Quote Originally Posted by sterl View Post
Actually: An oversize condenser with a small amount of its height devoted to subcooling(that is trapped....) will operate at LESS subcooling than smaller one....If the Big One handles the corresponding compressors at 15 degrees over ambient as a saturated condensing temperature, the best it can possibly do is 15-deg of subcooling. If a smaller condenser is selected for 25-deg over ambient, than the best it can do is 25-deg of subcooling. This becomes useful should the rest of the circuit be such that subcooling of this extent (not 60 or 70 Deg worth) is necessary to maintain TXV flow as commonly occurs if the liquid line has a couple of verticals built in.....
If the condensing temp is 15 degs higher than ambient (which is normal in most air cooled condensers)
the amount of energy used to lift the pressure / temperature will be a fraction of that used to lift
the condensing pressure / temperature up by 25 degs.

I can't see any advantage of lifting the condensing temp that high just to gain more subcooling
and bear in mind the subcooling will still be above ambient.

The only true advantage is when the liquid is cooled way below ambient and that can't be done
for free so a well designed system with extra / additional subcooling will improve the efficiency
of the system but the subcooling is additional to the free subcooling gained in the condenser.

Rob

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