Quote Originally Posted by tiborrr View Post
Don't know, but do you think If I rather go a bit easier on the CO2 charge and add some R-1150? I think I could get into -85°C league with some positive back pressure, what are your thoughts on this charge?
I know, replying to an old post, thread necromancy and all that But anyways...

If you have R1150, why not go with a charge of R290 and R1150? No worries about dry ice, and pressures shouldn't be a problem. Remembering stuff I read a while ago some refrigerants will dissolve into others and lower the boiling point of the higher boiling one. One would think that 1150 and 290 would do this well, being that both are hydrocarbon refrigerants. The SLHX might even condense a portion of the 1150 into it's liquid state before the phase sep and then it'll be in the "1st stage" half of the auto, cooling off the rest of the 1150 in the "second stage" half.

You've probably moved on from this build by now though...