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INDEX
Page No.
1) Abstract 1
2) Introduction 2
3) Conventional Method 2
4) Drawbacks of Conventional Method 5
5) Implementation of Fuzzy Logic 6
6) Advantages of Intelligent Cooling System 8
7) Conclusion 9
8) References 10
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ABSTRACT
In the present paper, efforts have been made to highlight the concept of an
“INTELLIGENT COOLING SYSTEM”. The basic principle behind this is to control
the flow rate of coolant by regulating the valve by implementing FUZZY LOGIC.
In conventional process the flow rate is constant over the entire engine jacket.
Which induces thermal stresses & reduction in efficiency.
The “INTELLIGENT COOLING SYSTEM” i.e implementation of fuzzy logic
will overcome the above stated drawbacks in any crisp situation. The flow rate of coolant
will be controlled by control unit & intelligent sensors.
This is a concept and an innovative idea not been implemented yet.
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INTRODUCTION
The name “INTELLIGENT COOLING SYSTEM” represents the improved
function of cooling systems. We have given this name because in this system the sensor
will sense the cylinder temperature as similar as thermostat and will control the opening
and closing of water passage in the piston cylinder arrangement. The mass flow rate of
water will be controlled by a valve arrangement.
For regulating flow rate, a separate programming can be done. In this
programming, the piston will be considered as an object and a relation of “temperature =
water” can be used for the above purpose.
Our system will work on the same principle of an “INTELLIGENT
CARBURETOR” In which its aim is to supply the correct O/P i.e. air fuel mixture by
sensing the I/P i.e. operating conditions.
But, the system which attracted the most is the “IDLE SPEED CONTROLLER”
which is used to control the idle speed of SI engine.
CONVENTIONAL COOLING SYSTEM :-
The following are the two main characteristics desired of an efficient cooling
system
1) It should be capable of removing about 30% of heat generated in the combustion
chamber while maintaining the optimum temperature of the engine under all
operating conditions of the engines.
2) It should remove heat at a faster rate when engine is hot. However, during
starting of the engine cooling should be minimum, so that the working parts of
the engine reach their operating temperature in a short time.
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a) Liquid Cooled Systems :-
In this system mainly water is used and made to circulate through the jacket
provided around the cylinder, cylinder-head, valve ports and seats where it extracts
most of the heat. The diagrammatic sketch of water circulating passage is shown in
Fig.
Fig. 1 Cooling Water Passage.
b) Variation of gas temperature :-
There is an appreciable variation in the temperature of the gases inside the engine
cylinder during different processes of the cycle. Temperature inside the engine cylinder is
almost the lowest at the end of suction stroke. During combustion there is a rapid rise in
temperature to a peak value which again drops during the expansion. This variation of
gas temperature is illustrated in fig (2). for various processes in the cycle.
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Fig. 2 Gas Temperature Variation during a Cycle.
The cooling system comprises of the following parts namely:
Radiator,
Thermostat,
Water pump &
Piston-cylinder assembly.Fig 3
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DRAWBACKS OF CONVENTIONAL COOLING SYSTEMS
EFFECT OF OVERHEATING :
Evaporation of lubricating oil that lubricates the piston and cylinder wall. This will
result in metal to metal contact of the piston and the cylinder wall leading to piston
scuffing and piston seizure.
Setting up of the thermal stresses in the cylinder, cylinder head and piston. This may
lead to cracking of them.
Burning of the piston crown.
Sticking of piston rings in the ring grooves, due to carbonization of the oil. Ring
sticking will result in inefficient sealing of the cylinder increased blow by of gases
and loss of thermal efficiency.
Reduction in volumetric efficiency i.e. reduced weight of charge retained in the
cylinder.
EFFECT OF EXCESSIVE COOLING :
Reduction in thermal efficiency
Increased corrosion of engine parts.
Reduced mechanical efficiency.
Improper vaporization of the fuel.
Also due to the inadequate supply of the coolant the machine parts get overheated
and this may lead to two effects:
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DRAWBACKSOVERHEATING
EXCESSIVE COOLING
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Generation of excessive heat which results in the break down of the engine.
Evaporation of the coolant (water) may results in SCALE formation.
Effect of high temperature on lubricating oil consumption :
High speed produces high temperature this in turn, lowers the viscosity of the oil.
Now it can more readily work past the piston rings into the combustion chamber, where it
is burnt. Due to more temperature more oil gets into the combustion chamber, where it
burns and fouls spark-plugs, valves, rings and pistons. Carbon formation worsens the
condition since it further reduces the effectiveness of the oil rings. The burning of oil in
the combustion chamber usually produces blue smoke from the tail pipe.
It should be remembered that abstraction of heat from the working medium by
way of cooling the engine components is a direct thermodynamic loss.
IMPLEMENTATION OF FUZZY LOGIC
Fig. 4 Principle of Engine idle speed control.
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To control the idle speed of spark ignition engine, there are two possibilities. The
first one is spark advancer and the second is volumetric control of air.
In spark advancer if revolution decreases then an advance spark increases the
torque and vice versa.
In second method if there is reduction in number of revolution, the auxiliary air
regulator increases the by-pass cross-section which increases the air flow and vice versa.