Thesis (MScEng (Department of Electrical Engineering))--University of Cape Town, 2008. / Energy drives technological societies. Developing countries such as South Africa are
caught between the desperate need for economic growth and the emerging obligations
to the environment. Efficient technologies can be used to mitigate the impact of these
seemingly conflicting requirements in urban and rural environments. In this thesis the commercially available white light-emitting diode (LED) with its inherent efficiency, longevity and mechanical strength, is used to show, that success in energy efficiency can be obtained. Two cases are used to illustrate the need for efficient demand-side technology: the electricity shortages of the Western Cape Province in South Africa and a white LED pilot project in Namulonge, Uganda. The Namulonge Solar-Home System (SHS) is analyzed with the intention of creating a more acceptable general lighting solution. The concept of appropriateness through self-determination is discussed within the context of location-specific information integrated into a design procedure. The major thrust and contribution of this thesis, however, is the design of an interior luminaire for Golden Arrow Bus Services (GABS). This is in part based on the
hypothesis that application-specific information will lead to implementation and
human-needs success, and is researched, designed, fabricated and then laboratory
tested. The biggest challenge to be overcome was the spatial light distribution of the
LED array. Thus non-imaging optical lens design became the main focus of this
project as it held the key to utilizing available light while conserving the light-systems energy. Circular Fresnel and Linear Fresnel (an adaptation of the concentric design) lenses were designed. Electrical, mechanical and thermal aspects of design are also detailed. Far-field, horizontal plane detection over the specified area is used to best gain the uniformity of distribution. The four criteria namely luminance, illuminance, intensity and étendue (collection efficiency), against which each design and focal length iv
configuration is compared to, are extensively explored and eventually lead to a final design. In the first designs, the area of the spatial distribution between 50% and 80% of its relative intensity is collimated. The Hybrid Circular Fresnel and Hybrid Linear Fresnel lenses now redirects the relative intensity in two areas, from 50% to 70% (creating parallel rays) and then from 70% to 100% (away from the central axis), renders a distinct difference is spatial uniformity and a reduction in the peak and offaxis located intensity.
All four criteria are met, with a minor adjustment of configuration within the bus
internal luminaire spacing, with the hybrid designs. It is proposed that GABS employ
polished designs of the Hybrid Circular Fresnel, in any of the configurations, which
have collection efficiencies ranging between 64.8% and 78.3%. / Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/357 |
| Date | January 2008 |
| Creators | Solomon, Ramzi, Pillay, P., Sebitosi, A.B. |
| Contributors | Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic Engineering |
| Publisher | Cape Town : Cape Town University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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