管壳式换热器热-磁-流耦合强化换热数值分析  

Numerical Analysis with Thermal-Magnetic-Fluid Coupling on Enhanced Heat Transfer for Shell-and-Tube Heat Exchanger

作　　者：谢志辉[1] 刘瀚钰 吴杰长[1] 陆卓群 张健[1] 奚坤 XIE Zhihui;LIU Hanyu;WU Jiechang;LU Zhuoqun;ZHANG Jian;XI Kun(School of Power Engineering,Naval University of Engineering,Wuhan 430033,Hubei,China;School of Energy,Mechanical&Electronic Engineering,Hunan University of Humanities,Science and Technology,Loudi 417000,Hunan,China)

机构地区：[1]海军工程大学动力工程学院,湖北武汉430033 [2]湖南人文科技学院能源与机电工程学院,湖南娄底417000

出　　处：《华南理工大学学报（自然科学版）》2023年第3期22-32,共11页Journal of South China University of Technology(Natural Science Edition)

基　　金：国家自然科学基金资助项目(51979278,51579244)。

摘　　要：采用Fe_(3)O_(4)/水磁性纳米流体和磁场改善管壳式换热器壳程的对流换热性能。通过三维数值模拟,分析了磁性纳米流体体积分数、流率和磁感应强度对管壳式换热器对流换热性能的影响。结果表明,换热器的传热率和强化效应会因为纳米粒子的导热系数和布朗运动而得到提高,但当体积分数大于1%时,提升幅度会逐渐减小并且效能评价系数会降低。相比其他性能强化技术,磁场对磁性纳米流体的作用可以使换热器在压降增加不大的情况下显著提高换热性能;与没有施加磁性纳米流体和磁场的情况相比,磁场下加入了Fe_(3)O_(4)/水磁性纳米流体的管壳式换热器的传热率提升最高可达68.2%,而压降只增加了13.8%,与施加了磁性纳米流体而没有施加磁场的情况相比,其传热率的提升最高可达46.7%,而压降只增加了1.96%。磁性纳米粒子本身具有的高导热性质和其布朗运动效应以及磁性纳米流体在垂直均匀磁场的作用下带动壳程流体形成的由内向外的旋流,加剧了对热边界层的扰动和冷热流体的混合,是对流换热性能增强的主要原因,且磁感应强度越大,流体流率越低,磁场对流体综合传热性能的影响越显著。This paper used Fe_(3)O_(4)/water magnetic nanofluid and magnetic field to improve the convective heat trans⁃fer performance of shell side of shell and tube heat exchanger.Through three-dimensional numerical simulation,this paper analyzed the effects of magnetic nanofluid volume fraction,flow rate and magnetic induction intensity on the convective heat transfer performance of shell and tube heat exchanger.The results show that the heat transfer rate and strengthening effect of the heat exchanger can be improved due to the thermal conductivity and Brownian motion of the nanoparticles,but when the volume fraction is greater than 1%,the improvement will gradually de⁃crease and the efficiency evaluation coefficient will also decrease.Compared with other performance enhancement techniques,the effect of magnetic field on magnetic nanofluid can significantly improve the heat transfer perfor⁃mance of the heat exchanger with little increase in pressure drop.Compared with the condition without magnetic nanofluid and magnetic field,the heat transfer rate can be increased by up to 68.2%,while the pressure drop only increases by 13.8%.Compared with the condition with magnetic nanofluid but without magnetic field,the heat transfer rate can be increased by up to 46.7%and the pressure drop only increases by 1.96%.The high thermal conductivity of magnetic nanoparticles and Brownian motion effect,as well as the inner to outer swirling flow driven by magnetic nanofluids under the action of vertical uniform magnetic field,aggravate the disturbance of thermal boundary layer and the mixing of hot and cold fluids,and this is the main reason for the increase of convective heat transfer performance.And the greater the magnetic induction intensity is,the lower the fluid flow rate is,and the more significant the influence of the magnetic field on the fluid is.

关 键 词：管壳式换热器 强化传热 多物理场耦合 磁场 纳米流体 

分 类 号：TK12[动力工程及工程热物理—工程热物理]