I saw an interesting article today about using a second turbo to compress the gas out of the 1st turbo. This hot high pressure gas (5 bar) is fed through an intercooled, then expanded through a turbine to cool it to -25°C and about 2 bar boost. This was on a gasoline engine and they claim to be able to run stoich air fuel and more timing at WOT due to the absence of knock from the super cool intake gas temp. This could be a killer set-up for pump-gas-drags or any other octane limited application (if it really works).

Anyone else seen or tried similar?

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Who's working with this looks off the wall.

 

Here is a link to the article; http://www.gtisoft.com/confarch/Volvo_Combustion-Cooling.zip

 

A lot of air conditioners do this in applications where noise is not a concern such as trains and airplanes. I didn't see what the second compressor/turbine was driven with. They are usually driven by a electric motor in the air conditioners.

 

I read the link, and I don't understand why CAC1 is connected ( via the dotted line ) to the wastegate.

 

I think its connected to control the boost pressure.

From looking at the setup, its driven by the first turbo's compressed air, but I could be wrong....
Bowtie Guy

 

it looks like a compound turbo setup with the second compressor feeding its own turbine. then the turbine feeds the intake manifold.
kinda like the perpetual motion thing which we all know doesnt work(on earth) due to friction loss.
I dont get it, the system relies on the primary turbine to do all the work.

 

The primary turbine is not doing all the work. If the secondary compressor and turbine are each 71% efficient, then overall efficiency of the secondary turbo is 0.71x0.71=50%. So half of the power to run the secondary compressor comes from the secondary turbine, and the other half comes from the primary turbo.

 

As air conditioners these things really do work and they are not perpetual motion. There is something shaft connected to the second compressor/turbine to drive it. In these setups the turbine that cools the air does help drive the second compressor but the net power is still always suppied by motor or something.

 

The question I had was, is it OK to run with inlet gas temps at -25 deg C. Would fuel not be hard to evaporate or would need to run fuel enrichment all the time. Perhaps it is only viable with GDI engines where you can inject all of the fuel into the hot compressed gas shortly before TDC firing.

 

I would be kinda worried about throttle blade icing...

 

I've often wondered about a setup like this over the years but always ended up feeling like it can't work or it would've been done before.

Even if it does work, I'd have to assume it'd be very unresponsive. Maybe a positive displacement supercharger as the primary compressor?

Yeah, an evaporator of some sort may be handy...

 

This looks utterly ridiculous.

 

I am selling the Eiffel Tower.

You can PayPal me the cash.

 

how much for delivery to oregon ?

 

I think it would work better if there was a shaft connecting the first (hot) turbo to the second (cool turbo) That way you'd have additional work not being spooted out the tail pipes.... Good ideal IMO, go ahead and do it and let us all know how well it works! :lol:

 

Quote:

"go ahead and do it and let us all know how well it works!"

I had a boss one time in Advanced Engineering who would never criticize anyone's
ideas. His comment was: "Put it together and show me the data" He was a Data Driven type of guy. His other comment was "Until you have real data, you are just another guy with an opinion".

Tom Vaught

 

Hahaha, awesome.

I have this theory about....well, I don't want to go too much into it (with patents applied for and all), but have you ever seen those birds that just keep dipping up and down drinking water? Think that, plus generator, is all I'm gonna say....

 

Sort of sound a little off the wall but it sure would be great to eliminate those icewater intercoolers. I think I'm going to look into this. I like to know why it won't work before I throw the idea out. I wonder what the pumping losses would be.

 

You won't be able to find a reason it won't work because it would work but at the end of the day things like cost, weight, size, etc. will make it loose to other more conventional approaches.