How long of copper tube of 1/4 size would I need to make a 3,100BTU water cooled condenser?

I plan on using a 1/2" PEX water pipe as the jacket and cooling the 1/4 inside.

I tried searching the forum but couldn't find any info on the heat rejecting ability of 1/4" copper per foot with a 10K delta-T.

I'm thinking with a 16C inlet temp I'd guestimate 6 feet or so?

Basicly I want to figur out how many BTU per foot of 1/4 at a dT of 10K in a water cooled aplication.