NEW! And revolutionary VAWT .

[wdyasq]

I came across this:

http://pacwind.net/

According to their claims, it makes 10kW at 28mph wind. For comparison, a 4m diameter HVAT is about 5% larger and about 25% of that output using realistic numbers.

I am glad to see Betz law finally getting shredded. There is a new day dawning in America and it is being lead by the VAWT.

I believe Pac-Wind will do for small wind-turbines what GM did for the diesel in America.

Ron

[bob golding]

hey ron, someone steal your horse? did you sell it to woof? i think we should be told.

[wdyasq]

bob,

I just don't know.

It seems scoop has my signature picture hidden. I had traded the Horse for a combine a few daze ago. Now, scoop has absconded with my combine!

Ron

[Nando]

ONE MUST REMEMBER that no wind mill will be able to HARVEST more energy than the wind can have at any time.

BETZ still is the KING of the Wind for many more centuries.

Nando

[TomW]

Ron;

Scoop only adds the .sig line to comments not stories, if thats what you mean by hidden.

T

[wooferhound]

You can beat the Betz limit if you buy some of that stuff on eBay

[Tritium]

An OU wind turbine?

Thurmond

[whiskey]

Where is Dougie Salesman when you need him?

"I have solved the energy crisis".

I digress, and agreed with Ron, what ever next

Whiskey

[dinges]

I am happy too that we finally got rid of that pessimist Betz. He has done too much damage to the wind industry, suppressing creative new ideas that could have solved our energy problems long ago.

We don't need any Betz and the likes of him.

What we need is more people who can think outside of the box. Like Pons and Fleischmann

But I do think you need to do a little more research and reading: I have never heard of a 'HVAT'. Or is it -because- of all that research that you know what a HVAT is and I don't ?

[vawtman]

Ron

 Betz isnt being shredded by the delta 2 turbine your thinking of but its right at it though.

[dinges]

Power available from the wind:

P = .5 * rho * A * v^3 * Cp * Ng

P = 10.000 W (their "rated value")

rho = 1.225 kg/m^3  (assuming standard atmosphere)

A = 12 m^2 (FULL frontal area...)

v = 12.4 m/s (28 mph, their "rated value")

Cp= coefficient of performance (should be < Betz=0.59)

Ng = generator efficiency; set to Ng=1 here

With these figures, solving for Cp, I get Cp=0.71)

Which means they get 71% of the energy of the wind from what's actually available.

So they beat Betz.

Now, this Cp was calculated using a frontal area of 12 m^2, assuming that the entire frontal (projected) area of the turbine generates power. Which it doesn't. I think half of the area is more closer to it, but I know too little of VAWTs to make a better guess. Smaller area means their (implicitly) claimed Cp gets even higher.

This was assuming that Ng, generator efficiency, was 1 (100%). I usually calculate my gennies for Ng = 0.70-0.75

If one would take these corrections in account, they would achieve overunity.

They either deserve a Nobel prize for physics or prosecution for fraud/misleading advertising.

I don't think they'll get either though.

Not only that, I notice two different diameters for their 'delta-II':

In this file it says dia = 158"(4 m) (http://pacwind.net/download-pdf/Delta_II7-23-07.pdf)

In here, it says dia = 96" (http://pacwind.net/):

"Physical Specifications:

Cage Height 120 inches

Cage Diameter 96 inches"

(I originally calculated using the 96" value and arrived at a Cp=1.15 instead of .71, wondering where my error was as I verified the calculations. Seems they give two entirely different diameters for the same product in different places).

Whatever way, even calculated 'in their advantage', they beat Betz. Depending on some other (realistic) assumptions, they even achieve overunity.

But I'm not even sure which data is the right one for their product. 96" diameter ? 158 " ?

Caveat emptor.

[vawtman]

Peter heres a little calculator that i play with.

http://users.xplornet.com/~rmanzer/windmill/hrotor_calculator.html

 I believe Reg used Paul Gipes figures for it.

 It doesnt facter in solidity or anything but you can see the max possible for different turbines.

[dinges]

If I've made an error in my calculations or assumptions, I'd like to hear it.

Apples and oranges.

Your calculator uses average windspeed as input, along with Rayleigh distribution to guesstimate annual average power output. It's a very different calculation from what I've been doing, which is basically determining maximum output power available from the wind.

