Gaussian Distribution of Solar Radiation Effect on Volumetric Porous Absorber Performance

This study numerically investigates the thermal performance of a volumetric solar receiver under varying solar flux distributions. Using the Local Thermal Non-Equilibrium (LTNE) model and Discrete Ordinates (DO) radiation approach, simulations were conducted for silicon carbide (SiC) foam combined with air as a heat transfer fluid (HTF). The thermal properties of both foam and fluid were assumed temperature dependent unlike the previous studies. The impact of Gaussian flux profiles (which can be achieved by varying the solar dish reflector geometry and design) (I_max/I_avg = 1–4) was evaluated at outlet temperatures of 1000 K and 1300 K. Results show that moderately peaked flux distributions (I_max/I_avg = 2–3) enhance efficiency by 3–5% by aligning radiation concentration with fluid flow and reducing re-radiation losses and hotspot formation at boundaries where viscosity suppresses flow of HTF. At 1300 K, efficiencies declined with about 5% due to intensified radiative losses. These findings highlight the importance of flux shaping and material–HTF pairing for optimized receiver performance in high-temperature solar applications such as methane reforming. An individual case was conducted to assess the influence of temperature-dependent foam properties on the receiver’s thermal performance. The results revealed that neglecting the variation of foam properties with temperature leads to 5% overestimation effect greater than that caused by flux distribution under comparable conditions.