Abstract
The performance of a new high-flux solar simulator consisting of 18 × 2.5 kWel radiation modules has been evaluated. Grayscale images of the radiative flux distribution at the focus are acquired for each module individually using a water-cooled Lambertian target plate and a CCD camera. Raw images are corrected for dark current, normalized by the exposure time and calibrated with local absolute heat flux measurements to produce radiative flux maps with 180 µm resolution. The resulting measured peak flux is 1.0-1.5 ± 0.2 MW m-2 per radiation module and 21.7 ± 2 MW m-2 for the sum of all 18 radiation modules. Integrating the flux distribution for all 18 radiation modules over a circular area of 5 cm diameter yields a mean radiative flux of 3.8 MW m-2 and an incident radiative power of 7.5 kW. A Monte Carlo ray-tracing simulation of the simulator is calibrated with the experimental results. The agreement between experimental and numerical results is characterized in terms of a 4.2% difference in peak flux and correlation coefficients of 0.9990 and 0.9995 for the local and mean radial flux profiles, respectively. The best-fit simulation parameters include the lamp efficiency of 39.4% and the mirror surface error of 0.85 mrad.
Highlights
Concentrated solar radiation is a high-exergy source of energy, suitable for efficient production of electricity, fuels, and commodity materials [1]
To measure the flux distribution produced by the array of radiation modules at the focus of the High-flux solar simulators (HFSS), we follow the common approach described in [13,14], which uses a diffusively reflecting (Lambertian) flat target plate, a CCD camera, and a heat flux gauge
This approach is based on four assumptions, elaborated : (i) the radiative flux is additive, i.e. the flux map resulting from any number of radiation modules equals the sum of the flux maps of the individual modules; (ii) calibration of the flux gauge is adapted to the spectrum of the light source; (iii) the radiation spectrum is uniform over the target area; and (iv) the CCD camera’s response is linear and uniform with respect to the incident radiative flux and position on the chip
Summary
Concentrated solar radiation is a high-exergy source of energy, suitable for efficient production of electricity, fuels, and commodity materials [1]. Research and development of high-temperature solar systems require stable and controlled experimental conditions for reproducible high-flux testing of materials, receivers, and reactor prototypes. High-flux solar simulators (HFSS) mimicking radiative characteristics of typical point focusing solar concentrators have been deployed to allow for testing under controlled laboratory conditions. They concentrate the emitted radiation on a small focal target area, corresponding to an aperture of cavity-type receivers that capture and convert the incident radiation. The characteristics of the high-flux radiative output significantly differ from those obtained with line or large focal target area focusing simulators. These values can be compared to the highest claimed values for an actual solar furnace, with 1.5 kW of solar energy and a peak flux of 16 MW m−2 for a 2 m2 parabola [10]
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