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A workable Hydrogen Fuel Cell?

Discussion in 'Environmental Discussion' started by klodhopper, Jul 29, 2008.

  1. qbee42

    qbee42 My other car is a boat

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    No, not a thought experiment, although she experiments with my thoughts.

    As for hysteresis, let me back up a bit. The notion of hysteresis is that some things lag or are retarded a bit when they change from positive to negative or the other way around. It's like friction when you ride your bicycle up a hill and then coast back down. You store up potential energy pedaling up the hill. When you coast back down the hill, you get most of that energy back, but not all of it, since some was lost to friction.

    A standard place for intentional hysteresis in a control loop is the dead band in your household thermostat. The dead band is the area where no change in control action occurs. Let's say you set your thermostat to 68°F and sit back to watch the action. For the sake of argument, let's say the temperature inside the house is 60°F. The furnace kicks on, adding heat, and the temperature starts to rise. When the temperature hits 68°F you expect the furnace to turn off, but surprisingly it keeps going until 70°F, at which point it turns off. The house starts to cool. At 68°F you expect the heat to come back on, but it doesn't until the temperature drops to 66°F. You observe that this cycle continues, so apparently it wasn't a one-time thing.

    Okay, so why does it do this? The thermostat is designed with hysteresis, where the on setpoint is higher than the off setpoint. The 4°F gap between the on setpoint and the off setpoint is called the dead band, so in this case we have a 4°F dead band. No control action ocures inside of this dead band. Note that 4°F is just a made-up value for this discussion.

    Thermostats are designed this way to avoid short cycling the furnace. Imagin a furnace attached to a thermostat with no dead band. The furnace would turn on and off very quickly as the room heated and cooled slightly. This would be okay for electric baseboard heat, but disasterous for a heat pump or forced air system.

    Control system theroy is fairly complex, involving a lot of differential equations, Bode plots, and other disagreeable math. Even a simple thermostat will use an anticipator to help avoid wide swings and oscillations. Complex math aside, it's easy to understand some real world examples. Car steering is one. The Prius uses electrically assisted steering with a minimal dead band. Even the slightest input from the driver's hands translates to a movement of the front wheel angle. This causes new Prius drivers to wander back and forth as they over-correct for each input.

    Adding more dead band would reduce the tendancy to wander for new drivers, but it would also make the steering feel sloppy. It's a trade off, as most things are in engineering.

    Tom
     
  2. jayman

    jayman Senior Member

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    Oy

    (Sound of Jay's palm smacking his forehead)
     
  3. qbee42

    qbee42 My other car is a boat

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    Jayman, there is an old story that I like to tell. Forgive me if you have heard it before. It goes like this:

    A man died and found himself in the afterlife, standing on a large, featureless, grassy field. Not knowing what to do, he started walking. Eventually he crested a small rise, and there stretching out in front of him was a long line of men. The line stretched all the way to the horizon. Not knowing what the line was for, and being afraid to ask, he decided to walk to the front of the line and see for himself.

    The man walked for hours before the front of the line drew into view. As he got closer to the front, he realized that there were two lines, not one. Over the huge line of men was a sign that read "MEN DOMINATED BY THEIR WIVES". Next to this was another sign, with a single, solitary man waiting under it. The sign over him read "MEN NOT DOMINATED BY THEIR WIVES". This really peaked the interest of our man, and overcoming his shyness he walked over the the solitary man under the "MEN NOT DOMINATED BY THEIR WIVES" sign and asked the solitary man "Why are you standing here in this line all by yourself when all of the other men are in the other line?" The solitary man replied "I don't know. My wife told me to stand here."

    Tom
     
  4. tripp

    tripp Which it's a 'ybrid, ain't it?

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    Tom, thanks. That makes perfect sense. I just don't have the engineers' lexicon so sometimes you might as well be typing in wing-dings vs ISO-8859-1. ;)

    Bloody brilliant story, BTW.

    Jay, you don't know what you're missing, mate. For all of our whinging, the missus are worth it. Though, I have to say I wish mine fancied sailing more than she does. Other than that she's mint.
     
  5. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    hehehehe...

    oh wait!!... why am i laughing??

    that story applies to me!!
     
  6. Fibb222

    Fibb222 New Member

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    Re: Cold Fusion and the BlackLight's process - they could be related:

    It's long and old, but worth the read:

    Wired 6.11: What If Cold Fusion Is Real?

    There is excess heat.... sometimes....
     
  7. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    One question never asked is what is done with the waste product? Not a question that anyone bothers with when the mechanism is not harnessed (or non-existent). A very relevant question if there is anything feasible. I fear that if something is discovered or invented along these lines, then the pollutant answer will be "Nothing" or "Nothing to bother with". That is certainly the myth right now.
     
