Page 169 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Engine systems 153

Figure 2.139 Convection

Figure 2.140 Conduction

Figure 2.141 Radiation

All three forms of heat transfer are used in the cooling system:
Convection occurs in the water jacket, creating fl ows of internal coolant from
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the cylinder block to the cylinder head ( Fig. 2.139 ).
Conduction occurs through the cylinder and combustion chamber surfaces as
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heat passes to the coolant ( Fig. 2.140 ).
Radiation of heat occurs from the radiator and cooling fi ns when heat is
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dissipated to the atmosphere ( Fig. 2.141 ).
The amount of heat transfer is dependent on four main factors:
the temperature difference between the engine and coolant
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the temperature difference between the coolant and the air stream passing
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through the radiator
the surface area of the radiator tubes and fi ns
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the rate of fl ow of air and coolant through the radiator.
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