Change search
ReferencesLink to record
Permanent link

Direct link
Accelerated aging of thick glass second surface silvered reflectors under sandstorm conditions
Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
2011 (English)Independent thesis Advanced level (degree of Master (Two Years))Student thesis
Abstract [en]

Concentrated solar power systems are expected to be sited in desert locations where the direct normal irradiation is above 1800 kWh/m2.year. These systems include large solar collector assemblies, which account for a significant share of the investment cost. Solar reflectors are the main components of these solar collector assemblies and dust/sand storms may affect their reflectance properties, either by soiling or by surface abrasion. While soiling can be reverted by cleaning, surface abrasion is a non reversible degradation. The aim of this project was to study the accelerated aging of second surface silvered thick glass solar reflectors under simulated sandstorm conditions and develop a multi-parametric model which relates the specular reflectance loss to dust/sand storm parameters: wind velocity, dust concentration and time of exposure. This project focused on the degradation caused by surface abrasion. Sandstorm conditions were simulated in a prototype environmental test chamber. Material samples (6cm x 6cm) were exposed to Arizona coarse test dust. The dust stream impacted these material samples at a perpendicular angle. Both wind velocity and dust concentration were maintained at a stable level for each accelerated aging test. The total exposure time in the test chamber was limited to 1 hour. Each accelerated aging test was interrupted every 4 minutes to measure the specular reflectance of the material sample after cleaning. The accelerated aging test campaign had to be aborted prematurely due to a contamination of the dust concentration sensor. A robust multi-parametric degradation model could thus not be derived. The experimental data showed that the specular reflectance loss decreased either linearly or exponentially with exposure time, so that a degradation rate could be defined as a single modeling parameter. A correlation should be derived to relate this degradation rate to control parameters such as wind velocity and dust/sand concentration. The sandstorm chamber design would have to be updated before performing further accelerated aging test campaigns. The design upgrade should improve both the reliability of the test equipment and the repeatability of accelerated aging tests. An outdoor exposure test campaign should be launched in deserts to learn more about the intensity, frequency and duration of dust/sand storms. This campaign would also serve to correlate the results of outdoor exposure tests with accelerated exposure tests in order to develop a robust service lifetime prediction model for different types of solar reflector materials.

Place, publisher, year, edition, pages
Borlänge, 2011. , 126 p.
Keyword [en]
Accelerated aging; Sandstorm simulation; Solar Energy
URN: urn:nbn:se:du-6207OAI: diva2:519165
Available from: 2012-01-16 Created: 2012-01-16 Last updated: 2012-04-24Bibliographically approved

Open Access in DiVA

fulltext(2537 kB)2128 downloads
File information
File name FULLTEXT01.pdfFile size 2537 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 2128 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: 280 hits
ReferencesLink to record
Permanent link

Direct link