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Physics
Classical Physics
Thermodynamics
How does evaporation generate cooling? Swamp coolers edition
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[QUOTE="russ_watters, post: 6855955, member: 142"] You seem to be describing the heat transfer backwards. If the water vapor condenses on the coils it heats the coils. The now liquid water will then run off the coils and drain. What happens to it after that doesn't matter. It doesn't condense on the coils and then evaporate again. You're not losing anything you are just gaining. The downside of this for heating has already been largely explained: it only works if your outdoor temperature and dew point are well above freezing, and at that time you don't need much heating anyway. If it's below freezing the water vapor will frost onto the coils and then you have to spend extra energy re-heating it to get it off the coils. Most of the available energy gain is lost to re-heating it. Either way, this is already a "feature" of all air source heat pumps. Also noted was that there is a lot less water in the air when it is cold than when it is hot. How much? Air with a dew point of 30F has less than half as much water as at 50F. at 10F it's 1/6th. A humid summer day at 70F dewpoint has twice as much as at 50F. For gases, pretty much yes. Loses. Potential energy is negative. What happens in evaporation (at 100C) is you input heat and instead of increasing the temperature of the water you just break a chemical bond. The 540 is the energy required to break the chemical bond. In this case the potential energy is chemical bond energy, which is electromagnetic in nature. No, force is not energy. If you have a book sitting on a table, the table is not consuming energy just by holding up the book. There is more than one type of potential energy. People are giving you analogies to other examples because "chemical bond energy" isn't something you can easily visualize. No. What you are saying is sort of true in Relativity, but this isn't Relativity. All of the energy is chemical and the mass (weight) of the fuel oil is not lost. Chemical bond energy. It's very similar to the energy required to pull apart two magnets. Gotta call it something. Since it consumes energy when you pump it up and gives you energy back when you release it, "potential energy" sounds reasonable to me. I suppose you could call it "Frank" if you want, but it wouldn't change the math. [/QUOTE]
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How does evaporation generate cooling? Swamp coolers edition
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