Modelling the convective flow in solar thermal receivers

Kevin Yeh, Graham Hughes, Keith Lovegrove

    Research output: Contribution to journalMeeting Abstract

    Abstract

    The natural convective flow inside a concentrating solar thermal cavity receiver is studied experimentally. The convective flow is driven by buoyancy forces and leads to heat losses. An experimental investigation of the flow inside a receiver was carried out using density differences produced using the varying salt concentrations in a water tank. The flow was visualised for a range of cavity receiver orientations 0° (horizontal) to 90°(downwards) and Flux Grashof numbers 7x104 to 1010. The results show a circulatory flow develops as ambient fluids enters, rise through ‘heating’ and exits the cavity. A stagnant volume at the top of the cavity forms as the inclination increases from 0°. When the inclination reaches 90°, the stagnant volume fills the entire cavity and convective heat losses minimised. The flows observed inside the model cavity receiver are laminar over the range of Flux Grashof numbers applicable to actual receivers (of order 107) are laminar. However, the
    transition to turbulent flow, which leads to greater heat losses, is also observed for Flux Grashof numbers of order 107.
    Original languageEnglish
    Number of pages8
    JournalProceedings of the 43rd Conference of the Australia and New Zealand Solar Energy Society
    Publication statusPublished - 2005
    EventAustralia and New Zealand Solar Energy Society Conference (Solar 2005) - Dunedin New Zealand
    Duration: 1 Jan 2005 → …

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