Refrigerant conversion of auto-refrigerating cascade (ARC) systems

Abstract This paper describes converting Auto-Refrigerating Cascade (ARC) ultra-low temperature systems from a multicomponent zeotropic working fluid containing CFS to a CFC-free mixture. The differences between azeotropes, mixtures and blends with minimal glides used in conventional refrigeration systems and the steep glide (wide span) zeotropes required for ARC system operation are compared. The design tools used include the Carnahan-Starling-DeSantis and the Peng-Robinson equations of state and relationships of components based upon Raoult's law. Some comparisons of prep and post-conversion operating data are presented. A brief history of ARC cycle cooling systemsis included.