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Nice simple experiment. Another way of looking at it is as a measure of efficiency. If the cooling was 100% efficient then the temperature change would be zero. You can calculate the watts lost by using the formula; Watts = specific heat capacity (c = 1 for water) x mass of water (m) x change in temperature in C (T) / amount of time the device was on (t). Good way of testing Peltiers though am not sure that like being soaked in water, maybe seal the edges and then immerse them in water?
I question the results in a way. Since heat rises and your have it at the top. Also I dont know if the hot side was up or the cold to go direct at the sensor. Best to measure the water before leave it for a bit and then take it out and swirl it and measure again. Or maybe your results are correct that it gives off more heat than cold.
Actually there is kinetic energy conversion. The water will cause a convection current. The hot water will move into the cold water making the water move.
If you are both heating and cooling water, the hot water will rise and the cold water will sink. Isn't that turning electrical energy into kinetic energy?
I really appreciate that you explain this with the First Law of thermodynamics. I usually go with the Second Law, that you cannot have 100% efficiency in a heat pump. But the nature of the Second Law makes it cumbersome to explain if the audience is not already well versed in basic concepts related to that law.
