Thermal modeling of a concentrator pipe composed with direct steam generation

Abstract

Deflections along the pipes of solar concentrators used for direct steam generation in thermosolar plants lead to some structural problems, due to temperature gradients in radial and angular directions. In this work, a thermal analysis of an absorber copper-steel pipe is made, based on the solution of heat transfer equations in stable and transient state, for the solution of model was used the finite differences method. Radial and angular temperature distributions are presented, as well as the instant at which the system reaches the stationary state under the studied conditions. The considered absorber pipe is a composed walls system of 20% Cu and 80% Steel, constituted by commercial copper pipe of type k with 61.849 and 66.675 mm of internal and external diameter respectively; and a steel pipe of schedule 160 with 66.7 mm of internal diameter and 88.9 mm of external diameter. The properties in the composed wall are favorable because achieves an isothermal state with a maximum gradient of 50°C/m. Therefore, the composed pipe proposed offers greater resistance to the deflection provoked by the direct steam generation.