I've always wondered exactly why I've not seen the application of an intercooler between stages on a diesel truck. i've seen a stage of nitrous added, but no intercooler. Say on a cummins, there seems to be enough space on the wraparound (see below) to put some type of liquid-air unit.



Would the pressure drop not be worth the density/temp change? I'm wondering if that is the biggest answer, among other factors. discuss.

11/11/2007 8:38:03 PM

one of the reasons why people put in intercoolers is so that you can lower intake temps and reduce the chance of detonation, which is obviously not a problem on a diesel

11/11/2007 8:41:36 PM

^actually that is not what I'm looking for. They've intercoolers anyway, just not between the stages. I'm talking about the whole "improving the thermodynamic cycle"...mike boles explanation shit.

11/11/2007 8:49:42 PM

what is the point...... the air will be its hottest at the end of the compressions and the same amount of heat will be added total anyway so why not just take advantage of the larger delta T that the intercooler would have if used after the 2nd stage.


basically it would make for an in-efficient intercooler

11/11/2007 8:55:22 PM

i would agree that the total energy added would be the same, but saying that the intercooler would be inefficient seems to be a stretch. It seems to me that the peak energy/temp level would be lower with the addition of a primary intercooler in the system. (aaahhh - I'm assuming that there is some current level of inefficiency going on with a single intercooler application....if that adds to thought)

[Edited on November 11, 2007 at 9:00 PM. Reason : -]

11/11/2007 9:00:18 PM

look

take MAE 412 and 407 and get back to us

11/11/2007 9:02:10 PM

dude, i was in your 412 class.

I guess I'm asking for the mixing of real-world knowledge and theory. or maybe thisfeeble attempt of a discussion is completely ambiguous.

[Edited on November 11, 2007 at 9:04 PM. Reason : -]

11/11/2007 9:03:50 PM

you must have me confused with someone else

11/11/2007 9:49:24 PM

Laws of diminishing returns. You might find intercooling of sorts on pulling tractors/trucks. But in reality, the added complexity of the system doesn't produce enough benefit to be worth the expenditure most of the time.

Add to this that the rate of heat transfer between your primary intercooler and atmospheric is exponentially less (temperature differential is relatively low in comparison to a single-stage aftercooler after the secondary compressor stage)...and its benefit becomes pretty questionable. THEN factor in pressure drop across the intercooler.

You'll notice that many pulling tractors or trucks actually inject nitrous and/or water/methanol between compressor stages. This is a much more effective means of charge air cooling without the need for excessively complex plumbing.

By the way, reducing charge air temperatures helps to reduce combustion chamber and exhaust gas temperatures. Diesels may not suffer from detonation, but if combustion temperature climbs too high, piston damage can easily result. So can turbocharger damage.

11/11/2007 10:07:16 PM

thanks zx, that's basically the level of explanation I was after. and yeah i mentioned the nitrous earlier

Quote :

"i've seen a stage of nitrous added, but no intercooler."

and yes aficionado, I'm pretty sure you were in Corson's 412 class last spring. amirite? you were in adam8778's group iirc

11/11/2007 11:24:40 PM

Corson is the man...my kinda weirdo.

11/11/2007 11:47:58 PM

haha definitely. I really enjoyed his lectures, and I gained a better appreciation for fluid mechanics as well. There's a few quotes of his that I thought were hilarious...

"...Fuck, I can't do this problem"

and my favorite was an email:

"Folks,
My email about the Final Exam was in error. The Exam is actually 1-4
pm this Tuesday. Don't come at 8 am. The faculty are using the room to look
at porn movies until lunch. They'll be upset if you insist on watching."

11/11/2007 11:51:43 PM

That is fucking PRICELESS. Like I said, my kinda weirdo.

11/12/2007 12:07:08 AM

Hah, I'm in his class now. First week or two of class, as he's working out a heat xfer problem:

"So you'll need to find Q by....*stares at the board*...Shit, I dunno. Oh well." *then his high pitched squeal of a laugh*

Knew it was gonna be a good class with him after that.

11/12/2007 1:49:45 AM

hahaha that's about the same way he came up with the

"...Fuck, I can't do this problem"

it was funny when he would giggle at himself for something random, either a joke or just getting lost in his calculations

11/12/2007 11:17:23 AM

Well put zx that is exactly what i was trying to say.

And even then i still feel that fluid injection is still more effective after the 2nd compression stage. because it is possible to use evaporation to drop air temps below ambient... which isn't possible with an air to air inter cooler and requires chilled/iced water in an air to water inter cooler.

11/12/2007 4:01:11 PM

^and yes, after some discussion with adam8778, I understand now what you were saying about the addition of an intercooler b/t stages making the existing intercooler inefficient.

11/12/2007 4:55:06 PM