| Author | Message | ||
     Anonymous |
wave energy | ||
| Zoch |
Ideas with no description, believe it or not, do not help. How bout that? Try explaining instead of posting two word ideas. | ||
| Matthew |
doesnt anyone delete these....? | ||
| Simon Quellen Field (Sfield) |
No, nobody edits them, nobody corrects spelling, and so far, I have not had to delete anything. People are being remarkably civil. Some people may not realize that what they say here will last a long time. What looks like nonsense to one person, might make sense to someone else. The idea of using ocean waves as a perpetual motion device is not that far fetched. Indeed, taking the term "perpetual" in a more figurative sense, as "until the parts wear out", it makes more sense than machines that claim to create energy. This thread may yet generate an interesting discussion. | ||
| Matthew |
Yes that might be a good use of the large amounts of open water everywhere.... For once someone might welcome a hurricane as an energy boost. If you made rafts about a half foot thick and had them ride high in the water you could have basins that catch the water from waves rolling over the rafts. Then you could have motors that generate energy as the water trickles down back into the ocean. | ||
| Anonymous |
Pretty much, tides are created by gravitation pull of the moon. Here's an experiment; fill a water bottle half full of sand, and another half full of water. Take both water bottles (not necessarily at the same time) and spin them in the air. The sand one will continue to spin till it hits the ground, but the water one will spin once or twice then stop. What I mean to say is... energy is wasted by the tides, and eventually the moon, or earth is going to stop spinning and crash into one another, maybe in a couple billion years. | ||
| Simon Quellen Field (Sfield) |
If we are talking about the "until the parts wear out" type of perpetual, then the tides and waves will be around long after our device that runs off of them has crumbled into dust. Anything longer than my lifetime is usually "perpetual" enough for me. My kids can build their own... ;-) | ||
| Charlie (Charlie) New member Username: Charlie Post Number: 1 Registered: 6-2006 |
Piezoelectric generators could be used to harness waves. Have an array of piezo-crystals (crystals that produce a voltage when compressed - Rochelle salt, Quartz, PZT, etc.) in multiple layers that are in a floating plastic chamber above the water near the beaches. A circular disc/hammer could be attached on a spring inside the chamber just above the crystals so that when a wave moves the chamber up and down the disc strikes the crystals producing voltage. Have a rectifier bridge that converts the AC signal of the crystals to a DC signal. Then, store the generated electrical energy in a battery or capacitor bank. If you wanted to get fancy, you could determine if waves have an overall frequency (how often one wave will follow another – a coastal wave train.) If there was a frequency to it, you could tune the spring in the chamber to be at the same frequency of the coastal wave train. This would set up what’s called resonance in the mechanical spring inside the chamber (this means the disc/hammer would rhythmically go up and down striking the crystals due to high point – compression – of the spring matching a high point in a wave), which would produce more energy overall. Food for thought I suppose... someone mentioned having ideas to go with waves; so there ya go! | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1252 Registered: 12-2004 |
Unfortunately, piezoelectric generators are not very efficient. A magnet rolling back and forth inside a coil would generate more energy from the waves that the piezoelectric generator. Putting an anchor on a buoy, and using the force on the anchor chain to turn a generator would also work, or using a hollow buoy with a hole in it where air can rush in and out past a turbine is another way people are doing it. | ||
| Charlie (Charlie) Junior Member Username: Charlie Post Number: 6 Registered: 6-2006 |
The magnet in a coil is a good idea but has a few disadvantages, you would be limited with the amount of continuous power you could generate with a coil and magnet since power obtained is derived from the strength of the magnet, the turns of the coil, and (more importantly) the speed of oscillation of the magnet inside the coil (the main factor of power generation in electric generators). Waves trains tend to follow each other on the coast every 5 seconds (assuming). The frequency of the moving magnet would be 0.2Hz (1 up/down translation every 5 seconds). Household electric generators require speeds of around 1000 rpm’s or greater which means the magnets inside (assuming a permanent magnet generator) move past the coil around 16Hz (or 16 times in one second). That’s 80 times faster than a wave. A magnet/coil generator would need to have much stronger magnets (large rare earth magnets maybe) and/or larger coils to make up the difference - which