Thermal and mechanical stresses in a solar central receiver

Failure in the tubes of the solar receiver is a problem that should be studied. This failure is caused by the combined action of the high temperature, stresses and corrosion. Commonly, the calculation of the stresses in the receiver tubes is carried out in the crossed sections, taking into account the radial and the circumferential variation of the temperature. However, the temperature gradient along the tube length has been ignored. In this study a new model for the stress calculation in the receiver tubes has been developed. This model includes the temperature gradient in circumferential, radial, and longitudinal direction, taking into account the movement restrictions. The results show that the mechanical boundary conditions have a large effect in the stresses of the tube, being 3 times higher than the stress when no movement restrictions have been imposed. Moreover, the stress profile is highly dependent on the temperature gradient and hence on the incident solar flux on the receiver. Homogeneous solar fluxes are then more suitable than lower levels of solar fluxes with important gradients.