Fig. 1. Effect of dust of concentrator surface on ray propagation path

Fig. 2. Effect of surface corrosion of concentrator on ray propagation path

Fig. 3. Layouts of dust samples. (a) Test device; (b) design diagram

Fig. 4. Comparison test platform of dual-axis tracking trough solar system

Fig. 5. Flow chart of thermodynamic performance test based on trough solar system

Fig. 6. Profile of cavity receiver

Fig. 7. Pictures of concentrators with dust under different working conditions. (a) Working condition 1; (b) working condition 2; (c) working condition 3

Fig. 8. Effect of environmental temperature on photothermal coupling factor of trough solar system

Fig. 9. Relative reflectance varies with wavelength at each measurement point. (a) Working condition 1; (b) working condition 2; (c) working condition 3

Fig. 10. Focal plane energy flux density on dusty mirror and clean mirror. (a) Working condition 1; (b) working condition 2; (c) working condition 3

Fig. 11. Acquisition factor varies with aperture width under different working conditions. (a) Working condition 1; (b) working condition 2; (c) working condition 3

Fig. 12. Change of acquisition factor correction coefficient caused by dust reflection factor

Fig. 13. Experimental and predicted values of thermal efficiency under different dust conditions