DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE

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

    Research output: Chapter in Book/Report/Conference proceedingChapter

    Abstract

    Proprietary evacuated tube solar water heaters have superior thermal performance in Northern Maritime climates compared with proprietary flat plate solar water heaters. Typically delivering 5-15% more thermal energy per annum, this is, however, achieved with higher capital costs. The adoption of thermosyphon fluid circulation compared with forced circulation systems allows the capital cost of solar water heating systems to be reduced, reliability increased and similar levels of performance to be achieved, for well designed systems. The thermal performance of an evacuated tube solar water heater system utilising thermosyphon fluid circulation subjected to Northern Maritime climatic conditions at the University of Ulster was monitored from the 23rd of September to 21st of November 2006. Measurements including collector outlet temperatures, mean bulk tank temperatures, ambient temperatures, and incident solar radiation levels were used to determine diurnal efficiency. The manifold of an evacuated tube solar water heater was inclined at 1˚: the manifold outlet being higher than the inlet. During the monitoring period it appeared that thermosyphon flow did not always occur in the direction expected. It was deduced that flow reversal had occurred when the collector inlet temperature was greater than that of the outlet. Comparison of the calculated diurnal efficiency for the days when flow reversal occurred with those when it did not indicated that flow reversal reduced the mean calculated diurnal efficiency by approximately 13%.
    LanguageEnglish
    Title of host publicationHeat transfer in components and systems for sustainable energy technologies
    Place of Publicationgrenoble france
    Pages611-618
    Volume2
    Publication statusPublished - 20 Apr 2007

    Fingerprint

    Solar water heaters
    Thermosyphons
    Flow of fluids
    Temperature
    Incident solar radiation
    Fluids
    Thermal energy
    Costs
    Heating
    Monitoring
    Water
    Hot Temperature

    Keywords

    • solar energy

    Cite this

    Redpath, D. A. G., Lo, S. N. G., & Eames, P. C. (2007). DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE. In Heat transfer in components and systems for sustainable energy technologies (Vol. 2, pp. 611-618). grenoble france.
    Redpath, David A.G. ; Lo, Stephen N G ; Eames, Philip C. / DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE. Heat transfer in components and systems for sustainable energy technologies. Vol. 2 grenoble france, 2007. pp. 611-618
    @inbook{28ad475634354e15b38df7055aae807d,
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    abstract = "Proprietary evacuated tube solar water heaters have superior thermal performance in Northern Maritime climates compared with proprietary flat plate solar water heaters. Typically delivering 5-15{\%} more thermal energy per annum, this is, however, achieved with higher capital costs. The adoption of thermosyphon fluid circulation compared with forced circulation systems allows the capital cost of solar water heating systems to be reduced, reliability increased and similar levels of performance to be achieved, for well designed systems. The thermal performance of an evacuated tube solar water heater system utilising thermosyphon fluid circulation subjected to Northern Maritime climatic conditions at the University of Ulster was monitored from the 23rd of September to 21st of November 2006. Measurements including collector outlet temperatures, mean bulk tank temperatures, ambient temperatures, and incident solar radiation levels were used to determine diurnal efficiency. The manifold of an evacuated tube solar water heater was inclined at 1˚: the manifold outlet being higher than the inlet. During the monitoring period it appeared that thermosyphon flow did not always occur in the direction expected. It was deduced that flow reversal had occurred when the collector inlet temperature was greater than that of the outlet. Comparison of the calculated diurnal efficiency for the days when flow reversal occurred with those when it did not indicated that flow reversal reduced the mean calculated diurnal efficiency by approximately 13{\%}.",
    keywords = "solar energy",
    author = "Redpath, {David A.G.} and Lo, {Stephen N G} and Eames, {Philip C}",
    note = "Reference text: DGS, 2005, Planning and installing solar thermal systems: a guide for installers, architects, and engineers, German Solar energy society, pp. 35 Morrison G, 1986, Technical note: Reverse circulation in thermosyphon solar water heaters, Solar Energy, volume 36, pp.377-379 Morrison G, Budihardjo I, Behnia M, 2004, Water-in-glass evacuated tube solar water heaters, Solar Energy, 2004, volume 76, issues 1-3, pp. 135-140 Morrison G, Tran N, McKenzie D, Onley I, Harding G, Collins R, 1984, Long-term performance of evacuated tubular solar water heaters in Sydney, Australia, Solar Energy, volume 32, pp.785-791 Murphy J M, Sexton D M H, Barnett D N, Jones G S, Webb M J, Collins M and Stainforth D A, 2004, Quantification of modelling uncertainties in a large ensemble of climate change simulations, Nature, volume 430, pp.768-772. Norton B, Eames P C and Lo S, 2001, Alternative approaches to thermosyphon solar energy water heater performance analysis and chararacterisation, Renewable and Sustainable Energy Reviews, pp79-96, volume 5, issue 1. Norton B and Probert S, 1986, Thermosyphon Solar Water Heaters, Advances in Solar Energy, Volume 3, part 3, pp.125-170 Norton B and Probert S, 1983, Achieving thermal rectification in natural-circulation solar-energy water heaters, Applied Energy, volume 14, pp.211-225 Prapas D and Sotiropoulos B, 1991, The elimination of the reverse circulation in thermosyphon solar water heaters, Solar Energy, volume 46, issue 4, pp.237-239 Redpath D, Lo S and Eames P, 2006, An experimental investigation of inclined thermosyphon fluid flow within an enclosed hexagonal cavity with heat transfer via pin-fins, Conference proceedings REMIC2, Dublin Institute of Technology.",
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    Redpath, DAG, Lo, SNG & Eames, PC 2007, DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE. in Heat transfer in components and systems for sustainable energy technologies. vol. 2, grenoble france, pp. 611-618.

    DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE. / Redpath, David A.G.; Lo, Stephen N G; Eames, Philip C.

    Heat transfer in components and systems for sustainable energy technologies. Vol. 2 grenoble france, 2007. p. 611-618.

    Research output: Chapter in Book/Report/Conference proceedingChapter

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    AB - Proprietary evacuated tube solar water heaters have superior thermal performance in Northern Maritime climates compared with proprietary flat plate solar water heaters. Typically delivering 5-15% more thermal energy per annum, this is, however, achieved with higher capital costs. The adoption of thermosyphon fluid circulation compared with forced circulation systems allows the capital cost of solar water heating systems to be reduced, reliability increased and similar levels of performance to be achieved, for well designed systems. The thermal performance of an evacuated tube solar water heater system utilising thermosyphon fluid circulation subjected to Northern Maritime climatic conditions at the University of Ulster was monitored from the 23rd of September to 21st of November 2006. Measurements including collector outlet temperatures, mean bulk tank temperatures, ambient temperatures, and incident solar radiation levels were used to determine diurnal efficiency. The manifold of an evacuated tube solar water heater was inclined at 1˚: the manifold outlet being higher than the inlet. During the monitoring period it appeared that thermosyphon flow did not always occur in the direction expected. It was deduced that flow reversal had occurred when the collector inlet temperature was greater than that of the outlet. Comparison of the calculated diurnal efficiency for the days when flow reversal occurred with those when it did not indicated that flow reversal reduced the mean calculated diurnal efficiency by approximately 13%.

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    Redpath DAG, Lo SNG, Eames PC. DIURNAL REVERSE FLUID FLOW IN THERMOSYPHON EVACUATED TUBE SOLAR WATER HEATERS IN A NORTHERN MARITIME CLIMATE. In Heat transfer in components and systems for sustainable energy technologies. Vol. 2. grenoble france. 2007. p. 611-618