is going to make them rather large. However, they would be cheaper to make and more efficient. You are very correct in that Piezo-electric generators are not efficient. However, the materials used in such generators can be made very lightweight and compact. We have a PZT thin film cantilever at work that is only about 3 inches long, half an inch wide, and as thin as a piece of paper. It produces about 1.8 volts when deflected about 2 inches. Its enough to light up a little low voltage light-bulb. You could probably fit quite a few of these (well over 1000) in a volume of about a cubic foot. If you compared two generators, one using magnet/coils and the other piezoelectrics, you would find that the piezoelectric (IF designed right) could output more energy even though it’s less efficient. It would have a greater mass to energy ratio. To produce adequate continuous power with the piezo, you would need to lower the electrical resistance of device and increase the current (PZT has a high electrical resistance). To do this you would form groups of cantilever arrays that are in electrical series – targeted at a desired voltage, and parallel these groups so to increase your current and reduce your resistance. It is also worth noting that the PZT cantilevers can be reduced to even smaller sizes to allow more energy collection. There are limits to this of course since the power density of the PZT reduces with size. One advantage to piezoelectric generators is that they produce no back torque (back EMF); a problem that arises in magnet/coil generators (i.e. electric generators) when current begins to flow in the coil and creates a magnetic field that apposes the moving magnet. This is a destructive plague that has haunted all electric generators since they were invented over 200 years ago and one of the main sources of loss in a generator. If back torque did not exist, then we would have something very close to perpetual motion. Hehe, however reality being what it is, back EMF does exist and is just something we have to live with I suppose. Really though, it would probably be alot easier to just stick copper/zinc electrodes into the salt water and make a battery. And just clean off the electrodes every so often. Or use a wind generator, since I don't think I've ever been to a beach that didn't have a breeze. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1255 Registered: 12-2004 |
The idea that piezoelectric generators don't experience opposing forces is silly. The force that opposes the magnet moving in the coil is an effect of the work done to generate the current. It takes work to generate electricity -- you are converting mechanical energy to electrical energy, not creating electrical energy out of nothing. What you are thinking of as some unfortunate loss akin to friction is actually the work you are doing to move those electrons. The same work is needed to make the piezoelectric generator move the electrons. You are pushing charges together and pulling them apart. That pushing and pulling is the mechanical energy that is being converted to electrical energy. Yes, if you could move electrons without doing work, you would have perpetual motion. But you can't. | ||
| Charlie (Charlie) Junior Member Username: Charlie Post Number: 10 Registered: 6-2006 |
Quote: "The force that opposes the magnet moving in the coil is an effect of the work done to generate the current." The requirement to generate electricity is not work, it is a changing magnetic field (V = I*N*d<flux>/dt). However, you MUST do work to change the magnetic field. These two concepts are coupled but very different. There are many different ways to change magnetic fields; all take energy, however some take smaller amounts of energy than others. Just like there are many different ways to harness the oceans wave power, they all use the energy, some will use it better than others. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 13 Registered: 6-2006 |
I need to make a correction to the above equation (V = I*N*d<flux>/dt) that "I" shouldn't be there. The correct equation is (V = N*dÖ/dt) or V = w*N*Ö*cos(wt) where Ö = the magnetic <flux> and w = radian frequency (2*pi*f). Sorry about that! | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1258 Registered: 12-2004 |
I stand by my original statement. It takes work to generate electricity. In a battery, work is done to move charges. In a coil, work is done to move charges. You are trying to split very fine hairs by saying that work is done to change a magnetic field, and then the magnetic field does work to move the electrons. Work is work. When you spin a generator with no load, it is easy to make it spin. When you short is out, it is difficult to make it spin. That difficulty is the work you have to do to generate the electricity. All generators share this feature. It is not some unfortunate loss that only electromagnetic generators have. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 14 Registered: 6-2006 |
