This paper presents a critical review of cascade refrigeration systems for low-temperature refrigeration. The recent interest and issues in the development of two-circuit cascade systems are highlighted. A survey of successful installations was carried out to judge the state of the art of the technology. A thermodynamic analysis of these systems was carried out using natural refrigerants with carbon dioxide as a lowtemperature fluid and propane, propylene, and ammonia as high-temperature fluids. The results are compared with a system using R-404A and CO² as high- and low-temperature refrigerants, respectively. The emerging trends and research directions for these systems are discussed in the paper.

Units: SI