As close to perpetual motion as we might ever get.

[WhatIfMachine]

I am here today to propose a "perpetual" device. it doesn't make energy, its perpetual in the sense that more energy (specificly electricity) is received that the amount used. Have your heard of the Dyson bladeless fan? well ill post a link for you to read, but ill put all the basic information you need to know here with my proposal that works with the laws of physics.

http://electronics.howstuffworks.com/gadgets/other-gadgets/dyson-bladeless-fan1.htm - note: there is a page before that, but its about the advertisement, absolutely no relavent facts are on that page.

The Dyson fan isn't really bladeless, inside the pedestal there is indeed a fan. "A motor rotates nine asymmetrically-aligned blades to pull air into the device. According to Dyson, these blades can pull in up to 5.28 gallons (about 20 liters) of air per second. " The air then proceeds to flow out of a ramp inside the circle. But that's not what you feel when the fluid flow of wind blows. You feel more than the 20 liters because

"It boils down to physics. While it's true that the atmosphere is gaseous, gases obey the physical laws of fluid dynamics. As air flows through the slits in the tube and out through the front of the fan, air behind the fan is drawn through the tube as well. This is called inducement. The flowing air pushed by the motor induces the air behind the fan to follow.

Air surrounding the edges of the fan will also begin to flow in the direction of the breeze. This process is called entrainment. Through inducement and entrainment, Dyson claims the Air Multiplier increases the output of airflow by 15 times the amount it takes in through the pedestal's motor."

Meaning 1/15 of the normal amount of electricity used in normal fans can influence the same breeze. So what if this fan was facing a wind turbine? (miniature of course, unless the fan where to be enlarged for this purpose) Couldn't it make more electricity than used?

 

[russ_watters]

No. Airflow energy comes from a combination of pressure and flow rate. The Dyson blower is very high pressure and very low flow. The induced air is high flow and virtually no pressure. The net result is a fan that is LESS energy efficient than a typical fan due to the losses involved in the high pressure/velocity flow.

 

[WhatIfMachine]

but doesn't inducement and entrainment cause both the area and preasure to increase? If the fan is putting out about 15 times as much as as it takes in, that means that either the flow or preasure is increased, either way the turbine spins more than it would without the multplication.

 

[cjl]

Not exactly. It's true that the flow rate is vastly increased, but the pressure drops off. The end result is a high-volume, low-pressure flow that actually contains less energy than the initial low-volume, high-pressure flow.

 

[WhatIfMachine]

hm, well I think it was a good thought. Maybe if I wait long enough someone will come up with a reason for it to work and an argument will insue, but so far it seems I picked out a dud idea.

 

[Academic]

Dud ideas are the easiest to pick out, unfortunately.

 

[WhatIfMachine]

haha, aint that the truth? of course I guess its my fault for thinking I of all people could make the closest thing to perpetual motion as will probably ever be made.

 

[alxm]

hm, well I think it was a good thought.

Sorry, but it was an abysmal thought. A machine which puts out more energy than it consumes (when the whole system is viewed) is considered a perpetuum mobile.

Energy is conserved. It cannot be created out of nothing.

 

[WhatIfMachine]

um, the Dyson fan isn't perpetual :P and the plan as a whole isn't perpetual, it just gets more electricity than used.

 

[alxm]

http://en.wikipedia.org/wiki/Perpetual_motion"

Perpetual motion describes hypothetical machines that once started operate or produce useful work indefinitely. This definition has been expanded to include any machine that produces more work or energy than it consumes, whether or not it can operate indefinitely.

You can't get more energy than you consume. The difference has to come from somewhere, because energy is conserved. This is the first law of thermodynamics.

 

[russ_watters]

It is a very common misunderstanding of people looking for perpetual motion to not know what "perpetual motion" means. And though you may not like it, conservation of energy has been exquisitely well proven, so the equations that describe how things like induction/the Venturi effect work all use conservation of energy as the framework on which the equations are built. Ie, the Bernoulli equation is a conservation of energy statement that can be used to relate high pressure, low velocity flow with high velocity, low pressure flow.

 

[WhatIfMachine]

it was a typo, the Dyson machine isn't perpetual, I don't mean the device as a whole is perpetual, I mean if you replace the word "energy" with "electricity" then its (not really) perpetual in the since that it puts out more energy that it consumes.

we might not be able to achieve perpetual motion, but that doesn't mean we can't build devices that put our more of a specific type of energy than it takes in. My Dyson proposal gets it extra energy from inducement and entrainment, but I am no expert in... well anything really so, as cjl said, "...the flow rate is vastly increased, but the pressure drops off." could be a possibility and I accept that.

 

[russ_watters]

You're not getting it: what you are saying is practically word for word the definition of a perpetual motion machine.

 

[WhatIfMachine]

I don't think you get it, that's my point. thus the title of this thread, "As close to perpetual motion as we might ever get."

