Simple cascade questions eh? Seems cascades are not very simple.

I do take your point Tom, that if you are trying to hit -70C that is one way you could possibly do it.

Really Teyber, it's a bit of a shot in the dark way of designing a cascade to say you have picked two compressors and the gasses and just want as cold as possible. Don't get me wrong, cascades are built like that all the time here, and it will function I have no doubt. To build it without understanding what will happen or why, I think you could spend your summer doing that, and by the end of the summer have a bit more experience. I don't have an alternate suggestion really. I don't think you would be allowed to sit in a Thermo course at some local univ. as this is pretty much senior level undergrad mechanical engineering stuff. I certainly wouldn't have had the skills at 16 to do it, but perhaps you're a refrigeration prodigy?