14_Water Cooling System
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Transcript 14_Water Cooling System
WATER COOLING SYSTEM
LESSON FOURTEEN
1. HEAT SOURCES
Burning of fuel
Heat developed by compression of air
Frictional heat
1. HEAT SOURCES
Burning of fuel
Heat developed by compression of air
Frictional heat
2. HEAT DISTRIBUTION
1/3 = converted into useful work ( transferred into mechanical energy /
BHP.
1/3 = lost as exhaust gases
1/3 = lost for cooling / absorbed by metallic walls of the combustion
chamber.
1. HEAT SOURCES
Burning of fuel
Heat developed by compression of air
Frictional heat
2. HEAT DISTRIBUTION
1/3 = converted into useful work ( transferred into mechanical energy /
BHP.
1/3 = lost as exhaust gases
1/3 = lost for cooling / absorbed by metallic walls of the combustion
chamber.
3. OVERHEATING
Breakdown of L.O. film
Loss in material strenght
Excessive stresses due to unequal temperatures
Faliure to maintain proper clearances between running parts.
4. COOLANTS
Fresh water
Luboil
4. COOLANTS
Fresh water
Luboil
5. COOLING WATER TEMPERATURE
5.1 The temperature should be kept as high as possible.
5.2 If to high, it will cause boiling of water and formation of scale
deposits ( incrustration )
5.3 If to low, it will lead to condensation of combustion gases on the
liner surfaces.
5.3.1 Product of condensation may:
contain acids causing corrosion
cause so called cold sludge in the L.O. increasing wear in all
moving parts
6. COOLING WATER TREATMENT & CONSEQUENCES
If the cooling water is not properly treated, the closed cooling
systems may undergo fouling, formation of deposits ( preventing or
disturbing the heat transfer ). The deposit consists of loose sludge and
solid particles.
Removal: mechanically ( first brushed or rinsed off with water ) or
chemically.
Narrow spaces are chemically cleaned.
Limestone deposits can be cleaned with acid solution.
6. COOLING WATER TREATMENT & CONSEQUENCES
If the cooling water is not properly treated, the closed cooling
systems may undergo fouling, formation of deposits ( preventing or
disturbing the heat transfer ). The deposit consists of loose sludge and
solid particles.
Removal: mechanically ( first brushed or rinsed off with water ) or
chemically.
Narrow spaces are chemically cleaned.
Limestone deposits can be cleaned with acid solution.
7. WATER COOLING SYSTEMS
Large slow speed, two stroke engines have 2 separate closed
cooling circuits.
A header or expansion tank allows venting of the system. The
header has connections from engine discharge & pump suction line.
A heater is fitted with by pass to warm the engine when necessary.
Cylinder jacket system
Water → lower end of the jacket → cylinder cover → exhaust valve cages
→ turbocharger → turbine cooling spaces → air separator → main
discharge.
The piston cooling system
Water → piston cooling tank → piston water cooler → piston cooling
connections → return by gravity to supply tank