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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-483-0

ISBN Online: 978-1-56700-482-3

4th Thermal and Fluids Engineering Conference
April, 14–17, 2019 , Las Vegas, NV, USA

COMPARISON OF NUMERIC MODELS FOR THE SIMULATION OF MOLTEN SALT THERMOCLINE THERMAL ENERGY STORAGE WITH FILLER UNDER DIFFERENT APPLICATIONS

Get access (open in a dialog) pages 1741-1750
DOI: 10.1615/TFEC2019.tes.027998

Abstract

To date, two-tank molten salt systems mark the current state-of-the-art for large scale high-temperature thermal energy storage applications. Single-tank thermocline systems with filler (TCF) promise significant cost reductions, but are still under development. Available publications have utilized various models with different assumptions. Most models have been developed for regenerator storage systems, such as Cowper stoves. Applications range from simple sizing up to annual simulations. So far, only a few publications deal with the different outcome of those models, no comparative work has been published particularly for molten salt applications.
Thus, a comparative study of four one-dimensional models for packed bed molten salt storage systems is presented. The investigated models are the single phase model, the Schumann model, the continuous solid phase model and our recently developed bidisperse model. Based on practical considerations, different representative outer boundary conditions are defined for the comparison. In the first case, the storage is charged from uniform temperature (single blow) followed by a standby period (hold), often used for model validations since it causes harsh gradients. In the second case, the storage is charged and discharged for 14 cycles, to unveil slowly developing inaccuracies.
The simulations show significant differences depending on the outer boundary conditions. The single blow operation must be evaluated carefully as it might lead to a false validation of a model. Furthermore, the investigated models differ by up to 14 % from the chosen reference model. This work contributes to a better understanding of single tank molten salt storage simulation with filler.