Improvement in the Flux Uniformity of the Solar Dish Concentrator System through a Concave Quartz Window

Abstract

A nonuniform and high-strength heat flux load would reduce the working efficiency, safety, and in-service life of a cavity receiver. Four types of concave quartz windows, including conical, spherical, sinusoidal, and hyperbolic tangent, were proposed to be used in the cylindrical cavity receiver of a solar dish concentrator system, which can improve the flux uniformity and reduce the peak concentration ratio of the receiver. For each concave quartz window, 36 structural schemes were offered. Based on the Monte Carlo ray-tracing method, the results showed that the nonuniformity coefficient of the receiver was 0.68 and the peak concentration ratio was 1320.21 by using a plane quartz window. At the same time, when the receiver is in the best optical performance, it is the receiver with sinusoidal, conical, spherical, and hyperbolic tangent quartz windows, respectively. The optical efficiency of the receiver with the above four types of quartz windows was basically the same as that of the receiver with the plane quartz window, but their nonuniformity coefficients were reduced to 0.31, 0.35, 0.36, and 0.39, respectively, and the peak concentration ratio was reduced to 806.82, 841.31, 853.23, and 875.89, respectively. Obviously, the concave quartz window was better than the plane quartz window in improving the flux uniformity. Finally, a further study on the sinusoidal quartz window scheme of all of the above optimal parameter schemes showed that when the installation position of the receiver relative to the dish concentrator was changed, the flux uniformity of the receiver could continue to improve. When the surface absorptivity of the receiver was reduced, the optical efficiency would be reduced. For the parabolic dish concentrator with different focal distance, the concave quartz window can also improve the uniformity of the flux distribution of the cylindrical cavity receiver.

Numerical analysis of convective heat loss from a cylindrical–hemispherical receiver using a glass cover and an air curtain

“…Wang et al 10 numerically analyzed the effect of a glass cover on the amount of heat flux distributed to a tube receiver used in a parabolic trough collector. Similarly, Nie et al 11 conducted a numerical study to analyze the heat flux distribution in a cylindrical receiver with a concave quartz window. The uniformity and density of the heat flux in the cylindrical receiver was observed using a quartz window.…”

Analysis of Solar Irradiance Variation on Heat Flux and Temperature Distribution for a Dish Concentrator Receiver

“…Zhang et al [8] investigated the optical performance and multi-objective optimization of GaAs solar cells to improve the photo-electronic capacity. Nie et al [9] proposed a concave quartz window to enhance the flux uniformity of the cylindrical cavity receiver of the solar dish concentrator. Four types of concave quartz windows, including conical, spherical, sinusoidal, and hyperbolic tangents, were employed for the analysis.…”