Engine Cooling System

While running, an engine continuously produces heat and converts it into power.

This heat is derived by burning fuel in the engine.

But as we all know, there is no engine in the world which is 100% efficient.

There is always some amount of heat energy which gets wasted. If we do not transmit this heat energy into the atmosphere, this heat will overheat the engine.

This overheating will result into engine seizing. In engine seizing, due to excess heat piston gets melted inside the cylinder.

It avoid this trouble of overheating a car is provided with engine cooling system.

What is a engine cooling system?

An engine cooling system is a system integral with the engines. It carries away excess heat from the engine with the help of a flowing fluid.

This fluid can be air or water.

Or we can say there are two types of cooling systems

  1. Liquid or indirect cooling system
  2. Air or direct cooling system

How engine cooling system works?

Working of both air cooled and water cooled system is different. We will understand them one by one.

Liquid or indirect cooling system

Water cooled engine

In a liquid cooling system, an engine is surrounded with water jackets. With the help of a pump this water gets circulated in this water jacket.

Water flowing in these jackets takes out heat from the engine. This hot water than flows through a radiator, where it gets cooled from the cold heat blown through a fan.

In this system the water takes heat from the engine and that water gets cooled by the air and than again gets circulated to the engine.

This is an indirect cooling process, where actual cooling thing that is air is not directly cooling the system. The air is cooling the water and water is cooling the engine.

Liquid or indirect cooling system is mainly used in big engines, like that of cars and trucks.

Advantages of liquid cooling system

  1. Compact design of engines
  2. It provides even cooling to the engine
  3. Engine can be installed at any location of the vehicle. It is not necessary to install engine at the front.
  4. It can be used in both small and big engines

Limitations of liquid cooling system

  1. Here water jacket becomes one extra part of engine.
  2. Water circulation consumes power, thus reduces engine efficiency.
  3. In case of failure of of cooling system, serious damage could happen to the engine.
  4. Cost of system is considerably high.
  5. It requires routine maintenance, and thus puts extra maintenance cost burden.

Air or direct cooling system

air cooled engine

In a direct cooling system an engine is cooled directly with the help of air flowing through it. It is the same cooling system which is used to cool our bike engines.

As we can see here, air is in direct contact with the engine hence it is also known as direct cooling system.

Air cooling system is used for small engines, like that of bikes and grass cutter etc.

Advantages of air cooling system

  1. Design of engine becomes simpler.
  2. Repair is easy in case of damages.
  3. Absence of bulky cooling system makes system maintenance easily.
  4. No danger of coolant leakage.
  5. Engine is not subjected to freezing troubles.
  6. Weight of the system is less.
  7. It is a self contained unit, as it does not requires radiator, header, tanks etc.
  8. Installation of air cooled system is easy.

Limitations of air cooling engines

  1. It is applicable to only small and medium sized engines.
  2. It can only be used at the places where ambient temperatures is lower.
  3. Cooling is not uniform.
  4. Higher working temperature as compared to water cooled engines.
  5. It produces more aerodynamic noise.
  6. Specific fuel consumption is slightly higher.
  7. Lower maximum allowable compression ratios.
  8. The fan, if used consumes almost 5% power generated by the engines.

Characteristics of an efficient engine cooling system

Following are two main characteristics of an efficient engine cooling system.

  1. It should be capable of removing about 30% of the heat generated in the engine, while maintaining optimum working temperature in the engine.
  2. It should remove heat at a faster rate when engine is hot and remove engine at slow rate when engine is cold.

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