The project aim was to investigate the potential of a large scale, inexpensive, solar thermal façade in the UK climate. Profiled steel cladding was utilised as a solar absorber, with the channels used to form a series of parallel ducts when covered by a glass surface. Air was considered to flow through the ducts in two modes; forced or buoyant convection. The factors affecting air flow were investigated in a laboratory experiment. The factors affecting solar heat transfer to the air were investigated using prototypes in field conditions. Three models for forced convection and two for buoyant were found in the literature. These were developed and compared against the experimental results to establish appropriate design models. The design models were used to optimise the duct geometry for three desirable outputs; mass flow, temperature output or power output. Optimal duct geometry was found to depend on the flow mode assumed. In addition, the optimal geometry also depended on the required output. Thus it was determined that an optimal hybrid system which could switch modes as required, could not be configured; the function and utility of the system must be decided at the design stage and not reconfigured afterwards. The annual performance of a building-scale south facing façade fitted with such a system (optimised for power output) was modelled for forced and buoyant convection modes. It was found that both flow modes had the potential to generate significant amounts of heat energy which could be used, for instance, to preheat ventilation air. The buoyant system also showed the potential for the generation of significant natural ventilation. However the forced convection system would have the advantage of being more controllable, have a better seasonal distribution of performance and have a greater potential for higher air exit temperatures to be achieved in winter.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:567550 |
| Date | January 2007 |
| Creators | Stevenson, Elizabeth Victoria |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/27935/ |
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