Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The increased necessity to obtain power from other sources than conventional
fossil fuels has led to the growing interest in solar power. The problem with
the proposed technology is that it can only provide power during the day
and therefore requires some sort of storage system, if power is to be supplied
throughout the day and night. A number of storage systems exist, but the one
of particular interest for this research, is packed rock beds. Rock beds have the
advantage that if designed right, they have the potential to be one of the most
cost effective means of storing thermal energy for solar power plants. Discrete
Element Models (DEM) of rock beds were therefore developed through both
experimental and numerical procedures, by conducting a series of sensitivity,
calibration and verification studies.
The developed models were then used to study various aspects associated with
rock beds, which were either too impractical, impossible or too expensive to
conduct through actual experimental work. This research focused specifically
on the potential of constructing self-supporting tunnels within the rock beds
in order to improve the air flow uniformity through the bed, while minimizing
the pressure drop. It was observed that if the appropriate steps were followed,
stable self-supporting tunnels could be formed. Valuable information such as
the rock orientations resulting from different packing directions could also be derived from the models and finally, a method to convert the DEM models into
the appropriate format such that it could be imported into a CFD preprocessor
for future CFD studies, was developed. / AFRIKAANSE OPSOMMING: Die verhoogde noodsaaklikheid om energie te verkry uit ander bronne as konvensionele fossielbrandstowwe, het gelei tot die groeiende belangstelling in
sonkrag energie. Die probleem met die voorgestelde tegnologie is dat dit net
energie gedurende die dag kan voorsien en dus word daar ’n stoorstelsel benodig indien energie deur beide die dag en nag voorsien moet word. Tans bestaan
daar wel ’n aantal van hierdie stoorstelsels, maar die een wat van besondere
belang is in hierdie navorsing, is verpakte klip beddens. Klip beddens het die
voordeel dat, indien dit reg ontwerp is, dit oor die potensiaal beskik om een
van die mees koste-doeltreffende middels te wees vir die stoor van termiese
energie vir sonkragstasies. Diskreet Element Modelle (DEM) van die klip beddens is ontwikkel deur gebruik te maak van beide experimentele en numeriese
metodes waartydens ’n reeks sensitiwiteits-, kalibrasie- en verifiëring studies
uitgevoer is.
Die ontwikkelde modelle is gebruik om verskeie aspekte van klip beddens te
ondersoek, wat of te onprakties, onmoontlik of te duur is vanuit ’n eksperimentele oogpunt. Hierdie navorsing het spesifiek gefokus op die potensiaal om
self-ondersteunende tonnels binne in die klip beddens te vorm, ten einde die egaligheid van die lugvloei deur die bed te verbeter, terwyl die drukval geminimeer word. Daar is waargeneem dat stabiele self-ondersteunende tonnels wel
gevorm kon word indien die toepaslike stappe gevolg is. Waardevolle inligting
soos die klip oriëntasies wat as gevolg van die verskillende verpakkings rigtings
onstaan kon ook vanuit die model verkry word. Ten slotte is ’n metode ontwikkel om die DEM modelle na die toepaslike formaat te omskep sodat dit ten
einde gebruik kan word in numeriese vloeidinamika studies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/80147 |
| Date | 03 1900 |
| Creators | Nel, Rick Guillaume |
| Contributors | Coetzee, C. J., 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 | Unknown |
| Type | Thesis |
| Format | xix, 125 p. : ill. |
| Rights | Stellenbosch University |
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