Radiation Characteristics of a Particle Curtain in a Free-Falling Particle Solar Receiver

Radiation absorption by a particle curtain formed in a solar free falling particle receiver is investigated using a Eulerian-Eulerian granular two-phase model to solve the two-dimensional mass and momentum equations (CFD). The radiative transfer equation is subsequently solved by the Monte-Carlo (MC) ray-tracing technique using the CFD results to quantify the radiation intensity through the particle curtain. The CFD and MC results provide reliable opacity predictions and are validated with the experimental results available in literature. The particle curtain was found to absorb the solar radiation efficiently for smaller particles at high flowrates due to higher particle volume fraction and increased radiation extinction. However, at low mass-flowrates the absorption efficiency decreases for small and large particles.