竖直通道内饱和蒸汽凝结换热数值模拟  

Numerical simulation of saturated steam condensation heat exchange in a vertical channel

作　　者：刘倩 桂南 杨星团 屠基元 姜胜耀 LIU Qian;GUI Nan;YANG Xingtuan;TU Jiyuan;JIANG Shengyao(Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education,Collaborative Innovation Center of Advanced Nuclear Energy Technology,Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China;School of Engineering,RMIT University,Melbourne VIC 3083,Australia)

机构地区：[1]清华大学核能与新能源技术研究院,先进核能技术协同创新中心,先进反应堆工程与安全教育部重点实验室,北京100084 [2]皇家墨尔本理工大学工程学院,澳大利亚墨尔本VIC3083

出　　处：《清华大学学报（自然科学版）》2023年第8期1273-1281,共9页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金项目(51576211)。

摘　　要：在依靠自然循环驱动的小型模块化反应堆主回路以及反应堆非能动安全系统中,冷凝换热是热交换过程的重要一环,因此对冷凝换热过程的深入研究和分析对提升换热效率、保障堆芯安全至关重要。该文基于格子Boltzmann方法,采用伪势模型,模拟研究了二维通道内静止饱和蒸汽在凝结过程中的流动和换热特性。结果表明:蒸汽冷凝会自发驱动蒸汽流动,蒸汽质量流速与通道宽度和凝结过程中的热流流量有关,保持壁面温度和通道宽度恒定状态下,液膜发展阶段壁面热流较大时,蒸汽质量流速增长较快;通道较窄时,入口处蒸汽平均质量流速初期增速较快但迅速达到稳态,通道宽度为150时的稳态入口平均质量流速约是通道宽度为500时的80.0%。对接触角的分析表明:亲水壁面上的液膜厚度受壁面亲水程度影响较小,壁面接触角为51°时出口处液膜厚度与接触角为72°时的相等。普通疏水壁面上珠状凝结难以维持,被液膜覆盖后相较于亲水壁面传热速率较慢,液膜滑移出计算域之前,壁面接触角为127°时壁面平均热流密度最大值约是接触角为51°时的75.8%,并随液膜滑移逐渐降低,但液膜受重力去除后再形成的过程能在一定范围内强化传热速率。[Objective]Condensing heat exchange is a crucial process in the primary circuit of small modular reactors and passive safety systems that rely on natural circulation as the driving force.With the higher requirements for heat exchange efficiency and reactor safety,in-depth research and an understanding of the condensation heat exchange process are needed.Therefore,numerical simulations of the condensing heat exchange process have attracted increasingly more interest.However,due to the complex phase change,the condensing heat exchange process is difficult to model using analytical equations.Traditional numerical simulation methods use the empirical equations summarized in experiments,and their universalities are controversial.In contrast,the lattice Boltzmann method is a mesoscopic-level numerical simulation method that tracks particle clusters and uses probability density functions to describe their distribution,resulting in a simple and clear structure that appropriately ignores the details of molecular motion.Moreover,it allows direct iterative solving of the probability density distribution function without relying on empirical equations.In previous studies,the feasibility of using the lattice Boltzmann pseudopotential model in condensation process simulation was verified.Subsequently,numerous researchers have used this model to analyze the condensation mechanism.[Methods] This study is based on the lattice Boltzmann method and uses a dual distribution function to simulate the condensation process of stationary saturated vapor within a vertical channel.To analyze the fluid flow characteristics,a pseudopotential model is used to simulate the density field variations during the vapor condensation.Additionally,a temperature distribution function is employed to simulate the temperature field changes during the vapor condensation,allowing for an examination of heat transfer efficiency.Throughout the simulation,we analyze the effects of channel width and the hydrophilicity and hydrophobicity of wall conditions on the

关 键 词：冷凝传热 格子BOLTZMANN方法 蒸汽流速 接触角 

分 类 号：O414.13[理学—理论物理]