Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The design, development and evaluation of a novel wave energy converter (WEC)
device, called the ShoreSWEC, in a South African port development is presented.
Based on the device requirements, site selection criteria were specified and applied
to identify a suitable deployment location. A wave modeling procedure was
developed to determine the operational wave conditions and available wave power
resource at the selected location. The site was found to have a low mean annual
average resource of approximately 2.3 kilowatt per meter wave crest (kW/m) due to
its relatively sheltered location. The wave model was further used to determine
design storm conditions and a structural stability analysis of the device was
conducted.
Experimental tests were performed to evaluate the hydrodynamic conversion
efficiency of a single chamber of the device at its most conservative orientation,
under a variety of wave energy conditions. The effect of a floor incline and an
additional chamber on the performance of the system was investigated. The incline
improved efficiency for low wave heights, making it ideal for the low wave power
resource conditions of the site, whilst the multi-chamber system experienced
increased performance at high wave periods. A comparison between the
ShoreSWEC and a conventional oscillating water column (OWC) WEC showed that
the OWC extracted 72% more energy, highlighting the sensitivity of performance on
device orientation. A three-dimensional (3D) numerical model of the experimental
setup was developed. The numerical model provided comparable water surface
elevations inside the flume and chamber, yet predicted significantly higher internal
chamber pressures and overall efficiency. The electricity generation potential of a 10
chamber ShoreSWEC at the specified location, approximated from the experimental
results and 11 years of hindcast wave data, was found to be 6 kW on average for a
15 kW capacity system.
Results of this study highlighted the need for greater understanding of the
hydrodynamic characteristics of a full length device. Experimental tests in a 3D wave
basin on a scaled full length ShoreSWEC model are therefore recommended. Once
conducted, South Africa will be one step closer to the deployment of the full scale
SWEC device. / AFRIKAANSE OPSOMMING: Die ontwerp, ontwikkeling en evaluasie van ‘n unieke golfenergieomsetter (GEO),
genaamd die ShoreSWEC, in ‘n Suid-Afrikaanse haweontwikkeling word aangebied.
Terrein evaluasie kriteria, gebaseer op die omsettervereistes, is ontwikkel en
toegepas om die mees belowende terrein te identifiseer. ‘n
Golfmodeleringsprosedure is ontwikkel om die operasionele golfkondisies en
beskikbare golfdrywinghulpbron te bepaal. Daar is gevind dat die terrein ‘n lae
gemiddelde golfdrywing van bykans 2.3 kilowat per meter golfkruin het as gevolg
van die beskutte ligging. Die golfmodel is verder gebruik om ontwerpstormkondisies
te bepaal en ‘n stabiliteitsanalise was op die toestel struktuur uitgevoer.
Eksperimentele toetse van verskeie golfenergie kondisies is gedoen om die
hidrodinamiese omsettingseffektiwiteit van ‘n enkel kamer van die toestel te bepaal
teen sy konserwatiefste orientasie. Die effek van ‘n vloerhelling en ‘n addisionele
kamer op die uitsette van die sisteem is ondersoek. Die helling het effektiwiteit
verbeter vir lae golfhoogtes wat dit ideaal maak vir die lae hulpbron by die terrein,
terwyl die veelvoudige-kamer-sisteem beter gevaar het by hoë golfperiodes. ‘n
Vergelyking tussen die ShoreSWEC en ‘n konvensionele ossilerende waterkolom
(OWK) GEO het gewys dat die OWK 72% meer energie onttrek. Dit beklemtoon die
sisteem se sensitiwiteit vir die inkomende golfrigting. ‘n Drie-dimensionele (3D)
numeriese model van die eksperimentele opstelling is ontwikkel. Die numeriese
model het aansienlik hoër drukke binne die kamer, en gevolglik algehele effektiwiteit,
voorspel as die eksperimentele toetse. Die elektriese opwekkingskapasiteit van ‘n 10
kamer ShoreSWEC by die terrein, gebaseer op die eksperimentele resultate en 11
jaar se golfdata, is bereken as 6 kW gemiddeld vir ‘n 15 kW kapasiteit stelsel.
Die bevindinge van hierdie studie het die behoefte aan ‘n beter begrip van die
hidrodinamiese eienskappe van ‘n vollengte sisteem beklemtoon. Eksperimentele
toetse in ‘n 3D golfbak op ‘n geskaleerde vollengte ShoreSWEC model word dus
aanbeveel. Sodra dit voltooi is, sal Suid-Afrika een stap nader wees aan die
ontplooiing van ‘n volskaalse SWEC toestel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85817 |
| Date | 12 1900 |
| Creators | Joubert, James Rattray |
| Contributors | Van Niekerk, J. L., Retief, G. de F., 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 | xviii, 150 p. : ill. |
| Rights | Stellenbosch University |
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