EULERIAN GRANULAR CFD MODELLING OF HYDRODYNAMICS OF A FREE-FALLING PARTICLE CURTAIN WITH PARTICLE SIZE DISTRIBUTION
A solid particle receiver is a principal element in concentrated solar power technology in which falling ceramic particles in a cavity are exposed to extremely concentrated solar irradiation. Such particle receiver holds great promise in achieving high thermal efficiencies due to the possibility of reaching temperatures as high as 1000° C. To accurately model the hydrodynamics and the radiation heat transfer, it is imperative to simulate particle-gas interactions more realistically. All the particle receiver modelling till date has used only monodisperse size assumption to simplify the simulation. However, the radiation interaction with the particle curtain is greatly dependent on the size-dependent radiation properties. In the present work, we aim to model the two-dimensional mass and momentum equations using an Eulerian-Eulerian multiphase granular model with a particle size distribution in the falling particles. Gaussian distribution is assumed as a representative size distribution spread around a mean particle size of magnitudes generally used in particle receivers (~100-500 µm). The distribution is then split into n size bands and the Eulerian granular flow is modelled for n secondary phases (up to 3 in this study) with a corresponding concentration to simulate the particle size distribution. Finally, a parametric study is carried out to understand the effect of different particle sizes and their concentration on the volume fraction distribution and particle velocities inside the receiver.