均匀壁面热流下太阳能腔式吸热器的自然对流数值模拟

在考虑变物性以及腔体固壁与流体间流固耦合的基础上,采用定热流的热边界条件和RNG k-ε紊流模型,对相同热流密度不同倾角以及相同倾角不同热流密度下的圆柱形腔式吸热器的腔体内的自然对流特性进行了三维数值模拟。结果表明:随着腔体壁面上的热流密度增加,内壁面上平均温度将升高,平均努塞尔特数增加;随着吸热器倾角的增大,平均努塞尔特数减小;随着离采光口距离的增大,腔体壁面温度近似呈线性规律升高,同一截面不同位置处的壁面温差减小,但减小的幅度不大。

Numerical investigation on natural convection of solar cavity receiver subjected to uniform wall heat flux

In this paper,a 3D numerical simulation,which is based on considering the variable properties and the fluid-structure interaction between the wall of cavity and fluid,was carried out to investigate the natural convection characteristics in a cylindrical cavity solar receiver with constant heat flux boundary condition.The natural convection characteristics of cylindrical solar cavity at different tilt angles under the uniform wall heat flux and at different wall heat fluxes under the same tilt angle have been examined by adopting renormalization group(RNG) k-ε turbulent model.The results show that the average temperature at the inner wall of the cavity increases with increasing wall heat flux and the average Nusselt number increases,the increased tilt angle of receiver leads to the reduced average Nusselt number.In addition,with the increment of distance departure from aperture,the cavity wall temperature increases linearly,while the wall temperature difference of various locations for the same cross-section decreases with a small range.