Radiation-induced natural convection in volumetrically absorbing solar thermal receivers: An experimental study
Why this work is in the frame
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Bibliographic record
Abstract
Volumetric solar thermal receivers are composed of semi-transparent media that are irradiated from the top and absorb solar radiation directly. Previous theoretical studies have suggested that these receivers can capture a high percentage of the incoming energy by eliminating temperature differences between the absorber and the heat transfer fluid. However, the complex interaction between radiation-induced natural convection and volumetric heating which governs the receiver thermofluid behavior has never been experimentally investigated. We present a comprehensive experimental study in which these interactions are investigated from a design perspective. A 6.5 kW solar simulator is installed in a beam-down configuration, and molten nitrate salts are used as base fluids to replicate real-life conditions. Key receiver parameters, namely the fluid absorption coefficient, receiver height, surface emissivity, input flux and heating time are varied experimentally to investigate their influence on operating regime transitions and capture efficiency. Receivers dominated by natural convection are shown to achieve capture efficiencies up to 20 times higher than those dominated by conduction. The χ 2 goodness-of-fit test is employed to demonstrate that theoretical predictions regarding the receiver physics are reasonably accurate and existing models can be effectively used for design optimization. Finally, a proof of concept for chloride salts-based high-temperature volumetric receivers is presented. The design insights obtained from the experiments are summarized as design guidelines for future commercial scale-up. • Experimentally investigated molten salts-based volumetrically absorbing receivers. • Investigated the effects of five key parameters on receiver thermofluid response. • Experimentally validated the presence of three distinct operating regimes. • Demonstrated that theoretical predictions regarding receiver physics are reliable. • Presented a proof-of-concept for chloride salts-based high-temperature receivers.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it