间歇热流下管式吸热器温度场及热应力场分析

Temperature and thermal stress field analyses of tube receiver under intermittent concentrated solar irradiation

吸热器温度场和热应力场的数值分析可以为吸热器热应力的抑制提供理论指导.采用Coupled-field element方法对管式太阳能吸热器在不均匀热流以及间歇热流情况下的温度场及热应力场进行了计算.在温度场计算过程中,将每一个网格单元面的太阳能热流入射方向与吸热器表面之间的夹角关系与汇聚热流的乘积作为热分析的边界条件.为了揭示热应力场沿长度方向变化规律,研究了温度场沿长度方向二阶导数变化规律.计算结果表明,轴向应力和切向应力是热应力场的主要影响因素,热应力曲线拐点处均是温度二阶导数曲线拐点发生处.

Temperature and thermal stress analyses of receiver can provide theoretical guidance to the suppressing of thermal stress. Coupled-field element method is adopted to conduct temperature and thermal stress field analyses of tube receiver under non-uniform and intermittent concentrated solar irradiation. During the temperature analyses of tube receiver, angle relationships between incident direction of solar rays and surface elements of tube receiver are calculated, and the relationships multiplied by magnitude of concentrated solar irradiation are used as the secondary boundary condition of temperature analyses. The secondary derivative of temperature field along length direction of tube receiver is also investigated to clarify the thermal stress distribution along length direction. The numerical results indicate that axial stress and tangential stress have much higher influence on thermal stress field than radial stress, and the inflexion of secondary derivative of temperature distribution will induce an inflexion of thermal stress distribution.