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  #16  
Old 03-14-2006, 09:02 PM
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Quote:
Originally Posted by ConnClark
Simple but there is no energy recovery from the presure drop across the plate.
In this particular system there is no energy recovered either. The system does work on the turbine, then work is put back into the system on the other side of the shaft (the compressor), making the additional turbo nothing more than a complex restriction.

Quote:
Originally Posted by ConnClark
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
Yes, indeed. I would like to see some numbers on this one. The website was just a diagram.

Quote:
Originally Posted by ConnClark
Dropping the presure across the turbine also converts some of the heat energy to mechanical energy.
Turbines are typically modled as adiabatic (no heat is lost). Since this is the real world, some heat is lost, but the temperature difference is because of the pressure drop.

Quote:
Originally Posted by ConnClark
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.
Agreed, the object of this system is to see how much heat can be removed. But whats the point? It's shown that three of engines made the same power. The modified engines did burn more fuel (yes, the difference it is slight at 6000rpm. This is also however not a typical throttle possition and engine speed where fuel consumption is important. A lower speed and throttle position would be a better compairison.) If the reason for the temperature drop is emmisions, I don't know right now how that would work out. It would have to be calculated to see if cylinder temps drop or not.

Also, where are you finding 30*C at? The lowest outlet temp on the chart I seen was 49*C


Last edited by imdavid28; 03-14-2006 at 09:07 PM.
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  #17  
Old 03-15-2006, 01:34 AM
ForcedInduction
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Here is an idea to lower your intake temps even further. Use a BIGGER intercooler, place it in the best possible airflow, isolate it from all engine/cooling system heat, and use a compressor that best suits the engine.
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  #18  
Old 03-15-2006, 11:16 AM
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Quote:
Originally Posted by ForcedInduction
Here is an idea to lower your intake temps even further. Use a BIGGER intercooler, place it in the best possible airflow, isolate it from all engine/cooling system heat, and use a compressor that best suits the engine.
Hmmm... I'm not sure if that would work or not...
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  #19  
Old 03-15-2006, 12:43 PM
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Quote:
Originally Posted by imdavid28
In this particular system there is no energy recovered either. The system does work on the turbine, then work is put back into the system on the other side of the shaft (the compressor), making the additional turbo nothing more than a complex restriction.
Actually the energy recovered goes into compressing the air to extract more heat out of it and to reduce the total effective pressure drop across the second turbo. Yes its more complicated than it could be but it gets you what you want in a small package. After looking at my thermodynamics book last night, this turbo expansion concept is used to provide airconditioning in some aircraft.

Quote:
Originally Posted by imdavid28
Yes, indeed. I would like to see some numbers on this one. The website was just a diagram.
Me too. They are out there, you just need to be a member of the SAE to get the paper mentioned in the refference section of this report.

Quote:
Originally Posted by imdavid28
Turbines are typically modled as adiabatic (no heat is lost). Since this is the real world, some heat is lost, but the temperature difference is because of the pressure drop.
A turbine is a form of heat engine. It gets its energy from more than just the pressure drop. It converts some heat to work. See this link http://en.wikipedia.org/wiki/Steam_turbine

Quote:
Originally Posted by imdavid28
Agreed, the object of this system is to see how much heat can be removed. But whats the point? It's shown that three of engines made the same power. The modified engines did burn more fuel (yes, the difference it is slight at 6000rpm. This is also however not a typical throttle possition and engine speed where fuel consumption is important. A lower speed and throttle position would be a better compairison.) If the reason for the temperature drop is emmisions, I don't know right now how that would work out. It would have to be calculated to see if cylinder temps drop or not.

Also, where are you finding 30*C at? The lowest outlet temp on the chart I seen was 49*C
He is doing this to show case the technology and to show what is possible. Once people know what is possible they can apply it differently to get what they want out of engines i.e. power, fuel economy, low emissions, etc... This study also was done assuming no changes to the engine. With a cooler intake charge you could up the compression ratio getting more power. For that matter, he also states he is using a software package that has models for standard turbo chargers and he is using those as well. Imagine what could be done with purpose designed turbos.

As far as the throttle position argument goes, with a turbo charged engine you don't have high boost numbers at low rpms, hence you don't have high inlet temperatures either. If you look at the graphs in the report, he charts them in engine power output from 110kW to 150kW. He also keeps the inlet temps almost constant 30 degrees C over this range.

Emissions control is becomming very very important to manufacturers. NOx emmissions in particular. They are throwing more and more money at it. Reducing the intake charge temperature is one of the more effective ways. Brandon's intercooler dropped his EGTs by 200 degrees F. In this case, since it was a gasser, the exhaust manifold temps did not drop much from looking at the table(four places down from the BSFC below the intake manifold temps).

Also while googling, I found that the guy who wrote this report is going to be presenting another paper on this at a conference at the end of the month. I think he is going to give out some more numbers on actual engines.


