Analysis of thermal stress, fatigue life and allowable flux density for the molten salt receiver in solar power tower plants

The solar power tower (SPT) receiver design should be able to stand with fatigue damage caused by the passage of clouds, start-up and shut-down. In this paper, to investigate the impacts of incident heat flux distribution and SPT site weather data on the thermal stress, fatigue life and allowable flux density (AFD) of the molten salt receiver, the relationship between the fatigue life and AFD of the tube wall is developed based on the coupled thermal-structural analysis and Miner linear damage theory. The results show that the cosine effect of the circumferential heat flux distribution considered has a significant influence on the location and magnitude of the maximum thermal stress of the tube wall, which lead to the difference in the tube wall fatigue damage. The AFD are, respectively, 829 kW/m(2) and 1037 kW/m(2) under uniform and cosine circumferential heat flux distributions for the site of Barstow, USA, when the design lifetime of the tube is 30 years. Compared with the SPT site of Barstow, USA, the fatigue damage of the tube wall in Sevilla, Spain, and Delingha, China, are lower under the same conditions due to lower insolation hours of direct normal irradiation in the range of 750-1100 W/m(2). The AFD are, respectively, 829 kW/m(2), 973 kW/m(2) and 997 kW/m(2) for the site of Barstow, USA, Sevilla, Spain, and Delingha, China, with 30 years design life. These findings give guidelines for the operation reliability of the SPT molten salt receiver tube.