Preliminary performance study of a high-temperature parabolic trough solar evacuated receiver with an inner transparent radiation shield

Solar evacuated receiver as a key part of parabolic trough collector (PTC) suffers considerable heat loss at high operating temperature, which exerts significantly negative effects on the overall performance of PTC system. Based on the fact of maldistributed solar irradiation around the inner absorber tube, a novel solar evacuated receiver with an inner transparent radiation shield (TRS) is proposed and designed. The heat loss of the proposed solar evacuated receiver is numerically studied by the established heat transfer model based on the spectral parameters. The heat-collecting efficiency of a commercial UrssaTrough solar collector installed with PTR 70 receivers using therminol VP-1 as heat transfer fluid is investigated to validate the performance of the proposed solar receiver. Moreover, the influences of the property parameters of films on the two sides of the TRS on the solar receiver are also studied. Comparisons between simulated and experimental results show the differences of their heat-collecting efficiencies are lower than 1%, which demonstrates that the model can yield satisfactory consistency with the experimental results. The simulation results show that the novel receiver exhibits dramatically superior thermal performance to that of the traditional receiver. The heat loss reduction percentages of the novel receiver can reach approximately 15.7% and 14.9% when the absorber temperatures are 400 °C and 600 °C, and the thermal efficiency can be enhanced by 0.93% and 4.42% at inlet temperatures of 400 °C and 580 °C, respectively.