  8. qbee42

    qbee42 My other car is a boat

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    Let me guess. Your wife made you say this. ;)

    Tom
     
  9. jayman

    jayman Senior Member

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    (Sound of Jay kissing the carpet directly under his computer desk, the carpet that hand't been vacuumed in at least 8 months and has a fuzzy layer of cat fur, hairballs, stale potatoe chips, and empty beer bottles, eternally grateful he's a happy bachelor)
     
  10. tripp

    tripp Which it's a 'ybrid, ain't it?

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    hah! that sounds like our carpet too. You just gotta pick the right lass, mate. ;)
     
  11. FreshAir

    FreshAir New Member

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    Now that we are on the brink of lots of changes it may be the time to bring new technology online, hopefully most of us are ready and aware of massive restructuring and all the unintended consequences that will no doubt pop up.
     
  12. Fibb222

    Fibb222 New Member

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  13. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i will echo the one scientist's comment in that the article is very interesting. its good to get some more background on what actually happened on the first cold fusion announcement.
     
  14. Celtic Blue

    Celtic Blue New Member

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    Until the physics can be explained, I'm skeptical. It's still all about supposed excess heat. The evidence of actual fusion is absent. Same story as 20 years ago.
     
  15. jayman

    jayman Senior Member

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    Correct. If this really is LENR, heat can be put to work, just as heat is already put to work. As I stated in the other thread on this subject, this sort of research can take DECADES to resolve
     
  16. Fibb222

    Fibb222 New Member

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    I think that if you delve deeper you'll see that there are some excess neutrons at least...
     
  17. Zythryn

    Zythryn Senior Member

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    One of the problems seems to be that the scientist 20 years ago as well as the current research done don't want to label this as fusion as they don't believe it really is fusion as most people define the word.

    It is, according to the report above, repeatable. It ISN'T reliable though. Sometimes it works, sometimes it doesn't sometimes you get a different amount of heat.
    It will take more study (lots more).
    However, if it pans out, it seems more applicable to batteries than hydrogen as an energy carrier.
     
  18. Celtic Blue

    Celtic Blue New Member

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    Not really. That's a key part of the problem. As I understand it the quantity of neutrons is inconsequential compared to the heat claim. It's off by several orders of magnitude as best I can tell. They can't even identify an actual reaction for this--that was the most notable part of the report and the litmus test I had going into it.

    The proponents can't come up with a plausible theory to explain it. And it is a bunch of electrochemists, not nuclear physicists. They need a plausible reaction equation so that the evidence of the products of the reaction can be tallied for confirmation.

    The preponderance of evidence so far indicates this is not fusion. It's not clear what it might be. All 20 years have produced is some excess heat, and not in a predictable or reliable fashion. Neutrons, gamma rays, and helium are absent (other than trace levels that fail to explain anything.) Three of four indicators are negative, one of four indicators is positive but only ~70% of the time and not in a predictable quantity or even timeframe. When evaluating experimental results or doing failure analysis that tends to scream out that the test was negative. When you look at the lack of products there is no consistency with this being fusion.

    It remains an interesting curiosity without explanation or practical application at the moment. I hope that someone eventually explains it. Of course it is hard to determine what "it" is. An unreliable, unpredictable quantity of excess heat? There are many ways to get that without any new science.

    If it really was producing the claimed heat then it would be rather facile to recover even a portion of the heat, convert it to electricity and make the system self-sustaining. Seal the system in a loop, disconnect the external electrical umbilical and if it produces energy and helium the accumulation will be obvious after a time. That's how I would go about converting skeptics.
     
  19. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    the report says the only inconsistency is the amount of power generated. heat seems to be generated EVERY TIME and a lot of it. there seems to be little question about that part.

    as far as an explanation of the physics of it. that might be decades away. most of the newer physics of Einstein is still mostly theory.
     
  20. Celtic Blue

    Celtic Blue New Member

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    Completely wrong. See the following from the 60 Minutes report: "But there's another problem that critics point out: the experiments produce excess heat at best 70 percent of the time; it can take days or weeks for the excess heat to show up. And it's never the same amount of energy twice." And it is definitely NOT the "only inconsistency", see the issues about lack of helium, neutrons, and gamma rays.

    There is a lot to be said about whether the "box" is being drawn properly. Since they still have not demonstrated a self-sustaining system after 20 years, I find it increasingly unlikely that the fusion claim is true.

    I'm actually fairly easy to convince on this, the cold fusion proponents just haven't designed and run an experiment that answers any of the questions that have been hanging over this for 20 years.