| ENGINE COOLING SYSTEM - WATER CIRCULATION |
| Heat
energy produced by a spark ignition engine constitutes less than 30 per
cent of the total energy required for useful work, while the rest has
to be disposed of without causing any harm to the engine parts. About
36 per cent passes out of the exhaust system, some 7 per cent is lost
to internal friction and heating the lubricating oil, while another 33
per cent is dissipated in the cooling system.
There are two types of cooling systems, direct and indirect. In the direct
system, air is blown over the cooling fins on the outside of the cylinder
heads. In the indirect system a coolant which is generally water, flows
through passages in the engine.
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| The
essential parts of a modern water cooled engine are: |
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A
jacket that surrounds all hot regions such as the combustion chamber,
cylinder bores, inlet manifolds and exhaust ports. |
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Radiator
that cools water that returns from the engine |
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A
pump to circulate water through the passages |
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A
fan to cool water in the radiator. |
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Hoses
connecting radiator to the engine to make a circulatory system. |
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Thermostat
to control circulation of cooling water so that engine remains at efficient
running temperature. |
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Pressure
cap on radiator to raise boiling point of water and thereby suppress formation
of steam pockets near combustion spaces.
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| The
ideal temperature for an engine to operate efficiently is that which heats
the coolant to a point near the thermostat housing to about 80-850C. |
Source
April 2001 |
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