非共沸工质薄液膜相变传热特性与机理

Non-azeotropic refrigerant has good design flexibility and good application adaptability. It has great potential in many engineering fields, such as refrigeration, energy and power, and has become the promising direction of new technologies. The non-azeotropic phase-change heat transfer is very important for many thermodynamic systems, and the thin film heat transfer is the prerequisite and basis for understanding the heat transfer of non-azeotropic phase-change heat transfer. This project takes the heat transfer characteristics and mechanism of non-azeotropic thin film as the research object, firstly studies the stability characteristics of non-azeotropic refrigerant phase-change thin film and thin film morphology control method; secondly, experimentally measures the thin film of controllable morphology thickness, temperature, concentration; performs numerical simulation and theoretical analysis of thin film heat transfer and heat transfer mechanism and characteristics; and develops the design method of thin film heat transfer surface structures for heat transfer enhancement. On the choice of working fluids, we choose the non-azeotropic refrigerants, such as hydrocarbon, fluoroalkene and mixture of alkanes, which are applied to other important areas, such as refrigeration and waste heat utilization. Through this project, we can have a deep understanding of the phase-change heat transfer mechanism of non-azeotropic refrigerant thin film and develop the design method for heat transfer enhancement surfaces.

非共沸工质热物性设计灵活、工况适应性好,在制冷、能源动力等诸多工程领域中极具发展前景、成为新兴技术发展方向。非共沸工质相变传热对诸多热力系统均至关重要，而薄液膜传热是深入认识非共沸工质相变传热的前提和基础。本项目以非共沸工质薄液膜相变传热特性与机理为研究对象，首先研究非共沸工质相变薄液膜的稳定特性，获得薄液膜形态的控制方法；其次，对可控形态的薄液膜进行厚度、温度、浓度多参数精确测量；基于实验测量，结合数值模拟和理论分析研究薄液膜传热特性和机理；基于传热特性和机理，发展薄液膜强化转热的表面结构设计方法。在工质选择方面，选取对制冷和余热利用等重要领域所适用的非共沸工质代表：碳氢氟烯烃类混合物以及烷烃类混合物。通过本项目研究，可建立非共沸工质相变薄液膜稳定性的理论分析方法和相变薄液膜参数精确测量方法，认识非共沸工质薄液膜相变换热的精细机理，获得非共沸工质薄液膜相变换热的强化表面设计方法。

非共沸工质的设计灵活、工况适应性好，在制冷、能源动力等诸多工程领域中极具发展前景、成为新兴技术发展方向。非共沸工质相变传热对诸多热力系统均至关重要，而薄液膜传热是深入认识非共沸工质相变传热的前提和基础。本项目以非共沸工质薄液膜相变传热特性与机理为研究对象，从液膜稳定性、参数测量、传热机理和强化传热四个方面开展了系统研究。发展了薄液膜稳定性理论，提出了薄液膜的稳定机制及形态控制方法；搭建了可视化的非共沸工质薄液膜相变换热实验系统，发展了薄液膜各处厚度、组分、温度的精确测量方法；运用CFD 数值方法精确计算液膜内部温度、速度、组分各参数分布以及液膜底部热流，并结合实验测量数据验证了数值模拟的可靠性，揭示了液膜整体传热的影响规律和作用机制；基于传热机理，研究了强化表面的微结构形态对薄液膜形态和传热的影响机制，分析了各参数对液膜传热的影响规律，建立了强化表面的多参数设计方法。项目研究结果可为非共沸工质在相变传热应用过程提供坚实的科学支撑。本项目组在国家自然科学基金的资助下，顺利完成了预定研究任务，发表相关论文15篇，其中SCI期刊论文12篇。培养出站博士后1人，毕业博士研究生3人。