You have a slight misconception here; work is not done by simply moving charge. Work in an electric circuit is done when the system has both moving charge along with potential energy. You may have 1000 amps worth of moving charge, however if there is no potential involved, no work is done. Likewise, if you produce 1000V of potential and no current, again no work is done. The equation for work in an electric circuit is W = q*int(E)dr where int(E) is the integral of the electric field (a potential field), q is the charge, and W is work. This very important equation translates to -- as a charge (q) moves (dr) under the influence of a potential gradient (E) work is done. There is no "work" function in Faraday's equation V = N*dÖ/dt. So I stand by my statement in that the only work being done is to change the magnetic field. Thereby, as you stated in an attempt prove me wrong, the magnetic field DOES in fact, convey that work to the circuit. The developed magnetic field in the coil is in the opposite direction as explained by Lorentz’s law, F = qv x B. where q is the charge, v is the velocity of the charge, and B is the magnetic field. Again, there is no work function associated with this equation - work is potential WITH moving charge. Lorentz’s law only describes the magnitude and direction of the force induced (i.e. how the potential energy will develop in the coil) which then dictates how the current will flow when work is done, which consequently produces a magnetic field in the opposite direction. This phenomenon of opposing field was derived first through experimentation; the exact reasons as of yet, cannot be explained. Believe it or not, most of the reasons for why electromagnetic interactions happen are not known. Much like gravity, these are basic phenomena we have come to accept through experimentation, but cannot fully explain. Why does a moving charge produce a magnetic field? Why does mass create gravitational effects? These are the questions we still grasp for. Indeed work is work, but where the work comes from is very important. The magnetic fields can be viewed as transmission lines for work to travel on, but the fields are not the source of the work. After all, a magnetic field is just that, a field. By itself it does no work, it is a force field - just force. Which is why a “perpetual motion machine” based on magnets alone is likely to never be possible. I would also like to draw your attention to another fact. When describing the losses in an electromagnetic generator, the back torque is clumped into the mechanical rotational losses. Core losses (from eddy currents) are also lumped into this category. They are different from electrical losses resulting from the resistance of the wire conductors. However, the total losses of the generation system are found by adding all these losses together. As for your statement regarding "All generators share this feature. It is not some unfortunate loss that only electromagnetic generators have." Counter torque (back EMF) is, in fact, an unfortunate loss that ONLY present electromagnetic generators share. Piezoelectric generators receive losses from physical friction and electrical resistance. Thermoelectric generators receive losses from improper heat transfer and electrical resistance. Neither produces back torque. I hope this has cleared some misconceptions you had; and please read carefully what I have written before you attempt to bash my statements. | ||
| Alex Roberts (Whoo_mythbusters) Senior Member Username: Whoo_mythbusters Post Number: 103 Registered: 9-2005 |
I tend to agree with Simon on this, if there is electricity moving in a wire or coil there has to be work there to move that electricity. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1259 Registered: 12-2004 |
You are again splitting hairs. Yes, a current of moving charges does not involve work. Until you change the current. To generate electricity, you must change a current from zero to something above zero, and that can't happen without a potential difference. You are arguing about the words and ignoring the concept. The force you feel resisting your efforts to spin a generator is mostly the cost of generating the electricity, unless your generator is grossly inefficient. It is not a loss like friction. A piezoelectric generator experiences the same force -- as you compress like charges in it together, or pull unlike charges apart, you feel the force. The work you do against that force is what generates the electricity, just like in any other generator. There is nothing magic about piezoelectricity. A magnetic field is just a relativistic effect of a moving charge. We have understood that since Einstein explained it. When you change your frame of reference, the electric fields and the magnetic field change, even though nothing about the system has changed. They are just two ways of looking at the same thing. Einstein also explained how matter distorts space, and causes gravitational effects. In both of these areas, theory preceded experimentation, and the experiments confirmed the theory. The same is happening with quantum theory. In many cases experiments happen first, and then theory has to be developed to explain the experiments. But the kind of experimentation that you are positing -- building a perpetual motion machine in order to disprove the laws of thermodynamics, has been fruitless. You are starting with the theory that all of the experiments that prove the laws of thermodynamics are correct have some flaw in them, but you don't know what the flaw is, you are just convinced that you can get something from nothing. Once you start generating free energy, I will be happy to buy it from you at that price. Until then, all we have is talk. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1260 Registered: 12-2004 |
