Characterization of selective solar absorber under high vacuum

Russo, R.; Monti, Matteo; Giamberardino, Francesco Di; Palmieri, V.G.

doi:10.1364/oe.26.00a480

Cited by 16 publications

(16 citation statements)

References 6 publications

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“…Suitable guides in the support pillars allow to easily adjust the distance between the light source and the illuminated surface to satisfy different measurement requirements. The system has been used to characterize the efficiency of selective solar absorber [45].…”

Section: Resultsmentioning

confidence: 99%

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Low Cost High Intensity LED Illumination Device for High Uniformity Laboratory Purposes

D’Alessandro¹,

Maio²,

Mundo³

et al. 2020

Preprint

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Uniform illumination is a key requirement in different research fields. However, this requirement is often difficult to achieve when high intensity is required at the same time. Recent advancements in LED lamps allow nowadays for compact and economical solutions. In this work we present a suitable solution for various laboratory purposes requiring stable, uniform and high intensity illumination. The system is composed of four identical high power white LED arrays of 30 mm diameter each, placed on a supporting and cooling structure having a minimum volume of 26 cm x 26 cm x 8 cm. A numerical model has been developed, based on a ray tracing software, in order to simulate the performances. These have then been experimentally validated with measurements of the power density map, carried out with a 1% uncertainty pyranometer. Data show that the built system is very stable over time and provides an illumination uniformity higher than 98%, on a surface of 50 mm radius, which reduces to 95% on a surface of 75 mm radius. The power density can be adjusted in the 390-1360 W m-2 range, not affecting uniformity.

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Section: Resultsmentioning

confidence: 99%

“…The main application of the system is the measurement of absorptance and emittance in selective solar absorbers [33][34][35][36]. As described in the work [37], the observed difference in solar absorptance between optical and calorimetric measurements was due to a not perfect calibration of the adopted illumination system. To achieve…”

Section: Introductionmentioning

confidence: 99%

Low Cost High Intensity LED Illumination Device for High Uniformity Laboratory Purposes

D’Alessandro¹,

Maio²,

Mundo³

et al. 2020

Preprint

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“…We validated eq. 2 by using an home-made experimental setup, the so called Mini-Test-Box (MTB) [31,32], which allows to evaluate the overall efficiency of the absorber by performing stagnation temperature measurements in high vacuum (see Material and Methods section for further details). Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The MTB has been numerically simulated using Comsol Multiphysics [36]. The experimental data were obtained illuminating the absorber with different light power using a calibrated LED illumination system described in [42] and recording the absorber stagnation temperature [32]. In such configuration the power losses are equal to absorbed power ε(T AS )…”

Section: The Mini-test-box Set-upmentioning

confidence: 99%

Efficiency of Selective Solar Absorber in High Vacuum Flat Solar Thermal Panels: The Role of Emissivity

Maio¹,

D’Alessandro²,

Caldarelli³

et al. 2020

Preprint

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This study refers to the optimization of a Selective Solar Absorber to improve the Sun-to-thermal conversion efficiency at mid temperatures in high vacuum flat thermal collectors. Efficiency has been evaluated by using analytical formula and a numerical thermal model. Both results have been experimentally validated using a commercial absorber in a custom experimental set-up. The optimization procedure aimed at obtaining Selective Solar Absorber is presented and discussed in the case of a metal dielectric multilayer based on Cr2O3 and Ti. The importance of adopting a real spectral emissivity curve to estimate high thermal efficiency at high temperatures in selective solar absorber is outlined. Optimized absorber multilayers can be 8% more efficient than the commercial alternative at 250 °C operating temperatures and up to 27% more efficient at 300 °C. Once the multilayer has been optimized the choice of a very low emissivity substrate such as copper allows to further improve efficiency and to reach stagnation temperature higher than 400 °C without Sun concentration.

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“…Russo et al [9] measured the total absorption and emission coefficients of selective solar absorbers under high vacuum conditions from room temperature up to stagnation temperature. They analyze these data to evaluate the solar absorption and thermal emittance at different temperature and these are useful to predict evacuated solar panel performance at operating conditions in turn.…”

Section: Solar Energymentioning

confidence: 99%