Study on the thermal performance of a novel cavity receiver for parabolic trough solar collectors

In this research, a novel cavity receiver for the parabolic trough solar collector (PTC) is presented. A center tube and two inclined fins act as the absorber to absorb the solar energy concentrated by the parabolic trough reflector. Its manufacture is simple. Compared to the tube bundle absorber, it is more convenient to connect in series and avoids the possible non-uniform distribution of the flow in practical applications. An experimental setup was constructed to test the thermal performance of this kind of cavity receiver. The experimental collector efficiency was in the range of 34.18-48.57%. The used physical parameters and installation error in the experiment resulted in the relatively low collector efficiency. A three-dimensional heat transfer model was established and validated by the test results. Effects of thermal conductivity of the insulation materials, emittance of the glass cover and absorber, and optical parameters on the thermal performance of the cavity receiver were estimated in detail. The results quantitatively indicated the importance of improving the physical property parameters of the collector, e.g. if the optimal parameters were selected, the collector efficiency could reach 64.25%, which was comparable to the metal-glass evacuated tube receiver. It indicates that the performance improvement potential of this kind of cavity receiver is huge and the results can theoretically guide the improvement in manufacture and installation. The present study is beneficial for promoting the large-scale application of the PTC in a simple and convenient way and the development of solar thermal technologies. The experimental test of the collector with the optimized parameters of this research and detailed cost analysis will be performed in the future work.