CFD Study of Fluid Flow in an All-glass Evacuated Tube Solar Water Heater

Ning Ai, Jianhua Fan, Yumin Li

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    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 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.
    Original languageChinese
    JournalJournal of Beijing University of Aeronautics and Astronautics
    Issue number10
    Pages (from-to)1195-1199
    Publication statusPublished - 2008


    • Key words: All-glass evacuated tube solar water heater, Flow field, CFD

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