RT Journal Article
T1 Numerical model of solar external receiver tubes: Influence of mechanical boundary conditions and temperature variation in thermoelastic stresses
A1 Montoya Sancha, Andrés
A1 Rodríguez Sánchez, María de los Reyes
A1 López Puente, Jorge
A1 Santana Santana, Domingo José
AB Failure in solar external receivers is mainly originated from the thermal stress, caused by the high non-uniform transient solar flux. The heat-up and cooldown of tube receivers in daily cycles produce low-cycle fatigue that limits the lifetime of tubes. The corrosion of tube materials produced by incompatibility between the decomposed heat transfer fluid and tube material may increase this issue. The temperature spatial distribution in these tubes has strong variations in radial, circumferential, and axial directions. The stress field, produced by the temperature gradients, has been commonly analyzed using bidimensional models in isolated tube cross sections, without taking into account the axial temperature variation, the mechanical boundary conditions, and the temperature-dependent thermomechanical properties. In this work, a three-dimensional finite element model has been developed in order to calculate the stress field distribution, without performing any geometrical simplification. In addition, appropriate mechanical boundary conditions have been imposed in order to adequately simulate the tube behavior. Besides, radial, circumferential and axial temperature variations have been studied separately to analyze how each of them influences the maximum stress distribution. This 3D modelhas been compared with analytical solutions for the two-dimensional thermal stress problem incircular hollow cylinders. The results show that the boundary conditions have a significant effect on the tube stresses, increasing the axial stress component and therefore the equivalent stress. The analysis of each of the temperature variations showed that the circumferential variationtemperature is the one that produces most of the stress, since it tries to strongly bend the tube, which is impeded by the boundary conditions. The results also present that 2D models are not capable of obtaining the correct stress distribution along the tube, since they are not taking into account the lo
PB Elsevier
SN 0038-092X
YR 2018
FD 2018-11-01
LK https://hdl.handle.net/10016/33992
UL https://hdl.handle.net/10016/33992
LA eng
NO This work has been supported by the Iberdrola Foundation Spain under the fellowship "Ayudas a la investigación en energía y medio ambiente". M.R. Rodríguez-Sánchez and D. Santana would like to thank the Ministerio de Economía y Competitividad the support of the project ENE2015-69486-R (MINECO/FEDER, UE).
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RD 30 jun. 2024