Cooling in IC Engine by Fuzzy Logic

ABSTRACT
In the present paper, efforts have been made to highlight the concep “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.

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.
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 as temperature is illustrated in fig (2). for various processes in the cycle. Fig. 2 Gas Temperature Variation during a Cycle.
The cooling system comprises of the following parts namely:
• Radiator,
• Thermostat,
• Water pump &
• Piston-cylinder assembly.

DRAWBACKS OF CONVENTIONAL COOLING SYSTEMS EFFECT OF OVERHEATING :

• Evaporation of lubricating oil that lubricates the piston and cylinder wall. This will esult in metal to metal contact of the piston and the cylinder wall leading to piston cuffing and piston seizure.
• Setting up of the thermal stresses in the cylinder, cylinder head and piston. This may ead to cracking of them.
• Burning of the piston crown.
• Sticking of piston rings in the ring grooves, due to carbonization of the oil. Ring ticking will result in inefficient sealing of the cylinder increased blow by of gases nd 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:

DRAWBACKS OVERHEATING EXCESSIVE COOLING
• 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.

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.

FUZZY IN COOLING SYSTEM :

Fig. 5 Basic Principle

1) Controlling valve
2) Sensors
3) Coolant Outlet
4) Coolant Inlet
5) Cylinders
6)Intermediate Jacket
7) Outer Jacket
Consider the engine jacket as shown in figure 5 above which shows the sensors, valve, cylinder & an intermediate jacket, in which sensors and valve are connected to control unit. This control unit will not work unless the temperature of the engine reaches to 700 C. When it reaches to 700C or beyond it the flow will start. It begins with maximum at middle two cylinder and less at first and last cylinders. This change in flow rate will minimize the temperature difference between the middle and the end cylinders. Due to this the thermal stresses get reduce and the optimum temperature will be maintained wear will not take place.
If the temperature of the engine cylinders increases, the sensor will sense the temperature and the signal is given to the control unit and it controls the valve opening resulting in increase in the flow rate. Similarly when the engine retards the temperature of the cylinder decreases which will be sensed by the sensor and will operate the valve.

ADVANTAGES OF INTELLIGENT COOLING SYSTEM
1) It will try to maintain the cylinder temperature within the certain limit so that lubricating oil should not evaporate and hence will prevent metal to metal contact.
2) It will help to reduce the thermal stresses and hence cracking of piston cylinder.
3) Thermal efficiency will improve.
4) It will prevent the carbonization of oil since dealing with the optimum temperature.
5) It will prevent the corrosion of engine parts.
6) Mechanical efficiency will improve.
7) Proper vaporization of fuel will take place.
8) Excessive cooling results in increased viscosity of lubricant oil and hence more friction and will consume more fuel to overcome the friction and hence results in decrease thermal efficiency. So, our system will prevent the above factors.
9) During starting, the engine takes some time to reach it's operating temperature and hence it requires less or no coolant to be circulated around if so that it can reach operating temperature easily.
10) Although initial cost will be more but running cost will be less.
11) Less maintenance will require.

CONCLUSION
We have proposed an approach to implement fuzzy logic in an "Intelligent Cooling System". Possible implementation of the system and an approach is discussed along with its possible advantages. The use of such system will solve the problems of technology acceptance in India. Scope for future work would concentrate on type of sensor's, valve opening
mechanisms and different coolants.

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