Narrow-Channel, Fluidized Beds for Effective Particle Thermal Energy Transport and Storage

Technical Report · Tue Apr 11 04:00:00 EDT 2023

DOI:https://doi.org/10.2172/2007141· OSTI ID:2007141

Jackson, Gregory S. ^[1]; Albrecht, Kevin J. ^[2]; Reimanis, Ivar E. ^[3]; Ambrosini, Andrea ^[4]; Arthur-Arhin, Winfred J. ^[3]; Brewster, Keaton J. ^[3]; Billman, Julia ^[3]; Madden, Dimitri ^[2]

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1. Colorado School of Mines, Golden, CO (United States); Colorado School of Mines
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Colorado School of Mines, Golden, CO (United States)
4. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies (CINT)

Colorado School of Mines (Mines) led this program in collaboration with Sandia National Laboratories (Sandia) to characterize narrow-channel fluidized beds of aluminosilicate particles – supplied by Carbo Ceramics – as a means for releasing high-temperature thermal energy in particle heat exchangers and for capturing concentrated solar energy in indirect particle receivers. Single-channel, heat transfer experiments at Mines and reduced-order 1-D models and 3-D two-fluid, CFD models explored many aspects of counterflow, bubbling fluidized beds (net downward particle flow and upward gas flow) for enhancing particle-wall heat transfer at elevated temperatures. Results at Mines on single-channel test sections consistently showed that mild bubbling fluidization increases particle-wall heat transfer coefficients (h_T,w) regularly by more than 4.0x over h_T,w values without fluidization at similar conditions (mean particle diameter d_p, bed depth Δz_b, and bed particle temperatures T_p). Insights from lab-scale tests and modeling studies provided Nusselt number correlations for h_T,w and informed the design and fabrication (by Vacuum Process Engineering) of a nominal 40-kWth, particle-sCO₂ plate heat exchanger (HX) with 12 parallel narrow-channel, fluidized beds bounded by stainless-steel walls with embedded microchannels for high-pressure sCO₂ flows. Tests of the 40-kW_th HX at the particle-sCO₂ HX test stand at Sandia's National Solar Thermal Test Facility (NSTTF) were limited, due to HX design, to particle inlet temperatures T_p,in≤ 520°C with maximum sCO₂ outlet temperatures T_sCO2,out ≈ 440°C, which are well below design conditions for a primary HX in a sCO₂ power cycle for a Gen-3 concentrating solar power (CSP) plant. Total heat transfer $$\dot{Q}_{HX}$$ remains relatively constant with increased fluidization for fixed particle and sCO₂ inlet conditions because higher h_T,w due to fluidization is offset by increased axial dispersion, which suppresses temperature differences between the particles and sCO₂ in the counterflow configuration. The axial dispersion reduces the effective overall heat transfer coefficient U based on T_p,in to values around 200 W m^-2 K^-1.

• Research Organization: Colorado School of Mines, Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• Contributing Organization: CARBO Ceramics
• DOE Contract Number: EE0008538
• OSTI ID: 2007141
• Report Number(s): ColoradoSchoolOfMines--EE0008538
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
Concentrating Solar Power
Fluidized Bed Heat Exchanger
Particle Thermal Energy Storage