I wouldn't use it for what you use it for: estimating max. possible for different turbines. I don't like the Rayleigh distribution thrown into this, for that sort of calculation. I'd use the equation I've used for that.

Whenever using someone else's data, equations, calculators, etc. it's important to know what the underlying assumptions are and what the goal is of the calculation.

If you want to know average power output, or total power output, over a year, your calculator (having as input avg. windspeed with Rayleigh weighting) seems ok. For calculating max. power output of a turbine, or trying to calculate efficiency of a generator, I'd use my method.

You just gave a wonderful illustration of why I dislike all those online calculators and graphs. They usually don't show their goal, how-to-use, assumptions, underlying equations, etc. (yours shows its equations though, which is already a major step forward from many calculators).

But all this is just fiddling in the margin as long as we don't know whether the turbine is 96" or 158" in diameter...

[vawtman]

I was just trying to show what would be the actual limit for the swept area.

 In reality who cares.

 High solidity in winds less than that would do better.A betz beater vawt probably wouldnt start at winds less than that 28 mph unless helped.

 Just thoughts

 Mark

[dinges]

"I was just trying to show what would be the actual limit for the swept area."

I know. And you are wrong

The actual limit for the swept area is shown in my calculation. 'your' calculator throws in a fudge factor, the Rayleigh distribution, that is totally irrelevant for determining maximum instantenuous power of a wind turbine.

As to who cares. Hm. Suppose we weren't talking about windgennies but about cars. Does your car have a maximum speed of 220 km/hr as advertised, or 130 km/hr in reality? Would I care? Not if it were your car, I would if it were mine.

Someone once sold me a 20 W PV panel that in reality was a 10 W panel (with MPPT; without MPPT it's just 7 W). I care.

"A betz beater vawt probably wouldnt start at winds less than that 28 mph unless helped."

Easy now... Please read again what you wrote.

1. Betz beaters don't exist; you seem to assume they do.
   
2. Betz, IF it could be beaten, could just as well be beaten at low windspeeds as at high ones. But it can't.
   

[CmeBREW]

Yes, I also am impressed--they are doing some good things. How they work, I have NO idea.  

Here is more info:

http://pacwind.remnet.com/index.html

Good pictures too.

[CmeBREW]

I also liked the Jay Leno installation video of that windmill, below. The blades must be 18" wide or more. Looks like the old 'giant arrow' shape thats been tried countless times since the beginning of windmills. They must have fine tuned it aerodynamically. Think I'm going to try the old giant arrow myself. Couldn't do any worse than my last endeavor.

http://www.popularmechanics.com/automotive/jay_leno_garage/4216780.html?series=11

[wdyasq]

If you didn't catch the sarcasm please, try again. It is my opinion false advertising is detrimental to the entire industry. As Peter said:

"If one would take these corrections in account, they would achieve overunity.

They either deserve a Nobel prize for physics or prosecution for fraud/misleading advertising."

When, not if, folks buy these and tell others of their 'good fortune', of being fleeced, honest folks will have a problem. It will become impossible for companies who do produce 'honest' products will not be able to sell them.  

If just 10% of the producers of products make bad products, that product type will become unable to finance, insure or sell the used machines. This means your used mill will be thought of as junk. Ordinances will be passed to, "Protect the public" and it will be illegal to erect such a device in (name location here).

Ron

[thefinis]

It is a shame that so many of the wind turbine builders make such outrageous claims. It is this marketing area/claims that I think causes some of the real/workable turbine builders to decide to fudge on their figures too just because real figures don't look near as good up against the advertised claims from many of the sellers.

If it sounds too good to be true it usually is.

Finis

[electrondady1]

the "betz limit"

"As formulated by German Physicist Albert Betz in 1919, 59% of the available energy in the wind can extracted. No wind turbine has come close to the Betz limit, most are in the 25- 30% efficiency range."

i think it's important to realize we are all at the begining of a new era .

one in which the production of energy by individuals will be common place

it's unfortunate that at this stage there is so much missinformation.

not much we can do about it except point it out when we see it.

cudos to ron

hollywood seems like they want to climb on board. maybe they can feel less guilt about there consumpion.

its ok ,it  might speed up the transition.

one way or another the transition will take place.

 as a species we have no choice

[CmeBREW]

Sorry, I did miss the Sarcasm. I'm not too bright. I know their figures are obviously way too high, but at least they gave the power charts unlike most. Anyone who gets one can call them a liar. Almost everyone exaggerates the numbers for marketing reasons. I hate that fact also. People need to be more educated with facts instead of bull. Those are mainly torque machines, so I also don't think they come close to BEtz. But even if they get half the power they profess, It would still be a pretty usable machine.

