SIPHON
BREAK
ADAPTER
THERMOSTAT
F,LL
HOUSING
WATER
MANIFOLD
&-
RUBBER
HOSE
EXHAUST WATER
DISCHARGE
FRESH
WATER
\
FRONT
CYLINDER
BLOCK
CONNECTION
I
INCLOSEDSYSTEM
I
I
INLET
-
SEA
WATER
CENTRIFUGAL
PUMP
(FRESH
WATER)
FIGURE
10.
HEAT EXCHANGER COOLING
Heat Exchanger Cooling System
Marine heat exchanger cooling systems work using
the same principle as city water heat exchanger
sys-
tems.
Cool
water from an unlimited source (flotation
water) is circulated by the sea water pump through a
set
of
tubes encased within a surrounding shell (Fig-
ure
10).
Engine coolant is circulated through theshell
but is not mixed with the sea water. A second water
pump is used to circulate the engine coolant
in
the
captive system. The sea water passing through the
heat exchanger tubes absorbs the heat from the
engine coolant. The heated sea water is discharged
through the exhaust system. Figure
10
shows a
schematic of atypical marine heat exchanger cooling
system.
Keel Cooling System (Or Skin Cooling)
Keel coolers arecomprised of aseriesof finned tubes
through which heated engine coolant is circulated.
The keel cooler is attached to the underside of the
boat (keel)
so
that flotation water can pass between
the fins. the heat from
the
engine coolant is trans-
ferred to the finned tubes and absorbed by
the
flotation water. Keel coolers function similar to
.radiators except that the heat is dissipated to the
flotation water instead of to the air. An engine'driven
pump is used to circulate the coolant through the
water jacket and cylinder heads to the keel cooler.
A second pump is sometimes used to draw flotation
water and discharge
it
through the exhaust system.
This cools the muffler and exhaust pipe and reduces
the amount of heat radiated from these components.
As
with heat exchanger systems, the sea water
is
never mixed with the engine coolant. Figure1 1 shows
a schematic of a keel cooler system.
Skin coolers function similar to keel coolers except
that a section of the hull with an extra skin is used to
dissipate the heat. Engine coolant passes between
the hull of the boat and the exterior skin. The heat is
transferred to the skin and absorbed by the flotation
water. The remainder of the system operates the
same as a keel cooler system.
Keel coolers must be designed to provide adequate
cooling when thewater flowing through thefins is at a
minimum and
the
temperature of the flotation water is
at its maximum. This is necessary because theengine
is often required to operate
at
its heaviest load when
the boat is not moving. For
this
reason a larger
keel
cooler is required for the generator set than would be
required for a propulsion engine of equal size.
19
Redistribution or publication of this document,
by any means, is strictly prohibited.
To Next Page
Loading...
Need help?
General
