Coil-less condenser design

[wysiwyp]

I am converting a pot stiil to LM reflux and, because of various economic constraints, I don't want to build a condenser using a coil. I want to use the existing head and temp probe which isn't compatible with a CM or VM still. I have already built a 32" column packed with SS scrubbers using a piece of 2" copper that I managed to track down after a long search. I have a fair amount of 1" and 1/2" pipe on hand, but I don't see how to fit a coil into anything smaller than 1-1/2" and I can't find anything shorter to buy than 10' which is freakin' expensive. I am trying to design a condenser that uses the sizes of pipe and random fittings that I have.

Here's a proposed design that I came up with.

single.png

The wires soldered on the sides of the 1/2" coolant pipe act as fins to increase the surface area. I figure this has about 3" of area per linear inch. Looking at some of the posts in this forum, the advice seems to be for around 100 sq in of surface area (1/4" line, coiled inside a 2" pipe @ 2 turns per inch for 12 inches). That means my condenser would have to be 33" long to be equivalent. That would probably be OK, but in order to keep it from getting ridiculously tall, I am thinking splitting it in two.

dual.png

I'm sure the calculations for condenser design are pretty much rocket science, but are there some rules of thumb for this?

Here is some additional data:

boiler: 7.5 gal beer keg
heater: 1000W electric
coolant flow: 1.5 gal/min
coolant temp: 50-80F depending on the season

Comments? Advice?