Compressor compound turbo setup

[storx]

I was watching tv at the doctors office earlier today and i beleave it was speed tv channel they had on.. and they were talking about an guy with an grand national that was pulling off magical work with a new style of compound turbos.
The way his turbos ran was he had a huge turbo tied into the exhuast manifolds throught the turbo and then out a downpipe through the exhuast. He stated that the turbo was so large that he wouldnt reach 12psi with it tell 5000rpms if he ran it singly.. so what he decided to play with was compounding the compressor side to increase airflow...

I am wanting to know if anyone else caught this as i couldnt finish watching it as i was called in for my appointment before it ended...here is a rough painting of what it looked like on the show...

 

[JFettig]

so its a perpetual loop in the center? lol

seriously dude, do some searching around here. There is limited info on this subject on this forum, but is there, including 2 current builds. The google will give you more than plentiful information on the subject.

 

[kooyajerms]

The google.

Next thread "turbine compound setup, which one?"

 

[storx]

i know it seems wierd but the idea that he was talking about was that it spools the smaller turbine with the larger compressor pushing large amount of preassure into the engine from the ratio differences.. and then there is a BOV or Wastegate between the two to keep compressor preassure under check to not stall the turbos i think is what he was saying...

 

[storx]

i may not be correct 100% but i tried to remember it the best i could.. he was using all cold side to compound the inlet preassure.

 

[LNXGUY]

This picture is going to end up at The Car Lounge.

 

[TDIMeister]

There is a technique with various names, e.g. super-chiller, turbo-cooler, etc., that kind of works in the way you describe, but as you have sketched it, I cannot see how it would have any advantages over a conventional system because of the massive irreversibility losses and lack of any heat exchangers... it's also not a compound as drawn and there's not way to rationalize it as one.

Going back to super-chiller, basically the idea is have the fresh-air flow going through BOTH the compressor and turbine with a heat exchanger or nozzle in between. Basically, it is an implementation of the Joule-Thomson effect. Pressurized air from a conventional turbo/supercharger is forced into another compressor, which raises its pressure (and temperature). This air is then routed to a heat exchanger bringing the temperature back down. This cooled air is the routed to the TURBINE INLET of the same second turbomachine, where it is expanded to a lower pressure and a (much) lower temperature than would have without this second stage. The overall effect is a much colder (and by extension denser) fresh charge at the cost of greater exhaust backpressure and adverse EMP/IMP ratio. However, it could be very beneficial to knock-limited spark-ignition engines because the charge temps could be reduced to well below freezing even with normal ambient temperatures.

I have done analysis and GT-POWER simulation of this.

 

[storx]

Wow some hatefull people messaging me...whatever I was looking for more info on if someone else caught the end of it...but I guess people rather be hate full then to answer what I was looking for.....

 

[VeeDubTDI]

Who's being hateful?

 

[Turbo Z]

The joule joule-thomsen effect, that was initially used to liquefied air, if the temperature is going to increase or decrease is depending on the initial temperature and pressure this process is called isenthalp and has a relative small effekt in compare using a turbine look at this
http://www.gtisoft.com/upload/Volvo_Combustion-Cooling.pdf

in a gasoline engine using where normally a lot of waste gating are taken place since the temperature is so much higher than in a diesel engine process and by that a lot more energy can be recovered in this case in form of boost, of couse it can be done for a diesel as well but the back pressure will be greater than for the gasoline engine. But the real benefit in the gasoline engine is that the combustion temperature lowers and unwanted ignition of the air fuel mixture is better controlled.

My concern, though I have no practise of this in real, would be that the moisture in the air that would come out, specially in a radial inflow turbine, the first radial inflow steam turbine lasted for an hour then there was nothing left of it since the water in liquid form hits the turbine again and again and do not want to come out since the density is so much greater then the gas. The liquified water grind down the turbine. and here it will even start to freeze since it would be sub zero, though I would say this is very interesting, but a good sized series of turbos will make a really good work

There is a technique with various names, e.g. super-chiller, turbo-cooler, etc., that kind of works in the way you describe, but as you have sketched it, I cannot see how it would have any advantages over a conventional system because of the massive irreversibility losses and lack of any heat exchangers... it's also not a compound as drawn and there's not way to rationalize it as one.

Going back to super-chiller, basically the idea is have the fresh-air flow going through BOTH the compressor and turbine with a heat exchanger or nozzle in between. Basically, it is an implementation of the Joule-Thomson effect. Pressurized air from a conventional turbo/supercharger is forced into another compressor, which raises its pressure (and temperature). This air is then routed to a heat exchanger bringing the temperature back down. This cooled air is the routed to the TURBINE INLET of the same second turbomachine, where it is expanded to a lower pressure and a (much) lower temperature than would have without this second stage. The overall effect is a much colder (and by extension denser) fresh charge at the cost of greater exhaust backpressure and adverse EMP/IMP ratio. However, it could be very beneficial to knock-limited spark-ignition engines because the charge temps could be reduced to well below freezing even with normal ambient temperatures.

I have done analysis and GT-POWER simulation of this.

