Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Concentrating solar power technology is a modern power generation technology
in which central receiver systems play a significant role. For this technology a
field of heliostats is used to reflect solar irradiation to the receiver located on
top of the tower. An extensive review has shown that contemporary receiver
designs face geometric complexities, lack of thermal efficiency as well as issues
with durability and cost. The purpose of this study is to develop a new receiver
concept that can potentially reduce these issues. A parametric analysis
was used to identify potential means of improvement based on an energy balance
approach including sensitivities involved with convection and radiation
heat transfer. Design criteria such as the use of headers to minimize pressure
drop was also investigated. Based on these findings the hybrid pressurized
air receiver was developed which is a combination of tubular and volumetric
receiver technologies. The fundamental idea of the receiver was investigated
by simulating the ray-tracing and coupled natural convection and radiation
heat transfer. The ray-tracing results have shown that the use of quartz glass
is a prospective solution to higher allowable flux densities, but with reflection
losses in the order of 7 %. The coupled natural convection heat transfer
simulation further revealed that the receiver concept effectively eliminates the
escape of buoyant plumes and radiative heat losses are minimized. Empirical
data was gathered from a medium flux concentrator and good agreement with
the numerical results was obtained. The thesis therefore concludes that the
research outcomes were met. Ongoing research aims to optimise the receiver
concept for a 5MW pilot plant. / AFRIKAANSE OPSOMMING: Gekonsentreerde sonkrag tegnologie is ’n moderne kragopwekkingstegnologie
waar sentrale ontvangersisteme ’n beduidende rol speel. Vir hierdie tegnologie
word ’n veld heliostate gebruik om sonstraling na die ontvanger wat aan
die bopunt van die toring geleë is te reflekteer. ’n Omvattende hersiening
het daarop gewys dat kontemporêre ontwerpe van die ontvangers ’n aantal
geometriese kompleksiteite, ’n tekort aan termiese doeltreffendheid sowel as
probleme in terme van duursaamheid en koste in die gesig staar. Die doel van
die studie is om ’n nuwe ontvangerskonsep te ontwikkel wat moontlik hierdie
probleme kan verminder. ’n Parametriese analise is gebruik om potensiële
maniere van verbetering aan te dui wat gebaseer is op ’n energiebalans benadering;
insluitend sensitiwiteite betrokke by konvektiewe en stralingswarmteoordrag.
Ontwerpkriteria soos die gebruik van spruitstukke om drukverliese
te minimaliseer is ook ondersoek. Gebaseer op hierdie bevindinge is die hibriede
saamgepersde-lug ontvanger ontwikkel. Laasgenoemde is ’n kombinasie
van buis- en volumetriese ontvangertegnologie. Die fundamentele idee van die
ontvanger is ondersoek deur straalberekening asook die gelyktydige natuurlike
konveksie en stralingswarmteoordrag te simuleer. Die straalberekeningsresultate
het getoon dat die gebruik van kwarts glas ’n moontlike oplossing is om
hoër stralingsintensiteit te bereik, maar met refleksieverliese in die orde van
7 %. Die gelyktydige natuurlike konveksie en stralingswarmteoordrag simulasie
het verder aan die lig gebring dat die ontvangerkonsep die ontsnapping
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/86377 |
| Date | 04 1900 |
| Creators | Kretzschmar, Holger |
| Contributors | Gauche, P., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xvii, 117 p. : ill. |
| Rights | Stellenbosch University |
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