Analysis of Radiation Propagation inside a Hierarchical Solar Volumetric Absorber

Abstract

The solar receiver is a critical component of concentrated solar power technology; it works as a heat exchanger, transforming the concentrated solar radiation into high-temperature heat. Volumetric receiver technologies, using air as a heat transfer fluid, are designed to reach higher temperatures than the current receiver technology, which is limited by material resistance and fluid instability. The higher temperature, up to 1200 K, could be used in high-temperature industrial processes or a high-temperature thermodynamic cycle. A correct radiation propagation is essential to develop their performances, reducing reflection and emission losses and promote the heat transfer to the fluid. In this study, the optical behaviour of a hierarchical volumetric receiver (HVR) developed in Bruno Kessler Foundation (FBK) has been studied using Monte Carlo ray tracing (MCRT) simulations. The simulations have been validated in an experimental setup that evaluates the light transmissivity of the HVR porous structure. Two different HVR structures are evaluated with MCRT simulations that use a real solar dish geometry to configure a complete concentrated solar power (CSP) plant. Results show that frontal and rear losses are, respectively, 12% and 3% of the incoming concentrated radiation. Inside the HVR, 15% of the incoming power is propagated trough the lateral void spaces. Therefore, the power spreading avoids the overconcentration of the centre of the focalized area. The HVR optical behaviour has been investigated, showing an optical efficiency of 85%.

The EU Training Network for Resource Recovery through Enhanced Landfill Mining—A Review

“…Consequently, within NEW-MINE, MgO-stabilized SrO was synthesized and successfully tested for heat storage via the SrO/SrCO 3 cycle [102]. This research was considered outside NEW-MINE with respect to radiation propagation in a heat exchanger transforming solar radiation into high-temperature heat [103], thermochemical energy storage in the CaO/CaCO 3 [104] [105] system and two reviews on thermochemical energy storage [106,107]. The most recent NEW-MINE publication in this field deals with thermochemical heat storage via the CuO/Cu 2 O redox cycle and describes the synthesis of granules with a gravimetric energy storage density in the range of 470 to 615 kJ kg −1 [108].…”

Design and Optimization of Hierarchically Ordered Porous Structures for Solar Thermochemical Fuel Production Using a Voxel-Based Monte Carlo Ray-Tracing Algorithm

“…However, the computational cost becomes prohibitively high when the goal is to simulate complex porous geometries at the pore level due to the significant number of surfaces required to describe them. Previous modeling studies of hierarchically ordered and multilayered solar volumetric absorbers were limited to the optical analysis of radiation propagation , but did not solve the equation of radiative transfer, and even that limited scope was computationally costly . To some extent, the computational cost can be alleviated by extracting the effective (homogenized) transport properties from the smallest representative volume for use in volume-averaged simulations of porous media, − but this approach obviously cannot be applied for pore-level optimization.…”

“…Previous modeling studies of hierarchically ordered and multilayered solar volumetric absorbers were limited to the optical analysis of radiation propagation 6,7 but did not solve the equation of radiative transfer, and even that limited scope was computationally costly. 6 To some extent, the computational cost can be alleviated by extracting the effective (homogenized) transport properties from the smallest representative volume for use in volume-averaged simulations of porous media, 8−13 but this approach obviously cannot be applied for pore-level optimization. In contrast, voxel discretization offers a very fast computational alternative.…”