Alex -- the first law of motion says that object at rest stay at rest, and objects in motion stay moving. It takes no work for something to move at a constant velocity, and indeed superconductors can sustain currents with no work. But generating the current in the first place takes work, which is where your intuitions are correct. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 16 Registered: 6-2006 |
Quote: "Yes, a current of moving charges does not involve work. Until you change the current." "But generating the current in the first place takes work, which is where your intuitions are correct." There is another misconception; no work must be done to change current. Charges may move without the presence of work. These effects are seen in both antenna theory and power transmission theory. If you tune an oscillating circuit such that the voltage standing wave ratio is set much greater than 1 (i.e. the system has a power factor of ZERO), then the power generated is reflected back. Current (movement of charge) and potential are indeed present in this situation, however their phase differences are 180 degrees out of phase. Therefore, the work done on the system is ZERO. Other than the work needed to overcome the friction in the generators, no electrical energy is transmitted. This is the same as the generator running idle with no load. This brings me back to my original point, that a magnetic field does not need work to be created. In presence of this reflective power, both magnetic and electric fields are produced yet no work is being done. I refuse to yield my point of view on this matter. These are not splitting hairs because common misunderstandings like these happen even among engineers and can cause improper utilization of electrical phenomena and annoying debates such as these. But debates like these are good (however annoying), because it strengths the knowledge of both parties. Always debate science laws, it is how good science is made! (Message edited by charlie on June 5, 2006) | ||
| Alex Roberts (Whoo_mythbusters) Senior Member Username: Whoo_mythbusters Post Number: 104 Registered: 9-2005 |
<exhales> | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1262 Registered: 12-2004 |
Is work being done when a pendulum swings? You have potential energy (the capacity to do work) when the pendulum is high, and kinetic energy (still capacity to do work) when the pendulum is at the bottom. Since the system has not lost any capacity to do work, work was probably not done. But again, like the case of a current flowing in a superconductor, work had to be done to get the oscillation started. This is simply another special case of current flowing until some work is done to change it. In the electrical oscillator, current flows and creates a magnetic field. As it does work to create that field, the energy in the current is used up, and the current diminishes, until it reaches zero. Now the field collapses, and this collapse generates a current in the wire. When the field has completely collapsed, doing work to generate a current, it has no energy left. The cycle continues. No net work has been done on the system, since energy has not been lost. (We are ignoring radiative and resistive losses for this discussion). But taking each part separately, the current has done work to generate the magnetic field, and then the magnetic field does work to generate the current. Each one has done work, as evidenced by it's lack of energy when it is done. It had the capacity to do work, and after doing the work, its capacity to do work is used up. The pendulum does work to accelerate up to some speed at the bottom of the swing. That kinetic energy does work to raise the pendulum up to the top. Again, no net work is done, but work is done in each half of the swing. It takes work to create a magnetic field. It takes work to create a current in a wire. No amount of toying with the semantics can get around the fact that energy is the capacity to do work, and that a change in energy implies that work has been done. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 17 Registered: 6-2006 |