[Tritium]

from this link description of their alternator:

http://remnet.com/WindEnergy/page5.html

They indicate 9 coils per phase, 3 groups of coils (three phase),delta connected.

36 positive negative pairs of magnets on 2 rotors. (is this 18 or 36 magnets per rotor)?

How do you obtain a three phase arrangement from these numbers of coils and magnets?

They also claim 12V charging at 2meters per second wind speed.

I just don't believe their claims are real world numbers.

Thurmond

[finnsawyer]

27 coils 36 magnets satisfies the 3:4 ratio.  It seems they have 36 magnets on each rotor with a north pole magnet on one rotor facing a south pole magnet on the other rotor.

[finnsawyer]

We've been around on this Betz limit thing before.  We all know that the air flow speeds up when the air flows around an object, and the faster moving air is capable of producing more power per unit of frontal area.  It is quite possible that structural items necessary to the construction of the VAWT might produce a sufficient speed up in the air to beat Betz relative to the undisturbed incident air flow.  For instance, placing a substantial cylindrical core in the mill might speed up the flow across the foils to such an extent that the Betz Limit is actually exceeded when the power output is compared with the theoretical power input from the undisturbed flow across the VAWT's area assuming 100% solidity.  You may have noticed that these people do manufacture a 500 watt unit that has a large cylindrical core.

You may not like this way of looking at it, but this mirrors reality.  The builders of any type of mill are going to compare the power output of the mill with the power available in the undisturbed air flow.  I believe there have been other claims that VAWTs can exceed the Betz Limit.  The idea that speeding up the flow can some how gain one more power than the incident air has may be a tough one to swallow, but there are mathematical solutions for fluid flow around a sphere and cylinder that bear this out.  You can check that out for yourself.

[Tritium]

Well it would help if I could add or multiply this morning. 3 times 9 is 27 not 18 as I  had it in my mind for some reason. Easy to see with the correct numbers. LOL.

Thurmond

[DanB]

Yes-  it seems way over the top.  The machine sweeps about 80 square feet - it seems similar in my mind to claiming that a 10' diameter HAWT is a 10KW machine @28 mph.  All of their power graphs seem quite optimistic/impossible to me.

It doesn't speak well for the credibility of a company that otherwise seems to be doing somewhat neat stuff.  Be nice if they could come out with a solid product and have it stand on it's own without such unrealistic hype.  Stuff like that bugs me...

[dinges]

GeoM,

Of all people (I understand you have a technical higher education) I thought at least you would be familiar with a concept known as 'system boundaries'. An important one in this respect; what is a system, where does it start and where does it end.

I have seen remarks by you on this board before where you claim that hills, large buildings, etc. speeds up the air that a windmill sees. Which it can.

However, to claim that this 'beats Betz' is nonsense; for a proper analysis you would have to take the larger, artificial frontal area of the windmill (which is in effect being largened by the hills/buildings/extra ring on the windmill) into account. Or the higher airspeed that the windmill sees at its frontal area.

By creatively setting your system boundaries you can indeed achieve 'overunity'. Within your (badly defined) system. But last time I checked there was still this thing called entropy.

I don't like Betz's limit, and I don't like the limit of the speed of light either. But what I like or don't like is entirely irrelevant.

But anyway, I'll pose another challenge to you: not only to build your radical new generator design, but also to build a Betz-beating windmill. Be a sport and take up the challenge.

Regards,

Peter.

[Tritium]

I just e-mailed PacWind and ask them If they would like to enter this discussion here.

Thurmond

[vawtman]

Boy that would be cool if they would.Very few understand the potential of these unless built.

