Full Intercooler piping around $300
Originally Posted by Fenris Ulf
Sound reasoning except for a few glaring errors. Convection may be the primary method that the pipes are heated, but the thermal energy must CONDUCT itself through the thickness of the pipe, creating a temperature gradient that varies through the depth of the piping material. This means that an aluminum pipe will absorb more thermal energy along its surface through convection, conduct the energy more quickly through the metal, and dissipate more of the heat it has absorbed into the charge air, thus heating it.
Originally Posted by Fenris Ulf
Buschur is 100% correct saying that SS is a much better choice for intercooler piping per above. Aluminum will get heat soaked quicker AND transfer more thermal energy to the charge air, do some heat transfer calcs since you seem to be up on your math and you will agree.
Originally Posted by Fenris Ulf
Titanium would be an even better choice, and a thermal barrier coating would further aid in making sure the temps stay low after exiting the intercooler.
The reasoning in my choice for Aluminum being better is for when the engine compartment reaches steady state conditions....
When the Piping has heated to the same temp as the engine compartment, and you floor it, the air passing through the piping (going with marksae's assumption that the charge air is cooler than the engine compartment air) will cool down the pipes. The total heat stored in the pipes will be much lower in the AL piping than the SS piping. Even though AL has a higher specific heat than SS, specific heat is related to density, and the amount that SS is more dense than AL is higher than the amount of AL's specific heat being higher than SS's. AL has a specific heat of .89 J/gC and SS has a specific heat of .5 J/gC. If you multiply these values by the materials density (8 g/cc for SS, 2.7g/cc for AL) you find out that more Joules of energy are stored in the SS for every degree C that it is heated per unit volume. This energy must be taken out of the pipe by the convection process occuring inside the piping. Since more heat must be taken out of the SS, the charge air will need to carry more heat away to cool it. And while yes, the engine air will continue to pour in heat while the charge air is cooling the pipes, you need to look back at the velocities that marksae calculated. The cooling convection is going to be occuring at a rate so much greater than the heating convection that the conductivity of the AL really won't matter.
Originally Posted by Fenris Ulf
Actually the rate of conduction is directly proportional to the area that the heat is conducting through. Check your heat transfer equations.
Conduction:
Q/t = kA(deltaT)/d
As d (the thickness) goes up, then t (time) must go up if Q is held constant, or Q (the heat energy being transferred) must go down to balance the equation. Meaning the heat is transferring slower, or less heat is being transferred in the same amount of time.
Originally Posted by Fenris Ulf
Discussions like this are much more interesting when someone who is ejumicated joins in
I'm not trying to put you down, but don't be so quick to think that someone is just pulling these thoughts out of their asses.
- Steve
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From: dublin, oxford, chillicothe OH
Originally Posted by SuperHatch
There is no glaring error there, I said that convection is the primary method in which the pipes are being heated, and it is, as a matter of fact it is the only method. I also said that " You are correct in saying that aluminum heats up faster than SS, this is due to it's higher thermal conductivity and lower heat capacity than SS. It accepts heat faster than SS and can hold less, so it reaches a given temp faster." Which is in total agreement with what you just said.
We already do agree, which I said the same thing you're saying. The part that I didn't agree with was Buscher's reasoning that the shineyness of the SS piping makes it a better choice because it reflects the heat more. Which is why I went into the radiant heat transfer equation. And even taking this conduction rate into account, I still choose AL, my reasoning is to follow...
Anything with a lower heat transfer coefficient would be a better choice, plastics are good, as well as a ceramic. The ceramic being ideal, but durability being in total question.
The reasoning in my choice for Aluminum being better is for when the engine compartment reaches steady state conditions....