Work is the activity involved with a force moving an object. Energy is the capacity for DOING work. Power is the rate of using energy. Yes you must do work to put energy into the system. However, how you store your energy has nothing to do with that work. You can store the energy as potential, or you can store it in kinetic. Work is only accomplished when the total energy of the system changes. The transition from one storage to the other is NOT work. Your pendulum - without a load - will not stop moving in a lossless environment after you give it energy. It will continue you swing back and forth forever. The energy you give the system will be stored in either potential or kinetic and will transition from one phase to the other 90 degrees apart. Work is not being done to transfer this energy from one phase to the other. The work has already been done to put the energy in the system. If work was being used to transfer between these phases, then your pendulum would never swing even in a lossless environment without a load. This same principle holds true with electricity as well. Let us first investigate how the pendulum works in an ideal lossless environment and NO load. Energy is put into the system. At the high point of the pendulum, the placed energy is stored in 100% potential. As it falls, the potential energy is converted into kinetic energy. Inbetween the highpoint and the low point, 50% of the energy is stored in kinetic, the other 50% is stored in potential. At the bottom, 100% of the energy is stored in kinetic, 0% in potential. Then, the pendulum begins to move up and the kinetic energy starts to reduce. Upon reaching the high point on the other side, 100% of the energy has returned to potential and 0% in kinetic. Work during these transitions is NOT being done. If it were, then the pendulum would never move. Simon says this however and he is correct. Now let us look at electricity. The exact same effect happens. The only difference between electricity and the pendulum is that we can't see the transitions of energy with our eyes. Electrical energy is stored in two forms, electric fields (potential) and magnetic fields (kinetic). Starting at the "high" point again, the energy placed into the system is stored in the electric field as potential. This energy begins to transition "down." At some point in the middle, 50% of the energy is stored as potential (the electric field) and the other 50% is stored as kinetic (magnetic field). At the "bottom" 100% of the energy is stored as kinetic (magnetic field). Like before, the kinetic energy will then transition to potential and "oscillate." The oscillation takes NO work, otherwise nothing would happen - the only work done is to place the energy into the system. This is where Simon is incorrect, since he claims that work is done and the current is used up in the magnetic field. In fact, the electrical energy is not used up and is at its maximum kinetic value. These are the misconceptions that arise when dealing with electricity. Voltage is NOT work or power, Current is NOT work or power. Voltage is electricity's version of potential energy, and current is electricity's version of kinetic energy. Work is not done to produce a magnetic field, neither is work done to produce an electric field. Work/Power is at a maximum when these two FORCES are together, in phase (i.e. the pendulum is falling yet the potential is not changing.) Going back to my previous statements, when a magnetic field is changed, work MUST be done to change it. Remember, the magnetic field is simply energy in the kinetic state. The work done to change the field puts energy into the system. The energy is transferred to the coil, which produces a potential energy in the wire. Remember how the electrical energy oscillated? (This by the way is known as a tank circuit, or an oscillator as Simon mentioned). Unfortunately, the potential develops in such a way that when a load is placed on the system, the current flow generates an opposing magnetic field. But why doesn't the energy oscillate back like in the tank circuit? This is because the load takes that energy and uses it, so you must do more work by changing the magnetic field, which places more energy in the system. You COULD make it oscillate by placing a capacitor (which is the electrical component that stores potential energy) in the place of the load. This would lead us into the realm of filters, Tesla coils, and radio transmitters/receivers. So this brings us to a very interesting topic. A magnetic field is electrical stored kinetic energy. This means that a permanent magnet is really an object that is storing electrical energy in the kinetic phase. Nothing too special about this (other than its wild when you think about kinetic energy in the pendulum sense) since it took work to put that energy there. However, look how long it takes a permanent magnet to demagnetize. Rare earth magnets can hold their field for greater than 13 years! That’s pretty impressive when you realize that most electrical potential storage devices can only hold the energy for maybe less than half that time. Another interesting thing about permanent magnets is that they fairly durable. Forcibly demagnetizing them takes large amounts of heat, slamming, or magnetic fields stronger than themselves, so they are pretty durable. Pretty interesting stuff! (Message edited by charlie on June 5, 2006) | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1264 Registered: 12-2004 |
