Our body is like a biological engine. In fact, most principles that affect machines also accrue to us. Therefore, in order to understand how an engine works, we’ll be taking cues from our bodies. In this section we’ll be looking at the engine’s pump system, using the human circulatory system as a case study.
HOW THE HUMAN CIRCULATORY SYSTEM WORKS
Our bodies are a complex system of pipes and each system carries out a different purpose. For example, the pipes that make up the digestive system serve to take food from the mouth to the stomach till it is ejected from the anus. The functions of the pipes in the circulatory system; however, cuts across the functions of several other systems. I’ll explain below.
The pipes that make up the circulatory system are the veins, arteries, and capillaries. Ultimately, all these pipes are connected indirectly to the heart through the ventricles and auricles. These pipes run through the pulmonary valve to the lungs to absorb oxygen.
They also run through the small intestine where they take in adenosine triphosphate- the chemical fuel which our bodies use. The oxygen and fuel are transported by the aortic valve to all the cells of the body. It’s in these cells that real energy production takes place.
The heart is the pump that powers the pipes. This mass of muscles contracts and expands due to electric impulses to supply blood and other necessities to every cell in the body. These electric impulses are responsible for your heart’s rhythm and rate. They ensure your auricles and ventricles follow a strict pattern with each cycle of blood.
Whenever you run or are engaged in some strenuous physical activity that requires more oxygen and energy, the heart’s electrical system picks up this need and boosts blood circulation so that more oxygen and energy-carrying blood is taken to the body.
How does this concern an engine? Let’s find out.
HOW THE ENGINE WORKS
While an engine doesn’t have a pulsating mass of muscles, it does have a fuel pump that takes fuel at high pressure from wherever it is stored and transfers it to where it will be burnt. This pump works constantly as long as the engine is running so that combustion doesn’t become stilted.
The fuel goes through the connecting pipes till it reaches its delivery point. In most petrol engines where fuel injection is done indirectly, this delivery point is either an inlet manifold or port. Just like with the heart and the lungs, this is where the circulation and aeration systems cross paths.
In this contraption, the injector sprays the fuel as a fine mist. This action is called atomization and is done to allow the fuel particles to mix more easily with the air in the manifold/port.
In a diesel engine, the injector sprays fuel directly into the combustion chamber where already compressed air is waiting. This injector sprays fuel in proportion to the amount of air in the system.
Because we’re dealing with only the circulation system in this post, I would have to stop here so that I don’t discuss the aeration and energy production systems yet. However, let me draw the following parallels between the human body and the vehicle engine:
- The heart never stops as long as a person is alive. The fuel pump doesn’t stop as long as the engine is on. In either case, the turning off of the engine means that the machine is laid to rest. The only difference is that the first scenario is permanent.
- Fuel mixes with oxygen in the air since both are necessary for generating energy. The same happens when blood passes through our lungs.
- The amount of fuel sent into the system by the injector is dependent on how much energy is to be expended by the machine. In other words, a greater electrical load on a generator will allow more air into the manifold, which in turn will demand more fuel to be sprayed in. We see the same things play in the body as the blood flow responds to activity, causing the body to take in more air and pump more blood.
What do you know about engines’ fuel circulation? Share with us in the comments. Until next time when we talk about the aeration systems.
