Hi, I am reading a book on two stage low temperature refrigeration (-70 deg C). They say that compression ratio`s shouldnt exceed 7-9 for a recip compressor (I presume this has to do with excessive current draw on start up, but unloaders should cater for this), but if using a screw, compression ratio`s can be 15 or higher. If dont want to embarrass myself by giving my opinion, so can someone give me their understanding of why a screw can handle such a higher ratio than a recip, even though both have means of capacity control.
Thanks