Analysis of thermal stress and fatigue fracture for the solar tower molten salt receiver

In this paper, the thermal stress and fatigue fracture of a single tube for the solar tower molten salt receiver are presented. First, the temperature distribution of the tube is simulated. Second, the thermal stress is calculated by solving stress equations. Then the minimum heat flux formula is derived when damage occurs on wall based on the yield criterion and heat conduction equation. Finally, the critical crack length on outer wall is investigated by using the Crack Tip Opening Displacement (CTOD) method. The results show that the distribution of stress is similar to that of inner/outer wall temperature difference. The maximum stress, which causes plastic deformation, occurs on outer wall. According to the minimum heat flux formula q≥[σs]/(KA2+B2+C2−AB−AC−BC) derived in this paper, the heat flux is only 0.19 MW⋅m−2 when damage appears on the receiver tube if the inlet temperature and safety factor are 560 K and 1.5 respectively. Furthermore, the critical crack length is 17 mm when the heat flux is 0.7 MW⋅m−2.