This paper presents a novel refrigeration system using natural refrigerant CO2 solid-gas tow phase flow. The proposed CO2 solid-gas two phase sublimation model can be operated below the triple point (-56.6℃) of CO2 fluid, so it can achieve good refrigeration performance under low temperature conditions. Fundamental experiments show that real stable refrigeration temperature below -62.0℃ can be achieved. By utilizing visualization apparatus in this study, the detailed two phase flow process and evolution of parameters are obtained and analyzed. In the experimental research, pipe sublimation flow control and two phase flow blockage phenomena are monitored and discussed. The basic information and future concerns are also put forward in this visualization study. It is hoped that this research can be useful in low temperature refrigeration, food engineering and medical cooling areas, etc.% 本文研究了一种采用自然工质 CO2在固气两相流条件下，进行升华换热实现低温制冷的新型制冷系统.相应的过程在CO2三相点-56.6℃以下通过相变的方式发生，从而能够在低温下达到良好的制冷效果.初步实验表明，实际可达到的稳定制冷温度可以在-62.0℃以下.研究从实验的角度探讨了相应的相变过程参数变化和固气两相升华流动的基本特性.实验设计了可视化方案，实现对于低温下复杂多变的两相流动性质和状态进行研究.特别是针对可视化实验中发现的管路控制和干冰颗粒沉积、堵塞的问题进行了多工况实验和讨论.研究期待对于相关低温制冷系统的进一步研发和实验优化提供有价值的参考.
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