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Discussion Starter #1
Hey guys,
So I have what I believe could be a gold mine idea. Its beautiful. Willi has inspired me with his "little red rocket."

What if we used a turbocharger like setup to power a generator instead of a compressor. So you see, I am not crazy!! I dont want an electric turbocharger. I want a turbine in the exaust that can power a high speed generator.

I Know that alternators generally dont run at such high rmp's as a turbocharger would. However, knowing only a little bit about the principles behind an ac generator.... i am sure that one can be designed to spin at turbo like rpms.

The real beauty of this added power generation is two fold.
1) It keeps with the Insight's theme of total efficiency. I mean really... we are just wasting all that exaust gas momentum (haha, thats the Aerospace engineer in me talking)

2) With what i think could be a significant increase in the available power for the electric assist you could both increase performace and gas millage.
One could simple use more IMA more often and less Gas engine for better millage. But also the added generating capacity would allow you to go under full IMA "boost" (haha, like a real turbo)...

And for those of you who are truley brave i offer a third option: Add a second electric assis package and add to the total power of the car.

Let me know what you think.
 

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Well, it will be significantly less efficient then a regular turbocharger due to the multiple energy conversions required.

If you could somehow source the parts, it will he horribly expensive due to the exotic gears required.

On the other side, assuming you are actually aiming for forced inductinon, you would need the same gearset and a large electric motor (oh, around 10KW or so) to run the compressor side of the turbocharger. You'll end up with something that would weigh 5 times what a normal turbo would, but is only 50% as efficient. :)

Honestly, it make no sense to do this. :)
 

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Re: Electric Turbo Charger.... dont yell at me, just hear me

JustinGray said:
Hey guys,
So I have what I believe could be a gold mine idea. Its beautiful. Willi has inspired me with his "little red rocket."

What if we used a turbocharger like setup to power a generator instead of a compressor. So you see, I am not crazy!! I dont want an electric turbocharger. I want a turbine in the exaust that can power a high speed generator.

<snip>

Let me know what you think.
Something similar was done in some WWII aircraft. Some had reciprocating engines with an exhaust turbine (that's what you're talking about, not a turbocharger) geared to the crankshaft. Fussy, unreliable system, quickly abandoned. But you might be able to capture useful watt hours via an exhaust turbine.

Not to be impolite or anything bad like that, but if you wanted a fast car why did you get an Insight?
 

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Hi Justin, I worked on Brazilsat and Sarsat as a technologist but that was long ago. You probably noticed we have technical folk, mechanics, pilots, etc. on the site. The Insight really appeals to those who don't want just an ordinary car.

The idea of recovering exhaust pressure and heat has been discussed at some length here. A link to a company making thermo-electric "alternators" for trucks was very interesting.

Your idea would work as long as it could replace the back pressure from the muffler. Furthermore a turbine in lieu of a muffler would work as well as a muffler. Note that Willie removed his muffler. I am sure you would agree though that any increase in back pressure over and above the current level would actually rob power from the engine as it would decrease the scavenging of exhaust gasses and require additional energy on the exhaust stroke.

As far as using an electric turbo charger to increase HP, I am very keen on the idea. It would actually put less of a strain on the engine than a typical turbo and would not have to deal with high exhaust temps.
 

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Re: Electric Turbo Charger.... dont yell at me, just hear me

The biggest limitation as I see it is how much energy is available to convert in the first place. There's a lot of wasted heat energy, but not nearly as much "flow" energy available. If you do the math I think you'll see the amount of energy recoverable including losses is very small.

:)
 

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Yes, I don't think that the exhaust from the insight is under particularly high pressure. The exhaust seems to barely drift out the tailpipe, not like the leaf blower exhaust pipes you'll find on muscle cars. ;)
 

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The Insight exhaust could be artificially accelerated by fitting an "AeroTurbine" muffer to replace the stock unit. This muffler claims to accelerate the exhaust.

This could help with spinning the turbine in the turbo for the generator. Maybe fitting a brushless generator would help with friction.
 

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Discussion Starter #8
ok... SO i think i have mislead some of you and others are getting the idea.

What i am proposing is not actually a turbo charger at all! The Exaust turbine is really what i am speaking of. I do not, repeat: do not, want to do forced induction on the insight.

While i respect the little red rocket... i am on a quest for something original to call my own.

As for the why would i buy an insight if i wanted a fast car. Not to be rude back, but i think your vision of what the insight could be is far too limited. It is so light, and so well desigined. It would be a shame not to explore every possiblity to increase the power output while improving efficency. I believe that this idea is promising.

Accounting for losses, i still think that there is energy to be recovered here people! Some of you have said that i would not be seeing much net killowats.... i dont understand the argument. If Willie found enough pressure gradient to power a small turbo to 5 pounds of boost, i am sure i can find enough pressure to power a small exaust turbine to spin a high speed generator!!! As for the friction.... the ac motors dont have much in the way of that. They do provide alot of magnetic resistance [email protected]!!!

I dont really want to gear down the exaust turbine, i want to design a generator to work at speeds that would be seen by a turbine...