You have some of the parts right. It takes work to raise the pendulum from the bottom to the top. You are lifting a weight. You are storing potential energy. Why do you think that work stops happening if you do something many times instead of once? It takes work to accelerate an object. The pendulum starts at zero velocity at the top of the swing, and accelerates to some velocity at the bottom. Work has been done. The total amount of energy in the pendulum remains the same as it swings, so no work has been done. The energy changes from potential to kinetic and back, but is not lost, so no work has been done. You say "the magnetic field is simply energy in the kinetic state". A magnetic field is not electrical stored kinetic energy. There is nothing kinetic about a stable magnetic field. It has potential energy, but the electrical energy that caused the field to be created has been converted into the potential energy in the magnetic field. It takes energy to create a magnetic field. That energy is stored in the field. If you make the field go away, you can get the energy back. Try this experiment: place a neodymium-iron-boron magnet in a coil. Attache the coil to a meter or oscilloscope. Heat the magnet to a temperature above its Curie point. The field will collapse, and the meter will show a current induced in the coil as the field collapses. But the whole point of this thread is to try to show you that it is not just an "unfortunate" side effect that the current flow generates a magnetic field that opposes the change you make to the system. That opposition is the work you are doing to make the change. And it happens in any generator, not just those made of coils and magnets. If you flex your piezoelectric element without a load, it is easier to flex than when you have it light a light bulb. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 18 Registered: 6-2006 |
First I would like to take back my comment on this conversation being annoying. In fact, this is a very good learning tool, I would like to thank Simon for his time. Now, lets break this discussion apart since I think we are saying the same thing on several topics. Topic 1: Work must be done to put energy into a system (whether its electrical or mechanical). We both agree on this. However, I feel we have two slightly different perspectives on the same thing and I feel we are both right. You refer to the work as still in the system, which will cause the transition from potential to kinetic and vice versa. This work stays in the system until it is used. My view is that the work is done and energy is in the system. This energy will not leave the system (in the ideal case of no losses) until it is used. While in this system, the energy undergoes different transitions between kinetic and potential and vice versa. -- We are saying the same thing but with slightly different viewpoints. I think this is probably due to my back ground in electrical engineering and Simon's background in (what I assume) is mechanical engineering (or atleast physical mechanics). I am not use to being able to see the energy transfer of my devices with my naked eye. To me these are the same things. Topic 2: A Magnetic field does/does not require work to be formed. Here is where we are in conflict. In a sense we are both right on this from a certain point of view. Simon's view is that you need to have "work" to generate the magnetic field in a coil or magnet. My point of view is that this work causes a chain of events that lead to the generation of the magnetic field in a coil - whether this work is used or not, a magnetic field can be produced. We are both correct, however I am placing more importance on the chain of events where Simon is condensing it. Looking more closely at these chain of events, the only requirement to induce electrical potential energy is the change in magnetic field. Unless you can show me where in the equation (V = N*dÖ/dt) other forms of energy would come from other than the work needed to change the field (dÖ/dt), I will not alter my view point. Once the field is altered, Lorentz's law explains how the potential energy will develop in the coil. When a load is placed on that coil, energy will flow and a counter field will be produced. Please don't interoperate this as a unfortunate chain of events, what I am trying to say is that this is what happens. You cannot alter these properties. In electrical generators, it is not the magnets that create the energy in the coil, its the work done spinning those magnets. Topic 3: A magnetic field is the electrical energy stored as kinetic energy. I probably should not have mentioned this. Simon is up to date with common physics beliefs in saying that the magnetic field is potential energy. However, from the research I am currently doing, I disagree with this description. I feel that magnetism is better explained as a kinetic energy phenomenon due to the fact that it is only present when charged species are in motion; whether in an electric circuit, an electric discharge, or the atomic domains of a ferrous metal - motion is present and thus kinetic. I will not disclose any more than this. You can therefore ignore my statements on magnetic fields being kinetic energy storage if you feel it is too outrageous a claim. Again thanks for your time Simon. | ||
