Selection of Surface Reflectivity for a Solar Cavity Receiver

The thermal performance of a saturated steam solar cavity receiver was numerically studied. In order to improve the uniformity of heat flux and wall temperatures on the boiling tubes, the proper selection method of the surface reflectivity for the boiling tubes and the other cavity walls was found. The uniform surface reflectivity of the boiling tubes can only obtain the highly non-uniform heat flux and wall temperature distributions. When the surface reflectivity of the boiling tubes is selected according to the non-uniform distribution of heat flux, the wall temperatures and the heat flux on the boiling tubes appear much more uniform. And when the surface reflectivity of the other cavity walls is selected as high as possible, the thermal efficiency of the receiver would be improved. Meanwhile, the increasing surface reflectivity of the cavity walls has slight effect on the heat flux and wall temperature distributions of the boiling tubes.