Dynamic Model of a Solar Thermal Transport Tube Reactor for Control Purposes

A solar thermal reactor receives concentrated solar irradiation and uses this energy to thermally convert biomass into synthesis gas (H2, CO and CO2). The operation of this reactor is affected by the presence of clouds, which act as a disturbance for this process. When clouds are partially covering the sun, the reactor can still operate but the flow rates need to be regulated in order to optimize its operation and to avoid complications in the separation processes downstream. Thus, a robust control system that will allow continuous high performance operation of the reactor is required to make the process more feasible. The first step for the development of the control system is to determine the dynamics of the process and to analyze the transient response to the presence of clouds. Therefore, a simplified dynamic model is developed, based on unsteady energy and mass balances. This model needs to be simple enough to be executed in real time on site, but still needs to describe the most important physical characteristics of the system. Experimental runs for model validation were performed at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL), using different power levels and inert particles with different emissivities. In this work, a comparison of the modeling and experimental results is presented.&'