A theoretical and experimental study of the time-dependent radiative properties of a solar bubbling fluidized bed receiver

Abstract

In order to evaluate the potential of solar bubbling fluidized bed receivers compared to other methods for the solar heating of gases at high temperature, a thorough knowledge of the heat transfer of the receiver is necessary. Since the external energy source of the system is radiative and because of high working temperatures, it is particularly important to model the radiative heat transfer to later predict the temperature field in the solar receiver. The aim of this study is to model the radiative flux distribution in a fluidized bed by taking into account the time-dependent absorption and scattering of light in the particulate medium. For this purpose, we propose a model using the Monte Carlo Method as well as a time-dependent field of optical properties that was predicted using a Computational Fluid Dynamics tool implemented with an Eulerian model. A statistical treatment using the k-distribution method was later applied to the time-dependency of the radiative properties of the solar fluidized bed receiver. This method has proven to be useful to reduce computational time while keeping a good accuracy. An experimental set-up was designed to validate the numerical predictions of the particle volume fraction and the penetration of radiation into the fluidized bed. The good agreement of the current model with the experimental data confirms its suitability.