Try and grasp this concept - PeachParts Mercedes-Benz Forum

ConnClark · #1 03-13-2006, 06:17 PM

I thought I had intercooling theory down, check out taking it to the next level.

http://www.wdlpower.co.uk/downloads/PTNSS_2005_TCS_Paper.pdf

TheDon · #2 03-13-2006, 06:23 PM

WTF

-curls into fetal position.. mommy help-

Diesel Giant · #3 03-13-2006, 06:30 PM

Oh that is some mild reading. You should read some of my A/C books!

MTUpower · #4 03-13-2006, 10:51 PM

The seven most important words in the whole paper are found in the conclusion:
"...now requires validation on a real engine."
Interesting concept.

ConnClark · #5 03-14-2006, 01:31 AM

Apparently its not just a concept any more..

"6) 2005: Lotus: The Turbo-expansion Concept - Initial Dynamometer Results (SAE2005-01-1853)"

RichC · #6 03-14-2006, 03:51 AM

Hello All

OK, I understand most of the technical mumbo jumbo. What I dont get is how adding the second turbo in series would cool the air? What am I missing?

#7 03-14-2006, 09:48 AM

Quote:

Originally Posted by RichC

Hello All

OK, I understand most of the technical mumbo jumbo. What I dont get is how adding the second turbo in series would cool the air? What am I missing?

As I understand this, the whole point is to obtain the minimum inlet air temperature by increasing the heat transfer across the second cooler. Normally the minimum temperature that can be obtained is limited by the size of the cooler and the temperature difference between the inlet air and the ambient air. In this case the second turbo is used to temporarily increase the inlet air temperature (by compression) so there is a higher temperature difference across the second cooler (more enthalpy can be removed). The inlet air is then expanded through the drive portion of the turbo and expanded to a lower temperature than it originally had (also a lower pressure). The result is a lower inlet air temperature than a normal cooler.

There is nothing wrong with the theory, but this is not a free lunch. The second turbo assembly will result in a net enthalpy loss that has to be compensated for by the main turbo (which means higher engine back-pressures). That challenge is to come up with a design that results in an overall increase in engine power/efficiency with reasonable cost/weight/complexity. It's an interesting concept.

#8 03-14-2006, 10:12 AM

I saw somewhere a super charger for a 1995 E420. What difference would a super charger make on that engine? Recommended? It was around $2000-$2500 for the kit.

imdavid28 · #9 03-14-2006, 10:27 AM

This system is unneccesarily complicated.

ConnClark · #10 03-14-2006, 11:37 AM

Quote:

Originally Posted by imdavid28

This system is unneccesarily complicated.

Lots of things on cars are over complicated. Take the transmission for example, how many parts are in that? The Tucker Torpedo's "Tuckermatic" transmission had only 27 parts (26 if you don't need reverse

). The only thing that matters is if it superior enough to justify the complexity and expense.

Bajaman · #11 03-14-2006, 11:44 AM

Quote:

Originally Posted by imdavid28

This system is unneccesarily complicated.

The one thing I really don't get is why have CAC1 before the turbo expansion turbine. Wouldn't all that rejected heat be put to better use driving the second compressor? So why not put CAC1 after the second turbine, and CAC2 after the second compressor?? Doesn't this make more sense?
What I really liked was the idea of the ebooster, this would effectively make turbo-lag non-existent.
bb

Toronto_300SD · #12 03-14-2006, 12:06 PM

Where was that!!!! If you could tell me I would be really interested in that kit

I saw somewhere a super charger for a 1995 E420. What difference would a super charger make on that engine? Recommended? It was around $2000-$2500 for the kit.

ConnClark · #13 03-14-2006, 12:09 PM

The whole point is getting as much heat out of the charge air before you let it expand. Putting a CAC behind the second turbine won't accomplish much because the temperature difference between the ambient air is almost nonexistant. There are a lot of variables to play with to optimize this however. The sizes of the play an important role. If CAC1 cools to much CAC2 may not get hot enough to disipate enough heat to be worth it.

If there is anything thats a possible problem I suspect it will be sensitive to changing conditions. You must admidt it puts energy that would be normally dumped through the wastegate to good use.

imdavid28 · #14 03-14-2006, 04:19 PM

His idea is to increase the pressure so that a pressure drop over a turbine would cause an temperature. He then runs it through another intercooler with a no doubtably lower temperature gradient, then increase the pressure again making the air hotter. GENIUS! not...

A simpler way of making the same device would be to put a restrictor plate with a small hole drilled in it after the intercooler, and run your boost sky high. Simple enough right?

Furthermore, his findings prove the idea is flawed. The WOT BSFC goes up and his pumping losses more than doubled while the hp and torque remain the same. This doesn't even mention part throttle operation, where 99% of the life of your engine dwells.

ConnClark · #15 03-14-2006, 06:06 PM

Quote:

Originally Posted by imdavid28

His idea is to increase the pressure so that a pressure drop over a turbine would cause an temperature. He then runs it through another intercooler with a no doubtably lower temperature gradient, then increase the pressure again making the air hotter. GENIUS! not...

A simpler way of making the same device would be to put a restrictor plate with a small hole drilled in it after the intercooler, and run your boost sky high. Simple enough right?

Simple but there is no energy recovery from the presure drop across the plate. The Lotus aproach is similar to your in a way except they drop the pressure across a turbine to recover energy and convert it to mechanical energy to drive something. http://www.grouplotus.com/eng/track_record.php?section=17&page=25&id=91

Dropping the presure across the turbine also converts some of the heat energy to mechanical energy.

Quote:

Originally Posted by imdavid28

Furthermore, his findings prove the idea is flawed. The WOT BSFC goes up and his pumping losses more than doubled while the hp and torque remain the same. This doesn't even mention part throttle operation, where 99% of the life of your engine dwells.

I think he was gearing this example to demonstrate how much he could cool the air instead of how much power and efficiency he could get out of the engine. To take air and cool it from 178 Degrees C to 30 Degrees C with ambient air temps of 27 Degrees and only use 2 grams more fuel per KWh is very impressive.

If you can do this any more efficiently without using an intercooler the size of a car I'm sure the auto industry would be interested.