Naked Science Forum
On the Lighter Side => That CAN'T be true! => Topic started by: McQueen on 14/12/2013 07:32:20
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Removing this post as it is counterproductive.
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The video clip from "Bang goes the Theory" shows a vacuum cleaner consuming 1kW of electricity while doing no useful work.
It is beyond extrapolation to imagine a vacuum pump which can generate useful work while consuming no electricity.
It still looks like another Perpetual Motion Machine to me - see discussion at http://www.thenakedscientists.com/forum/index.php?topic=49077.0.
I'm afraid that I would have to recommend that people see a working model before investing any money in it.
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.. I would like to hear your views on the presentation.
At first glance it looks like yet another perpetual motion (http://en.wikipedia.org/wiki/Perpetual_motion) scheme [:(]
There has to be a source of energy* somewhere to exploit for it to work, (energy cannot be created (http://en.wikipedia.org/wiki/First_law_of_thermodynamics)),
I cannot see where that source of energy is in your presentation.
[ * the Newcomen atmospheric engine (http://en.wikipedia.org/wiki/Newcomen_atmospheric_engine) you mention has a fire as a source of energy , where is your source of energy ?]
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It is quite amazing that the weight of the hundreds of miles of air above us cannot be thought of as a source of energy, surely it is as tangible a force as solar or wind ?
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It is quite amazing that the weight of the hundreds of miles of air above us cannot be thought of as a source of energy, surely it is as tangible a force as solar or wind ?
It's not amazing at all. You can't use a magnet as a source of energy either.
If you can't see that this is an energy-from-nowhere scheme, look at it another way. If you use energy to do work, it's no longer available in its original form. Suppose these machines worked, and you covered the surface of the Earth with them to use the energy of all that weight of air, converting it to various forms of work and heat. What would you expect to happen - would you use up all that weight so the air became weightless? would you use up Earth's gravity so everything weighed less? would we all float off into space? [:o]
If the weight of the atmosphere could be a source of energy, why not try it at the bottom of the ocean where there's even more pressure? [::)]
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It is quite amazing that the weight of the hundreds of miles of air above us cannot be thought of as a source of energy, surely it is as tangible a force as solar or wind ?
The only angle I can think of how the [changing] weight of the atmosphere can be a source of energy is using changes in atmospheric pressure caused by weather, like this clock ... http://en.wikipedia.org/wiki/Cox%27s_timepiece
That device generates the same amount of power as an electric clock battery , so not sufficient to light a home.
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If the weight of the atmosphere could be a source of energy, why not try it at the bottom of the ocean where there's even more pressure? [::)]
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As for this gem it is totally out of this world: The only angle I can think of how the [changing] weight of the atmosphere can be a source of energy is using changes in atmospheric pressure caused by weather, like this clock ... http://en.wikipedia.org/wiki/Cox%27s_timepiece
Here the changing weight of the atmosphere presumably refers to barometric pressure ! And this from a member who has made above 6500 posts !
Maybe you can enlighten me as to the difference between the pressure due to the weight of the atmosphere and "barometric pressure".
Maybe obfuscation with terminology serves your purposes but that is antithetical to the goals of this forum.
Clocks powered by changes in atmospheric pressure, aka barometric pressure, have been running for over a century, so unlike your proposed scheme, have been proven to work.
Your idea is an oscillating system which employs dynamos, electric motors and air-tight high-friction components ...
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Dynamos and electric motors are only 70-90% efficient so each cycle you will loose around a quarter of the energy in your oscillating system, and that's before you attempt to extract energy from it to do useful work. And then you have to include the frictional losses in the air-tight seals. Your idea is a non-starter.
BTW can you give me the email of the person who contributed $140 to your project, I have some swamp land prime real estate I could sell them [:)].
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For more than a hundred years the weight of the atmosphere was used as a source of energy in the Newcomen engine and that surely is the point here.
The Newcomen Engine (http://en.wikipedia.org/wiki/Newcomen_atmospheric_engine) has energy input (fire & steam), and alternates between steam pressure and vacuum from condensation.
The question here is will this design work as postulated and the answer is that it will.
Your system will not produce any results without any external energy source. The energy to pull the vacuum will be exactly the same as that supplied by the atmospheric pressure (minus system losses).
As RD mentioned, you could use periodic variations in barometric pressure (a few mm Hg), to supply some energy. Or, perhaps if it is and elevator, force the users to walk up the stairs, then descend using the elevator, thus with a net gain of energy. (not counting calories burnt climbing the stairs).
With no external energy source added to the system, the system as designed will consume energy due to friction, and would stop rather than generating energy.
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I am grateful that you have at least raised a practical objection: The Newcomen Engine has energy input (fire & steam), and alternates between steam pressure and vacuum from condensation.
