An Experimental Investigation of Ultra-High Temperature and Pressure Fluidized Bed for Thermal Energy Storage and Transfer

Pressurized fluidized beds (PFB) have many applications such as fluidized bed combustion, heat exchange processes, and even to accelerate chemical reactions. A novel energy storage system designed by the National Renewable Energy Laboratory (NREL) utilizes an ultra-high temperature and pressure PFB to transfer heat from particles to air. Experimental data under such conditions are rare in the literature[1], [2], and our work presents data from a laboratory-scale PFB and comparisons to computational models. To validate the computational models, a laboratory-scale PFB was built to operate at 1000°C and 10 bar. The PFB has an inner diameter of 3.125” and the bed height varies from 3” to 9”. The particles used were silica sand with a mean diameter of 625 microns. The minimum fluidization velocity, bed pressure drop, and heat transfer coefficient of the PFB were determined from the experimental data. The minimum fluidization velocity and heat transfer coefficient obtained were compared to existing correlations [3]–[6]. Discrete element modeling (DEM) simulations using the Multiphase Flow with Interface Exchanges (MFiX) on the lab-scale PFB were also compared to the experimental results. The models for particle-to-gas heat transfer and fluidization characteristics are validated via comparison to the experiments for a range of temperatures and pressures [1][2].

References

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