Fig. 1. Schematic diagram of SPLFR concentrators^[23]

Fig. 2. Schematic diagram of LFR with parabolic reflectors^[24]

Fig. 3. Enhancing the optical efficiency by increasing the length of the receiver^[28]

Fig. 4. Enhancing the optical efficiency by moving the receiver^[28]

Fig. 5. Enhancing the optical efficiency by increasing the length of the receiver and moving the receiver^[28]

Fig. 6. Schematic of the proposed two-axis tracking LFR (1: Crank-rod mechanism; 2: Linear actuator; 3: Receiver and its supporter; 4: Linear actuator; 5: Reflector and its supporter; 6: Slide rails and pedestals)^[29]

Fig. 7. General scheme of the optimized LFR (1: West reflector surface; 2: East reflector surface; 3: Receiver; λ: Tilt angle of the reflectors and receiver; β: Angle of the east-west rotation; dz: Displacement angle of the receiver)^[30]

Fig. 8. Schematics of single-axis and double-axis tracking systems^[5]

Fig. 9. [in Chinese]

Fig. 9. Main performance of LFR concentrator with the same width of the primary reflector^[41]

Fig. 10. Optical efficiency of LFR concentrator with the same width of the primary reflector^[41]

Fig. 11. Flux distribution on the absorber tube surface in the single-tube receiver with a secondary collector^[57]

Fig. 12. Flux distribution on each absorber tube in the multi-tube cavity receiver ^[57]

Fig. 13. Polar coordinate diagram of flux distribution on the surface of heat absorption tube^[41]

Fig. 14. Schematic diagram of heat transfer path in local section of solar vacuum collector pipe^[98]

Fig. 15. Temperature field in the insulating material and around absorber tube^[8]

Fig. 16. Line graph of heat loss as temperature increases^[8]

Fig. 17. Sketch of the different LFC receiver configurations analyzed. (a) An receiver with non-evacuated glass envelope; (b) An evacuated tube receiver; (c) An receiver with a flat glass receiver cover^[113]

Fig. 18. Influence of wind velocity on the heat loss of three different LFC-receivers ^[113]

Fig. 19. Influence of Direct Normal Irradiation on the heat loss of three different LFC-receivers ^[113]

Fig. 20. Influence of ambient temperature on the heat loss of three different LFC-receiver^[113]

Fig. 21. Heat transfer model of LFRC with CPC absorber^[114]