Effects of Wear-Induced Surface Roughness and Pore Taper on the Performance of Porous ZnS/Ag High-Temperature Solar Absorbers

High-temperature radiative cooling is essential for solar absorbers, as it mitigates efficiency degradation resulting from thermal accumulation. While porous structures have proven effective in enhancing absorber performance, practical manufacturing processes and prolonged operational wear inevitably introduce surface roughness and structural deviations, which profoundly impact radiative properties. This study constructs a ZnS/Ag solar absorber model with surface roughness and employs the finite-difference time-domain method to investigate how characteristic length, surface roughness, porosity, pore shape factor, and taper influence its radiative properties in the 3 μm–5 μm band at 750 K. Results show optimal absorption at a 1 μm characteristic length with a 36.72% improvement compared to the model with l = 0.25 μm, increased absorption with higher porosity with a 69.29% improvement at 0.6 compared to the non-porous structure, lower circularity with a 19.03% improvement for C = 0.89 compared to C = 1.00, while surface roughness with a 61.24% improvement at RMS = 0.031 compared to RMS = 0 and taper with a 38.29% improvement at β = 20° compared to β = 0° also exert significant effects. This work provides engineering design guidelines for high-efficiency, low-cost absorbers.