自然非共沸混合工质分凝式双温制冷循环特性及其系统优化研究

The vapor-compression refrigeration cycle system with zeotropic mixtures is proposed to be an efficient energy savings technology. In this project, we will carry out the simulating and experimental studies on the operating characteristics and the optimization of the segregation-cycle based dual-temperature refrigeration system using the natural binary mixtures. We will investigate the effects of the binary refrigerant pair and its composition on the cycle performances with thermodynamic analyses and clarify the inner relationship between refrigerant properties and cycle performances, and then obtain the optimal refrigerant pair. We will also establish the dynamic simulation model and investigate the effects of the refrigerant composition, segregation temperature, operating condition and component configuration on the system operating characteristics, and then reveal the inner mechanism for the system performances improving potential. Ｗe will carry out the experimental study to investigate the dynamic behaviors of the system with the variations of refrigeration capacity, operating models switch and frosting condition, and then obtain the efficient energy saving control methods and strategy for the dual-temperature refrigeration system. Furthermore, we will investigate the coupling features between the components matching and system operating characteristics, and then obtain the optimized method of system design through the object-oriented model established on advanced exergetic analysis. These studies will enrich the theory of mixtures refrigeration and expand the application of the natural refrigerants in the small and medium scale refrigeration systems, which will promote the development of the related energy saving technologies.

采用非共沸混合工质制冷循环是实现制冷装置节能的有效技术途径。本项目采用计算机模拟和实验方法对二元自然混合工质的分凝式双温制冷系统的循环特性及其系统优化进行深入的理论与实验研究。基于热力学原理分析自然工质的二元配对及其组分对循环特性的影响关系，根据工质物性和循环性能优选出最佳的工质组合。建立制冷系统的动态仿真模型，研究非共沸混合工质组分、分凝温度、工况条件及部件配置等关键参数对循环性能的影响规律，揭示分凝式双温制冷循环性能提高的内在机理。基于先进火用分析方法构建面向对象的系统优化模型，探索部件匹配与系统整体运行特性间最佳耦合关系，获得系统优化设计方法。通过实验研究掌握变工况及动态工作条件下双温制冷系统性能随工质组分、分凝温度、充注量等的变化规律，获得适合于双温制冷系统的高效节能的控制方法和策略。本研究将丰富混合工质制冷方法，推动自然工质在中小型冷冻冷藏领域的应用并促进节能技术的发展。

本项目采用数值模拟和实验研究相结合的方法对碳氢类自然非共沸混合工质分凝式双温循环制冷系统的运行特性及节能机理展开研究。构建了新型的基于天然非共沸混合工质的双温和单温制冷循环，并着重对采用天然非共沸混合工质双温制冷系统进行了理论分析和实验研究，掌握了新型循环系统的热力学特性，获得了系统运行的基本规律和系统优化方法；采用CFD模拟和实验方法研究了组分分离的关键部件气液分离器内流动和组分分离特性，确定了最佳的结构匹配原则，获得了气液分离器在采用混合工质的小型制冷装置应用中的设计方法；研究了系统动态运行过程中多参数对系统动态运行特性的影响规律及其与系统能耗特性的耦合规律，获得了最佳的系统调控和部件参数匹配准则；研究了不同运行参数对制冷剂浓度分布和迁移特性的影响规律，并阐明了其与系统整体热力特性的耦合机制，掌握了基于系统性能优化的浓度调控策略；本研究从深层次揭示了基于二元天然非共沸混合工质的双温制冷系统的热物理过程和基本规律，丰富了混合工质制冷技术体系，同时为该技术在普冷双温制冷领域的应用奠定了基础并提供了开发思路。