Integrating fluidized bed heat exchangers and particle thermal energy storage with sCO₂ recompression Brayton cycles for concentrating solar power

Oxide particles provide a cost-effective solution for thermal energy storage (TES) in future concentrating solar power (CSP) plants that implement supercritical carbon dioxide (sCO2) cycles at firing temperatures above 700°C. However, the design of effective particle-sCO2 HXs (HX) remains a challenge. Recent studies have explored how mild fluidization of gravity-fed particle flows can increase overall particle-sCO2 heat transfer coefficient, U_{\mathrm{HX}} to \approx 600 W m2 K-1 by decreasing thermal resistance between the particles and the walls. A test apparatus was set up to study heat transfer in a single-channel fluidized bed at temperatures up to 500°C. Particle-to-wall heat transfer coefficient, h_{\mathrm{T,\ w}} increases to a maximum at each temperature at intermediate gas velocities. Correlations for h_{\mathrm{T,\ w}} fitted to the experimental data are implemented into a quasi 1-D model of a particle-sCO2 HX core with narrow-channel fluidized particle beds and micro-channel sCO2 counter-flows in the HX walls bounding the fluidized bed. A process model of an sCO2 recompression Brayton cycle (RCBC) with turbine firing temperatures > 700°C was integrated with the 1-D particle-sCO2 HX model and a particle TES sub-system model to assess optimal operating conditions for CSP. Am optimization routine was used to identify HX designs and operating conditions which reduced HX costs ($ kWth-1) and full-system costs based on the levelized cost of electricity, LCOE ($ kW-1 h-1). Test results from a baseline 40-kWth demonstration HX provided a basis to scale HX performance to a multi-unit 100-MW CSP plant with TES. Full plant process model suggests HX costs below 150 $ kWth-1 and LCOE < 0.06 $ kW-1 h-1 cost targets can be achieved with particle-{\rm sCO}_2 HXs operating at mild fluidization conditions with predicted U_{\mathrm{HX}} = 464 W m-2 K-1 and with low parasitic losses due to small fluidizing gas mass flow rates below 2% of the net losses. An effective fluidized-bed particle-sCO2 HX design was identified for a 100-MWe CSP plant with TES at a HX cost of 130 $ kWth-1 and LCOE = 0.055 $ kW-1 h-1.

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2023

Author dc:creator

• Hernandez, Xavier

Advisor dc:contributor.advisor

• Jackson, Gregory

Committee members dc:contributor.committeemember

• Braun, Robert J.
• Tabares-Velasco, Paulo Cesar

• concentrating solar power
• fluidized bed
• heat exchanger
• particle-wall heat transfer
• sCO₂ power cycle
• thermal energy storage

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 9692

OAI identifier oai:identifier

oai:repository.mines.edu:11124/179127