Performance analysis on a cavity solar receiver with tubes filled with nickel foams

A solar receiver capable of achieving an outlet temperature of 1200 K and a power of 40 kW_th is required to drive He-Xe gas turbines in a newly designed solar dynamic space power system. In the initial phase of the project, a scaled-down receiver was designed for the ground test demonstration. This paper presents the design of a novel cavity solar receiver with tubes filled with nickel foams and reports on its performance analysis using a 3D coupled heat transfer model. The model employs a homogeneous equivalent approach with local thermal assumptions for fluid flow and heat transfer in porous foams. Absorbed solar flux is integrated into the model using Monte-Carlo ray tracing, while the discrete ordinates method is used to model thermal radiation transport in the cavity and quartz window. The model is utilized to ensure the local high temperature remain within the material's allowable limits. Additionally, the effects of varying dimensional and operational parameters on performance are investigated. The results indicate that, under design operational condition, the thermal efficiency can reach 83.5 % at an outlet temperature of 1292.6 K without exceeding the material temperature limits. Thermal efficiency increases with the reduction in cavity diameter (from 0.3 to 0.18 m) and tube length (from 0.36 to 0.24 m). However, these changes may lead to increased local high temperatures. The proposed receiver design can be extended to other fields of solar thermal power applications.