Equipment and methods for measuring reflectance of concentrating solar reflector materials

Fernández-García, Aranzazú; Sutter, Florian; Martínez-Arcos, Lucía; Sansom, Christopher L.; Wolfertstetter, Fabian; Delord, Christine

doi:10.1016/j.solmat.2017.03.036

Cited by 50 publications

(26 citation statements)

References 48 publications

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“…The optical characterization device used for this study was the 115R-USB reflectometer manufactured by Devices and Services Co. (D&S, Dallas, TX, USA) [19]. This instrument is able to measure the specular reflectance ρ λ,φ (λ,θ i ,φ), at a the wavelength of λ = 660 nm, an incidence angle of θ i = 15 • and an acceptance angle of φ = 12.5 mrad.…”

Section: Methodsmentioning

confidence: 99%

Water Saving in CSP Plants by a Novel Hydrophilic Anti-Soiling Coating for Solar Reflectors

Wette¹,

Fernández-García²,

Sutter³

et al. 2019

Coatings

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In this work, results of the outdoor exposure campaign of a newly developed hydrophilic anti-soiling coating for concentrated solar thermal power (CSP) mirrors are presented. The material was exposed for nearly two years under realistic outdoor conditions and the influence of two different cleaning techniques was evaluated. Mirror samples were analyzed during exposure and their reflectance and cleanliness were measured. The performance of the anti-soiling coated mirror samples was compared to conventional uncoated silvered-glass mirrors. The coatings showed appropriate anti-soiling and easy-to-clean behavior, with a mean cleanliness gain of 1 pp and maximum values under strong soiling conditions of up to over 7 pp. Cleanliness of the coated samples stayed higher throughout the whole campaign before and after cleaning, resulting in lower soiling rate compared to the reference material. Taking into account these values and supposing a threshold for cleaning of 96%, the number of cleaning cycles could be decreased by up to 11%. Finally, the coated material showed negligible degradation, not exceeding the degradation detected for the reference material.

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Section: Methodsmentioning

confidence: 99%

Water Saving in CSP Plants by a Novel Hydrophilic Anti-Soiling Coating for Solar Reflectors

Wette¹,

Fernández-García²,

Sutter³

et al. 2019

Coatings

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“…The scanning spectrophotometer (model Lambda 1050, Perkin Elmer (PE), Waltham, MA, USA) with a 150-mm diameter integrating-sphere accessory was employed to measure ρ λ,h (see Figure 3) [37]. It is a UV/Vis/NIR double beam and double monochromator instrument with two light sources, a deuterium lamp for the UV range, and a halogen lamp for the Vis/NIR range.…”

Section: Spectrophotometermentioning

confidence: 99%

“…The conventional method applied is in agreement with the current version of the "SolarPACES Reflectance Guideline" [15], which has been extensively employed to characterized solar reflectors in durability studies [37][38][39]. According to it, the following parameters must be measured to monitor the aging of solar reflectors: As it is recommended in this guideline, ρ λ,ϕ was measured in five points of each reflector sample, taken in the center of the sample and close to the four corners of the sample (see Figure 4), and the average value as well as the standard deviation was reported.…”

Section: Conventional Reflectance Measurement Techniquementioning

confidence: 99%

Section: Conventional Reflectance Measurement Techniquementioning

confidence: 99%

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Advanced Analysis of Corroded Solar Reflectors

Buendía-Martínez

Fernández-García

Sutter³

et al. 2019

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The corrosion of the reflective layer is one of the main degradation mechanisms of solar reflectors. However, the appropriate assessment of the corroded reflector samples is not accomplished by the current analysis techniques. On the one hand, the reflectance measurement protocol of non-damaged solar reflectors for concentrating solar thermal technologies is widely addressed in the SolarPACES reflectance guideline. However, this methodology is not adequate for reflectors whose surface is partially corroded by many kind of corrosion agents. In this work, a new measurement technique to properly assess corroded samples was developed. To check the usefulness of the method, several damaged samples (subjected to two accelerated aging tests) were evaluated with the conventional technique and with the improved one. The results showed that a significant discrepancy is observed between the two methods for heavily corroded samples, with average reflectance differences of 0.053 ppt. The visualization of the reflector images illustrated that the improved method is more reliable. On the other hand, both the corrosion products formed and the corrosion rates were identified after each corrosive test. The chemical atmosphere significantly affects the products formed, whereas the corrosion rates are influenced by the test conditions and the reflector quality.

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“…1, and their main features are listed in Table 1. Table 1 Main features of the D& S 15R-USB and Abengoa Condor SR-6.1 reflectometers (Fernández-García et al, 2017). , with both 550 nm and 660 nm sources, but always with acceptance apertures less that the Condor (23 mrad, 12.5 mrad, 7.5 mrad, or 3.5 mrad).…”

Section: Instrument Descriptionmentioning

confidence: 99%

Reflectometer comparison for assessment of back-silvered glass solar mirrors

et al. 2017

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This paper compares the two most common reflectometers used to assess the specular reflectance of back-silvered glass mirrors for Concentrating Solar Power (CSP) applications, namely the Device and Services (D&S) 15R-USB and the Abengoa Condor SR-6.1 instruments. Comparisons are first made between the two instruments themselves using a Gage Repeatability and Reproducibility (R&R) study. Results are given for the as-cleaned collector mirrors and then as the mirrors become naturally soiled over a one month period. The results of the Gage R&R study show that for the D&S the gage itself contributes 40.97% of the variability, whilst 59.03% is due to part-to-part (location on the mirror under investigation) variability. For the Condor we show that the % Contribution from the gage is 62.18% of the total variability with only 37.82% of the contribution attributable to the location dependent reflectance. The Condor has a wider acceptance angle, and over the reflectance range of 0.91-0.95 the condor was found to measure higher than the D&S by an average of 1.53%. The differences between the soiling results obtained from the two instruments are explained, and the results are used to derive a predictive model for the soiling of solar collectors. In conclusion, both instruments have advantages and shortcomings, and the factors that influence which instrument to select are discussed.

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Equipment and methods for measuring reflectance of concentrating solar reflector materials

Cited by 50 publications

References 48 publications

Water Saving in CSP Plants by a Novel Hydrophilic Anti-Soiling Coating for Solar Reflectors

Water Saving in CSP Plants by a Novel Hydrophilic Anti-Soiling Coating for Solar Reflectors

Advanced Analysis of Corroded Solar Reflectors

Reflectometer comparison for assessment of back-silvered glass solar mirrors

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