Skip to comments.The Race to 100 MPG
Posted on 10/25/2006 7:13:52 AM PDT by Red Badger
Jet-Engine Inspiration Another potential player in the race to 100 mpg is the StarRotor, which began life as an air conditioner at Texas A&M University. Chemical-engineering professor Mark Holtzapple and his colleague Andrew Rabroker were attempting to build a better compressor for an air conditioner when they hit on the idea that became the StarRotor engines basic architecture. Once they made the connection to car engines, we quickly forgot about air conditioners, Rabroker says. They have since formed a business (also called StarRotor) to commercialize the technology.
The StarRotor uses the same thermodynamic process as jet engines to recuperate some of the heat normally lost to exhaust, something that the design of a piston engine doesnt allow. The exhaust heat warms the air that comes into the engine before the fuel is added [see illustration, below]. This hot air leads to more powerful combustion, which means the StarRotor can extract more energy from a given amount of fuel than a conventional engine could.
Intake air is compressed [A] and heated [B] before it ignites in the combustor [C]. The exhaust spins the rotor [D] that drives the wheels. It then warms the heater [E].
Based on data from compressor prototypes, Rabroker believes the StarRotor will convert between 45 and 65 percent of the chemical energy in its fuel to mechanical energy, irrespective of the engines operating speed or power. In contrast, a typical gasoline engine has a peak efficiency of about 30 percent at full throttle and operates at a much lower efficiency during typical driving conditions. Double is a gimme, Rabroker says of the StarRotors potential. I think we can ultimately triple the fuel mileage.
Double or triple, though, whats important is that innovators are developing solutions to our oil predicament solutions that could have a huge influence before the first hydrogen-powered car ever leaves the lot.
When Billy Baker isnt writing about the automotive industry, hes working on a book about the juggling subculture.
If you want on or off the DIESEL "KNOCK" KIST just FReepmail me........
Seal issues. Think Wankel.
I don't wank seals..........
That compressor doesn't look very efficient.
Looks can be "deceiving", lesser_satan.........
It's actually not all that dissimilar from a rotary engine that Mazda RX-7s and RX-8s have.
I think you blew a seal,
no it's just ice cream
LOL...or blow them.
Look promising, of course the proof is in the pudding. They need a working prototype, and need to prove its efficiency in typical automotive use, plus it has to have similar longevity compared to todays piston engine. I wish them the best.
This is a standard turbine engine with a positive displacement compressor and turbine instead of centrifugal. The heat recuperator is nothing new either. Actually, I have often wondered why there hasn't been more development in this technology before.
If it's in production why isn't anyone using it?
If it's in development why would they broadcast their invention before production?
The key differences from a wankel that I see are that the combustion takes place away from the moving parts, and the compression and the expansion take place in separate mechanisms. It seems that the "seal" issues of the Wankel may not be as much of an issue here.
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Looks to me like one of those jet engines you make from an old automobile turbocharger. Just hook a drive shaft up to it...
What's the bid geal with 100mpg? My mother drives a diesel Citroen C1 which does 83mpg at a steady 56mph. On gentle runs she's got nearly 90mpg. . . . .
Yup... and Wankels are not very fuel-efficient engines to begin with, compared to piston engines of similar horsepower. It looks like they've managed to recapture some waste heat and use it, upping the efficiency, but these claims sound terribly speculative.
Also, what's with the "the exhaust spins the rotor that drives the wheels" part? That sounds a lot like the old Chrysler Turbine setup. The diagram shows no connection between the compression and drive rotors, not even a viscous coupling. The vehicle better be small and light, because I suspect this design will share another Wankel characteristic - low torque. Efficiency is great, but if it can't do the work...
Isnt this pretty much a turbine engine? Chrysler tried that once and failed.
"The exhaust heat warms the air that comes into the engine before the fuel is added [see illustration, below]. This hot air leads to more powerful combustion, which means the StarRotor can extract more energy from a given amount of fuel than a conventional engine could."
While heating intake air increases atomization (Richard Petty), thermodynamically you want cold/dense air coming in. Otherwise supercharger intercoolers wouldn't be used. Add to that the seal problems.
Not saying it won't work (yet), just saying your milage may vary somewhere less than utopia.
The "separate" combustion chamber sort of threw me. It makes more sense if you think of the combustor as part of the drive rotor assembly, which it is (albeit not in a familiar sense).
This thing really is sort of a combination of a Wankel and a jet turbine. I wish them luck with it - should make an interesting aircraft engine, if nothing else.
On further inspection, I see they are judt running a recuperator. You could do the same thing by taking a V8, using 4 pistons for compression and 4 for 2 stroke combustion with a recuperator. You'd end up with the same problem, one hell of a lot of heat.
There is no reason why transportation to anywhere on earth and back should have to consume any energy at all. Get to work on the friction thing.
Or overcome gravity.
Tunnels straight thru the earth with 4 quadrant mag lev rails.........
Gravity is not the problem. It is fully restorative. Maybe there is another word to carry that meaning, but you get it all back when you get home. 100%
Winkle, winkle, little wankle. Whats all of those RPMs you'll crankle.
That depends on the turbine. Many, many industrial turbines operate 10,000 hours or more before shutting down for any maintenance at all. Nearly all operate continuously for years before any major maintenance is performed. This type of application is typical for a Natural Gas Pipeline or other similar service.
Tried and failed?
Not really, more like the car was a success, so long as mileage was not a concern, and many of the test drivers wanted to keep the cars.
Chrysler and Rover both had technically successful turbine cars, and both simply chickened out.
They ate up fuel at a fantastic rate, but they burned most anything,including Fry fat, I believe they had a lot of trouble braking the thing and it wouldnt get off the line very well. Acceleration was slow and they didnt have much pulling power.
Makes sense to me. perhaps a small engine could provide electric power and get good mileage.
That's exactly right and what I thought when I started reading this.
But if you go to the website you find out that the fuel-air mixture is heated after the compressor stage. Makes a little more sense now.
From their website:
To create an even more efficient engine, atomized liquid water can be sprayed into the compressor inlet to keep the compressor cool. Keeping the compressor cooler allows compression to be more efficient thus the engine will be more efficient.
You'll like this ....http://www.turbinecar.com/top.swf
Nope. More like the gas turbine engine......
It wasn't a failure, it was very much a success, unfortunately, big oil and the Big Four shelved the idea and took the cars back, pretty much destroying the majority of them, the few remaining examples are in museums, but it had a very successful run. Unfortunately they did with the Chrysler turbine what GM did with the EV1 (leased out to people, then recalled them). The Chrysler Turbine was very efficent for its day, doing a then outstanding 30 mpg in city driving, with some minor tuning capable of 45+mpg. That in a vehicle that weighs as much as a modern hearse.
"I think you blew a seal."
"Just fix the damn thing and leave my personal life out of this!"
/kooky song mode
Cool, as long as a portal is near my house, but not in y bak yard. Maybe the next town over, in someone elses back yard.
>Gravity is not the problem. It is fully restorative. >Maybe there is another word to carry that meaning...
The other word is actually 'conservative'!
Gravity is a conservative force, in that it conserves energy.
What is the proper Republican stance on gravity, a conservative field?
We should be in favor of gravity.
Without it, people keep flying off the handle, like democrats.
Nat gas is up 60 cents today. Retail gasoline has finally declined a few cents in Fairbanks just in time for the wholesale gasoline index to pop up ten cents. We got some snow a couple days ago that stuck and it is fun to watch the chechakos try to drive their Trans-Ams and 454 Silverados the first day--a good day to stay home.