Coupled optical-thermal-stress characteristics of a multi-tube external molten salt receiver for the next generation concentrating solar power

To guarantee safe and efficient operation of the molten salt receiver for the next generation concentrating solar power, a coupled optical-thermal-stress numerical model base on the three-dimensional structure of the receiver is constructed, in which the Monte Carlo ray tracing method, finite volume method and finite element method are included. To validate the model, simulation results are compared with experimental and analytical results. After validation, receiver's optical-thermal-stress characteristics are analyzed at noon of spring equinox. Then, stress characteristics of different receiver tube panels are investigated in different dates and heat fluxes. In the end, a hybrid aiming strategy for the heliostat field is proposed based on the obtained optical-thermal-stress characteristics. The results show that tubes in the middle part of the flow path are most likely to occur stress failure compared with those near the receiver's inlet and outlet. Higher heat flux will produce higher stress, which may cause receiver failure. The critical heat flux for the receiver, beyond which the receiver will occur stress failure, is not the maximum heat flux. Moreover, the molten salt can absorb more energy which is increased by 4.7% at noon of summer solstice after the hybrid aiming strategy is adopted.