Quote Originally Posted by mytekcontrols View Post
Yes it should be. In fact Polycold has a system called a PGC-150 that utilizes this many stages, and the same refrigerants (although it does have a subcooler and small amounts of R-14 and Argon as well). It does -120C at just over 300 watts, and utilizes a 1 1/2 HP reciprocating compressor.

But if you are just starting out with autocascade design, it is better to keep it simple, and build up from what you learn.

Edit: the PGC-150 also uses Ethane as part of its blend.
I reviewed the link for the PGC-150 and it states rated amps 12.5 at 230VAC (2875W). Even with the air-cooled condenser fan, this seem way over 1.5-hp (1.5*750/0.85 = 1324W, the 0.85 is the electric motor efficiency). So it appears to me closer to a 3-hp used by this reciprocating compressor. What am I missing?

Kevin