Hope that clears some things up.... [/quote]
 

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Before running any scheme, I always like to scratch a few numbers on paper...(putting on thermodynamics hat for a moment)

If the Insight is getting a "real world" efficiency of 60MPG @ 60 MPH (makes math easy) and steady state cruising puts the most energy into any device because when you stop, exaust energy probably falls close to zero (especially in idle stop):

In one hour, you burned one gallon of fuel ~115,000 BTU. I have seen estimates of heat going out the tailpipe of 30-40%, we'll be generous and say 40%, so that puts (115K * 40%) = 46,000 BTU/hr out the tailpipe.

Punch up the Carnot heat engine equation and... find that under ideal circumstances if we can recover heat in the exaust and go from 700*F inlet to 350*F outlet is 30% efficient so (46K * 30%) = 13,800 BTU.

Next, you'd have to pass that energy through a power converter to the battery, then back through a power converter from the battery and finally to the electric motor. So figure about 90% for each conversion or about (90% * 90%) 81% overall and you wind up with 13,800 * 81% = 11,200 BTU/hr as a very generous estimate of useable energy. Fire up the conversion program and... you are making about 3.3KWh or about 4hp.

The other side is that when you cool the exhaust by any means (turbo generator, thermopile, steam generator, etc), you will surely loose some exhaust gas velocity, which will increase exhaust gas backpressure and mean that the ICE is loosing some power.

It's a heckuvalotta work for a couple HP.
 

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Discussion Starter #11
I will grant to you that there is not much hoarse power to be gained here... however... lets just say 3 hp is what you would get.... thats 3 extra hp that you can use to further increase your fuel efficiency!
 

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Corey872 did the math for you. Its horsepower that will cost in equivalent pounds of gold.

Even with mass production and some real engineering effort in ironing out the kinks and reliability issues it will be the most expensive horsepower produced by the car.

Kevin Dougherty's heat scavenging thermocouple idea is the most elegant. But unless its integrated into overall IMA management its a difficult add-on. And still a very high cost per horsepower effort.

Except in NG discussions and dreams cost is always an issue. :)
 

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Effort would be better spent on an computer controlled intake that would keep air temp at the proper range. Some type of y-valve that would use the perfect amount of outside air along with heated air off of the CAT.

Or If the use of ceramic coatings was implied then engine heat could be reduced and the front air intake could be smaller. Thus less wind resistance.
 

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Well, I think his point was, although you may get 3 horsepower, you're going to lose more than that by the increased backpressure. Themopiles/thermocouples are in theory an elegant approach, but only put out a laughable amount of energy.
 

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I dunno, thermocouples/themopiles are usually rated in millivolts, (and usually only that in the neighborhood of a few hundred degrees Celcius) and so are generally only useful as high-temperature sensors.
 

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"The other side is that when you cool the exhaust by any means... you will surely loose some exhaust gas velocity, which will increase exhaust gas backpressure..."

I don't quite see how you come up with that conclusion. Surely if you cool the exhaust, you drop the pressure on the outlet side of the turbo.

As to making "only" 4 HP, look at it from the other direction. I once worked out (from speed down a constant grade) that it takes roughly 17 HP to propel my Insight at a constant 60 MPH. Add 4 free horsepower to that, and you've cut fuel consumption by maybe 20%. So I go from my average of 70-75 mpg to 85-90 mpg.

You also have to factor lean burn into the mix. Lean burn happens under light load. Add those free HP, and you widen the window under which it can happen.

I agree that it would take a lot of engineering - you'd have to hack the ICU for one - but it seems perfectly doable. Maybe not for your average shade tree mechanic, but for Honda R&D :)

There is some ongoing research into the concept. Do a google search on something like "exhaust recovery turbine" to find it.
 

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First. "electric turbo charger" is bad. A better description would be "Exhaust gas driven generator"

Second: Look at a gas-powered 4HP electric generator and see how big just the generator is. It is neither small nor light. And that a light duty model that won't withstand the vibrations and heat of being mounted next to the exhaust of a moving car.

Finally: The automotive industry is pretty competitive. If someone came up with a way that increases efficency by 10% or more, don't you think we would be hearing about it if not seeing it on the road.
 
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Of Black Helicopters and Plasma weaponry ...

Hi Flunkysama:
flunkysama said:
Finally: The automotive industry is pretty competitive. If someone came up with a way that increases efficency by 10% or more, don't you think we would be hearing about it if not seeing it on the road.
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"If someone came up with a way that increases efficency by 10% or more, don't you think we would be hearing about it if not seeing it on the road."

No. First off, there's a simple way to increase overall fuel efficiency by a couple hundred percent, which is simply to build and promote reasonably sized cars instead of SUVs. But is the auto industry interested? Don't seem like :)

Second, the important point about an exhaust recovery turbine is that you also need some sort of system or linkage to feed the captured power back into the system. With a hybrid, you already have that system in place. You only need to add the turbo/generator itself, and a bit of control logic, so there wouln't be a whole lot of incremental cost.
 
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