h a l f b a k e r y"Bun is such a sad word, is it not?" -- Watt, "Waiting for Godot"
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I've seen too many dual-temperature water coolers (i.e. that dispense cold and hot water) that have condensers on the back from the cool water, and they use a separate heater for the hot water. Why not simply wrap the hot water reservoir with the condenser coils, therefore re-using the heat energy from
the cool water?
Heat Exchanger thermodynamics
http://web.mit.edu/.../notes/node131.html
If you look at the formulas, the rate of heat exchange (Q{dot}) is lower for lower Delta T. Since a condensor in this case will only reach about 40 °C, heating will be very slow. Additionally, around those temperatures, and with the long heating times, you're creating the ideal circumstances for legionella to thrive. [sdk16420, Sep 25 2014]
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This could probably go as a separate idea, but there are so many instances where hot/cold energy could be used more efficiently.
At my gym, pump cold air in to the gym, yet separate heaters heating the water |
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your idea makes me think of the people who realized that putting the motor on top of the fridge saved a bunch of energy compared to putting it under the fridge ...where it warmed up the fridge |
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motor on top fridges remain rare as a result of tipping hazard; maybe they could have ductwork like Ben Franklin thought of |
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Isn't there a rule of thermodynamics or
some such, which says that cool things
and hot things near each other attempt
to reach each other in temperature? |
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If this is true (and forgive me, for I am
no more a scientist than a bakery
expert) then you'd have two new
problems: one, to stop the hot water
transferring all its heat to the
condenser and thus cooling down, and
two, to stop the condenser getting
hotter from the hot water, and thus
heating up (which it's not supposed to
do cos it's supposed to carry excess
heat away from the cold, not add to it). |
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Or something. Anyway, if you end up
having to re-heat the hot water and re-
cool the cool water then surely there's
some loss of energy somewhere, or at
least not any gain... |
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Not a bad summary, [cheesecake].
The Devil is in the Detail. |
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//motor on top fridges remain rare as a
result of tipping hazard// |
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Which is kind of a shame, because the
tipping hazard could be overcome with a
50-cent bracket. |
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// Isn't there a rule of thermodynamics or some such, which says that cool things and hot things near each other attempt to reach each other in temperature? // |
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The Zeroth Law, maybe? If the condenser and the hot water reservoir are touching, they will reach an equilibrium (??speling), and their temperature will be equal. If anything, this will reduce work on the heater if it must be installed to produce a *hot* hot water temperature, and reduce the work on the condenser, if it must be installed to completely condense the refrigerant. |
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This is actually a very good idea, thermodynamics wise, but I think the isue would be one of scale. The compressor runs only when the cold water needs cooling, running it when the hot water needs heating could lead to freezing the cold water, or, conversely, when a lot of cold water is needed, it might boil the hot water side. |
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//when the hot water needs heating could lead to freezing the cold water// |
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Rainy Day + Reverse Cycle Air Conditioner = Ice |
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Probably best used as a system to increase efficiency, rather than to replace the current system totally [+] |
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