Session: 05-09 Particles for Thermal Storage in CSP 2

Paper Number: 116867

116867 - Adaptation of Two-Fluid Models for Particle-Wall Heat Transfer in Fluidized Beds for Concentrating Solar Applications 

Oxide particle thermal energy storage (TES) has been proposed to replace molten-nitrate salt TES for integration with next-generation concentrating solar power (CSP) plants [1]. However, the design of efficient particle receivers and cost-effective primary heat exchangers between the particles and working fluid of the power cycle poses a major challenge for deploying particle-based TES [2]. Our team has demonstrated that narrow-channel, bubbling fluidized beds offer a pathway for enhancing particle-wall heat transfer for fluidized bed heat exchangers and indirect receivers with particle-wall heat transfer coefficients over 1000 W m-2 K-1 at bed temperatures above 400oC for small particles with mean diameter below 250 mm [3]. To explore various aspects of particle flow-path design, our team developed and calibrated a 3D two-fluid model in ANSYS Fluent using extensive experimental data from heat transfer studies in a single-channel flow rig. This presentation demonstrates the importance of understanding particle-wall interactions and assessing the sensitivity of the particle-wall heat transfer on the parameters in the two-fluid model to capture the trends observed in narrow-channel fluidized bed experiments. 

In this study, the 3D, two-fluid model of a narrow channel fluidized bed is presented and calibrated to capture trends observed in both solid volume fractions and particle-wall heat transfer coefficient as a function of bed temperature and particle size. We show that particle-wall interactions as dictated by the gas-flow turbulent models, interphase drag coefficients models, and particle-wall collision parameters have a significant impact on the predicted particle-wall heat transfer coefficient and its variation with fluidization velocity and particle properties. We perform a sensitivity analysis of the particle-wall heat transfer on the particle-wall collision parameters, and we identify the values that best capture the observed trends in particle-wall heat transfer coefficient with respect to fluidization velocity, bed temperature, and mean particle diameter. We then use the resulting two-fluid model to explore particle dispersion within the bed, and its impact on particle temperature profiles and overall particle-wall heat transfer at conditions relevant for TES in next generation CSP applications.  

References: 

[1] Calderón, A., Barreneche, C., Palacios, A., Segarra, M., Prieto, C., Rodriguez‐Sanchez, A., & Fernández, A. I. (2019). Review of solid particle materials for heat transfer fluid and thermal energy storage in solar thermal power plants. Energy Storage, 1(4), e63. 

[2] Ho, C. K., Carlson, M., Albrecht, K. J., Ma, Z., Jeter, S., & Nguyen, C. M. (2019). Evaluation of alternative designs for a high temperature particle-to-sCO2 heat exchanger. Journal of Solar Energy Engineering, 141(2). 

[3] Fosheim, J. R., Hernandez, X., Abraham, J., Thompson, A., Jesteadt, B., & Jackson, G. S. (2022, May). Narrow-channel fluidized beds for particle-sCO2 heat exchangers in next generation CPS plants. In AIP Conference Proceedings (Vol. 2445, No. 1, p. 160007). AIP Publishing LLC. 

Presenting Author: yahya bokhary Colorado School of Mines

Presenting Author Biography: Yahya Bokhary is a Ph.D. graduate student at the Colorado School of Mines. He received his bachelor’s degree in mechanical engineering from the King Fahad University of Petroleum and Minerals (KFUPM) in Saudi Arabia and His master’s degree, also in mechanical engineering, from the Colorado School of Mines. His research focuses on concentrated solar energy and high-temperature energy storage. he is currently working on modeling a 3D fluidized bed using a two-fluid model.