Cooling System for I C Engines Internal combustion

• Cooling System for I. C. Engines � Internal combustion engines at best can transform about 25 to 35 percentage of the chemical energy in the fuel in to mechanical energy. About 35 percentage of the heat generated is lost in to the surroundings of combustion space, remainder being dissipated through exhaust’ and radiation from the engine. The temperature of the burning gases in the engine cylinder is about 2000 to 2500° C. The engine components like cylinder head, cylinder wall piston and the valve absorb this heat. Such high temperatures are objectionable for various reasons state below.

Ø Air cooling (Direct cooling) � cooling � � (Direct cooling) In air cooling, air is circulated around the cylinder block and cylinder head, fins are provided outside the cylinder and on the cylinder head. Fins increase the surface area exposed to the atmosphere and the heat radiation from the surface also increases. More air passes over the fins and comes contact with the cylinder, thus the engine heat is removed efficiently. The use of fins increases the heat transfer surface by 5 to 10 times its original value (i. e. without the use of fins). The high velocity of air required for cooling is obtained by the forward motion of the engine (vehicle) itself. In stationary engine, air circulating fan is provided. � Application � The engine design is much simpler and lighter in weight than water cooling engine. These types of cooling are used for small industrial engines and small capacity engines such as motor cycle engine and scooter engine.

vehicle's cooling system

§ Water cooling (Indirect cooling) � � � � Advantages of air cooling The engine design is much simpler. Lighter in weight than water cooled engines since there is no water jacket, radiator, pump etc. It also minimizes the maintenance and operating cost. There is no danger from freezing water in cold climates. This is very much useful in water scarcity areas and desert. Less space is required. Warming up the engine is faster than water cooled engine. Disadvantages of air cooling Air cooling is not as effective as water cooling and efficiency of the engine is reduced. Engine parts are not uniformly cooled. The front portion of the engine which faces the air is cooled more than the rear portion. This results in slight distortion. Not suitable for multi-cylinder engines. This requires a separate fan for circulation. Fans used for a stationary engine consumes 5% of engine power. Such engines are suitable only for low horsepower engines

• Radiator –cooling -system

� Cooling by Forced Circulation of Water

§ Water cooling (Indirect cooling ) � Water cooling (Indirect cooling) In this system, water is circulated around the cylinder and cylinder heat to carry away the heat. The water passes through a passage called “water jacket” There are two methods of water cooling; (i) Natural circulation of water. (ii) Forced circulation of water.

Ø Methods of cooling There are two methods of cooling an l. C. engine. They are: Air cooling or Direct cooling. Water cooling or Indirect cooling

q cooling (Indirect cooling) � cooling � Water (Indirect cooling) cooling (Indirect cooling) � In this system, water is circulated around the cylinder and cylinder heat to carry away the heat. The water passes through a passage called “water jacket” There are two methods of water cooling; � (i) Natural circulation of water. � (ii) Forced circulation of water.

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