Solar receivers and reactors are critical equipment to convert high-flux solar energy into thermal and chemical energy. However, the high flux solar energy is highly uneven and may shorten the solar receiver and reactor life due to considerable fatigue strain. This paper proposes a new Light Uniform Device (LUD) design, which aims to mitigate the non-uniformity of irradiance at the focal plane. The main structure of LUD is a conical frustum filled with glass spheres. The Monte Carlo Ray Tracing (MCRT) method is used to investigate the effect of sphere diameter, LUD thickness, and aperture ratio on the non-uniformity of irradiance and total transmittance. The results show that spheres with a small diameter are more beneficial in reducing the non-uniformity of irradiance. In contrast, the effect of the aperture ratio on the non-uniformity of irradiance is negligible if most incident solar irradiation enters the LUD. When fixing the sphere diameter and aperture ratio, there is an optimal solution for the thickness of LUD to minimize the non-uniformity of irradiance. The sphere diameter, LUD thickness, and aperture ratio under the design condition are 6 mm, 30 mm, and 1.1, respectively. MCRT results indicate that the non-uniformity of irradiance and total transmittance under the design condition are 0.8775 and 0.7052, respectively. Then the designed LUD is applied to a micro-tubular receiver in the last section. The results show that this LUD can extend the receiver life by 83.01%, while the perfect LUD can extend the receiver life by a factor of 1000. Although the proposed LUD can improve the non-uniformity of irradiance, the transmittance is significantly affected. Thus, improvement is necessary before it applies to real solar receivers or reactors.
Zhang, Q., Chang, Z., Fu, M., Nie, F., Ren, T., & Li, X. (2023). Performance analysis of a light uniform device for the solar receiver or reactor. Energy, 270, 126940. https://doi.org/10.1016/j.energy.2023.126940
Published in the May Issue of Energy