Operational Modes of a 2.0 MWth Chloride Molten-Salt Pilot-Scale System

Kenneth Armijo, Matthew Carlson, Dwight Dorsey, Jesus Ortega, Dimitri Madden, Joshua Christian, Craig Turchi

Research output: Contribution to conferencePaperpeer-review

1 Scopus Citations

Abstract

The limit of traditional solar-salt thermal stability is around 600 °C with ambient air as the cover gas. Nitrate molten salt concentrating solar power (CSP) systems are currently deployed globally and are considered to be state-of the art heat transfer fluids (HTFs) for present day high-temperature operation. However, decomposition challenges occur with these salts for operation beyond 600. Although slightly higher limits may be possible with solar salt, to fully realize SunShot efficiency goals of $15/kWhth HTFs and an LCOE of 6¢/kWh, molten-salt technologies working at higher temperatures (e.g., 650 °C to 750 °C) will require an alternative salt chemistry composition, such as chlorides. In this investigation a 2.0MWth Pilot-scale CSP plant design is developed to assess thermodynamic performance potential for operation up to 720 . Here, an Engineering Equation Solver (EES) model is developed with respect to 14 state-points from the base of a solar tower at the Sandia National Laboratories, National Solar Thermal Test Facility (NSTTF), to solar receiver mounted 120 ft. above the ground. The system design considers a ternary chloride ternary chloride (20%NaCl/40%MgCl/40%KCl by mol%) salt as the HTF, with 6 hrs. of storage and a 1 MWth primary salt to sCO2 heat exchanger. Preliminary system modelling results indicate a minimum non-dimensional Cv of 60 required for both cold and hot-side throttle recirculation valves for the operational pump operating between speeds of 1800 and 2400 RPM. Further receiver comparison study results suggest that the ternary salt requires an average 15.2% higher receiver flux with a slightly lower calculated receiver efficiency when compared to a binary carnelite salt to achieve a 2.0 MWth desired input power design.

Original languageAmerican English
Number of pages9
DOIs
StatePublished - 11 Dec 2020
Event2019 International Conference on Concentrating Solar Power and Chemical Energy Systems, SolarPACES 2019 - Daegu, Korea, Republic of
Duration: 1 Oct 20194 Oct 2019

Conference

Conference2019 International Conference on Concentrating Solar Power and Chemical Energy Systems, SolarPACES 2019
Country/TerritoryKorea, Republic of
CityDaegu
Period1/10/194/10/19

Bibliographical note

Publisher Copyright:
© 2020 American Institute of Physics Inc.. All rights reserved.

NREL Publication Number

  • NREL/CP-5700-78804

Keywords

  • associated liquids
  • concentrated solar power
  • engineering thermodynamics
  • heat transfer mechanism
  • materials properties
  • plant design

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