Intercooler setups

[Skip]

Skip hang on,

You said air can be modeled as incompressible if flow (velocity) is greater than 102ms-1. Then you calculated V to = 43.66ms-1 and said its OK to model as incompressible. Contradiction.

Your "volume of air consumed" calculation does not account for boost either, and this in turn will affect the velocity you calculated.

Also, you have used a STANDARD VALUE for density as you stated, but...
Density should = STANDARD VALUE X pressure ratio (boost in bar + 1) X Compressor efficiency.
Compressor efficiency is a measure of density ratio.


These calculations are suitable for the pipework, but the "sum of frictional coefficients" will make it difficult to work for an IC. You need a stated value from the maker or else you need to break down the cooler into every tube and start crunching numbers. You end up where Mick said;

Go calculate away, and then ill show you how far off you were on a bench.

Mick, the graph i posted shows the compromise you speak of. More turbulators means more charge air face required so that the velocity drops more and subsequently friction remains about the same (minimal). Ill post up a pic that shows what i meant by "longer charge air channels, for the same frontal area tends to reduce internal flow area".


My school of thought is getting the IC and all bends etc right is FAR more important than the size of pipework, as this is where frictional loss lies. Pipe work size = compressor outlet or slightly greater (as said).

No I said the air speed has to be less than 102 m/s.

My volume of air calculation does not account for boost no, but that factor comes into VE as I mentioned. Pressure is irrespective when using Bernoulli equation like this as what we are trying to determine is the pressure drop, therefore the actual pressure doesn't matter and only effects the density, so to the temperature effects the density as follows:

The absolute pressure p = rho x R x T therefore rho = p / (RxT)

where p = pressure say 11psi = 75842 pa + atmo (101353) = 177195 pa
R = gas constant for air = 2.869 x 10^2
T = absolute temperature = 90 degrees c + 273 = 363 K

therefore the density would equal 1.7 kg/m^3, so plug that back into the equation and see what comes out

I realise these calcs are for pipework and never said anything different. The original question was will 60mm pipe be okay then went on to intercoolers, attempting to estimate the friction loss across an intercooler core would be possible but difficult, as you said the simplest way would be a sum of small pipes, it could be done, but it would only be an estimate as per the pipe loss calculation.

Im sure you would show me how far i would be off on a flow bench but where in this thread did I claim the accuracy of doing it theoretically compared to actual testing??? You seem to be blowing alot of hot air out.

[Skip]

[IMG][/IMG]

These two coolers have the same frontal area. Same heat transfer area. Same efficiency (measure of ability to change charge air temp back to cooling air temp).

The bottom one has less pressure loss becuase it has more tubes - ie more charge air face and/or internal area.

I know which one Id pick.

That is rubbish, just because it has more tubes doesn't mean it has less pressure drop. It may have stagnation points and vast areas of tubes that arent being used efficiently if the air is not being directed into all the tubes as evenly as possible. There is so many more variables at play here.

[kingmick]

Yes i understand that bit, and that post.

But;
One hose at one length against two hoses at a different length flowing the same volume over a given time =???.

Too many variables as you said in the other post.

The two intercooler pics have different number of tubes as well as different length of tubes.

I just couldn't undersatnd the post that i quoted at all.

were is the one length against two?
its one against one, one has short runs and the other has long runs! no wonder your getting confussed! i said two pipes meaning one pipe for the longer run intercooler and one pipe for the shorter run intercooler.
See what happens when you try to make a simple thing complex for no reason?

[jonra23]

The picture of the two intercoolers show that they both have different LENGTH tubes and different NUMBER of tubes is where the two tubes come from.

Therefore for your example to be relevant it must take in both differences.

See what happens when you try make real thing too simple to make a point.

[Classique71]

No ones really touched on an intercooler actually in a gt4 - that works with reasoably good effect

My setup works - even though tis back yard , and not created by king micks personal scientists at Nasa

2 inch off turbo - into 2.5 -> 3 inch adaptor into the core - then out via a 3- 2.5 inch adaptor - to 2.5 inch all the way thru to the inlet .

On a cold day - at full operating temp - i see intake charges of under 5 degrees

on a normal day - its usually around 15- 20 Degrees depending on traffic

Running 15PSI strong daily , without fail , netting better than normal GT4 Dyno results , with my ECU ..

You know where i live .. just takes a drive down the princess highway to see a fully functioning setup Or try and track down lances Gt4 - as its setup is nearly identical to mine

[kingmick]

The picture of the two intercoolers show that they both have different LENGTH tubes and different NUMBER of tubes is where the two tubes come from.

Therefore for your example to be relevant it must take in both differences.

See what happens when you try make real thing too simple to make a point.

so you mean make them the same length core? well yes that will be a good test, testing a mirror against itself! WTF
it isnt the top or side mounting its the length or the core run.
See, i can be very patient at times, you can thank my kids for that.