| Charlie (Charlie) Member Username: Charlie Post Number: 19 Registered: 6-2006 |
Quote: "Heat the magnet to a temperature above its Curie point. The field will collapse, and the meter will show a current induced in the coil as the field collapses." I wanted to comment on this quote if it is ok. I mentioned this earlier, by heating the magnet you are causing the atoms to rub together causing friction. This friction re-randomizes the magnetic domains of the metal, which in turn destroys the field. Thus the field changes. As the field changes, voltage is induced into the coil. As you mentioned, this voltage should be readable on the oscilloscope. Current will only be produced in the coil if there is a load. But I know what you mean by this and it’s very correct. | ||
| anuj (Anuj2929) New member Username: Anuj2929 Post Number: 3 Registered: 6-2006 |
anybody... do you have some approx. idea on the energy consumed in superconducting magnet for the boil-off of nitrogen and replenishing the nitrogen bath --in dewar flask. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1337 Registered: 12-2004 |
That will depend on the dewar and the temperature of the surroundings. The greater the difference between the temperature inside and the temperature outside, the more heat transfer there will be. The greater the insulation of the dewar (including any opening and stopper) the less heat transfer there will be. Contact the manufacturer of the dewar for specifications. | ||
| anuj (Anuj2929) Junior Member Username: Anuj2929 Post Number: 4 Registered: 6-2006 |
simon, I checked many journals and found that supermagnet consume few mW of energy to generate mag field but they consume many watt of energy in cooling the coil. Is this true??? Do you know any site which can give an idea how supermagnet works along with some detail on consumption of energy in cooling the ciol. Do you know the smallest sized supermagnet evermade ?? | ||
| anuj (Anuj2929) Junior Member Username: Anuj2929 Post Number: 5 Registered: 6-2006 |
simon, As the energy losses in the superconducting coils are almost neglizible than why the energy is consumed in replenishing the nitrogen bath , we can make a very perfact insulatar cabin where this nitrogen can be kept with the coil. Not sure how it will sound to you ?? Thanks | ||
| anuj (Anuj2929) Junior Member Username: Anuj2929 Post Number: 6 Registered: 6-2006 |
Simon, Do you have an answer of my above question?? | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1357 Registered: 12-2004 |
What made you think that the current superconducting magnets aren't already using the best insulation available? Since high temperature superconductors can't handle the same currents as low temperature superconductors, most high power magnets use liquid helium. Liquid helium is more expensive, and is even harder to insulate, because it is colder, and it leaks easily. | ||
| anuj (Anuj2929) Junior Member Username: Anuj2929 Post Number: 7 Registered: 6-2006 |
Simon, help advising in brief.....what are the method by which superconducting coil can be cooled. If a low current is passed...than i think HTS can work fine. Can LN2 can be used for this purpose.. What is the difference between Nitrogen bath , boil-off of nitrogen and replenishing the nitrogen bath. What is cryocooler and how does this work. Can you suggest the best way of cooling the coils of SCM....where low energy is consumed in cooling unit?? Can you please suggest some links which can give some idea of these cooling unit and their working method. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1360 Registered: 12-2004 |
If you are going to use a low current, you don't need a superconductor. Why do people ask me to do their Google searches for them? | ||
| John Kondo (Smartypants) Member Username: Smartypants Post Number: 13 Registered: 4-2008 Posted From: 141.156.34.193 |
Flame warrrrrrr! charlie vs simon lol as for the wave energy, you know how when you're ridin' the wves on a tire tube you go up and down up and down (repeat as many times as necessary) right? well, the pistons in a car go up and down up and down (repeat as many times as necessary, AGAIN) right? i dont think i need to explain this anymore. all it is, is an engine without the spark plugs, camshaft, valves, and whatnot. and has holes in the sides of the tubes to keep the water level in the ocean, the same to the level in the cylinder. add a flywheel and a generator, and you have free power. |