 Thanks Thurmond

 Mark

[finnsawyer]

You correctly invoked the effect of hills on the wind flow.  You seem incapable or unwilling to go beyond what you already know or think you know.  There is an interesting phenomenon that shows up around here, which you may never see where you live.  We get upwards of three feet of snow on the ground in the woods.  There will appear around the trees a saucer shaped depression that extends out about one radius from the tree.  Now, this is not due to the sun, which never shines on the north side of the tree in the winter.  It must be due to speed up of the air as it goes around the tree.  This speed up, which is twice the incident air speed, means there is available eight times the energy next to the tree trunk to scoop out the snow.  Of course, the effect decreases both away from the tree and with depth in the snow, so it is limited in scope.  Nor does nature seem to feel that this violates any thermodynamic laws.  The important thing is that the wind is doing more work as a result of the speed up than it would do with no speed up of the air.  After all, the air flow doesn't remove all the snow everywhere.  If the air does more work in that case, then the effect can be put to use by proper design.  Nature does what it does and you would do well to pay attention.

One note here.  The depression scales up with the diameter of the tree, which is consistent with the theory for fluid flow around a cylinder.    

[dinges]

I have little doubt that the effect that you observe (snow depression around trees) is real. I have strong doubts about your interpretation of it, that it means you can extract more energy out of it, of beating Betz.

Let's see; an imaginary cylinder of air, containing a certain amount of energy, all of a sudden can do more work as it passes a tree?

Where does the extra energy come from ?

I have learnt, in my thermodynamics, aerodynamics and aircraft instrumentation classes, that the amount of energy in a given amount of air stays the same, no matter whether one compresses it, speeds it up or slows it down (with e.g. a venturi), etc. The Total Energy (potential energy and kinetic energy, or, in this case, static pressuse p (p = m*g*h) and 'stuw' pressure (sorry, only know the correct Dutch word for it) q=1/2* rho*v^2) in a given amount of air stay constant, unless one adds energy (by means of a fan, for example) or removes energy (by means of a windturbine, for example).

(The TE=constant rule assumes that there's no friction/viscosity with air; there is in real life, so the friction heats up the air as it loses kinetic energy. But hey, guess what, as it loses kinetic energy, it gains heat energy. Could it be that the TE , when it also includes thermal energy, stays the same after all, even including friction effects ? OMG. I guess the thermodynamic laws may be true after all ?!)

Air flowing through venturis or around objects does NOT majically gain extra energy (we need energy to do work). Even worse, due to friction it LOSES energy!

But we're getting far removed from the original topic: the Cp of that VAWT. If I have made an error in my calculations or assumptions I would have liked to know. I'm assuming that, since no one corrected them, they were correct.

I suggest you contact PacWind with your observed phenomenon. They may be interested in incorporating the effect in their future Delta-III product.

This is my last comment on the topic.

Kudos to Ron, he did it again...

[finnsawyer]

"I have learnt, in my thermodynamics, aerodynamics and aircraft instrumentation classes, that the amount of energy in a given amount of air stays the same, no matter whether one compresses it, speeds it up or slows it down (with e.g. a venturi), etc"

That is a strange statement since everyone knows that if you speed up a mass it has more kinetic energy.  You have contradicted your own statement about the effect of hills in the air flow.  Similarly, if you compress a gas its internal energy increases.  Of course, we are not talking about Carnot Cycles here.  In fact, the accepted model for the air's behavior is the same as that for water, at least for air speeds less than 200 mph.

There appeared on this site at one time a posting about a power generating facility on a German river which utilized the constricting of part of the river's flow rather than a dam.  The claim was that that was at least as effective as damming the river, due to the large increase in kinetic energy that resulted, that velocity cubed term.  So, presumably, one could do similar things relative to the air flow.  My claim is that a (simple) analysis of the two cases that I presented reinforce that conclusion.  And I have presented in general terms the procedure to follow.  What I don't understand is why someone like yourself, who claims to know all the fundamentals, chooses to ignore a simple challenge.  Is it because it wasn't presented by a Professor in a class room?

 

[whatsnext]

GeoM, What I don't don't understand is why you don't build a simple test mill incorporating your ideas and show us all how well it work. If the air or water speeds up due to some restriction then the energy required to cause that increase in velocity has to come from somewhere. So it isn't some sort of "free energy" that you can harvest. Once you put something in it's way to harvest anything you will be creating another restriction that will have an effect on on the air before it has a chance to reach your harvesting device.