北京航空航天大学学报 ›› 2008, Vol. 34 ›› Issue (10): 1195-1199.

• 论文 • 上一篇    下一篇

全玻璃真空管型太阳热水器内流场的CFD模拟

艾 宁1, 樊建华2, 李育敏3   

  1. 1. 浙江工业大学 机电工程学院, 杭州 310032;
    2. 丹麦技术大学 土木工程系, 哥本哈根;
    3. 浙江工业大学 化学工程与材料学院, 杭州 310032
  • 收稿日期:2007-09-25 出版日期:2008-10-30 发布日期:2010-09-16
  • 作者简介:艾 宁(1977-),男,江苏江宁人,副教授,aining@zjut.edu.cn.

CFD study of fluid flow in an all-glass evacuated tube solar water heater

Ai Ning1, Fan Jianhua2, Li Yumin3   

  1. 1. College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310032, China;
    2. Dept. of Civil Engineering,Technical University of Denmark, Copenhagen;
    3. College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032, China
  • Received:2007-09-25 Online:2008-10-30 Published:2010-09-16

摘要: 全玻璃真空管型太阳热水器是技术相对成熟、应用最广的太阳能利用方式.通过对全玻璃真空管型太阳热水器内流场的计算流体力学模拟,研究了器内的对流换热过程,分析了真空管截面的流体流动速度分布,考察了真空管不同位置处的流体循环速度及箱体内水温对循环速度的影响.结果表明,随着流体温度的升高,器内出现随机的湍动涡流;涡流的存在将造成管内冷热流体的混和,对换热过程不利;在真空管内安置引流挡板将抑制流体的湍动,确保有序的热对流流动,提高对流换热效率.研究结果有助于剖析热水器内对流换热的机理,对技术革新提供参考.

Abstract: The all-glass evacuated tube solar water heater is one of the most widely used solar thermal technologies. The aim of the paper is to investigate fluid flow in the solar water heater by means of the computational fluid dynamics (CFD). The investigation was carried out with a focus on the convective heat transfer in the tube. The buoyancy induced flow circulation in different parts of the tube was analyzed. It is shown that fluid flow becomes stochastic and turbulent if fluid temperature is high enough. The flow instability leads to mixing of the warm uprising flow and the cold downward flow, which decreases efficiency of the heat exchange process. A baffle in the tube can prevent the flow instability and secure the flow circulation in the tube. The results of the investigation provide a helpful guidance for further investigation of the mechanism of heat transfer processes and a reference for future system optimization.

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