It appears they are using a liquid nitrogen boiler to chill a helium loop through their heat exchanger and in turn chill the air.
So, perhaps someone better at these calculations can help out, cooling incoming air by 160°C by moving nitrogen from -195°C to -15°C is going to require them to haul up liquid nitrogen and cool a bunch of atmospheric nitrogen that they don't really need. The heat of vaporization is the key that will make their solution win, but by what factor? How many grams of nitrogen must they haul to chill a gram of atmospheric oxygen?
It appears they are using a liquid nitrogen boiler to chill a helium loop through their heat exchanger and in turn chill the air.
So, perhaps someone better at these calculations can help out, cooling incoming air by 160°C by moving nitrogen from -195°C to -15°C is going to require them to haul up liquid nitrogen and cool a bunch of atmospheric nitrogen that they don't really need. The heat of vaporization is the key that will make their solution win, but by what factor? How many grams of nitrogen must they haul to chill a gram of atmospheric oxygen?