With liquid nitrogen at −196°C and the average temp in the places you suggest well below freezing (A few minutes of googling suggests it wouldn’t be hard to find an average annual temp of −20°C.), I think you could use a more-optimistic ΔT of 175°.
There is a good idea along these lines, though. Have an outer shell cooled by dry ice, which takes about 6 times more heat per unit volume than nitrogen to heat from solid to gas at ambient temperature. The dry ice sublimes at −78C.
If you do this, the ΔT that the dry ice sees matters, so building the facility somewhere with a very cold winter temperature makes sense.
With liquid nitrogen at −196°C and the average temp in the places you suggest well below freezing (A few minutes of googling suggests it wouldn’t be hard to find an average annual temp of −20°C.), I think you could use a more-optimistic ΔT of 175°.
There is a good idea along these lines, though. Have an outer shell cooled by dry ice, which takes about 6 times more heat per unit volume than nitrogen to heat from solid to gas at ambient temperature. The dry ice sublimes at −78C.
If you do this, the ΔT that the dry ice sees matters, so building the facility somewhere with a very cold winter temperature makes sense.
Sure, you could do that. You only gain a factor of 1.25 for that, though.