[NoRemorse]

The reason I think it may be possible is that the coolant is... well not all that cool. because of the Leidenfrost effect, the nitrofen touching the evaporater flash boils, and nitrogen in gas form is one hell of an insulator. This will keep it from getting too cold.

But this leads me to another idea.... what about 2 heat exchangers, but not in series. you fill the box with water, pour in ln2 into one of the exchangers, which will freeze the entire box, and run the coolant through the other. THat is what i will do i think if it gets too cold, use water as a buffer. The thing is though, ln2, has WAY better heat dissapating charactoritics than ice.