Fused silica windows for solar receiver applications

Hertel, Johannes; Uhlig, Ralf; Söhn, Matthias; Schenk, Christian; Helsch, Gundula; Bornhöft, Hansjörg

doi:10.1063/1.4949072

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…However, convective losses also account for a considerable share of 20-40% of the losses, depending on the operation temperature. Different solutions have been proposed to prevent these losses: install a transparent window (e.g., made from quartz) [1], which potentially would entirely eliminate convection losses. Due to the challenge of producing a quartz window of the required size and durability, an array of quartz tube segments compiling the window has been proposed [2].…”

Section: Introductionmentioning

confidence: 99%

Experimental Test Setup of an Airwall to Reduce the Convective Heat Loss in Solar Thermal Cavity Receivers

Bitterling,

Bern,

Fugmann

et al. 2023

SolarPACES Conf Proc

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An experimental setup is presented which allows to experimentally determine the thermal heat losses from a heated solar cavity receiver with an airwall. The setup is a ‘near-full-scale’ replica of a receiver, which ensures that the characteristic fluid dynamic numbers are in a range relevant for practical industrial applications. The executed tests show that – at ideal configuration – the airwall can reduce the overall thermal losses by 7±2%. The reduction of the convective losses amounts to 32±11%, which is in line with the known predictions from CFD simulations.

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Section: Introductionmentioning

confidence: 99%

Experimental Test Setup of an Airwall to Reduce the Convective Heat Loss in Solar Thermal Cavity Receivers

Bitterling,

Bern,

Fugmann

et al. 2023

SolarPACES Conf Proc

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“…Quartz has been considered for a number of concentrated solar thermal applications. Dome-shaped quartz aperture covers were investigated for pressurized receiver applications [18]. The mechanical properties of quartz were measured at elevated temperature, and dome-shaped quartz windows were successfully pressure tested at ambient temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of Quartz Aperture Covers on the Fluid Dynamics and Thermal Efficiency of Falling Particle Receivers

Yue

Mills

Christian

et al. 2022

Journal of Solar Energy Engineering

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Falling particle receivers are an emerging technology for use in concentrating solar power systems. In this work, quartz half-shells are investigated for use as full or partial aperture covers to reduce receiver thermal losses. A receiver subdomain and surrounding air are modeled using ANSYS® Fluent®. The model is used to simulate fluid dynamics and heat transfer for the following cases: (1) open aperture, (2), aperture fully covered by quartz half-shells, and (3) aperture partially covered by quartz half-shells. We compare the percentage of total incident solar power lost due to conduction through the receiver walls, advective losses through the aperture, and radiation exiting the aperture. Contrary to expected outcomes, results show that quartz aperture covers can increase radiative losses and result in modest to nonexistent reductions in advective losses. The increased radiative losses are driven by elevated quartz half-shell temperatures and have the potential to be mitigated by active cooling and/or material selection. Quartz half-shell total transmissivity was measured experimentally using a radiometer and the National Solar Thermal Test Facility heliostat field. Average measured total transmissivities are 0.97±0.01 and 0.94±0.02 for concave and convex side toward the heliostat field, respectively. Quartz half-shell aperture covers did not yield expected efficiency gains in numerical results due to increased radiative losses, but efficiency improvement in some numerical results and the performance of quartz half-shells subject to concentrated solar radiation suggest quartz half-shell aperture covers should be investigated further.

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“…Properties of quartz glass for solar window applications are described in [3]. Design criteria for quartz glass are discussed, data for mechanical strength and for degradation (i. e. crystallization) are given, as well as information about the preparation of the anti-reflective coating.…”

Section: Introductionmentioning

confidence: 99%

Optical performance of segmented aperture windows for solar tower receivers

Buck

2017

AIP Conference Proceedings

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Abstract. Segmented quartz windows are a concept to build larger windows for receivers that require a closed aperture. Reflection losses are a significant loss factor for such solar receivers. Without any additional measures, the reflection loss can reach about 12%. One important measure to improve transmission is the application of anti-reflective coatings, which is beneficial in any case. Another option is modifying the window geometry, especially the edge surfaces of the glass segments. A certain fraction of the reflection losses are caused by a light-guide effect in the glass body, for rays entering through the front surface. Changing the cut surfaces in a way reducing the light-guide effect can significantly improve transmission of a segmented window. Several possible configurations are evaluated and discussed. The results of raytracing simulations verify the improvement. The final selection of the window configuration depends on the optical properties and on mechanical strength, manufacturing and cost considerations. This has to be evaluated for any specific receiver design.

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Fused silica windows for solar receiver applications

Cited by 7 publications

References 8 publications

Experimental Test Setup of an Airwall to Reduce the Convective Heat Loss in Solar Thermal Cavity Receivers

Experimental Test Setup of an Airwall to Reduce the Convective Heat Loss in Solar Thermal Cavity Receivers

Effect of Quartz Aperture Covers on the Fluid Dynamics and Thermal Efficiency of Falling Particle Receivers

Optical performance of segmented aperture windows for solar tower receivers

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