| Low-temperature refrigerating cascade cycle systems are widely used in preservation of biological tissues, cooling detectors, cooling the detecting instrument of x radiation and y radiation, cryosurfaces and providing circumstances for material and component testing. The paper focuses on rectifying column as gas-liquid separator and carries out both theoretical and experimental research on Auto Cascade Refrigerating Cycle(ACR) system.The research and development history in the field of Auto Cascade Refrigeration Cycle is reviewed. Contrast to some traditional cascaded cycles and ACRs, a new ACR that employs a rectifying column is proposed.Non-azeotropic refrigerant mixtures R23/R22 is used as working fluid. The rectifying column is employed to separate high boiling component, low boiling component and lubricant. The thermodynamic property of the mixture is also studied with MBWR equation. By computation, the influence of different combination, suction temperature and evaporating temperature on cycle performance is also analyzed based on the study of the mixture property. Under the same condition, the parameters of different state are also computed.An experimental apparatus has been set up and experiments have been carried out successfully. It used non-azeotropic refrigerant mixtures, a rectifying column and a compressor in the ultra-low temperature refrigeration cycle. High boiling component, low boiling component and lubricant can be separated effectively. The temperature in the ultra-low temperature box can reach -60 ℃ to -80 ℃. The performance of Auto Cascade Refrigeration Cycle at different operation modes is investigated. According to a series of experimental data, the effect of following factors on the refrigerating capacity and COP are analyzed: the mixture composition, the temperature in the ultra-low temperature box and the quantity of heat. The experiment result proves the theoretical analysis. By comparison, several problems are put forward which need further study.
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