Optical performance of a solar dish concentrator/receiver system: Influence of geometrical and surface properties of cavity receiver

• The Monte Carlo Method is employed to evaluate the optical performance of the system.
• The effects of diameter ratio, height ratio and sidewall absorptivity are investigated.
• An optical efficiency correlation is further developed.
• The radiation flux distribution of the absorber is mainly affected by height ratio.

The optical performance of a solar dish concentrator/cavity receiver system based on the Monte Carlo Ray Tracing Method (MCRTM) was carried out under ideal optics. The study was precipitated by a need to analyze the influence of geometrical parameters and surface properties of a cavity receiver systematically and to understand the mechanism of the optical performance under various parameters. These include diameter ratio (the ratio of aperture diameter to absorber outer diameter), height ratio (the ratio of absorber height to absorber outer diameter) and sidewall absorptivity of cavity receiver. In addition, an optical efficiency of the absorber is defined and presented for the first time. The analysis indicates that the optical efficiency increases and then decreases with higher height ratio, while optical efficiency curves are reduced monotonically with diameter ratio. Simultaneously, the effects of the height and diameter ratios on optical efficiency are both influenced by sidewall absorptivity. Based on the results, a correlation of optical efficiency was further developed to quantify the influences of these factors. The maximum optical efficiency and its corresponding optimal height ratio from both simulation and correlation are presented and obtain reasonable agreement. The optimized selection of height ratio along with diameter ratio are suggested using this result. The height ratio is found to be a pure controlling parameter of the radiation flux distribution.

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