small scale heat- electric converter

Discussion in 'The Projects Forum' started by agsnip, Jan 13, 2011.

  1. agsnip

    Thread Starter Member

    Nov 19, 2009
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    I've been working on a special design for a blinking device that is install in the middle of the road to replace the light reflector that is used now to help drivers detect the white line that divide the road especially at night. But the problem of the current light reflector is, it's not really effective during raining especially heavy raining and at the hazing area due the the biasing of the cars light by the water drops.
    My main idea is when the source of light comes from the blinking device itself, the biasing problem would reduce by 50% and because it is blinking, it's easier to detect it (from a psychological view, blinking light could attract the brain)

    Let's go to the design part. I refuse to use solar as a generator to battery for the device due to the price of solar system in Malaysia is expensive and because the road in Malaysia is easily damaged (tropical region), it could increase the road maintainance cost.

    Instead of solar, i decide to take advantage of the heat produced in the road especially during midday and convert it into electrical energy. for this purpose, most of the device body would build up using a steel because steel is a good heat conductor and would survive the road condition.


    I try to design a dynamo-like system, with rotating magnet in the middle with hope the magnetic flux produced by it would be accelerated by the heat absorbed from the road, and produced more current from what is used by the initial battery that rotate the magnet. But, for a small scale device, the chance is below 3% and the heat doesn't really accelerate the electron movement in the flux generated before. The easiest way to translate this is like I'm buying ikan masin with a price of RM10 in Kota Kinabalu and resell it in Ranau with the price of RM20. (please ignore other costs).
    From that, i gained double of my money. for the system, it's like using the energy from the battery to produce at least twice the energy used from the system. By that way, it could recharge everyday and solve the energy problem for the system.

    My only problem is i'm losing hope to design a small scale heat- electric converter. if manage to create such a system, it would be the first one.It maybe sounds like impossible, but nothing is impossible right?

    Thanks
    [​IMG]
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    What you have described is a perpetual motion device, and that is utterly impossible.

    If you were fabricating a road panel that could convert the up and down motion of the plate (causes by a car passing over it) into rotary motion, you might be able to generate useful power to charge batteries. The mechanism would have to be very heavy duty and either waterproof or very well drained, which might make it impractically expensive.
     
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  3. agsnip

    Thread Starter Member

    Nov 19, 2009
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    but to produce the rotary motion needs the car to constantly passing over it and the idea is to install it in the middle on the road. at the white line.
    i guess solar is the only option. failed again. huhu
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    You could use a combination of solar, as well as small magnets on light springs that would vibrate through many coils (dozens to hundreds), which would scavenge power from vibrations on the road, but I doubt you'll get anything near "Bright" out of them.

    A Rechargeable AA cell, and a 1 square meter solar panel per km would keep the batteries charged, but wires would need to be run under the road to power the charging circuits for the batteries, so it is still economically doomed.

    The ONLY way I can see it working would be making it a Strobe Light, with as big of solar cell you can get embedded into the upper window of the unit. It would only activate when heavy fog is around (another hard sensor that would need power).

    The way this problem is solved here is to make each dot a 1"-2" tall, 4" square pyramid, spaced about 2 feet apart. Then if the car gets close to one side or the other, the wheels hit the pyramids (no damage), it just makes a loud "brrrrrrrd" sound, they are called "rumble strips" in local lingo.

    --ETA: Vibration or solar are the only forms of energy something laying on a road will harvest. Heat differentials are very minute, only swings when the sun shines or stops shining on the road. Cars going over the road do not even create enough heat to melt ice, let alone charge a battery.
     
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  5. agsnip

    Thread Starter Member

    Nov 19, 2009
    12
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    ok, i'll try to design according what u suggest and later upload the design pic. thanx.:)
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    Thanks for the chuckle. Plenty of things are impossible, but few are as surely impossible as your perpetual motion machine.

    Turning a heat differential into electrical energy is very difficult, though not strictly impossible. If it was easy, there would be no such thing as "waste heat" - we'd turn it all into valuable electricity. The state-of-the-art technology (steam turbine) requires a differential of hundreds of degrees. A pelltier device can use a smaller delta, but is expensive and impractical. The laws of thermodynamics are against you.
     
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  7. agsnip

    Thread Starter Member

    Nov 19, 2009
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    i think i forgot to mention something. the circuit i design is actually a rough draft. when the battery is charging, the LED will not blinking because the charging circuit is active. it will only blink during night when the charging system stop because there;'s no more heat, for example during night, raining, or foggy situation. actually it is not really perpetual motion device
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What current is used for each flash? How often does the LED flash?

    Sum all of the discrete flash's currents and times together to get an amp-hour figure. Compare to a roughly 2000 mAH rating of a rechargeable AA battery. Next, take the largest, highest efficiency solar cell you can find to add to your enclosure. If the solar cell output (remember, only 4 hours of peak rating, the rest taper off quick), is less than 2200maH (extra 10% in charging losses), you are looking at a magical perpetual motion device.
     
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