The National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories is conducting research on a Generation 3 Particle Pilot Plant (G3P3) that uses falling sand-like particles as the heat transfer medium.&nbsp; G3P3 proposes 6 MWh thermal energy storage in cylindrical bins made of steel that will be insulated internally using multiple layers of refractory materials [1].&nbsp; The refractory materials can be applied by stacking pre-cast panels in a cylindrical arrangement or by spraying liquid refractory to the walls (shotcrete).&nbsp; A study on the two methods determined that shotcrete would be the preferred method in order to minimize geometric tolerance issues in the pre-cast panels, improve repairability, and to more closely resemble commercial-scale construction methods.Testing was performed to verify whether the coarse inner layer of high-density shotcrete would impinge on the softer subsequent refractory layers, whether moisture from the wet refractory would transfer to subsequent layers and cause damage, and whether shotcrete would successfully adhere to subsequent layers [2].&nbsp;&nbsp; Results showed acceptably low levels of wear caused by shotcrete impingement.&nbsp; A chemically applied moisture barrier was sufficient to prevent leaching of moisture.&nbsp; The high-density shotcrete adhered successfully to a Calcium-Silicate panel and was manually pried off to inspect for damage at the interface of the surfaces.&nbsp; Minimal material peeling or damage was observed.Thermal analysis was conducted to model the expected heat losses attributed to the increased effective conductivity of the steel anchors used to support the shotcrete walls.&nbsp; Prior studies have shown that steel reinforcement has a significant effect on the conductivity of reinforced concrete [3].&nbsp; Other work has shown that modeling this heat loss can have a dependency on the dimensionality of the model used with 1-D, 2-D, and 3-D models showing contradictory levels of thermal bridging [4].&nbsp;1-D analytical thermal resistance models and 3-D FEA steady-state models were performed on model cross-sections of the G3P3 storage bin with and without steel anchors to derive an upper and lower bound of the overall increase in heat lost.&nbsp; The additional heat loss was then used to calculate the effective increase in conductivity of the materials.&nbsp; Cyclic models used in previous studies [1] were re-run with the increased conductivity coefficients to determine the expected increase in heat loss after the refractory layers reached cyclic steady-state conditions.&nbsp; This heat loss yielded a simulated increased drop in bulk outlet particle temperature from 11 °C to 12.8 °C at equilibrium (e.g., cyclic steady-state) after 10 hours of storage, which was deemed acceptable to meet G3P3 design requirements.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology &amp; Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.1.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jeremy N. Sment, Design Considerations for a High-Temperature Particle Storage Bin.2.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Lambert, M., Inspection of Calcium Silicate Board after Direct Contact Shotcrete Installation.3.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Shunbo Zhao, Study on Thermal Conductivity of Reinforced Concrete Plate.4.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Greg Palmer, Heat Transfer Design Considerations for Refractory Linings with Steel Anchors, &nbsp;

Application Methods for Refractory Insulation in Hot Particle Storage Bins

Paper Proceedings: https://asmedigitalcollection.asme.org/ES/ES2021/volume/84881

ASME 2021 Energy Sustainability (ES2021)

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