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How the Combustion System IC Engines Work

Understanding How the Combustion System IC Engines Work

When it comes to energy production, the combustion chamber and the mitochondria share a lot of things in common. If you want to understand how engines work to produce energy, this is the article for you.

Before we begin, let’s summarize all we have learned in the previous articles.

We said that the blood acts as a circulator, taking food from the small intestine into the bloodstream. Remember that food is the fuel of the body. While the other classes of food serve various other functions, carbohydrates, fats, and oils primarily work to produce energy for the body. This carbohydrate enters the bloodstream as glucose.

Also, we pointed out how the lungs act like the Air-Intake system of the engine, supplying the oxygen in the air for the combustion process.

The blood goes through the lungs to pick up this oxygen and the heart pumps this blood to all the cells in the body. What happens in the cells to create energy? Let’s find out.


The mitochodrion is an organelle within the cell. Popularly known as the powerhouse of the cell, the mitochodrion makes use of oxygen and glucose to produce adenosine triphosphate (ATP) and Carbon dioxide. Kreb’s cycle fully illustrates this process.

The body stores this energy in the form of chemical bonds. In order to access the energy, the cell breaks down ATP into Adenosine diphosphate (ADP).

Glucose + Oxygen → ATP + Carbon dioxide

The carbon dioxide is taken into the bloodstream and out of the body.

Car engines work quite similarly. Let’s see how.


Basically, all engines do the same thing, though in different ways.

The engine’s combustion chamber has a piston within a cylinder. This piston works by reciprocation. The fuel and air pumps feed a rich air/fuel mixture into the cylinder for combustion.

The mixture is delivered as a fine spray- a phenomenon called atomization. Atomization ensures that air and fuel mix evenly for proper combustion. In modern petrol engines, atomization occurs before delivery into the combustion chamber while, in diesel engines, atomization happens within the engine.

There are two types of engine combustion: compression ignition and spark ignition. The pistons of compression ignition engines simply compress air during their upward stroke till the air is hot enough to cause fuel combustion.

Diesel engines are mostly compression ignition engines. Spark ignition engines require a spark plug to create the spark that starts the burning. Petrol engines are mostly sparked ignition.

Whatever the type of engine, the resultant explosion generates enough heat and pressure to push the piston backward. This forward and backward motion of the piston is due to the kinetic energy provided by the combustion process. This kinetic energy can be converted to electrical energy using motors or used to move vehicles such as cars or ships.

The end product of combustion is Carbon dioxide and water. They might be accompanied by other gases due to impurities in the fuel. These waste gases leave the engine through the exhaust pipe.

Engines work quite similarly to the body. We can see the following parallels between both systems:

  • Both systems burn fuel and oxygen to produce energy and carbon dioxide.
  • Both systems are dependent on various other systems to function.


In summary, everything in existence was designed based on something else in nature. That’s why many famous engineers and inventors like Leonardo Da Vinci and Isaac Newton were lovers of nature.

Maybe if we paid more attention to nature we’d have more solutions to the world’s problems.

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