We live on a planet earth where we have surplus of energy everywhere even in things we are yet to discover. The wind gives sufficient energy for power, the sun provides abundant energy, i even read our urine could produce energy. Not forgetting the steemstem distilled i read few days ago about the piezoelectricity from shoes. Isn't the world amazing?
Let's not forget those from the fossil fuel even though there are arguments that they do more harm than good in recent years apart from the pollution of both land and water they are known to be less efficient.
Most of us have a car and have even driven one particularly the ones that are powered by fossil fuels and an internal combustion engine but did you know that these engines have great power loss (if you don't understand that they simply are not efficient). You might not be able to see that, but as an engineer, this is what i have to tell you. A bitter truth you would have to accept today.
Ever wondered why some car engines are so expensive and they have super sounds when you step on their throttle? Am sure you look at them in wonder like wow! The hosepower and the response of this engines are great while your 1973 Volkswagen just sounds like a little dog when you press the throttle down to the maximum. Well, it is not your car engines fault it was developed that time when there was no breakthrough in improvement of engines.
You watch some movies or advertisements where they mention the car would attain a certain speed in a very short period (let us say it goes from 0 to 60mph in 2.4 seconds). I call this response to throttle and this explains why some cars would move very fast than others even though you have the same number of engine cylinder.
There could be one reason for why that your car in your compound was left to dust on the road by a little Mercedes, even though your car looks more recent in shape. Today that reason could be a supercharger or a turbocharger.
Have you ever heard of the turbochargers?
If you have seen these cute little things in the picture i am showing you then you have probably come across a turbocharger unknowingly you may not know what it is, but speed racers or engine lovers love what you just saw. I guess you are inquisitive right now, but chill out as i explain these things to you.
During the operation of an engine what they tell you is that the flames go out, well that is true, but don't you think the incomplete gases are being wasted and should be used for something else?
If you have thought so, then you are smart.
This is what the turbocharger does it harnesses or derives energy from the waste or the exhaust pipe of the cylinder combustion and supplies back to the engine cylinder.
You might be asking what kind of energy it supplies back to the engine. I will answer that question but first, you have read either in a book about how the engine takes in air and mixes with the fuel. Yes, that is indeed correct, but this happens naturally at atmospheric pressure what now happens when there is a shortcoming in pressure? This shortcoming in pressure, can lead shortage of air in the air fuel mixture and then cause the engine to perform below expected efficiency and at this point your fuel is just being wasted and you are not getting maximum energy from it. But How does air get in to the engine at the pressure below atmospheric?
This is where the super and turbo chargers come into play.
The turbochargers make use of these exhaust gases to get more air into the cylinder of the engine. I would be explaining how the turbocharger does that soon.
As for the superchargers they work just like the turbochargers except for the fact that they use the power from the engine to get more air into the cylinder. Which is not as efficient (it takes out of the useful energy to get more energy) but some people find it cool.
How does the turbocharger operate?
Like i said earlier what most textbook tell you after completing the diesel or spark ignition is that air enters the engine through the intake and leaves through the exhaust. But what they do not say is how the engine manages to attain the same and constant amount of air throughout its operation as it is found that they operate adequately only at atmospheric pressure but anything beyond or below the engine can only get more air through the turbocharger. What the turbocharger does mainly is to increase the efficiency and horsepower of the engine at the points where it begins to go low.
Let me describe a bit what is inside the turbocharger.
The turbocharger simply consists of a shaft with like two wheels (compression and turbine) and we all know what two wheels on a shaft does, they rotate together at the same speed. But the difference is that as one rotates due to the exhaust the other draws in air.
As the burnt gases leaves the engine, it rotates one end of the wheel (i.e. the turbines wheel) as the energy is converted to the kinetic energy, the kinetic energy of the other wheel (i.e. compressor wheel) draws in air which is hot.
The problem of the hot air is solved using a heat exchanger which reduces both the pressure and the temperature of the air before it goes back to the cylinder for use. The exchanger it passes through is called an intercooler which is located between the compressor turbine that and the intake valve of the engine.
This is basically how the turbocharged engines operate but I am guessing you have a pending question about what happens when the air is at atmospheric pressure?
The thing about the turbo charged engines is that they have like a wye shaped exhaust manifold before the turbochargers such that when the air passes a certain amount of pressure the manifold opens and lets out the excess air. This prevents the turbochargers from getting destroyed during its operation and regulates the intake of the engine cylinder.
The superchargers
Just like the turbocharger, the supercharger does the same thing but in a different way. The supercharger is located beside the engine and connected using a belt drive such that as the engine operates and turns, it does so alongside the engine. There are several types of turbochargers but they all have a simple operation. The types of superchargers include; the root type (positive displacement), the centrifugal type, and the dynamic superchargers. unlike the turbochargers, the superchargers do not require engine oil and are said to be more efficient (they supply the power immediately you need them) and therefore people love them.
The operation of a supercharger
The supercharger consists of a single wheel that is connected to a pulley and this pulley is then connected by either a belt or chain drive as it is connected to the crankshaft. Therefore, the rotation of the crankshaft brings about the turning of this single wheel. The single wheel operates just like an extractor fan if you have seen one, then you should know what they do. (they suck air in and not blow air out) and just like the turbocharger the wheels of the supercharger is called the compressor wheel and what it does is to rotate at high speed as the engine rotates.
As it rotates it draws in air which is compressed and with the help of an intercooler called heat exchanger reduces the pressure of the compressed air and also the temperature before the air finds its way into the intake manifold. Which gives the required and sufficient air for combustion.
This is basically how the supercharged engines relate.
Turbocharger or Supercharger?
The turbochargers are efficiency boosters and apart from that, they have the advantages of letting you gain maximum power from your engine through the use of waste gases from your engine.
But there is a thing about the turbochargers, they do not kick in immediately as they have to wait till your engine is operating before they begin to function.
Meaning when you ignite your engine, you will have to wait for the exhaust to occur before you start getting the extra power you need, this explains why some engines take time to react to the accelerator pedal when you need the extra work. whereas in the supercharged engines they begin work immediately the engine starts and as soon as the accelerator is pressed it sends the required energy you need, this means they react instantly.
Conclusion
The cry out for a more efficient engine has been heard by our engineers and technologists and they found out the cause of this problem in incomplete combustion of fuel due to shortage of air in the air fuel mixture. This has led to them deriving a way from using the waste gases to create more air for the engine in the turbochargers.
Although turbo and superchargers have the same job in supply of air into the combustion chamber for adequate combustion. The superchargers use the engine power for carrying out the job which make them swing into action faster than turbocharged engines. Whereas, turbocharged engines uses the flue gases of the cylinder to supply more air for usage. This means its saving you more energy and to me its more efficient regardless of the time spent to swing into action.
But the supercharged engines need less maintenance as the turbochargers have lube oil flowing in between the shaft of both wheels which is missing in the superchargers.
As a car or engine lover, which would you prefer?
The turbocharged or supercharged engines?
References
For further reading kindly visit these links or get any of the following books;
- basic turbocharging components and theory
- explainthatstuff
- understanding turbochargers
- Wikipedia supercharger
- mech stuff- how superchargers work
Turbochargers textbook by Hugh MacInnes, Betty MacInnes
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