Optical Performance Comparison of Different Shapes of Cavity Receiver in the Fixed Line-Focus Solar Concentrating System

To optimize the fixed-focus solar concentrating system (FLSCS) and linear cavity receiver of better optical performance, the effects of receiver parameters (geometric shape, receiver position f, receiver internal surface absorptivity alpha(ab), and end reflection plane reflectivity rho(r)) on the relative optical efficiency loss eta(re-opt)(,loss), the maximum value of the local concentration ratio X-max, and the non-uniformity factor sigma(non) were studied in the present study. The results showed that the increases of sun declination angle delta in the range of 0-8 degrees have a weak effect on the eta(re-opt)(,loss). The eta(re-opt)(,loss) are 2.25%, 2.72%, 12.69% and 2.62%, 3.26%, 12.85%, respectively, when the solar hour angle omega is 0 degrees, 30 degrees, 60 degrees as delta = 0 degrees and 8 degrees for linear rectangular cavity receiver. The X-max mainly depends on the energy flux distribution of first intercepted sunlight on the cavity absorber inner wall. Increasing the distance between the cavity absorber inner wall and the focal line Delta f can affect the X-max. The smaller the Delta f, the greater the X-max, and vice versa. The changing trend of sigma(non) is basically consistent with that of the X-max. When the f is 600, 625, 650, 675, 700 mm and the omega = 0 degrees, the sigma(non) are 0.832, 0.828, 0.801, 0.747, and 0.671, respectively, for linear rectangular cavity receiver. This work could establish the foundation for further research on the optical to thermal energy conversion in the FLSCS.

Automated summary

This study aimed to optimize the fixed-focus solar concentrating system (FLSCS) and linear cavity receiver by studying the effects of receiver parameters on optical performance. The results showed that the sun declination angle had a weak effect on the optical efficiency loss, and the X-max mainly depended on the energy flux distribution. The changing trend of sigma(non) was consistent with that of the X-max.