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Title: An experimental investigation of thermosyphon heat pipe evacuated tube solar water heaters subjected to a northern maritime climate
Author: Redpath, David A. G.
ISNI:       0000 0001 3510 9290
Awarding Body: University of Ulster
Current Institution: Ulster University
Date of Award: 2007
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Proprietary evacuated tube solar water heaters (ETSWH) have superior thennal perfonnance in Northern Maritime climates compared with proprietary flat plate solar water heaters (FPSWHs). ETSWHs with heat pipe absorbers are especially suited for use in Northern Maritime climates due to their freeze tolerance and self-regulating heat transfer characteristics and ability to act as thennal diodes. Typically delivering 5-15% more thermal energy per annum, than FPSWHs, 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 ofperfonnance to be achieved, for well designed systems. This thesis presents experimental data concerned with thermosyphon heat pipe ETSWHs operated under Northern maritime climatic conditions. It was determined that current proprietary designs of heat pipe ETSWHs originally designed for forced circulation can operate effectively when subjected to a Northern Maritime climate when thennosyphon ' fluid circulation is used instead. Though it was fo~nd that current designs are prone to diurnal reverse fluid flows which 'reduce diurnal efficiency by 11.5% Over the monitoring period from January 2007 to June 2007 it was calculated that predicted and measured solar fractions were within 2.5%. Simple payback periods and costs of the delivered energyare presented and discussed using collected and average meteorological data for the test site located at the Jordanstown campus(fthe University ofUlster. Natural convection within the manifold chamber was investigated through construction of physical models of the manifold chamber under investigation. Reverse thennosyphon fluid flows were recreated under laboratory conditions. Interactions between the pin-fin array within the manifold occurred and it was shown how these affected heat transfer within the manifold cavity. Two dimensional particle imaging velocimetry was used to visualise the thermosyphon fluid flow regime within the manifold chamber. The processed images validated the observations made by previous research that at the pin-fin diameter to spacing ratio used in proprietary heat pipe ETSWHs that locally heat transfer is degraded as the fluid travels through the cavity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available