[Cuzzo]

So does the shorter hose stay colder or is it a trick questions because they are flowing the same rate and everything would they be the same temp... No one has answered it yet.. ????


I have NFI on all this just wanted to know.

[kingmick]

yes the water out of the shorter hose will be cooler Cuzzo, wasnt a trick question at all, i tried to make it really simple, as i guess most people would have turned a hose on in summer to take a drink and it was very hot and most people dont have short hoses

[mic*]

OK before eveyone gets carried away with this, there is a simple fomula for a good intercooler!
Pick the right core, get the core as light as it can be and hold 30-50% over the boost you are going to use, have the right shaped SIDE endtanks with deflectors in them, have nothing infront of the airflow to the said core when mounted in the car and angle the cooler as much as you have the room to do it.
Now show me a formula with all that worked out with math and ill get you a job in a formula 1 team.
lmao

Nothing Infront of airflow to said core? (cooling airflow i assume)
Done much work on ducting?

From what i see in practice, and read about, any duct over with a X-section area >25-30% but less than 100%(unless done REAL well) than the X-sectional area of the core you are ducting to will be better than nothing at all...

Also, the hose analogy. First of all, since you didnt say, I am taking the water getting hotter as supposing to resemble charge air getting cooler right. So the more time in the sun, ie the hotter the better? Backwards analogy but anyway...

You cannot say that the Top/Bottom tank IC is a "shorter hose" because you have to get each tube and stand them end to end, and you have way more tubes than the End/End tank IC. That is the point Jon tried to make.

AND, my point is suggesting general trends. GEEZZZZ.

Skip, you may say rubbish, but as a GENERAL TREND, im sorry its true!!!! The factors you speak of are more to do with END TANK DESIGN. And turbulators - refer back to the graph i posted for how this affects internal area.

[jonra23]

Luckily i also have kids, bloody teenagers now.

I am not saying to make them the same lenth core as that wouldnt fit in the same space.

What i am saying is that yes one longer hose will exchange more than 1 short hose.

BUT as the bottom intercooler has more but shorter "hoses" the comparison of the "hose" example must allow for this to be relevant.

There is probably the same "length of hose" in both coolers but they are configured differently.

Also as both "sets of hoses" are flowing the same volume the air will spend the same amount of time in each "set of hoses", it is the time and surface area available for heat exchange that will dictate the temperature drop more than the configuration.

[jonra23]

The hose in the sun is badly effected by heat soak and is obviously been poor set up and should have better airflow, after staging and turning on the thermo fans that should have been fired up at the start the water came out at the same temperature.

[mic*]

Pressure is irrespective when using Bernoulli equation like this as what we are trying to determine is the pressure drop, therefore the actual pressure doesn't matter and only effects the density

EXACTLY!

And the BOOST affects the density as per what i said! The temp rise is the density loss!

How the hell can there be twice as much pressure and only a small percentage more mass. More molecules = more mass. Its fundamental physics.

The density you are using is based on STANDARDISED VALUES of atmospheric air, heated to certain temps at certain altitudes so on and soforth.

To take another angle, if a compressor was IDEAL (100% efficiency) the density would be equal to the STANDARD VALUE (1.23kg/m^3) X the pressure ratio. Because it heats the air, the STANDARD VALUE for air density gets lower as the air gets hotter, which you have pointed out. This results in a lower density than if the air had not been heated to acheive the given pressure ratio.

And Skip, go back and edit, coz you distinctly said <102ms-1 = compressible. Which is right, but 43.66ms-1 isnt >102ms-1 so it NOT INcompressible...

[mic*]

Using your hose analogy Mick, since we've got it sorted that the "length" is roughly the same;

Which will incur more pressure loss?
one big ass long hose (the END tank IC - smaller effective X section for charge air),
or splitting the water into lots of hoses that add up to the same length, and bringing them back together (the Top/Bottom tank IC - larger effective X section for charge air)?

Its the whole concept of cooling im sorry. Otherwise your cooler/radiator would just be a big snaking path, back and forth.

Apart from the fact that physics (heat rises & water is denser) further supports my arguement, why do you think nearly every radiator built has TOP/BOTTOM tanks, and is wider than it is high?

[kingmick]

mate, i give up! yes the shorter interwarmer will have less pressure lose, but the longer intercooler will bring the charge temp down.
There prob isnt a nice way to tell you what i think, so ill just leave the above as as my final word to you.
Actually i think i might be able to make it clearer, what sales do you work in MIC?

[mic*]

mate, i give up! yes the shorter interwarmer will have less pressure lose, but the longer intercooler will bring the charge temp down.
There prob isnt a nice way to tell you what i think, so ill just leave the above as as my final word to you.
Actually i think i might be able to make it clearer, what sales do you work in MIC?

I understand you're frustrated coz you just cant seem to understand that THE CORE IS NOT SHORTER.

Chop it in half, stick the ends together and you might be able to see it!

I dunno how else to explain it Mick. Jon has tried too...