Modelling atmospheric transmittance for clear-sky spectral solar radiation in practical applications
| dc.contributor.advisor | Strauss, Johann | en_ZA |
| dc.contributor.author | Lewis, Carmen | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. | en_ZA |
| dc.date.accessioned | 2021-10-12T07:17:36Z | |
| dc.date.accessioned | 2021-12-22T14:16:27Z | |
| dc.date.available | 2021-10-12T07:17:36Z | |
| dc.date.available | 2021-12-22T14:16:27Z | |
| dc.date.issued | 2021-12 | |
| dc.description | Thesis (PhD)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Solar radiation technological advancements are contributing to increased solar power generation, energy access, and innovative use of solar power. However, developing countries still experience contention in adopting renewable energies as competitor energy generation technologies. A significant barrier for these countries is data-scarcity, which results in solar radiation research deficits. Developing countries, therefore, require innovative solar radiation characterisation, modelling and forecasting methodologies to circumvent this data-scarcity and still access the global technological advancements. Specific solar radiation methodologies often include several sub-models (or processes, which are formulated sequentially. Although the advantage of this approach is flexibility, the resulting model is influenced by the accuracy of sub-models. Considering that sky condition classification is an imperative component of clear-sky model conditioning, it is of interest whether the specific subjectivity and interdependence observed in literature can be removed from the classification process. As a result, a new solar resource classification methodology is formulated from fundamental frequency theory to overcome these interdependencies, while requiring few input parameters. A predominantly qualitative analysis of the classification results is pursued, due to the inherent subjectivity of classification and the validation method deficits in the literature. High-resolution sky images are used to demonstrate the character of each solar resource class, and the conservatism and flexibility of the classification methodology. In this dissertation, atmospheric transmittance methodologies for clear-sky spectral solar radiation modelling and assessment are further discussed. Technical applications of spectral models require a balance between rigour and accessibility - a balance not yet found in atmospheric transmittance literature. In general, transmittance methodologies formulate individual atmospheric extinction events to determine terrestrial radiation. These extinction events include Rayleigh and Mie scattering, and selective atmospheric gaseous absorption. Due to the varying influence (on solar radiation of the latter, the transmittance of these gaseous absorbers is inconsistently considered in literature, and often includes estimates and parametrisations. Transmittance methodologies generally also assume a single-layer atmospheric structure, which results in convoluted (atmospheric pressure and temperature adaptations. In this study, a minimal spectral clear-sky terrestrial model is developed for calculating the atmospheric transmittance of gaseous absorbers. The atmosphere is modelled according to a representative atmospheric layer, and the Bouguer-Beer-Lambert law is adopted to for- mulate gas-speci c transmittance functions. This approach can be used to calculate separate transmittances for speci c atmospheric layers, in simulation to more rigorous codes, while maintaining the simplicity expected for solar radiation applications. This approach also ex- cludes the use of uncommon ground-based data - accessible remote retrievals are adopted. However, this approach is exible and allows reference pro les and monthly averages of gaseous absorbers use. As a result, the proposed gaseous absorber transmittances based on a representative atmospheric layer, are well suited to data-scarce locations such as southern Africa. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Tegnologiese vooruitgang met sonstraling dra by tot verhoogde opwekking van sonkrag, toegang tot energie en innoverende gebruik van sonkrag. Ontwikkelende lande ervaar egter steeds twyfel oor die aanvaarding van hernubare energie as mededingende tegnologieë vir energieopwekking. `n Belangrike hindernis vir hierdie lande is die skaarste aan data, wat lei tot navorsingstekorte op sonstraling. Ontwikkelende lande benodig dus innoverende metodieke vir die karakterisering, modellering en voorspelling van sonstraling om hierdie data-skaarste te omseil en steeds toegang tot die wêreldwye tegnologiese vooruitgang te verkry. Spesifieke sonstralingsmetodologieë bevat dikwels verskeie submodelle (of prosesse wat opeenvolgend geformuleer word. Alhoewel die voordeel van hierdie benadering buigsaam- heid is, word die gevolglike model beà nvloed deur die akkuraatheid van submodelle. Aan- gesien die klassifikasie van lugtoestande `n noodsaaklike onderdeel van `n helderlugmodel- kondisionering is, is dit van belang of die spesifieke subjektiwiteit en interafhanklikheid wat in die literatuur waargeneem word, van die klassifikasieproses verwyder kan word. As gevolg hiervan word `n nuwe sonhulpbron klassifikasiemetodiek geformuleer uit die fundamentele frekwensie-teorie om hierdie onderlinge afhanklikheid te oorkom, terwyl daar min insetpa- rameters nodig is. `n Oorwegend kwalitatiewe analise van die klassifikasie-resultate word nagestreef vanweë die inherente subjektiwiteit van klassifikasie en die valideringmetode te- korte in die literatuur. Hemelbeelde met hoë resolusie word gebruik om die karakter van elke sonhulpbronklas en die konserwatisme en soepelheid van die klassifikasiemetodologie te demonstreer. In hierdie proefskrif word metodieke vir oordrag deur atmosferiese strukture vir die modellering en assessering van helderlug spektrale sonstraling verder bespreek. Tegniese toepassings van spektrale modelle vereis `n balans tussen strengheid en toeganklikheid - `n balans wat nog nie gevind word in atmosferiese transmissie-literatuur nie. Oor die algemeen formuleer transmissiemetodieke individuele atmosferiese uitwissingsgebeure om die aardstra- ling te bepaal. Hierdie uitwissinggebeure sluit in die verspreiding van Rayleigh en Mie en selektiewe atmosferiese gasabsorpsie. As gevolg van die wisselende invloed (op sonstraling van laasgenoemde, word die oor- drag van hierdie gasvormige absorbeerders inkonsekwent in die literatuur oorweeg, en bevat dit dikwels ramings en parameteriserings. Transmissiemetodologieë neem gewoonlik ook 'n enkellaag atmosferiese struktuur aan, wat ingewikkelde (atmosferiese) druk- en temperatuur- aanpassings tot gevolg het. In hierdie studie word 'n minimale aardse model vir spektrale helderlug ontwikkel vir die berekening van die atmosferiese transmissie van gasabsorbeerders. Die atmosfeer is gemo- delleer volgens `n verteenwoordigende atmosferiese laag, en die Bouguer-Beer-Lambert-wet word aanvaar om gasspesifieke deurlaatfunksies te formuleer. Hierdie benadering kan ge- bruik word om aparte transmissies vir spesifieke atmosferiese lae te bereken, in simulasie na strengere kodes, terwyl die eenvoud wat verwag word vir sonstralingstoepassings behoue bly. Hierdie benadering sluit ook die gebruik van ongewone grond-gebaseerde data uit - toeganklike afstandherwinnings word gebruik. Hierdie benadering is egter buigsaam en laat verwysingsprofiele en maandelikse gemiddeldes van gasdempers toe. As gevolg hiervan is die voorgestelde gasabsorbeerder transmittansie gebaseer op 'n verteenwoordigende atmosferiese laag, baie geskik vir data-skaars plekke soos suidelike Afrika. | af_ZA |
| dc.description.version | Doctoral | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/123697 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch Univesity | en_ZA |
| dc.subject | Practical Applications | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.subject | Solar Radiation | en_ZA |
| dc.subject | Solar power | en_ZA |
| dc.subject | Atmospheric transmission of infrared radiation | en_ZA |
| dc.title | Modelling atmospheric transmittance for clear-sky spectral solar radiation in practical applications | en_ZA |
| dc.type | Thesis | en_ZA |