I know perpetual motion is impossible, as you cannot create or destroy energy, but this isn't creating anything. it mearly puts out more ELECTRICITY that is consumes. If I just said energy, yes that would be perpetual, but no, the idea of the device is to put out more electricity.

 

[Q_Goest]

The Dyson fan apparently uses the same principal as eductors (sometimes called jet pumps or ejectors). They take a high pressure fluid, accelerate it, then use the kinetic energy of the flow stream to entrain additional fluid. So the energy put into accelerating the motive stream is transferred to the air that is being entrained. The primary difference between the Dyson fan and an eductor is the eductor entrains air inside the device whereas the Dyson fan entrains air outside the device. Otherwise, the basic principal is the same.
http://en.wikipedia.org/wiki/Eductor-jet_pump

If you looked at the overall isentropic efficiency of such a device, you'd find they are typically lower than a device that accelerates all the fluid without entrainment. That's because the compression of the motive air already results in losses, and additional losses occur due to the turbulence between the motive flow and entrained flow. So although it *sounds* like the Dyson fan is more efficient than a conventional fan, the overall process is likely much less efficient than a conventional fan.

 

[WhatIfMachine]

ah well, I guess there is nothing left to do but let the thread die. Thank you everyone for the detailed explinations

 

[cjl]

I don't think you get it, that's my point. thus the title of this thread, "As close to perpetual motion as we might ever get."

I know perpetual motion is impossible, as you cannot create or destroy energy, but this isn't creating anything. it mearly puts out more ELECTRICITY that is consumes. If I just said energy, yes that would be perpetual, but no, the idea of the device is to put out more electricity.

Since the only kind of energy that the Dyson fan consumes is electrical, it would be a perpetual motion machine if it was able to put out more electrical energy (through any mechanism) than it consumes. This is because if you managed to hook up a generator in such a way as to generate more energy than the fan consumes, you could hook the fan up to its own output, which could then run perpetually (ignoring things like the motor burning out) without any outside input of energy.

 

[Xtensity]

Since the only kind of energy that the Dyson fan consumes is electrical, it would be a perpetual motion machine if it was able to put out more electrical energy (through any mechanism) than it consumes. This is because if you managed to hook up a generator in such a way as to generate more energy than the fan consumes, you could hook the fan up to its own output, which could then run perpetually (ignoring things like the motor burning out) without any outside input of energy.

Not perpetually... but for a very long time perhaps. Some energy is lost through kinetic friction...simply with air particles touching other physical constructs(such as the fan frame)

 

[cjl]

Not perpetually... but for a very long time perhaps. Some energy is lost through kinetic friction...simply with air particles touching other physical constructs(such as the fan frame)

If it genuinely put out more electrical energy than it took in, it would run perpetually. You're right that in reality, there are losses, but they would cause the output power to be less than the input.

 

[RonL]

If one can really flex their thinking, it is the same as a steam or air jet ejector, instead of a high pressure moving out of a small orifice at the center, this device changes size of the orifice and pressure of the air.

 

[Xtensity]

If it genuinely put out more electrical energy than it took in, it would run perpetually. You're right that in reality, there are losses, but they would cause the output power to be less than the input.

Yes but overtime the output power would slow(due to environmental factors) and eventually it would go under 100% efficiency as a device.

 

[russ_watters]

Yes but overtime the output power would slow(due to environmental factors) and eventually it would go under 100% efficiency as a device.

Again, the definition of a perpetual motion machine is a machine that outputs more power than is input into it. Period. There is nothing in the definition about degredation over time. If a device ever, even for 2 seconds, outputs more power than is input, it is a perpetual motion machine. By definition!

See:

The hypothetical continuous operation of an isolated mechanical device or other closed system without a sustaining energy source.

http://www.answers.com/topic/perpetual-motion

Many people see the words "perpetual motion" and think that "perpetual" requires the literal operation of a device forever. It doesn't. In fact, just having motion forever is not a violation of the laws of physics but is a fundamental principle embodied in Newton's 1st law.

 

[Xtensity]

Again, the definition of a perpetual motion machine is a machine that outputs more power than is input into it. Period. There is nothing in the definition about degredation over time. If a device ever, even for 2 seconds, outputs more power than is input, it is a perpetual motion machine. By definition!

Another more specific definition from google definition

The term perpetual motion, taken literally, refers to movement that goes on forever. However, the term more commonly refers to any device or system that perpetually (indefinitely) produces more energy than it consumes, resulting in a net output of energy for indefinite time. ...
en.wikipedia.org/wiki/Perpetual_machine

It is not perpetual because it would not run for an indefinite amount of time. Sure it would output more energy than it consumes for a period of time but overtime the efficiency would decrease meaning it would not run indefinitely, meaning its not a true perpetual machine. By definition!

