Tomography based pore-level structural optimization for reducing pressure drop of porous volumetric solar receiver

Porous solar receiver is the key component converting the solar energy to high-temperature thermal energy of working fluid. However, a large pressure drop brings additional energy consumption. In this work, an adjoint algorithm is employed to optimize the structure of tomographied porous solar receiver for reducing pressure drop. To this end, the flow and heat transfer characteristics of the porous receiver are analyzed and compared between the original and optimized receiver. The structural optimization is carried out with a pore-level method, which mainly consists of the incompressible Navier-Stokes equations and their adjoint counterpart. The results indicate that the pressure drop of the porous receiver decreased significantly after optimization with the porosity unchanged. In addition, although the solid skeleton temperature of the optimized foam is higher, the comprehensive efficiency η = h_v/(ΔP)^1/3 does not decrease. Finally, it is found that under different inlet velocities between 1 and 5 m/s, the pressure drops of three samples (φ = 0.87, 0.77 and 0.70) are reduced by 30%, 34% and 43% after optimization, respectively. The present work can provide useful guidance for improving the performance of porous volumetric solar receiver.