Performance test of a solar concentrating system with cylindrical fresnel lens

An experiment was carried out on a solar concentrating system with cylindrical Fresnel lens which was produced industrially. Each concentrator is consist of four cylindrical Fresnel lens, a secondary reflector and a vacuum-tube receiver, and the aperture area is 2.5m2. The vacuum-tube receiver is placed at the focus of the concentrator, and the secondary reflector is used for concentrating the deflected rays caused of incidence error. This solar concentrating system has the advantages of low cost, less weight, compact volume and modularization. The Fresnel lens is fabricated by injection moulding and the material is PC. Compared with the trough type solar concentrator, its advantages also include with better anti-wind, snow and dusty performance. Besides, the driving torque is small. The optical simulation about the system is completed before experiment to obtain the optical efficiency of the concentrator for different incidence angles and therefore determine the allowable tracking error. It has been found that about 90% of the incident lights can still be gathered by absorber when the error of tracking is 1.5 degrees. Optical efficiency measurements have been carried out and the system is driven to real-time tracking. Some experimental results have been introduced including the collecting heat efficiency with the solar radiation. The experimental data generally agrees with the simulation result. In addition, the losses of system also analysed. As the results, this system can be considered to be an effective structure as a medium temperature solar collector.