Super TECH Question

supercar1of1

supercar1of1

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If you have an 87 octane gasoline internal combustion engine that is consuming 100cfm at 1 atmosphere, an A/F ratio of 14.7 to 1, what would be the volume/cfm (approx) of the exhaust gas/air.







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TNVIPER said:
Is this a trick question?.....:confused: :dontknow: ;)
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No It is real, and I would even compensate someone to tutor me on the formula and provide the answer.



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Silverback said:
At what point are you looking for the volume?
Click to expand...



Approx 10 meters.

Thanks for chiming in!:rock:


PS: Need the # after it cools to 65 F


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supercar1of1 said:

If you have an 87 octane gasoline internal combustion engine that is consuming 100cfm at 1 atmosphere, an A/F ratio of 14.7 to 1, what would be the volume/cfm (approx) of the exhaust gas/air.







.
Click to expand...

Okay John, I will attempt to answer your question for you, but there are two factors to consider here. First is I have not done any thermodynamics work since school, and the second is I have close to a short case of Bud in me. :eek:


First off, the octane will not be a factor, as it does not directly contribute to the energy output. All it does is allow higher compression, more advanced timing, etc, that does allow you to generate more power.

Now there are a lot more variables that would factor into this, but I think in the end they will not matter.

Let me see if I can explain why in simple terms.

What happens during the combustion process? You have taken a mixture of air and fuel, compressed it, and then ignited it. All you have done in reality is create heat. That heat causes the air within the cylinder to expand because the heat is attempting to increase the volume of the air, but it's contained within the cylinder until the exhaust valve opens. This allows the air to continue expanding. And just on a side note, that is what drives a turbocharger.

One more comment at this point before I continue. Gasoline engines are very wasteful of energy. Of the energy released in the combustion process, only about 35% (if I remember right) of it is used to move a vehicle. The rest is lost and disappated as heat through radiation off the engine, or through the cooling system.

Okay, where was I? Sorry, had to get another beer.:eek:

So, let's use 65 degrees as the ambient temperature of the air. We take 50 cubic inches of it, and compressed it, which in itself generated some heat, then we lit if off, and for the sake of this discussion let's assume that it reached 1100 degrees. That change in temperature has greatly increased the volume of that air at 14.7 psi. However, when it has returned to 65 degrees, the volume has returned to it's original 50 cubic inches. We did not create anything. All we did was convert the energy of the gas into heat, which was used to expand the air.

Make sense????:dontknow:
 
Silverback said:
Okay John, I will attempt to answer your question for you, but there are two factors to consider here. First is I have not done any thermodynamics work since school, and the second is I have close to a short case of Bud in me. :eek:


First off, the octane will not be a factor, as it does not directly contribute to the energy output. All it does is allow higher compression, more advanced timing, etc, that does allow you to generate more power.

Now there are a lot more variables that would factor into this, but I think in the end they will not matter.

Let me see if I can explain why in simple terms.

What happens during the combustion process? You have taken a mixture of air and fuel, compressed it, and then ignited it. All you have done in reality is create heat. That heat causes the air within the cylinder to expand because the heat is attempting to increase the volume of the air, but it's contained within the cylinder until the exhaust valve opens. This allows the air to continue expanding. And just on a side note, that is what drives a turbocharger.

One more comment at this point before I continue. Gasoline engines are very wasteful of energy. Of the energy released in the combustion process, only about 35% (if I remember right) of it is used to move a vehicle. The rest is lost and disappated as heat through radiation off the engine, or through the cooling system.

Okay, where was I? Sorry, had to get another beer.:eek:

So, let's use 65 degrees as the ambient temperature of the air. We take 50 cubic inches of it, and compressed it, which in itself generated some heat, then we lit if off, and for the sake of this discussion let's assume that it reached 1100 degrees. That change in temperature has greatly increased the volume of that air at 14.7 psi. However, when it has returned to 65 degrees, the volume has returned to it's original 50 cubic inches. We did not create anything. All we did was convert the energy of the gas into heat, which was used to expand the air.

Make sense????:dontknow:
Click to expand...
now I need a beer:confused:
 
Silverback said:
Okay John, I will attempt to answer your question for you, but there are two factors to consider here. First is I have not done any thermodynamics work since school, and the second is I have close to a short case of Bud in me. :eek:


First off, the octane will not be a factor, as it does not directly contribute to the energy output. All it does is allow higher compression, more advanced timing, etc, that does allow you to generate more power.

Now there are a lot more variables that would factor into this, but I think in the end they will not matter.

Let me see if I can explain why in simple terms.

What happens during the combustion process? You have taken a mixture of air and fuel, compressed it, and then ignited it. All you have done in reality is create heat. That heat causes the air within the cylinder to expand because the heat is attempting to increase the volume of the air, but it's contained within the cylinder until the exhaust valve opens. This allows the air to continue expanding. And just on a side note, that is what drives a turbocharger.

One more comment at this point before I continue. Gasoline engines are very wasteful of energy. Of the energy released in the combustion process, only about 35% (if I remember right) of it is used to move a vehicle. The rest is lost and disappated as heat through radiation off the engine, or through the cooling system.

Okay, where was I? Sorry, had to get another beer.:eek:

So, let's use 65 degrees as the ambient temperature of the air. We take 50 cubic inches of it, and compressed it, which in itself generated some heat, then we lit if off, and for the sake of this discussion let's assume that it reached 1100 degrees. That change in temperature has greatly increased the volume of that air at 14.7 psi. However, when it has returned to 65 degrees, the volume has returned to it's original 50 cubic inches. We did not create anything. All we did was convert the energy of the gas into heat, which was used to expand the air.

Make sense????:dontknow:
Click to expand...



PERFECT sense. What is your Pay pal would $50.00 cover your service?





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supercar1of1 said:
PERFECT sense. What is your Pay pal would $50.00 cover your service?





.
Click to expand...

No f*cking way. Hopefully we will meet someday at a get together and you can buy my a beer.

Now a question for you. Did this answer your question, that drove out the question that you posted?
 
Silverback said:
No f*cking way. Hopefully we will meet someday at a get together and you can buy my a beer.

Now a question for you. Did this answer your question, that drove out the question that you posted?
Click to expand...




Yes it fully answered the question, I just wanted a professional to confirm

the theory. Some friends and I are tinkering with a project and I like to

know as much as possible before committing time or $.


IOU: ALL THE BEER YOU CAN HANDLE!!!!!!:rock:


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Silverback said:
Well in that case, you would save money by just sending me the $50.00.:eek: ;) :D
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It's your call! Wish I didn't live so far away, but I plan to travel your way in the next several months sight seeing all the stuff I missed when I was there last.





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Maybe we are descended from apes after all............

How come we got dumber as we evolved.....

That's it.... :idea: The DEVO factor....

D
 
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