 

[TDIMeister]

http://www.gtisoft.com/upload/Volvo_Combustion-Cooling.pdf

Yup, the work I've done on turbo-coolers (around labels 4 and 5) is exactly the same architecture as in page 7 of the above, right down to using a VNT turbine for control.

I did not look into effects of the charge air temperature dropping below the dew point. Arguably the turbine, being usually made of Inconel, is better able to withstand liquid erosion than the aluminum compressor wheel, keeping in mind that ambient air at 25°C, 1 bar and 60% relative humidity only has about 0.012 kg of water per kg air. However, it is a legitimate concern.

 

[madcowintucson]

I think I may know what's going on here storx. I called a Garrett master distributer in Phoenix or Denver, I forget, we'll anyways they have a diesel race truck and the turbo guy told me they used a large gtx turbo in a compound setup I never heard of before. He told me the big turbo get all the exhaust energy and the compressor discharge actually drives the turbine side of a smaller turbocharger. No intercooler in between. Then the compressor discharge of the smaller turbo is intercooled and feeds the engine. I don't know how this is better except that maybe the smaller turbo would run cooler?? Maybe a lot less exhaust back pressure? Maybe a large turbo rated at 700 hp could feed a smaller turbo to get 500 hp. He says it will spin the smaller turbo up super fast.

 

[Turbo Z]

Are you really sure? If I understands you right it make no sense?

What GTX turbo and engine size?

I think I may know what's going on here storx. I called a Garrett master distributer in Phoenix or Denver, I forget, we'll anyways they have a diesel race truck and the turbo guy told me they used a large gtx turbo in a compound setup I never heard of before. He told me the big turbo get all the exhaust energy and the compressor discharge actually drives the turbine side of a smaller turbocharger. No intercooler in between. Then the compressor discharge of the smaller turbo is intercooled and feeds the engine. I don't know how this is better except that maybe the smaller turbo would run cooler?? Maybe a lot less exhaust back pressure? Maybe a large turbo rated at 700 hp could feed a smaller turbo to get 500 hp. He says it will spin the smaller turbo up super fast.

 

[madcowintucson]

Are you really sure? If I understands you right it make no sense?

What GTX turbo and engine size?

That's what the man told me. I think it was a class 8 pikes peak racer. Call up to central motive power in colorado, talk to the turbo guys and ask them about it.

 

[newlitemotorist]

I think I may know what's going on here storx. I called a Garrett master distributer in Phoenix or Denver, I forget, we'll anyways they have a diesel race truck and the turbo guy told me they used a large gtx turbo in a compound setup I never heard of before. He told me the big turbo get all the exhaust energy and the compressor discharge actually drives the turbine side of a smaller turbocharger. No intercooler in between. Then the compressor discharge of the smaller turbo is intercooled and feeds the engine. I don't know how this is better except that maybe the smaller turbo would run cooler?? Maybe a lot less exhaust back pressure? Maybe a large turbo rated at 700 hp could feed a smaller turbo to get 500 hp. He says it will spin the smaller turbo up super fast.

So does their set up feed the same air that drives the turbine of the smaller turbo into the inlet of the smaller turbo? Looking at those pictures it looks like that is what they have going on. To me that would seem to present a restriction, but maybe I am looking at this wrong. How does the smaller turbo spool up or does it? I have always been under the impression that is was due to the expansion of the hot exhaust gases that causes a turbo to spool. I do know that when you run a high speed air tool off previously compressed air it does get really cold so maybe that is what is going on with that smaller turbo. But does that colder denser air more than offset the pumping losses of pushing that air through another turbo?

And to go along with turbo z's concerns about moisture, I have had my high speed die grinder freeze up when using it in the winter in a cold garage. Is this something to be concerned about with a setup like this?

Edit: And I just realized that TDImiester has already answered some of the questions I brought up....

 

[KB3MMX]

I think I may know what's going on here storx. I called a Garrett master distributer in Phoenix or Denver, I forget, we'll anyways they have a diesel race truck and the turbo guy told me they used a large gtx turbo in a compound setup I never heard of before. He told me the big turbo get all the exhaust energy and the compressor discharge actually drives the turbine side of a smaller turbocharger. No intercooler in between. Then the compressor discharge of the smaller turbo is intercooled and feeds the engine. I don't know how this is better except that maybe the smaller turbo would run cooler?? Maybe a lot less exhaust back pressure? Maybe a large turbo rated at 700 hp could feed a smaller turbo to get 500 hp. He says it will spin the smaller turbo up super fast.

He was probably referring to a aftermarket compound turbo setup on a Duramax although his description of the plumbing was wrong. It is common for performance Duramaxes to be upgraded to compound twin turbos.

 

[jsf350]

compounds arent to difficult to understand...

ive fabbed my own sets and installed countless others

exhaust goes to the small turbo first and then to the larger one... wastegate on the smaller turbo opens sooner so that the exhaust energy will drive the larger turbo harder and also not over speed the smaller turbo...
i want to do compounds but there is a need for much larger fuel flow/head studs to make it all work... and time lol