Request for input on radically new turbine concept!

[Furcifer]

So, i think that numbers about efficiency are quite important here. Just reducing the unit cost is only a very short term benefit. Once the fuel and operating costs kick in, you have to consider these factors as well.

Greetings,

Chris

Efficiency has always been the drawback of using turbines. High output to weight ratio and reliability are the biggest reasons to consider them in applications. You wouldn't typically consider using a turbine where efficiency is your main consideration.

 

[Christian Klippel]

Efficiency has always been the drawback of using turbines. High output to weight ratio and reliability are the biggest reasons to consider them in applications. You wouldn't typically consider using a turbine where efficiency is your main consideration.

Right. But i was referring to a comparison of the efficiency of existing turbines to the proposed one. If the efficiency is considerably less, at a given output power, compared to an existing unit, the savings in material/production cost gets eaten up very quickly by the cost for fuel. In such a case i simply don't see any benefit to already existing units.

Sure, the size factor may be important, but then again, it should be compared to existing units, i think. Like, i could produce paper bags that cost only half the price of the others. Sure, the thickness of the paper would be only one quarter of that used by regular bags. So you can put much less goods in it, requiring you to buy twice as much bags at least. So, while a single bag would be cheaper then, there is no net gain for the consumer.

Greetings,

Chris

 

[tsig]

Thanks for the reply mhaze. One follow up question question for now; did you read all of the explanation on the PDF File?.


I believe if you read the PDF linked above you'll see what is being proposed here is quite different from what Tesla had in mind.



This was only released this morning 3bod. Perhaps GE will be interested.



Actually, I'm one of the very few still a tiny bit skeptical about going ddwfttw casebro, and am looking forward to the NALSA test in a couple months. But I can tell you this topic was discussed for over 3k replies here on JREF, and only 2 people-humber and Christoph-remained unconvinced. Ask sol invictus or Dan_O about it, or look for yourself where it began here. -- http://www.internationalskeptics.com/forums/showthread.php?t=128483

Wrong

 

[Furcifer]

Right. But i was referring to a comparison of the efficiency of existing turbines to the proposed one. If the efficiency is considerably less, at a given output power, compared to an existing unit, the savings in material/production cost gets eaten up very quickly by the cost for fuel. In such a case i simply don't see any benefit to already existing units.

Sure, the size factor may be important, but then again, it should be compared to existing units, i think. Like, i could produce paper bags that cost only half the price of the others. Sure, the thickness of the paper would be only one quarter of that used by regular bags. So you can put much less goods in it, requiring you to buy twice as much bags at least. So, while a single bag would be cheaper then, there is no net gain for the consumer.

Greetings,

Chris

They function like any other turbine using the Brayton cycle so they have the same theoretical efficiencies.

 

[sol invictus]

IF recursive prophet actually can sail down wind faster than the wind, I suppose the same technology (perpetual motion) could be used to built a fuel-less turbine.

How is a wind powered vehicle "perpetual motion"? It only works when there's wind, and wind is powered by the sun - which will eventually go out.

If you think it's impossible to beat the wind to a downwind point for some mechanical reason, well... you're wrong. Land and ice sailors do it routinely, and fast sailboats can do it too.

 

[recursive prophet]

@tsig-Yo T-indeed I was wrong and I apologize. I think I forgot about you still being active here as most of your posts I read on ddwfttw were at TR. Sorry. You should come back. Harold has dropped out and humber could use some support. Big weekend in Cartville. I suspect they aren't ready for prime time.

Any thoughts on the XT? The presentation needs work, but the concept has a lot of promise IMHO.

@3bod: Thanks for the explanation. Brayton cycles are one of many things I need to read up on. Did you ever show the PDF to the engineers at your job? I would really appreciate any critiques, and as I've mentioned you can actually contact the inventor via the number on the website.

@Ol Sol Invictus; been a while good sir. I've been meaning to send you a PM and ask you to take a look at this. You're far better at finding flaws in new concepts than most, and I'd love to read your analysis of this one. (Oh,and if a NALSA video is posted I'll PM you a link. I'm betting it ain't gonna happen. Too many drive/stability problems; not enough time.

 

[Furcifer]

I didn't have a chance yet. Probably next week. I did bring it up with a friend and told him to check it out. He mentioned the same thing I had, that GT turbines are typically running at higher temps for maximum efficiency. The alloys they use in the turbines today are some of the most exotic metals on earth because of this. We don't evem have the rods to weld them. The manufacturer typically sends you an unmarked rod at your request, if they can be repaired at all. The idea of lower temperature turbine with less exotic metal seems very appealing. I'm sure the guys will be interested but highly skeptical. Or maybe not, I'll let you know.

 

[MRC_Hans]

Have downloaded pdf. Will read and comment. Later.

Hans

 

[MRC_Hans]

OK, I have read through it. I must admit that my scam indicator went right into red.

The last few lines are a heavy scam indicator:

XpoTurbine technologies are proprietary and the property of John Popovich.


The technologies have patents pending status and are available for licensing and partnering.

Developers kits are available.

That is usually what people write when trying to scam investment money.

