sounds like a great idea, this is something we should have had a long time ago. just make it so it won't dissipate over time like NICE or LN2, that way we can use it to cool things without adding alot pressure (like with LN2)
We don't need N2(g), that is just jetting ridiculous... if you need some thing to be cold, use the "COOL" tool. You know, that blue one in the special menu? yes, believe it or not, it actually makes things cold with out generating pressure!
Using COOL requires you to sit there and hold it on the element, so its not good for permanent cooling.
Nitrogen gas is not typically used as a coolant (LN2 and NICE are).
An LN2 cooled diamond works, as long as you have it cloning LN2 as it evaporates, making it unsuitable for practical permanent cooling.
The LO2 (liquid oxygen) in the beta could work for this same purpose (it doesnt create pressure), but I could still see a use for a coolant gas (if you need coolant to flow freely in space through vertical pipes, etc). It would also make for another use of the insulator.