Quote:
Originally Posted by ForcedInduction
Here is an idea to lower your intake temps even further. Use a BIGGER intercooler, place it in the best possible airflow, isolate it from all engine/cooling system heat, and use a compressor that best suits the engine.
To drop the the intake temps over 100 degrees C and get them within 3 degrees of ambient temperture with just intercooling means your intercooler is going to be very very large. This would also mean you would have to have a very large frontal area on a car. You also would have to have a lot of air flowing through it. None of these factors is good for aerodynamics. To over come the aerodynamic losses you would need more power.

While I was looking this turbo expansion concept up in my thermodynamics book, I came up with the idea of using an absorbtion cooling loop. These systems are driven by heat alone. The temperatures encountered fall into the range of making this feasible. The big problem is these systems don't like being pulled every which way by G-forces. Another problem is the substances that need to be used (anhydrous amonia) the legality and saftey of putting them in a vehicle. They use these systems in some RV refrigerators so its not a insurmountable problem.
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white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
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  #20  
Old 03-15-2006, 03:08 PM
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Quote:
Originally Posted by ConnClark
To drop the the intake temps over 100 degrees C and get them within 3 degrees of ambient temperture with just intercooling means your intercooler is going to be very very large.
It's been done. http://www.are.com.au/Big%20HP/CraigsComm/hidden%20files/CraigsAWComorig.htm

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  #21  
Old 03-15-2006, 03:38 PM
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Quote:
Originally Posted by ForcedInduction
Yeah, but look at the size of the icebox in the trunk
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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png
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  #22  
Old 03-15-2006, 07:11 PM
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I'm an ass

Quote:
Originally Posted by ConnClark
Actually the energy recovered goes into compressing the air to extract more heat out of it and to reduce the total effective pressure drop across the second turbo. Yes its more complicated than it could be but it gets you what you want in a small package. After looking at my thermodynamics book last night, this turbo expansion concept is used to provide airconditioning in some aircraft.
I now see what you are talking about now. I just skimed over it the first few times, but now that I report a little better it finally makes sence to me what he was doing.

I was assuming that first device after the first intercooler was a tubine, while the last device was a compressor. So essentially you would be cooling the air, decompressing it, possibly heated by the second heat exchanger, and then compressed on top of that. Therefore, nothing was making any sence.

Quote:
Originally Posted by ConnClark
Me too. They are out there, you just need to be a member of the SAE to get the paper mentioned in the refference section of this report.
We have a library of them at school and I could probly look it up.

Quote:
Originally Posted by ConnClark
A turbine is a form of heat engine. It gets its energy from more than just the pressure drop. It converts some heat to work. See this link http://en.wikipedia.org/wiki/Steam_turbine
Nevermind. No heat is rejected from the turbine. The heat does do the work though. Bla...

Quote:
Originally Posted by ConnClark
As far as the throttle position argument goes, with a turbo charged engine you don't have high boost numbers at low rpms, hence you don't have high inlet temperatures either. If you look at the graphs in the report, he charts them in engine power output from 110kW to 150kW. He also keeps the inlet temps almost constant 30 degrees C over this range.
I missed his bypass system in there as well. This would get rid of the intake/exhaust restrictions that I was anticipating when the turbo's were dormant.

Quote:
Originally Posted by ConnClark
Emissions control is becomming very very important to manufacturers. NOx emmissions in particular. They are throwing more and more money at it. Reducing the intake charge temperature is one of the more effective ways. Brandon's intercooler dropped his EGTs by 200 degrees F. In this case, since it was a gasser, the exhaust manifold temps did not drop much from looking at the table(four places down from the BSFC below the intake manifold temps).

Also while googling, I found that the guy who wrote this report is going to be presenting another paper on this at a conference at the end of the month. I think he is going to give out some more numbers on actual engines.
Since the EGT's are about he same, doesn't it defeat the purpose of the device?

Last edited by imdavid28; 03-15-2006 at 07:59 PM.
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  #23  
Old 03-15-2006, 07:25 PM
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turbo

I saw a guy running a diesel, dodge truck with a cummins... he
had installed 2 turbos... one was normal and the other was from
a tractor trailor.... the smaller turbo provided the preasure to run
the larger turbo. The larger tractor trailer turbo provided the preasure
to the engine.... and this old boy was a hay seed.... but i think
he had these scientist beat.....

and if you just want a good intercooler then go to a junk yard or
to ebay and buy the one from a saab 900.... probably the best one
going...
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  #24  
Old 03-16-2006, 11:30 AM
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Quote:
Originally Posted by imdavid28
Since the EGT's are about he same, doesn't it defeat the purpose of the device?
The increased load on the primary turbo has upped the pressure in the exhaust manifold, hence contributing to the higher EGTs. EGTs may be about the same, but combustion chamber temps may have dropped a lot more. Its at peak pressure and temp when most NOx is formed.

He is just using it to show case the technique. As I have stated before, the rest of the engine has not been optimized to take advantage of the cooler intake temps. After tweaking the engine and adjusting the intake cooling to optimize toward some goal other than demoing the cooling itself, I would expect to see signifigant gains.


BTW, your not an ass, your learning.
__________________
green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png
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  #25  
Old 03-16-2006, 01:23 PM
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No, honestly, should of know better. My thermo final is next Thursday. But thats a whole other story...

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