Numerical analysis of inserts configurations in a cavity receiver tube of a solar power tower plant with non-uniform heat flux

In order to analyse the effects of inserts configurations on heat transfer performance of solar cavity receiver tube (RT), a three-dimensional numerical model with four different inserts under non-uniform heat flux boundary condition was developed. Based on this model, the effects of inserts configurations, the effects of non-uniform heat flux boundary condition, the effects of thickness and positions of twisted-tape were analyzed. The numerical results show that RT-I with the twisted-tapes has the better comprehensive performances than those of other three kinds of RTs, and the RT-I with twisted-tapes is recommended to the solar cavity tower receiver. The twisted-tape RT-I has the highest Nu and the lowest circumferential temperature difference ΔT and average temperature of outer surface of receiver tube Tm, which are 21.74, 43 K, and 586 K, respectively. In addition, the thickness of twisted-tape has the significant effect on heat transfer performances of RTs. The twisted-tape with much more thickness will enhance the heat transfer and reduce the ΔT and Tm. Moreover, under the non-uniform boundary heat fluxes, RT-I with twisted-tapes placed in the back-sunlight domain is favorable than that of twisted-tapes placed in the sunlight concentrated domain. The contribution can provide a reference for this type of receiver design and reconstruction.