非均匀热流密度下槽式集热器吸热管热应力分析

Thermal Stress Analysis for Absorber Tube of Parabolic Trough Solar Collector under Non-Uniform Heat Flux

为了分析槽式集热器吸热管的热力性能及其对集热系统安全运行的影响,以LS-2型集热器为研究对象,通过有限元数值模拟方法对槽式集热器吸热管进行热-结构耦合分析。结果表明:吸热管管壁最大温度位于出口处下端(抛物面反射镜反射光线照射区域),吸热管管壁最小温度位于入口处上端(太阳辐照直射区域);太阳直射辐照强度(400～900 W/m^2)越大,工质入口温度(50～300℃)越低,入口流速(1.0～3.5 m/s)越慢,对吸热管的热变形量和热应力影响越大。在集热器实际运行中,当太阳直射辐照强度较高时,工质入口温度和入口流速不能选取太低,否则会造成吸热管热应力增加,影响集热器的使用寿命。

In order to analyze the thermal performance of the absorber tube of the parabolic trough solar collector and its influence on the safe operation of the collector system,In this paper,the LS-2 type collector is taken as the research object,and the thermal-structure coupling analysis of the absorber tube of the parabolic trough solar collector is carried out by finite element numerical simulation.The results of simulation calculations show that the maximum temperature of the wall of the absorber tube is located at the bottom end of the outlet of the absorber tube(the area of light reflected by a parabolic mirror),and the minimum temperature of the wall of the absorber tube is located at the upper end of the inlet of the heat absorber tube(the area of direct sunlight).When the direct normal solar irradiation(DNI) is higher(400~900 W/m^2),the inlet temperature is lower(50~300℃),and the inlet flow rate is slower(1.0~3.5 m/s),the effect of thermal deformation and thermal stress on the absorber tube is greater.During the actual operation of the collector,when the DNI is high,the inlet temperature and flow velocity of the heat transfer fluid(HTF)cannot be selected too low,otherwise it will cause the thermal stress of the absorber tube to increase,thereby affecting the service life of the collector.