When we look at the product, I haven't gone enough into it to have an opinion on whether the principle is viable, but many of the features you list are mutually exclusive, for example high power density and ability to work in a low temperature differential: The principle may be adaptable to both, but not in the same device.

Hans

 

[Furcifer]

When we look at the product, I haven't gone enough into it to have an opinion on whether the principle is viable, but many of the features you list are mutually exclusive, for example high power density and ability to work in a low temperature differential: The principle may be adaptable to both, but not in the same device.
Hans

Power density is an inherent property of turbines, usually offset by their inefficiency. Relative to another prime mover in the same application ie; a low temperature differential, a turbine is still going to have a higher power density.
In this case we're talking about comparing the Brayton cycle and say the Otto or Rankin cycle.

 

[MRC_Hans]

Mmm, I think that turbines have a far from linear response to flow speeds and hence pressure differentials. Whereas many primary movers are fairly linear, at least in a given range. So I don't think the density advantage for turbines is true for all ranges.

Anyhow, I was challenging the sweeping statements given in the text, and pointing out that these devices will have a lot of compromizes, like any other device.

If you list only the strong sides of many different optimisations, you may list the same advantages for many other devices, but that is dishonest.

Hans

 

[recursive prophet]

@3bod and Hans: Thanks for your comments. As I mentioned in the OP the PDF file posted on the website is a work in progress, and all analysis as to it's strengths and weaknesses is appreciated and helpful.

The inventor's top priority right now is completion of some drawings and a video of one of his prototypes running. The explanation of it's advantages definitely needs work, and to be shortened. I will pass on that potential disadvantages should also be noted though; good point Hans.

 

[MRC_Hans]

@3bod and Hans: Thanks for your comments. As I mentioned in the OP the PDF file posted on the website is a work in progress, and all analysis as to it's strengths and weaknesses is appreciated and helpful.

The inventor's top priority right now is completion of some drawings and a video of one of his prototypes running. The explanation of it's advantages definitely needs work, and to be shortened. I will pass on that potential disadvantages should also be noted though; good point Hans.

Thx, however, my main point, which I may not have expressed explicitly, is:

**** the pretty presentations and drawings. Make some prototypes and show that they work. That will impress the world. Anyone can make pretty presentations.

Hans

 

[ben m]

The inventor's top priority right now is completion of some drawings and a video of one of his prototypes running. The explanation of it's advantages definitely needs work, and to be shortened. I will pass on that potential disadvantages should also be noted though; good point Hans.

Hello RP,

As for me, I'd say that I don't need "explanation of its advantages"---I need

a) evidence that this design actually has the advantages the inventor says that it has. A prototype experiment is a good start, but unlike MRC I'd actually be *more* convinced by a competent CFD numerical simulation. The numerical model allows you to see the scaling laws---"will this be better or worse if I scale down by a factor 2"---and it allows you to separate the fundamental behavior of the gas from the specific compromises you made in building the prototype. (It's very easy to build a garage-workshop-quality prototype, find that it coughs along at 2% efficiency, and say, "Look it works! Pay no attention to the performance, I blame that on the bearings and the inlet piping and etc. etc. I bet the polished-up version will be 30% efficient." That's not convincing. Of course if the garage-workshop-quality results are impressive on their own---as MRC Hans says, that speaks for itself!)

b) Comparison of this design's properties to the state of the art. You don't just want to say, "Here is the efficiency-vs-power curve, here is the weight, here is the estimated cost per unit, here is the fuel cost per joule of output, here is the speed at no load" (or whatever is on the list of things one asks about a turbine). Then pick three competing technologies for the same application---piston engines, microturbines, fuel cells, batteries, whatever---and line up all of those properties in a matrix. Be scrupulously honest on this; if you've got a hoped-for number that you aren't sure you can achieve, say so and put both an optimistic and a pessimistic value into your table.

 

[recursive prophet]

Thanks again for the input guys. John does read this thread, and I'm sure some of your suggestions here will be helpful. As I mentioned before though, his first priority right now is getting some good pictures and and videos of some of the prototypes in action.

As I am unable to adequately answer many of the questions put forth here, I will not respond further until the inventor has time to provide more guidance on the issues already raised, and hopefully some YT videos of the XpoTurbine in action.

Again thanks to all who have taken the time to read and comment on this idea. Your time was much appreciated and I hope others do likewise. Just understand it may take a while before you get any significant feedback from John Popovich. I will say I've known him for nearly 40 years, and have been to his incredible shop just off the ocean in Solana Beach slightly north of Del Mar. He has made his living through licencing agreements of his patents for many years now, and I've known highly regarded experts in various fields who have been quite impressed with his past work. This said, whether or not the XT is really the breakthrough he believes it to be is sadly beyond my capacity to evaluate. Hopefully that will change in the near future.

 

[Furcifer]

The design seems to be like a pinwheel, as the fluid expands through the passages like a typical reaction turbine it passes through the disc and then exhausts. If I'm correct, multistage designs would use and axial arrangement.
I'd be cautious of the porousity claims. Even natural gas has its impurities, it seems the design would be prone to clogging. Especially with biofuels or other less pure combustibles.
Just an observation.