Thermal Stresses Analysis of a Circular Tube in a Central Receiver

Abstract

The tubes of central receiver power plants are designed to work under very demanding conditions, with heat fluxes varying between 0.2 to 1 MW/m2, depending on both the weather conditions and the operating regime of the plant. Also, the heat flux is localized along the circumferential coordinate of the tube, on the outward facing side of the tube. This results in a non-uniform temperature distribution with strong gradients both in the heat transfer fluid and the pipe walls. Predicting this distribution is important since it can induce high thermal stresses on the pipe walls and it is a key factor for the fluid decomposition.In this work we have studied different configurations to analyze the effects of tube diameter and wall thickness in the temperature distributions in the fluid and solid, for a typical concentrated solar heat flux distribution. HITEC salt and 316L stainless steel have been used as the heat transfer fluid and the material of the tubes in the receiver, respectively. A numerical method has been used to calculate the temperature distribution of the fluid and the convection coefficient along the circumference. Finally the Von-Mises thermal stresses of the tube receiver have been calculated.