The Race to 100 MPG

PopSci.com ^ | 9/1/2006 | Billy Baker

[sgtbono2002]

Isnt this pretty much a turbine engine? Chrysler tried that once and failed.

[HuntsvilleTxVeteran]

"The diagram shows no connection between the compression and drive rotors, "

There is a direct connection!



http://www.starrotor.com/index.htm

[fireforeffect]

Yes, 40 years ago.

Do not make the same mistakes that the environmentalist make in using old data.

The M1 tank is turbine powered (yes it is not very fuel efficient, 80 ton vehicles seldom are) as are several modern types of war ships.

The problem with turbines is that they use X amount of fuel per hour. Whether they are moving or not. (NOTE: You can burn more than X amount of fuel to increase power or even add on a secondary combustion chamber and use even more fuel but you always use a rather large minimum amount) Also they generate a lot of waste heat.

The problem with the Chrysler turbine was durability, the engine did not last long. A car engine usually last about 3000 hours before a major rebuild(diesels can go 10,000+), but a turbine requires major maintenance every few 100 hours.

The materials to make turbines that can withstand the high heat are also expensive.

Where this engine might have use is in a turbine-electric drive system. This turbine drives a generator which drives an electric motor. Batteries are used for high discharge situations.

[mysterio]

That's awesome.

[FastCoyote]

"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.

[Charles Martel]

Okay, I see it now (had to click the image to see the animation). I had it turned around... the drive rotor is actually the portion that takes combustion energy and turns it into rotation.

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.

[FastCoyote]

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.

[RightWhale]

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.

[bmwcyle]

Or overcome gravity.

[Red Badger]

Tunnels straight thru the earth with 4 quadrant mag lev rails.........

[RightWhale]

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%

[lmailbvmbipfwedu]

Winkle, winkle, little wankle. Whats all of those RPMs you'll crankle.

[getsoutalive]

Honda has a diesel Accord that can reach 90+mpg.....

http://www.carpages.co.uk/honda/honda_diesel_sets_new_world_records_12_05_04.asp

[thackney]

but a turbine requires major maintenance every few 100 hours

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.

[Richard-SIA]

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.

[sgtbono2002]

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.

[Jackson Brown]

One of the problems that Turbine engines had was low end torque was very poor.

I often thought if they had an electric motor to get it up to speed, the turbine could take over/"join in"...and there is NO reason the turbine couldn't supply the charging of batteries. I thought this in the 70s well before they had the battery charging tied to the wheels and braking.

[sgtbono2002]

Makes sense to me. perhaps a small engine could provide electric power and get good mileage.

[avg_freeper]

"thermodynamically you want cold/dense air coming in."

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.

[avg_freeper]

"You'd end up with the same problem, one hell of a lot of heat."

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.