ADS二回路冷却系统流-热-固顺序耦合体系传热特性研究

The problem of long-lived fission products disposal restricts the development of nuclear power industry. Accelerator Driven Sub-critical System (ADS) has become the preferred technical approach for the effective use of nuclear resources and transmutation of nuclear waste. Convection heat transfer characteristics of liquid lead-bismuth (LBE) and helium in the two-loop cooling system is the urgent scientific problem for the security and economic benefit of ADS. In this project, the turbulent Prandtl number model is rebuilt under different thermal boundary conditions for low Prandtl number liquid metal. Using this model, the velocity and temperature fields of liquid metal turbulence flow in the pipe are accurately predicted by large eddy simulation, and the related experimental study of LBE and helium convection heat transfer in high temperature and heat flux is carried out. The variation of transient velocity and temperature fields with operation parameters is analyzed, and effective heat transfer correlations are obtained. The enhancement mechanism of helium external forced convection heat transfer is analyzed using the field synergy principle. The special flow-hot-solid sequential coupling system composed of LBE, intermediate heat exchanger and helium are the research object as a whole. From the overall perspective, characteristics of LBE and helium coupling heat transfer are systematic analyzed, and the dynamic influence of various factors on coupling system is surveyed. Investigation of heat transfer theory and the characteristics of the ADS two-loop cooling system can provide the theoretical basis and technical reserves for design and optimization of efficiency heat exchanger system.

核乏料处理难题制约着核电产业的扩大发展。加速器驱动次临界系统（ADS）已成为有效利用核资源、嬗变核废物的首选技术途径。液态铅铋（LBE）与氦气在二回路冷却系统中的对流换热特性是关系ADS反应堆安全性和经济性的亟待解决的科学问题。本课题拟构建不同热边界条件下适用于液态金属的湍流普朗特数模型，为低普朗特数液态金属的湍流传热理论计算提供准确依据。通过实验和大涡模拟方法分析高温高热流密度下液态LBE与氦气湍流瞬态速度场和温度场及其随各参数变化规律，获得有效的传热关联式，并运用场协同原理分析氦气对流换热的强化机理。以液态LBE、换热元件及氦气组成的流-热-固顺序耦合传热体系为研究对象，从整体角度出发系统地分析液态LBE与氦气耦合传热特点，考察各因素对耦合体系传热特性的影响规律，揭示二回路冷却系统流-热-固顺序耦合体系的传热机理，为ADS系统高效换热体系的设计与优化提供理论基础和技术储备。

液态铅铋合金是目前ADS二回路冷却系统中散裂靶兼冷却剂和新一代液态金属反应堆冷却剂的首选材料。液态铅铋合金与氦气在二回路冷却系统中的对流换热特性是关系ADS 反应堆安全性和经济性的亟待解决的科学问题。揭示二回路冷却系统流-热-固耦合传热机理及其动态变化规律，为高效主换热器的设计提供理论基础和技术储备。在国家自然基金的资助下，本项目主要开展了：（1）液态金属湍流普朗特数模型及适应性研究；（2）低普朗特数液态金属管内强制对流换热特性研究；（3）可压缩流体强制对流换热及液态金属-氦气耦合传热机理；（4）液态铅铋合金-氦气流动换热特性及热力学性能分析等相关问题的理论研究和实验研究，按照研究计划较好地完成了上述研究任务。获得了适用于液态铅铋合金的湍流普朗特数模型及换热关联式，再此基础上开展了液态铅铋合金管内强制对流换热特性及液态金属-氦气耦合传热机理研究及实验研究，并基于先进火用分析方法，进行了热力学分析，获得了液态铅铋合金与氦气的耦合换热过程中由温差和压降引起的不可避免火用损失的最佳比，及换热器的最小火用损失。该研究的理论及专利成果对于ADS系统的研发和顺利实施、推动核电产业可持续发展提供了坚实的理论基础和可靠的技术手段。在本项目的资助下，发表学术论文15篇，其中SCI收录论文8篇, EI收录论文2篇；申请发明专利5项，获得授权发明专利2项。