MARC系统强非共沸混合工质气液相平衡及系统循环特性研究

Tumor cryoablation targeted therapy is the frontier of the development of contemporary clinical medicine. However, many defects of the traditional liquid-nitrogen cryotherapy and argon-helium knife system based on pure-refrigerant J-T refrigeration have hindered its sustainable development. The throttling refrigeration with mixed-refrigerant has become a research hotspot of cryogenic medical refrigeration technology. Based on the existing research foundation and experimental platform of refrigerant thermophysical properties and auto-cascade refrigeration, this project establishes the prediction model of vapor liquid equilibrium (VLE) characteristics of mixed refrigerants and the thermodynamic model of refrigeration cycle. Meanwhile, the experimental platform of VLE and a five-stage micro auto-cascade refrigeration cycle (MARC) device are improved. Combining auto-cascade refrigeration technology with cryogenic medical system, the VLE behavior of the strong-zeotropic mixture of R32+R1150+R50 system that is suitable for the working temperature zone of tumor cryoablation system is investigated theoretically and experimentally. The two-phase flow characteristics and heat transfer mechanism of mixed refrigerants in auto-cascade refrigeration system are revealed. The research results of this project will provide theoretical and technical foundation for the performance study and the optimization design of cryogenic medical system.

肿瘤冷冻消融靶向治疗是当代临床医学发展的前沿，传统的液氮冷疗和采用单一工质J-T节流制冷的氩氦刀系统因存在诸多缺陷难以得到可持续发展，混合工质节流制冷已成为低温医疗制冷技术的研究热点。本项目基于现有制冷剂热物性和自复叠制冷研究基础及实验平台，建立混合工质气液相平衡特性预测模型及系统循环热力学模型，同时改进气液相平衡实验台及微型自复叠制冷循环(Micro Auto-cascade Refrigeration Cycle, MARC)装置。将自复叠制冷技术与低温医疗系统相结合，开展适用于冷冻消融工作温区的强非共沸混合工质R32+R1150+R50系气液相平衡的理论及实验研究，深入揭示混合工质在自复叠循环中的两相流动特性和换热机理。本项目研究成果将为低温医疗系统的性能研究和结构优化设计提供理论和技术基础。

混合工质单级蒸汽压缩制冷循环具有热力学效率高，工作压力低，结构紧凑等优点，在肿瘤冷冻消融中具有很大应用潜力。本项目采用数值模拟和实验测试相结合的方法对单级林德循环(LHR)、三级自复叠循环(ACR)以及两者耦合制冷循环(LHR-ACR)的热力学特性进行了深入的研究。理论研究表明，耦合制冷系统中第三级冷凝蒸发器的㶲损失最大，其次是ACR压缩机和ACR冷凝器，这为进一步的实验研究提供了优化方向。搭建了双混合工质制冷系统平台，研究了混合工质组分和配比、节流阀开度、冷凝温度等操作参数对系统稳态运行特性和热力学特性的影响规律，掌握了系统主要部件优化匹配原则，以及运行参数对保温箱降温速度、冷冻负荷的影响规律，获得了实现系统高效稳定运行的最佳运行策略；实验结果表明，耦合制冷系统能够稳定获取约-150 ℃的低温，同时保持较高的制冷效率和制冷量，这为肿瘤冷冻消融系统的开发提供了理论及技术基础；此外，对-40 ℃～-150 ℃范围的冷却温度梯级利用的可行性进行了评价，这一思路为实现制冷量回收提供了新的途径，从而提高能源利用效率。课题组发表的已标注基金号的国际期刊论文有9篇，申请3项专利，其中1项已授权。本课题从更深的层次上揭示了混合工质制冷循环的热力学原理和系统工作基本规律，进一步丰富了自复叠超低温制冷技术的理论体系，为相关制冷循环在肿瘤冷冻消融、低温保存等低温领域的应用打下了良好基础。