Wankel-Electric Hybrid?

My guess is that you would get more bang for your buck from a small diesel paired to an electric motor.

In a proper hybrid, the engine does not need flexibility, so I see no advantage on working to increase flexibility (rpm and load range). So, yes, in a sense a hybrid does make a poor flexibility engine useful. If the rotary can provide a better specific power (hp per weight) then it is a candidate, but it should also have good efficiency to start with, or else proping it up with hybrid mode seems like a bandaid rather than a good idea.

" snipped-for-privacy@yahoo.com" wrote in news: snipped-for-privacy@g14g2000cwa.googlegroups.com:

Go to

to see the next actuall usable version of a rotary eng. now in protype testing and see the future. lighter, more efficent, cheeper. KB

" snipped-for-privacy@yahoo.com" writes in article dated 27 Sep 2005

02:28:22 -0700:

Wankel has higher emissions and lower gas mileage. Those are exactly the problems that the hybrid concept aims to solve. So a Wankel-hybrid would be better than a plain old Wankel but not as good as a piston-hybrid.

Your light-fuel comment seems to apply equally well to piston-hybrids.

The main advantage of the Wankel is its higher power-to-weight ratio, which would not come through in a hybrid because power and weight depend more on the size and type of battery than on the combustion engine.

-- spud_demon -at- thundermaker.net The above may not (yet) represent the opinions of my employer.

Wankels have only 2 advantages: smaller size and weight and cheaper production (far fewer parts). Their hydrocarbon emissions are inherently higher because of the large surface area/volume of the combustion chamber.

There is no reason to do a wankel based hybrid; unless, there is something about a wankel that makes it desirable.

You left out that a wankel is smaller than a comparable piston engine, with no reciprocating masses and fewer parts.

These might be reasons to go with a wankel, except that gas turbines are even smaller and have even less parts. The abysmal part-load performance of a gas turbine are solved by making it part of a hybrid that never runs the turbine at less than full rated power.

Hi,

I hear what you're saying, but turbines don't like to stop and start frequently, from my understanding., and you know that's going to be a requirement for normal driving applications.

What I've also heard is that turbines also run hot and very noisily, and are considered to be fuel-guzzlers. Yet I've never quite understood why they're considered to be fuel-guzzlers if they're supposed to have relatively higher Carnot efficiency. I'd also think that modern advances in insulation would make the high temperatures of the turbine less dangerous to deal with.

Is there any way to design a turbine that can have multiple optimal power ratings? Or could a turbine merely be switched on to recharge a battery/supercap that had dropped below 20% of its charge?

Is the Wankel perhaps the best possible compromise between the reciprocating piston engine and the turbine? I'd suggested the Wankel because it seems to cater to the opposite end that an electric motor excels at. The electric motor seems good for high-torque acceleration in the low-velocity range ("low-gear"), while the wankel seems more specialized for the lower-torque higher-rpm range ("high-gear").

Comments?

Hi,

I've read about this Randcam for a number of years now, and I guess I'm wondering why hasn't it taken off yet? What are the shortcomings of the Randcam? With its use of diesel, it seems to have better compression ratio than most wankels, although I wonder if this is at the expense of rpm-cieling.

I also remember reading about the Dynacam, which features a circular arrangement of reciprocating pistons, and a sinusoidal cam. Again, I haven't heard much happening from that either, and I'm not sure what its drawbacks are.

Gee, it's hard to believe that no further significant improvements are possible in engine design, with all the advances in CAD, materials, and even electronic valves.

Actually, then would it be possible/useful to literally fuse a turbine and electric motor together onto the same shaft, as a single integrated apparatus?

Both roughly have the same geometry, with the shaft inside the cylindrical casing, and requiring tight tolerances for smooth rotation.

Would this be feasible, and would there be any benefit to this?

Exactly what is happening inside the partially-loaded/throttled-down turbine to make it less efficient? Lower compression ratio?

That higher surface area to volume ratio is also one of the reasons for lower fuel efficiency. At least, that is the case for any non-adiabatic Wankel, and I haven't heard of an adiabatic one yet.

Almost all GTs run with much excess air to hold down turbine temperature. Even with our best materials for turbine blades, they cannot run at flame temp. Now, the Carnot efficiency is dependent on using a high temp. Very expensive commercial and military engines get their high efficiency by running very hot (high TIT). So low efficiency and high temps do not go together. Yes, good insulation solves the high surface temps of GTs.

I believe a good metallurgist or materials expert who can come up with a good material for turbine blades that allows very high temp, but yet, easy, low cost fabrication, can achieve fame and fortune. People have been trying for over half a century. I'd like to have a nickel for all the press releases that have been issued in last half century by some person or company who has claimed to have solved the problem.

While turbines do not like wide operating range, this is also true of throttled gasoline engines, so in both cases this is a good reason to use with hybrid setup.

Many of those "inventions" are based on a myth that since the connecting rod isn't perpendicular to the crank throw there is a loss of efficiency.

The big breaktrough still to be made is the adiabatic engine where the combustion chamber and cylinder walls are uncooled and allowed to reach average temperature of combustion gases. This needs new materials and especially new lubricants. Petroleum oils coke at these temperatures.

Since approximately one third of energy in fuel goes out exhaust in enthalpy of exhaust gases, one third goes into cooling system, leaving one third for useful work, an uncooled engine can be an enormous boost, almost doubling efficiency.

Don Stauffer wrote in news:Ufx_e.4$Be5.209 @news.uswest.net:

connecting

efficiency.

The bigest impediment to adopting a new technoligy is almost due to the need to retool. The industry has a enormous inerita effect that will eventually be overcome when one of these invensions is shown to be too efficient and supperior to ignore. KB

There's a step missing there somewhere. Not removing the heat cannot automagically convert the heat to work.

15-30 years ago, Mercedes said their turbine concept car would get 70 MPG on the freeway, 17-18 MPG city.

Regards,

Bill Ward

>

" snipped-for-privacy@yahoo.com" wrote in news: snipped-for-privacy@z14g2000cwz.googlegroups.com:

The generator would have to be capable of turning at a turbine's typically high shaft speed and the output, if AC, would be at a very high frequency. This can complicate the electronic design, but is doable.

It would have the advantage of eliminating a reduction gear box.

--Damon

The biggest reason for going to a direct drive turbine (unlikely, but possible) is that the generator also becomes very small. Roughly speaking, for a given power, the product of length times radius times frequency will be constant across all possible AC machines. Losses go up with frequency, but if a 1000Hz generator can be economical, the turbine speed would be 60,000 rpm, not far out of line for an automotive turbine engine. A combination of battery power and stored compressor bleed air would make for reasonably fast startup.

There is no complication in the electrical design, the problem is that at a higher frequency (power kept constant) more waste heat has to be extracted from a smaller machine.

Actually, this is one reason the steam turbine was invented. People were having to GEAR UP the output of reciprocating steam engines driving commercial generators. Steam turbines turned faster, allowing higher frequency AC without gearing up.