The rate of condensation better equal the rate of vaporization, or you have a problem. The rate of vaporization is up to you.

certainly, my understanding is that a pool of liquid which experiences a drop in pressure beneath its boiling point at that pressure/ temperature will boil more vigorously to make up the slack. there may be an issue in keeping up with a very fast rate of evaporation temperature wise, which may be remedied by an immersion heater. my main problem is that it seems to be very difficult to calculate the amount of condensation per square inch of radiator.

To figure it out, you'll need to calculate the heat transfer to whatever your vapor stream is for whatever your condenser configuration is. As Compositepro said, you need over 100% capacity or else you'll have problems. The Soxhlet extractors I've used for oil extractions would cycle through vigorous and steady boils during the siphon period, so my condenser was set up for the maximum rate at all times.

I'm not sure I'm understanding your system from your description, but I think you can treat it like a shell and tube heat exchanger with one pass and plug in the values for your system: Design of Condenser

Andrew H.
www.mototribology.com