coolant to maintain temperatures
between established limits. For example, the
temperature limits might be 70°F and 76°F. As you can
see, Type III systems are used where tighter control is
required.
Liquid cooling systems are composed of piping,
valves, regulators, heat exchangers, strainers,
circulating pumps, expansion tanks, gauges, and a
demineralize. In some systems, there are specialized
components to monitor cooling water to the electronic
equipment. Lets examine this in greater detail by
discussing the operation of the three types of liquid
cooling systems. Before doing so, however, lets look
at the systems in terms of primary and secondary
systems.
PRIMARY COOLING SYSTEM
The cooling water for the primary cooling system is
either seawater or chilled water. The seawater,
obviously, is from the sea and the chilled water is from
the ships air-conditioning plant. Figures 1-6,1-7, and
1-8 show the basic arrangements of systems using
seawater and chilled water.
In figure 1-6, seawater from a sea connection is
pumped by a seawater circulating pump in one of the
ships engineering spaces through a duplex strainer to
remove all debris and then through the tubes of a heat
exchanger. Finally, it is discharged back into the sea at
an overboard discharge. The seawater system shown in
figure 1-6 is a multiple-branch system. As such, it
supplies a number of heat exchangers for electronic
equipment. To regulate the proper amount of seawater
to each cooling system, an orifice plate is installed in the
line between each heat exchanger and the duplex
strainer.
The heat exchangers are referred to as
seawater-to-distilled-water heat exchangers.
Another means of providing seawater is through the
ships firemain, as shown in figure 1-7. The seawater is
Figure 1-7.Type II liquid cooling system.
1-5