Radiation Heater for Snow melting

Discussion in 'The Projects Forum' started by absoluteZro, Dec 10, 2011.

  1. absoluteZro

    Thread Starter New Member

    Nov 12, 2011
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    Here is the plan for this winter break: A system powered by my 12v or 24v battery(not sure which one), to melt the damn snow that will cover my walkway.

    I have several questions about logistics before I start designing anything. I plan on making two solar panels, both being 36 cell 12v (actually 18v) 3-3.5amp panels. These will in turn charge the 12v battery. So Question 1: Do I buy a 24v battery? Do I put the panels in parallel and buy a 12v battery? Do I put two 12v batteries in series? What the blankety blank do I do? I suppose the answer might depend on the next question.

    I initially was thinking of heating water and pumping it through PEX tubing to heat the walkway, but if I can somehow make use of the 12-24v DC that I have and create a heater that is essentially just wire, i will overcome gravity, my greatest enemy! Several problems with this are: 1) Is it possible to make a heater like what I have in mind? (please tell how if it is!), 2) My solar panels are in the back of my house, my walkway is in the front. How does wiring work for long distances. 3) How can I hook up a heater to both the battery and the solar panels? If the battery is full and the panels are still making energy, why use the battery? Or if the battery is getting close to a too low voltage, how do I switch to the Panels?

    SO many questions...AH! Help please?

    I have done some googling and found something called heating or resistance wire. I am guess the wires resistance is causing it to heat up. So how can I safely make a system of resistance wire, and how much must I have per sqft?
     
    Last edited: Dec 11, 2011
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Nichrome wire is "heating element wire" as you'd use in a toaster or bag sealer/cutter, etc.

    You'll need a lot of power to melt your driveway if you do not already have the elements embedded in the concrete.

    You'll not only need to melt the snow and ice, the wires will fall down to the concrete, you'll then be heating up the concrete AND melting snow and ice until it evaporates. There isn't that much solar power available. If you don't mind augmenting solar with a thousand watts of household current at low voltage, something could probably be worked out, but there's the hazard of wire breakage, damage, salt causing shorts, and a host of other issues to think through.
     
  3. absoluteZro

    Thread Starter New Member

    Nov 12, 2011
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    I was scared that might be the case. I don't think heating my driveway will be possible, but I still have hope for my walkway.

    I don't see why I need such high temps though. If I had a wire at 100C on the concrete, for 3 hours at that temp, I feel like that should do some damage. But again, that will probably use quite a lot of power. Are there equations I can use to calculate the Power required for a certain temperature for a certain area? I found this website, but I don't understand what their resistance is measured in/what that tells me about the temperature needed.

    Theoretically, how many solar panels, or really what voltage/amp system would I need set up to heat both my driveway and walk way. Might make that a long term project.

    If nothing is possible :)(), could someone just tell me what makes the most sense for storing power from two 12v panels, a 12v or 24v battery?
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Wintertime, 2 12V in parallel will give enough current to charge a battery at a decent rate.

    You could make a "rake" of sorts out of a length of nichrome wire about 30" wide to cut slits through the ice so it is easier to scrape. You wouldn't want to push on it, or pull hard to get it out, the wire gets fragile at those temp extremes, but it would give you a leg up in breaking up ice.

    Another thought is if you could find a ceramic heater rod about 1/4" diameter that is essentially a heating element like an electric stovetop, or space heater, but in stick form, and doing the same thing, it'd be a bit more reliable. With Nichrome wire, one side needs to be mounted with a spring to take up tension, since it expands when hot, and contracts when cold. Making a big grid of them would mean a lot of springs and adjustments, and broken wires. The wires break in normal usage of sealing bags, if that gives you an idea.

    What you might want to look for is a short sample of in floor heating element, that's the ceramic rod I was talking about, and ask them what voltage/current it can handle. Water is an extremely efficient heat sink (takes a LOT of energy to change ice to water, and even more to evaporate water), so melting will take time if done from the top down. That's why heaters are in floor for garages, and a few driveways (heat rises). Even those with driveway warmers only use them for ice-off once the snow is blown/shoveled/plowed away, as it is too expensive to run continually.
     
  5. absoluteZro

    Thread Starter New Member

    Nov 12, 2011
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    I just looked at a site that had efficient heaters rated at 35-50watts per sq-ft. WOW. I did not realize how much I needed for an application like this. I guess that puts this out of the question.

    So I should go with a 12v battery charged by two 12v panels in parallel? That would make life easier in terms of charge controllers I guess. Is there any basic everyday stuff that could be powered by only a 12v 18ah battery? (I can use that as my battery right?)
     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    That's why a good snowblower still sells for over $1,000.

    For the second part, get an inverter, maybe 300W and hook a DVD player and battery pack to your shovel? :D
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    This is why salt is most frequently used.

    It takes a tremendous amount of energy to turn ice at 31°F into water at 33°F.

    Salt works by lowering the freezing temperature of the water. Cheap, and effective.
     
  8. absoluteZro

    Thread Starter New Member

    Nov 12, 2011
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    Go chemistry! If only I didn't care about getting salt in my lawn. I guess I won't be able to sit inside and watch the snow magically melt away. Maybe I'll find some scrap metal and try and make an insanely strong reflector.
     
  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    The albido of snow is quite high, so unless you place something black on top of it, most of the long wave energy(heat) will reflect back into space.
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    It is a bad idea to melt snow because the water that is formed will simply freeze nearby.
    I like to walk on snow but not on ice.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    If you are determined to use solar energy to do the job, this would be FAR superior to converting the solar energy to electricity and back to heat. That conversion process is maybe only 5% efficient in turning the original solar energy to heat doing the melting work. And it uses expensive equipment. The solar cells are ~10% efficient, and the battery storage process is ~50% efficient. Turning electricity to heat is roughly 100%.

    Capturing heat and putting it directly to work on melting ice can approach 100% efficiency. Keep in mind though that the area to be warmed must be smaller than the solar collector. My black driveway will, on a cold day, sustain a sheet of ice. In other words a pretty good collection surface can't even keep itself warm enough to drive away the ice.

    'Round here, they fling sand on the snow. It lowers the albedo and provides traction as well. No ecological problems, except the pile of grit on my garage floor. Salt (calcium chloride plus beet juice) is reserved for only the most difficult times.
     
  12. absoluteZro

    Thread Starter New Member

    Nov 12, 2011
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    Heh, apparently the albedo of snow can be close to .9; I would probably light an adjacent tree on fire. It would seem science is against snow removal by means other than the dreaded shovel. I think I will invest in a really good shovel this year then.

    Next thread: building a snow blower? Maybe next year...
     
  13. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Not for lack of trying. Look at patents related to snow removal. Everything has been tried.
     
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