Systematic approach for design optimization of a 3 kW solar cavity receiver via multiphysics analysis

Abstract

Use of Computational Fluid Dynamics (CFD) modeling for solar reactor design optimization is a powerful tool in developing efficient reactors for solar thermochemical applications. CFD models can capture complex multiphase flow dynamics to explain the physics linking the heat transfer and flow dynamics on chemical conversion efficiency and continuous operation of a solar reactor. Flux map and temperature data can be numerically obtained via CFD inside the solar reactor, which is a harsh environment for penetrating measurement tools. In this paper, a CFD analysis of a solar cavity receiver operated with air flow and is directly irradiated by a 10 kWe High Flux Solar Simulator (HFSS) is presented. Radiative heat transfer from the HFSS is modeled by implementing Monte Carlo Ray Tracing (MCRT) for tracking the ray paths from the radiative source to the aperture plane of the receiver. Flux densities were computed at the aperture and validated by experimental heat flux characterization of the solar simulator. The validated MCRT model provided directional information on the radiative flux and was sequentially coupled to the computational fluid domain. Through experimental testing, receiver temperatures up to 1200 K were measured with solar input at the entrance of the cavity of around 3 kW radiative power. Experimentally measured non-uniform temperature distribution in the axial direction was recorded, which developed a hot spot at the backplate of the cavity. Accuracy of the numerical model was validated by comparing the temperature prediction inside the cavity receiver to experimental results. Validated model was then used to conduct a parametric study on the flow configuration to identify run conditions yielding enhanced fluid mixing and improved heat transfer characteristics. The results showed that altering the angle of the main inlet ports proved to be effective in reducing the local hot spot in the back of the receiver. Moreover, results of the parametric study identified the increase of main flow rate as a positive contribution towards temperature uniformity throughout the fluid domain.