Cooling system of the I-C engine
Introduction:-
Due
to combustion of air fuel mixture in engine a large amount of heat is
generated.
Which should be removed,
otherwise it will wear tear the engine different parts.
Objective:-
1)
How to remove the extra or surplus heat from
the engine.
2)
How to maintain an optimum operating
temperature on which engine works optimum.
3)
How to maintain an optimum temperature as
soon as possible.
Three
jobs to do:-
1)
To remove extra heat from engine.
2)
To maintain optimum temperature.
To maintain optimum
temperature as soon as possible
There
are two methods for cooling.
1) Air
cooling system (usually use in 2 stroke engines).
2) Water
(
o) cooling system (usually use in 4
stroke engines).
o) cooling system (usually use in 4
stroke engines).
Here we are going to discuss the water
cooling system, in which water is use a coolant.
In
car engine there are water jackets (pipes usually white in color) which contain
water as a coolant. These water jackets extract heat from different
parts of engine.
Properties
of coolant (which is necessary for coolant to be used for cooling purpose)
1) Low
freezing point.
2) High
boiling point.
3) Minimum
capacity.
So
water has all these properties, thus water are used as a coolant.
Now,
problem No#1
How
to circulate water through the water jackets..
Solution: using pump water is circulated in water
jackets.
Problem
no #2:
water boiled at certain
temperature (e.g. at 100c0 and 1 ATM pressure).
Solution: we can cool back water through radiator.
Radiator
Radiator consists of upper tank and
lower tank, and between these two tanks there are tubes and fins.These
tubes and fins admit air to pass through it but not water to move out of it.
There
is also a fan connect with radiator with pass the air through radiator tubes
and fins. In this way water cooled down.
Hose (pipes):-
These are pipe which connect engine to
radiator. In cooling system there are two hose.
These
are lower and upper hoses.
Upper
hose transmit hot water from engine to radiator upper tank
And
lower hose transmit cool water from radiator to lower tank.
So
here the first job is completed.
Job
2nd and 3rd
To
maintain temperature:
Thermostat is value that opened and closed with
respect to temperature increases and decreases respectively.
Note:
when engine is on optimum temperature the thermostat value remains closed.
And when temperature increase from
optimum temperature the value opened and hot water moves through upper hose to
upper tank of radiator for
Again
cool purpose.
Problems
no #3 when thermostat value is closed
how water is circulates.
Solutions: there is bypass connected with lower hose
through which water circulate in the engine.
In
this way 2nd and 3rd jobs completed.
Problem
No #4:-
when we move up on hilly
area the ATM pressure decrease, as ATM pressure is directly proportional
boiling point. So boiling point of water decrease on hilly area (means water
will boil early).
Solution:
radiator cap is used to increase boiling point by applying pressure on water in
radiator.
Main
functions of radiator cap.
1) Increase
Boiling point by applying pressure on water.
2) Release
extra pressure.
3) Release
vacuum.
Explanation:
When coolant fluid overheats, it expands, causing the fluid to become highly
pressurized. When it enters the radiator, the pressure increases even more
because it’s in an enclosed space. The radiator cap acts as a release valve set
to open at the maximum pressure point. Usually this is set at a density of 15
pounds per square inch (psi). When the fluid pressure inside the radiator
exceeds 15 psi, it forces the valve open, allowing heat to escape and excess
coolant fluid to overflow into the tanks on either side of the radiator. Once
the radiator cools down, the coolant fluid in the overflow tanks gets sucked
back into the pump, continuing its route through the cooling system.
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