Almost like you said, even for 2 seconds, outputs more power than is input, would NOT be a perpetual machine unless it could go on doing so forever.

Perpetual means never ending or never changing, not an efficiency over 100%. It would only be a perpetual machine if the efficiency could be maintained over 100 and not decline, but with this device, it can only have 100%+ efficient for a limited amount of time, because the efficiency declines.

edit: I posted this after you edited your previous post, but by definition, it isn't perpetual.

 

[russ_watters]

I don't think you get it, that's my point. thus the title of this thread, "As close to perpetual motion as we might ever get."

I do get it: What you are saying is wrong and you don't see it and we're trying to help. What you have proposed is not close to perpetual motion, it is perpetual motion.

. it mearly puts out more ELECTRICITY that is consumes. If I just said energy, yes that would be perpetual, but no, the idea of the device is to put out more electricity.

"electricity" is electrical energy. A device that puts out more energy than it consumes is - not "is close to" a perpetual motion mathine. By definition.

 

[russ_watters]

The Dyson fan apparently uses the same principal as eductors (sometimes called jet pumps or ejectors). They take a high pressure fluid, accelerate it, then use the kinetic energy of the flow stream to entrain additional fluid. So the energy put into accelerating the motive stream is transferred to the air that is being entrained. The primary difference between the Dyson fan and an eductor is the eductor entrains air inside the device whereas the Dyson fan entrains air outside the device. Otherwise, the basic principal is the same.
http://en.wikipedia.org/wiki/Eductor-jet_pump

AKA, the venturi effect: http://en.wikipedia.org/wiki/Venturi_effect

 

[pallidin]

Ok, let's see if we all agree that "For a closed system, more total energy cannot be extracted from a system than what is in the system"

Everyone OK, with that? Good.

 

[Academic]

I think calling it perpetual motion is a bit of a misnomer because that implies the device should go on forever. Even though its called 'perpetual motion', there is more to it than that. A more descriptive label might be over unity, or something like that. That encompasses even 2 seconds of more output than input, which is just as much a violation as perpetual motion.

 

[pallidin]

This sort of reminds me of a scenario where one doesn't look at the TOTAL picture:
A 9-year old hooks up a 12-volt battery to a step-up transformer that outputs 120 volts.
The step-up transformer receives no power other than from the battery.

"Look daddy, I have free energy!"
"No you don't, son"
"Yes I do daddy! I can prove it! The meter on the battery says 12 volts and the meter on the output of the transformer says 120 volts!
"No, son, your not looking at the TOTAL picture. Your 12-volt battery is 12 volts at 1 amp. The output of the transformer is 120 volts BUT ONLY 1/10th amp. The POWER is the same, son, minus some loss"

"Ok, daddy, darn! So I was only looking at part of the picture which made me think I invented free energy?"
"That's right, son"

 

[RonL]

About generated electricity, It might help to understand a simple truth, it does not matter if it is a motor turning a generator or a single unit acting as both. It makes no difference how small you slice the amperage or how short the cycle duration.

A generator supplies power exactly equal to the demand and a motor demands power exactly equal to the load, there is no way to balance the time/loss between supply and demand.
The other question is which needs to come first ?

I have not been able to get either one to tell a lie.

Ron

 

[RonL]

AKA, the venturi effect: http://en.wikipedia.org/wiki/Venturi_effect

Gadds I missed his post

 

[mugaliens]

Goest, you nailed it.

 

[Freshtictac]

Thermodynamics hommie,
it's all about transferability. If you make a device to utilize less energy then it's output you demonstrate a greater function of thermodynamics. The closest thing to this is a magnetic generator. Not perpetual but defiantly long lasting motion. I believe the Dyson fan could be evolved into a tesla turbo prop similar to your initial description. take out the turbine, poke some holes and smack some N/S alternating magnets in said holes.

 

[WhatIfMachine]

most of you seem to miss the point, the Dyson machine is a real thing, so its not perpetual. however, inducement and entrainment are what I thought would cause the surrounding air to fallow the flow of what the small fan does produce. since the breeze is "multiplied" I figured that if a tube was placed far away enough to allow inducement and entrainment but close enough to catch the breeze, and a cone inside the tube blew the wind straight into the turbine's blades, there would be more kinetic energy turning the turbine than electric energy turning the fan.


@Freshtictac

Honestly, I have no idea what you just said, but it sounds like you know what your doing, so hey, you got my vote... now if only this where an election...

 

[Redbelly98]

... the breeze is "multiplied" ...

To have a discussion about this, you need to be clear just what property of the breeze is being multiplied. Pressure? Flow rate? Either (but not both simultaneously) are possible. Energy or power? Not possible.

 

[pallidin]

Right, to have both simultaneously increase is what is required, and this cannot be done without an increase in input electricity greater than what the turbine could produce.
So no, your design will not, cannot nor ever will work as you describe.