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… and electricity to run the multistage turbine comes from an alternator … The energy to run the alternator comes from the kinetic energy of a descending counterweight. Thus if the counterweight weighs 150 Kg and is situated at a height of 10m its kinetic energy as it descends will be 14.7 KJ , more than enough energy to run the alternator and therefore the vacuum turbine.
An alternator which are typically only around 70% efficient , driving an electric motor in a vacuum pump which is about 90% efficient. That's around 25% loss of energy from each cycle of your oscillating system, which allegedly has a period of "2.5 seconds". The total energy in this oscillating system reducing by 25% of every 2.5 seconds. Any oscillations in your apparatus will die away within less than a minute, even before you extract any useful energy from the system. [ If the frictional losses of air-tight seals is included then I doubt it will perform even one cycle ].
Once the gravitational potential energy of the 150Kg at 10m has been used, either in combating friction / electrical resistance / or useful work , your apparatus will grind to a halt as you have no other source of energy.
Cuckoo clocks are powered by a similar system : a pair of linked weights where one falls ...
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but at some point someone has to lift the fallen weight back up, putting energy into the system, to keep the clock going.
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Right RD,
This seems to be a little better Your idea is an oscillating system which employs dynamos, electric motors and air-tight high-friction components ...
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… PTFE has a frictional co-efficient that at 0.6 is less than the friction produced by ice on ice.
… systems work at 70% - 80% efficiency …
Let’s say you could achieve the impossible : frictionless apparatus with magic electrical devices which are 100% percent efficient, then you could create a perpetual motion machine, (which in reality is impossible). (http://en.wikipedia.org/wiki/Perpetual_motion)
Once set in motion this hypothetical perpetual motion machine would run forever without applying any additional energy.
However this hypothetical machine would begin to run down as soon as you extract energy from it to do work.
At best you can only get the same amount of energy out of such a system that was in it initially , ( in reality less ). Machines cannot make energy : energy cannot be created (http://en.wikipedia.org/wiki/First_law_of_thermodynamics), only converted from one form into another. Other than the gravitational potential energy of your 150Kg weight your machine does not have a source of energy, once that energy is used game-over.
… systems work at 70% - 80% efficiency …
Ignoring friction your machine looses approximately 25% of the total energy every cycle via electrical losses, so even ignoring frictional losses within a minute it will run down to a stop.
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If you have a perfect counterbalance, then you have minimal energy raising and lowering the main component & counterbalance, and likewise, no energy recovered.
You can simplify your system to a horizontal double ended piston with a pump between them.
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Even with the best seal and least resistance, you still loose energy when using the pump to push the piston back and forth.
If you wish to extract energy from any system, then you need to define some kind of an energy gradient. A static field doesn't give you an energy gradient.
Place a barbell on a table. The table exerts an upward force on the barbell. The barbell exerts an equal downward force on the table. As long as the barbell is sitting on the the table, no work is being performed, and no energy is being transformed. Knock the barbell off the table, and it will fall to the floor, as a one time burst of energy. Then if you wish it to be back up onto the table, you have to put a reciprocal amount of energy back in, with no net gain.
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For more than a hundred years the weight of the atmosphere was used as a source of energy in the Newcomen engine and that surely is the point here.
Ah, no. The Newcomen engine (http://en.wikipedia.org/wiki/Newcomen_atmospheric_engine) was a condensing steam engine, and was powered by a fire (coal or wood) that heated water to produce steam.
Magnetism is a force but has no energy of its own, exactly the same thing applies to atmospheric pressure, unless it has a vacuum to work against it does not constitute a form of energy, so what are you quibbling about.
Not so much quibbling as trying to find a way to explain to you why this idea fails. You seem to overlook how this vacuum will be maintained if you can take energy out of the system without putting energy into it. As Dr Johnson said, "Sir, I have found you an argument; but I am not obliged to find you an understanding."
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The Newcomen engine , as you had pointed out worked, why under the same conditions won’t my system work ?
The difference is that the Newcomen engine had energy input from a heat source. Your system has no energy input. Energy output equals energy input minus inevitable losses.
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Let’s say you could achieve the impossible : frictionless apparatus with magic electrical devices which are 100% percent efficient, then you could create a perpetual motion machine, (which in reality is impossible).
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The main problem with your similie of a pump is that the same source of energy is being used, naturally there is no energy gradient and that is the reason perpetual motion machines don't work. In the case of 'Home Grid' two forces are utilised.
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Apparently the editors object to this post on the grounds that it is self promotion and ‘unproved’ science and will soon delete it. Well and good!
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Instead of sinking huge quantities of capital into a fullsize device, why not build a scale model to convince your potential backers that you can set aside the laws of physics?
Then nobody will delete your post, or even take issue with it.
