Cooling System

A typical 4 cylinder vehicle cruising along the highway at around 50 miles per hour, will produce 4000 controlled explosions per minute inside the engine as the spark plugs ignite the fuel in each cylinder to propel the vehicle down the road. 

These explosions produce an enormous amount of heat and, if not controlled, will destroy an engine in a matter of minutes. 

Controlling these high temperatures is the job of the cooling system.

For Example, Air and Water Cooling System (Thermosyphon and Thermostat Cooling).

Types of Cooling System in Automobile:

Generally, there are four types of cooling system we can see in an automobile engine, and those are:

  • Air Cooling System
  • Water  Cooling System
  • Steam Cooling System
  • Liquid Cooling System

Air Cooling system:

This System is a simple type of cooling system used in scooters, motorcycles, and tractor. 

Meanwhile this system heat from the engine, the cylinder is directly dissipated to the atmosphere.

The Basic Principle of this type of system is to allow a flow of current through the parts from which heat is to be dissipated, which depends upon the surface area of metal in contact rate of flow of air, a temperature difference between hot surface and air. 

And Surface area of metal will be increased by providing the fins around the cylinder which is made of copper or steel.

Advantages of Air Cooling System:

  • Light in weight
  • No antifreeze is required
  • This system can be used where water scarcity is there
  • Simple in design
  • Require less space
  • No tapping up of water, etc.

Disadvantages of Air Cooling System:

  • More noise in operation.
  • The coefficient of heat transfer of air is less, hence less efficient in working.

Water Cooling System:

This type is the most commonly used type of system.

In this system dissipation of heat is done by the circulation of water through the jackets around the cylinder and passes this hot water through the radiator where air absorbs heat from the water.

There are two types of water cooling system. 

  1. Thermosyphon
  2. Pump circulation system

Thermosyphon System:

The pump is not fitted in this system.

Circulation of water is done due to the difference in densities between hot and cold water.

Circulation of water is due to natural convection.

The rate of cooling is low.

Nowadays it uses is limited because there must always a level of water is needed.

It is simple in construction and cheap.

Working of Thermosyphon System:

The thermosyphon cooling system operates on the principle of natural convec­tion.

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Thermo-syphon water cooling system is based on the fact that water becomes light on heating and,

The top and bottom of the radiator are connected to the top and bottom of the cylinder water jacket respectively with the help of pipes.

The radiator is cooled by causing air to flow over it. Airflow is achieved by vehicle motion or a fan provided.

The heated water in the cylinder water jacket becomes light and moves out of the upper connection pipe into the radiator and travels down from the upper tank to the lower tank, rejecting heat as it travels.

This cooled water from the lower tank is passed into the cylinder water jacket and hence circulated again for the process.

An important limitation of this system is that the cooling depends only on temperature and is independent of engine speed.

Pump Circulation System:

Circulation of water is done by providing a centrifugal pump.

Due to this pump, the rate of flow of water is more.

Here radiator may be fitted at any place convenient to the designer.

The pump is driven by a belt from a crankshaft.

Working of Pump Circulation System:

The water-cooling system has major components such as water jackets, circulating pump, fan, thermostat, connecting pipes and hoses, radiator and radiator cap.

The direction of cooling water flow is upward from the cylinder head to the top tank of the radiator, then down through the radiator core to the bottom tank.

From the bottom tank,  it moves through the lower radiator hose to the cylinder block water jackets and then through the water pump, which circulates the water.

Water enters the engine at the center of the inlet side of the pump.

The circulating pump is driven by a belt from the crankshaft.

As engine speed increases, the flow of coolant increases.

Parts of the Water Cooling System:

  • Radiator
  • Water Pump
  • Fan
  • Thermostat

Advantages of Water Cooling System,:

  • In these types of cooling, we see a high heat transfer rate.
  • This type of cooling system is used where the size or power of the engine is more.
  • Thermal Conductivity is more
  • Water is easily available
  • Liquid has a high enthalpy of vapourization so that e=the efficiency of water cooling is more.

Disadvantages of Water Cooling System:

  • Some time corrosion occurs inside the radiator or pipe or storage.
  • Due to scaling heat transfer rate is goes down after the long run, so it needs regular cleaning and maintenance.

Steam Cooling System:

In this system, the radiator is in the form of the condenser.

Water from the condenser enters the jacket and converted into steam. 

Water flows from the top of the block and dissipates the heat and steam are condensed in condenser converts to water and used for next circulation.

Advantages of Steam Cooling System:

  • It is simple in construction.
  • In this system, there is no vibration.
  • Low maintenance and production cost.

Disadvantages of Steam Cooling System:

  • This requires a high vacuum inside the evaporator for perfectly working.
  • COP is very low.

Liquid Cooling System:

Liquids other than the water if circulates around the cylinder is called the liquid system.

The liquid of higher boiling point such as Glycerine (Boiling point 195ºC) is used.

The higher boiling point increases the rate of dissipation of heat and reduces the size of the radiator and coolant required.

Advantages of Liquid Cooling:

  • Hassle-free operation.
  • No chance of corrosion
  • Some time heat transfer rate is more than a water cooling system.

Disadvantages of Liquid Cooling:

  • Little costlier if we used the working fluid other than Water.
  • It needs regular maintenance.

Check Out this video by Autotechlabs :

So this is all about Engine Cooling System, I hope you like this article and able to learn something from this stuff, feel free to ask your doubts on the comment section and share your thoughts regarding this article.

Free to share this article on your favorite social media and be a part of #spread_the_knowledge club, see you on some another article, till then enjoy the rest of your day, work hard, learn new things, and be happy always. Cheers!

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About the Author

Amrit Kumar

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Amrit is a Co-founder of Learn Mechanical Portal (Previously owned ""). He completed his diploma in Mechanical Engineering from Acharya Polytechnic Bangalore and also completed his B-Tech from Delhi.

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