Side effects of an oversize condensor
 

Hi, a few questions for you all :)

I and a friend (Jack the Ripper) are constructing a Phase Change R290 chiller much in the fashion of the unit devised by Bowman in the other thread here.

We've begun calculations and while determining optimum surface area per BTU and temperature difference, that by increasing the condenser size to nigh-infinite values would bring down the temp difference to nil while remaining a 900 BTU unit. This must be wrong somewhere.

So I'm at a loss to ascertain the optimum size of the condensor unit. What are the side effects of too much capacity, so to speak?

And how is temp-differential calculated initially? Using 75f as Ambient and R290 as a refridgerant.

Thank you in advance.