Engineering is about realising our dreams, so instead of "imagining a 150 kg counterweight..." why not just build a little Meccano model with a 1.5 kg weight?
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The problem is one of energy!
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Crap. You can generate a reasonable vacuum by modifying a bicycle pump.
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Good on you!
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So you are in effect admitting that the ‘vacuum elevator’ is theoretically impossible.
No such claim, pneumatic tube delivery systems (http://en.wikipedia.org/wiki/Pneumatic_tube) do work but have an external energy supply : you've said yourself the ‘vacuum elevator’ uses a "small power input (3 KW motor)" (http://www.thenakedscientists.com/forum/index.php?topic=49798.msg426682#msg426682), (a 3kW generator operating continuously could heat and light a small home in the UK in winter). Your 150Kg falling weight could only supply 3kW for a few seconds then its potential energy is used up and the machine will stop.
... RD for instance insists that there is no free energy, then how the hell did people sail around the world ?
Sailing is via wind power : harnessing the kinetic energy of moving air. Your proposed device doesn't use wind power : it has no source of energy other than the potential energy of the weight raised to a height.
Some people are obtuse.
At last we agree on something.
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... my design of a rotary pulse jet engine ( http://conceptengine.tripod.com/rpj/flywheel_assisted_rotary_pulse_j.htm
We at Green Initiative have designed a completely new type of engine ...
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http://conceptengine.tripod.com/rpj/flywheel_assisted_rotary_pulse_j.htm
Well not "completely new" : the basic design is at least 2000 years old ... https://en.wikipedia.org/wiki/Aeolipile
BTW what is the pressure on the “compressed air/fuel mixture” due to centrifugal force (https://en.wikipedia.org/wiki/Centripetal_acceleration#Circular_motion) as this mixture travels out toward the nozzles when the device is rotating at say 5000rpm ? , ( NB: fuel-air mixtures will explode when compressed sufficiently , as in a Diesel engine (https://en.wikipedia.org/wiki/Diesel_engine) )
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The engine uses pre-compressed air from a tank that is topped up from time to time, a pressure of 125psi would be equivalent to a compression ratio of about 0:1.
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... a pressure of 125psi ...
Looks like you didn't follow my link about centripetal acceleration (https://en.wikipedia.org/wiki/Centripetal_acceleration#Circular_motion) which the fuel-air mixture is going to experience as it travels outward towards the nozzles.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2Fforum%2Findex.php%3Faction%3Ddlattach%3Btopic%3D49798.0%3Battach%3D18311%3Bimage&hash=d19bc39c71fcb881615502c4c8eda0ce)
Rotating at say 5000 rpm, ( 524 radians per second ), with a radius of say 10cm,
then the force on the fuel-air mixture at the nozzle will be about 27458 Newtons , ( that's 2800 times the force of gravity ). If the fuel-air line has a crossection of say 1cm2 then that force causes a pressure of almost 4000 psi , (not "125psi").
So as your device spins-up the fuel-air mixture in the fuel-line in the rotor will increasingly be compressed by centripetal-force, soon reaching the point at which it explodes blowing the fuel-line apart.
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The principle has been used to power helicopter rotors. Not a wild success, but interesting.
The idea of centrifugal compression ignition does however make it the more fascinating. Suppose we introduce a combustible mixture at the hub, and put a flame trap (as per Humphrey Davy) somewhere near the tip. Now start the rotor spinning. The centrifugal force will suck the mixture in at the hub, and the compression force will ignite it at the tip. Not a pulse jet but a continuous rocket.
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You have a $140 donation.
Kick in $1000 of your own money if you wish.
And build your system in miniature.
Look at engine parts.
A piston engine (or piston vacuum pump) has a vertical cylinder, with a piston that moves up and down. The connecting rod and crankshaft gives you good vertical to rotary energy conversion, and usually already has a counterbalance built in. Anyway, if you can't get it to work on small scale, then scaling it up certainly won't do much.
There are lots of vacuum pumps available, from small lab grade pumps to large industrial pumps.
I've never actually seen a vacuum elevator. Do you know where one is located that you can inspect and play with? What is the Duty Cycle? I'd assume that they likely have a large vacuum tank. Evacuate the tank, and you can go up once or twice reasonably quickly. Try to go up and down 10 times in rapid succession, and it may move slower than molasses.... unless it has an awfully big vacuum pump.
Although, I suppose I could imagine a 1HP electric winch connected to an elevator. With good gearing, it should be able to lift the elevator in 30 seconds to a minute. Theoretically a vacuum pump should be able to do the same.
Anyway, all of your examples of what does work. Steam Engine, Sailboat, Windmill, etc all have an external power source, and energy differential. Without it, there is no energy captured. The bane of the existence of all sailboats are days with no wind. One can literally sit in one place and go nowhere.