uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Characterization of selective solar absorbers: Experimental and theoretical modeling
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Materials Science.
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the preparation, optical characterization and analyses of experimental work and theoretical modeling on selective solar absorbers used in solar thermal collectors. The overall goal has been to obtain efficient absorbers by optimizing the optical properties, and to improve their durability using cost-effective techniques.

A Ni-Al2O3 absorber was pyrolytically coated with SnO2 to improve its coating quality. Undesirable increase of solar reflectance obtained as a result of the SnO2 was reduced by applying a silica antireflection layer produced by a dipping technique from colloidal silica sol. Annealing of Ni particles in an Al2O3 matrix was also carried out and compared to particles heated without the matrix. Due to the Al2O3 matrix, a much slower oxidation rate was found for the embedded particles. In addition, the optical performance of commercial Ni-Al2O3 and Ni-NiOx absorbers were experimentally compared at oblique incidence. A better solar-absorptance of the Ni-Al2O3 at higher angles of incidence was found. This is due to enhanced optical interference in the double-layer structure of Ni-Al2O3, which could not be achieved in the graded index film of Ni-NiOx.

The optical properties of Si-Al2O3 films of different thicknesses have been investigated by preparing the films using an integral coloration method. The solar-absorptance and thermal-emittance were found to increase with increasing film thickness. Due to high thermal-emittance, the Si-Al2O3 coating shows non-selective absorbing properties. Its feasibility for a selective solar absorber was studied by modeling the coating as a function of coating thickness for different particle size and volume fraction using four-flux theory. The results indicated that the Si-Al2O3 coating is not a suitable candidate for selective solar absorbers.

Scattering and absorption cross-sections of FeMnCuOx and black carbon pigments have been obtained from reflectance and transmittance measurements in the solar wavelength range. The cross-sections were determined by using pellets consisting of low pigment volume fractions dispersed in KBr matrix. The cross-sections exhibit linear dependence of the volume fraction, indicating that single scattering dominates. The cross-sections were used to model the optical properties of solar selective paints using four-flux model resulting in good agreement between calculations and experiments.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2000. , 79 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 556
Keyword [en]
Materials science
Keyword [sv]
National Category
Materials Engineering
Research subject
Solid State Physics
URN: urn:nbn:se:uu:diva-1065ISBN: 91-554-4772-4OAI: oai:DiVA.org:uu-1065DiVA: diva2:160605
Public defence
2000-09-29, Rum 2001, Ångströmlaboratoriet, Uppsala, 09:30
Available from: 2000-09-08 Created: 2000-09-08Bibliographically approved

Open Access in DiVA

fulltext(1588 kB)12939 downloads
File information
File name FULLTEXT01.pdfFile size 1588 kBChecksum MD5
Type fulltextMimetype application/pdf
Buy this publication >>

By organisation
Department of Materials Science
Materials Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 12939 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 2319 hits
ReferencesLink to record
Permanent link

Direct link