How and where does the nitrogen boiler(?) get its energy too cool helium to -170C at a constant rate? Is it effective to chill what must be ginormous amounts of air to -150C? It's all nice that the heat exchanger works, but where does that heat go?

There's a large discrepancy between the inlet air temperature (1000C vs 20C) in the article.

Somehow my sense for violation of the laws of thermodynamics is tingling.