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If a pipe that is 1km long can collect low grade heat that may raise the collecting liquid by 5 degrees. Is there a device that will concentrate that into a heat exchanger that is 1m long at say 50-90 degrees so the distance and change in temperature balances. This is to increase the low grade heat from a ground or air source to medium grade heat suitable to warm a home (which has far less volume than the ground that the heat was extracted from) to a comfortable level (many heat pumps have a COP of 4 or above but the heat generated gets lost too fast to warm a home properly). Note: how does a heat pipe freeze the ground or keep a permafrost without the use of electricity? And how does a room have a higher temperature at the ceiling than the floor?

Lonewolf
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2 Answers2

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Heat moves spontaneously from hot systems to cold systems. This is the definition of temperature.

A device which moves heat from a cold system to a hot system is called a “refrigerator.” (If the point of the refrigerator is to increase the temperature of the hot system, it is sometimes called a “heat pump.”) A refrigerator, even an ideal refrigerator, requires external work input which depends on the temperature difference between the two systems.

rob
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It doesn't matter how you try, unfortunately there is no way to make heat flow from an area of lower temperature to an area of higher temperature without energy input. One of the side effects of this is that you can't collect heat energy from the ground at say 60 degrees F and have it flow into a home at 70 degrees F. Doing so must require energy. This is the same reason that if you focus light from the sun using a huge magnifying glass you can never achieve a higher temperature than the sun.

Because of the 2nd law of thermodynamics, energy always wants to spread out. There is no way to make the energy from the 1km long pipe concentrate itself together in a 1m long pipe without using energy (like a heat pump) to do so.

You are right that in both cases the total energy might be the same (5 degree 1km long pipe vs. 90 degree in 1m long pipe), but the useful energy isn't the same in both cases.

Hunter
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