When the Piping has heated to the same temp as the engine compartment, and you floor it, the air passing through the piping (going with marksae's assumption that the charge air is cooler than the engine compartment air) will cool down the pipes. The total heat stored in the pipes will be much lower in the AL piping than the SS piping. Even though AL has a higher specific heat than SS, specific heat is related to density, and the amount that SS is more dense than AL is higher than the amount of AL's specific heat being higher than SS's. AL has a specific heat of .89 J/gC and SS has a specific heat of .5 J/gC. If you multiply these values by the materials density (8 g/cc for SS, 2.7g/cc for AL) you find out that more Joules of energy are stored in the SS for every degree C that it is heated per unit volume. This energy must be taken out of the pipe by the convection process occuring inside the piping. Since more heat must be taken out of the SS, the charge air will need to carry more heat away to cool it. And while yes, the engine air will continue to pour in heat while the charge air is cooling the pipes, you need to look back at the velocities that marksae calculated. The cooling convection is going to be occuring at a rate so much greater than the heating convection that the conductivity of the AL really won't matter.
Conduction is related to the area and the thickness, you need to check your equations. The area you're thinking of is the area being heated, think 3 dimensionally, area of the outside of the pipe, thickness of the pipe. And yes, a thicker material will slow the rate of heat transfer.
Conduction:
Q/t = kA(deltaT)/d
As d (the thickness) goes up, then t (time) must go up if Q is held constant, or Q (the heat energy being transferred) must go down to balance the equation. Meaning the heat is transferring slower, or less heat is being transferred in the same amount of time.
If somehow you are inferring that I am not "edjumicated" you are sorely mistaken. I have a degree in Mechanical Engineering with a concentration in thermodynamics and heat transfer as well as fluid dynamics. I aced all the classes and know the subject very well. Not to mention I work in the aerospace industry and do this for a living every day. The DOD seems to agree with the work I do, so I have some confidence in what I say.
I'm not trying to put you down, but don't be so quick to think that someone is just pulling these thoughts out of their asses.
- Steve
We already do agree, which I said the same thing you're saying. The part that I didn't agree with was Buscher's reasoning that the shineyness of the SS piping makes it a better choice because it reflects the heat more. Which is why I went into the radiant heat transfer equation. And even taking this conduction rate into account, I still choose AL, my reasoning is to follow...
Anything with a lower heat transfer coefficient would be a better choice, plastics are good, as well as a ceramic. The ceramic being ideal, but durability being in total question.
The reasoning in my choice for Aluminum being better is for when the engine compartment reaches steady state conditions....
When the Piping has heated to the same temp as the engine compartment, and you floor it, the air passing through the piping (going with marksae's assumption that the charge air is cooler than the engine compartment air) will cool down the pipes. The total heat stored in the pipes will be much lower in the AL piping than the SS piping. Even though AL has a higher specific heat than SS, specific heat is related to density, and the amount that SS is more dense than AL is higher than the amount of AL's specific heat being higher than SS's. AL has a specific heat of .89 J/gC and SS has a specific heat of .5 J/gC. If you multiply these values by the materials density (8 g/cc for SS, 2.7g/cc for AL) you find out that more Joules of energy are stored in the SS for every degree C that it is heated per unit volume. This energy must be taken out of the pipe by the convection process occuring inside the piping. Since more heat must be taken out of the SS, the charge air will need to carry more heat away to cool it. And while yes, the engine air will continue to pour in heat while the charge air is cooling the pipes, you need to look back at the velocities that marksae calculated. The cooling convection is going to be occuring at a rate so much greater than the heating convection that the conductivity of the AL really won't matter.
Conduction is related to the area and the thickness, you need to check your equations. The area you're thinking of is the area being heated, think 3 dimensionally, area of the outside of the pipe, thickness of the pipe. And yes, a thicker material will slow the rate of heat transfer.
Conduction:
Q/t = kA(deltaT)/d
As d (the thickness) goes up, then t (time) must go up if Q is held constant, or Q (the heat energy being transferred) must go down to balance the equation. Meaning the heat is transferring slower, or less heat is being transferred in the same amount of time.
If somehow you are inferring that I am not "edjumicated" you are sorely mistaken. I have a degree in Mechanical Engineering with a concentration in thermodynamics and heat transfer as well as fluid dynamics. I aced all the classes and know the subject very well. Not to mention I work in the aerospace industry and do this for a living every day. The DOD seems to agree with the work I do, so I have some confidence in what I say.
I'm not trying to put you down, but don't be so quick to think that someone is just pulling these thoughts out of their asses.
- Steve
so how about those pics?
