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Old 09-16-2007, 08:06 PM   #11
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Its a good idea, but.....I don't quite think this is going to work.....

your smaller jet engines that people will use to power stuff with the rotating shaft are pushing like 20 shaft horsepower. (IE shaft drive jet carts) They are making that kind of power at around 60k-90k rpm's. Do you know under what conditions it takes to spin a small turbocharger to 60k-90k rpms? At least WOT and around 4 grand PLUS on your average 4 cylinder.

look at a turbo compressor map once and just see how much cfm of exhaust it takes to spool one up to make a sufficient ammount of boost on a turbocharged engine.

So IF you can get that turbo spooled up to even start to make any kind of shaft horsepower, you still have to realize that your turbo is not near the size of even a small jet engine thats producing 20 some odd hp. So how much is yours pushing..... 4hp? 3hp? max.

then comes the next problem.... what are you going to do when you aren't producing sufficient cfm of exhaust to spool your turbo? thats right, its still connected to the crank, robbing power from it....


There are bolt ons that will net you 4hp, even 10hp across the board for far less headache, and money than it would take to get this running, if it even could at all.
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Old 09-16-2007, 08:46 PM   #12
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He's not trying to make boost -- so his energy requirement can be much lower as he won't be generating extra entropy compressing air And as he's not trying to generate any pressure, he doesn't need as big a compressor that you'll find in your typical 4 cylinder.

Combinations like that are why others have been successful with reclaiming exhaust energy and putting it back to the crank -- at non high rpm loads.

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then comes the next problem.... what are you going to do when you aren't producing sufficient cfm of exhaust to spool your turbo? thats right, its still connected to the crank, robbing power from it....
That's a problem that can be easily designed around and plenty of simple mechanisms exist for situations just like this

While we only have a slight idea of what he wants to do - it's been proven that a compressor to mechanical output is a viable way to recover energy.
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Old 09-17-2007, 04:57 AM   #13
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I do realize that he isn't trying to create boost..... I was just referring to the amount of shaft speed and power it takes to create it.

can you also link me to some sites that show that harnessing the power of the rotating shaft of a turbo is an efficient way to recover energy? I'd really like to see some of these.
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Old 09-17-2007, 05:14 AM   #14
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I'm not utilizing a turbo and the exhaust gasses are NOT directly going to be powering the accessories.
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Old 09-17-2007, 07:10 AM   #15
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Quote:
Originally Posted by Pyrorocketeer View Post
I do realize that he isn't trying to create boost..... I was just referring to the amount of shaft speed and power it takes to create it.

can you also link me to some sites that show that harnessing the power of the rotating shaft of a turbo is an efficient way to recover energy? I'd really like to see some of these.
See my earlier link -- or search google for a turbo-compound engine (or system) - or blow down turbine

That's the thing that's great about turbines, it doesn't take much power to generate shaft speed (you only have to overcome bearing resistance and angular momentum - weight of the rotating assembly) -- but it does take quite a bit of power to make torque.
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Old 09-18-2007, 10:00 AM   #16
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How about using the gear drive and pulley off a vortech supercharger? See http://vortechsuperchargers.com/cate...=SUPERCHARGERS
You'd need to fabricate and attach some sort of a turbine (or whatever meets your needs) instead of a compressor section. This also gives you the option of changing pulley sizes for different shaft speeds.

I'm also curious how you're going to get much energy out of 220 degree gasses? Is that in degrees C or F? Exhaust gas temp under typical freeway cruising conditions usually run around 720 to 820*C, so either way you're trying to use a cool, low energy gas.
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Old 09-20-2007, 06:49 PM   #17
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Rough math today yielded approximately 400 cfm available with the possibility of more depending on a couple of variables right now. I know 400 cfm is not much, but I had no idea what this device might possibly yield before, but now I know what it could do so now I have a starting point to work with.
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Old 10-14-2007, 03:11 PM   #18
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http://ntrs.nasa.gov/archive/nasa/ca...1984024237.pdf

"Waste heat recovery from adiabatic diesel engines by exhaust-driven Brayton cycles"
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Old 10-17-2007, 05:45 PM   #19
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Well, I made a discovery! It seems as though part of the device that I came up with is otherwise known as a Rankine Cycle!!! My sketches that I made are identical to this device.

I'm still continuing with this idea, especially now that I know that my idea is sound!!
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Old 02-18-2008, 08:28 PM   #20
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Well, I found out today that both BMW and Honda were already working on the idea I had without me even knowing that I was not the first to come up with it. See these 2 links for more info........



http://www.autoblog.com/2005/12/09/b...-hot-and-goes/



It does bum me out a bit, but I'm also really excited that this device not only works, but it works good enough that they are looking into putting it into production automobiles!!


So, I'm still going to keep designing this device and gathering parts so I can make my own. BMW reported a 15% increase in efficiency as well as a 14 hp and 15 ft lb increase in overall power on a 1.8L 4 cylinder gas motor!! I'd be happy if I could make a system that only gave 5-10 hp!
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