An Experimental Investigation Of Inclined Thermosyphon Fluid Flow Within An Enclosed Irregular Hexagonal Cavity With Heat Transfer Via Pin-Fins

David A.G. Redpath, Stephen N G Lo, Philip C Eames

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    Evacuated Tube Solar Water Heaters (ETSWHs) have superior thermal performance in Northern Maritime Climates compared with Flat Plate Solar Water Heaters (FPSWHs) delivering 5% to 15% more energy per annum. ETSWHs with heat pipe absorbers are especially suited for use in Northern Maritime Climates due to their freeze tolerance and self-regulating thermal diode characteristics. ETSWHs have a higher capital cost than FPSWHs and have yet to be extensively tested and optimised under Northern Maritime climatic conditions. The adoption of thermosyphon fluid circulation in conjunction with ETSWHs has the potential to reduce capital and maintenance costs whilst increasing reliability, without affecting thermal performance. Previous research has reported that inclining thermosyphons influences flow structure and only focused on inclined cylindrical manifolds with a single orifice, and the inlet and outlet located at the same end of the inclined manifold. Other research into enclosed natural convection has focused on inclined rectangular cavities. This paper describes the construction of a truncated, 5-pin fin system, laboratory model of a proprietary ETSWH manifold. This manifold has separate orifices for the inlet and outlet, with an irregularly shaped 6-sided, rather than cylindrical or rectangular manifold cross section. This was incorporated into a collector loop and storage tank mimicking an operational thermosyphon solar water heating system. A range of existing empirical relationships for natural convection within enclosed horizontal cavities was compared to the experimental data. It was found that the best agreement was obtained for the case of natural convection from inclined horizontal smooth cylinders
    Original languageEnglish
    Title of host publicationRenewable energy in maritime island climates, conference proceedings REMIC 2
    Place of PublicationAbingdon, UK
    PublisherInternational Solar Energy Society
    ISBN (Print)0 90496372 1
    Publication statusPublished (in print/issue) - 28 Apr 2006

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    • natural convection
    • solar energy
    • fluid flows


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