流体力学与飞行力学

螺旋管内超临界CO2流动方向对换热的影响

  • 李洪瑞 ,
  • 徐肖肖 ,
  • 刘朝 ,
  • 刘新新
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  • 重庆大学 动力工程学院 低品位能源利用技术及系统教育部重点实验室, 重庆 400030
李洪瑞 男,硕士研究生。主要研究方向:超临界二氧化碳在螺旋管中的换热和流动特性。Tel:023-65112469,E-mail:893703924@qq.com;

收稿日期: 2015-06-19

  修回日期: 2015-09-02

  网络出版日期: 2015-09-16

基金资助

国家自然科学基金(51206197);中央高校基本科研业务费专项资金(CDJZR12140032);重庆市研究生科研创新项目(CYS16011)

Flow direction effect on heat transfer of supercritical CO2 in helically coiled tube

  • LI Hongrui ,
  • XU Xiaoxiao ,
  • LIU Chao ,
  • LIU Xinxin
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  • Key Laboratory of Low-grade Energy Utilization Technologies and Systems, College of Power Engineering, Chongqing University, Chongqing 400030, China

Received date: 2015-06-19

  Revised date: 2015-09-02

  Online published: 2015-09-16

Supported by

National Natural Science Foundation of China (51206197); the Fundamental Research Funds for the Central Universities (CDJZR12140032); Project supportod by Graduate Scientific Research and Innoration of Chongqing (CYS16011)

摘要

应用重正化群(RNG)k-ε湍流模型对超临界CO2流体在内径为9 mm,有效受热长度为5.5 m,节距为32 mm,绕径为283 mm的竖直螺旋管中的加热过程开展了数值模拟。研究了质量流速、进口压力、热通量以及不同流向对超临界CO2换热和压降的影响,并进一步分析变物性、浮升力和离心力在不同流动方向上对螺旋管中换热的耦合作用。结果表明:浮升力对超临界流体在螺旋管向上流动与向下流动的影响差别不大,而对水平流动的影响较大尤其是当流体在螺旋管的截面到入口截面的距离与管径之比为150~350之间(即临界温度附近)时,由于变物性、浮升力和离心力的耦合作用,导致水平流动方向上换热系数的震荡。

本文引用格式

李洪瑞 , 徐肖肖 , 刘朝 , 刘新新 . 螺旋管内超临界CO2流动方向对换热的影响[J]. 航空学报, 2016 , 37(7) : 2123 -2131 . DOI: 10.7527/S1000-6893.2015.0245

Abstract

Numerical analysis on heat transfer of supercritical CO2 in heated vertical helically coiled tubes is performed by renormalization group (RNG) k-ε turbulent model. The tube diameter, effective heated length, tube pitch, curvature diameter are 9 mm, 5.5 m, 32 mm and 283 mm, respectively. The influences of the mass flux, inlet pressure, heat flux and flow direction on heat transfer and pressure drop of supercritical CO2 are studied. Furthermore, the combined effects of variable physical properties, buoyancy and centrifugal force in different flow directions of helically coiled tubes on heat transfer are analyzed. It is found that the influence of the buoyancy on the supercritical fluid flow up and down in helically coiled tubes is not significant, while the influence of the buoyancy in the horizontal direction is great, especially when the ratio of the distance which a cross-section of helically coiled tube to the entrance section and the pipe diameteris between 150 and 350 (near the critical temperature). The variable physical properties, the coupling effect of buoyancy and centrifugal force cause the fluctuation of the horizontal heat transfer coefficient.

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