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General Forum

  1. Subscriber Ponderable
    chemist
    29 Nov '17 13:21
    Originally posted by @shallow-blue
    https://youtu.be/VnbiVw_1FNs?t=127
    Indeed:

    1. "Work is heat and heat is work" (or energgy is convertible)
    2. heat can not of itself pass from a Body to a hotter Body.

    So in essence if you invest some work you can Transport heat from a cold Body to a hot Body. The Refrigerator does that. (kompressing a fluid cooling the compressed fluid, then expanding that fluid, which will cool down the fluid. This cold fluid is taking up the heat of the goods in the refridgerator, effectively transferring heat from a cold Body (beer in fridge) to a hot Body (air of the surroundings).

    That is what a heat pump does: transferring heat from the relatively cold ground to the relatively hot flat. And you Need electricity for it to put the work in.
  2. Standard member sonhouse
    Fast and Curious
    29 Nov '17 13:40
    Originally posted by @ponderable
    Indeed:

    1. "Work is heat and heat is work" (or energgy is convertible)
    2. heat can not [b]of itself
    pass from a Body to a hotter Body.

    So in essence if you invest some work you can Transport heat from a cold Body to a hot Body. The Refrigerator does that. (kompressing a fluid cooling the compressed fluid, then expanding that fluid, which will ...[text shortened]... vely cold ground to the relatively hot flat. And you Need electricity for it to put the work in.[/b]
    And you can do that job with no moving parts in a Peltier device, a semiconductor that does that job with just electric current input. Not exactly the most energy efficient device but it works for beer at the beach, they are built into beach coolers now, some with solar panels on the lid.

    Usually they plug into a car cigarette lighter socket, 12 volts at around 10 amps, 120 ish watts which you won't get from a solar powered lid but it can recharge some kind of battery if left out all day in the sun. You get about 125 watts per square foot of solar energy hitting the top of the atmosphere and you get say half that on the ground so say 60 watts per square feet, you need about 10 square feet to get full power for the refrigerator from solar alone. 2 square feet but since it is only 20% efficient, 5 times. 2 = ten square feet.