Session: 06-01: Thermal Energy Storage

Paper Number: 131719

131719 - Discrete Modeling of Flow and Heat Transfer in High-Temperature Gravity-Driven Granular Flows for Thermal Energy Storage 

Abstract: 

Gravity-driven dense granular flow can be a suitable heat transfer fluid (HTF) for high-temperature thermal and thermochemical energy storage (TES and TCES). To that end, particulate materials are becoming increasingly attractive for heat exchanger and solar receiver/reactor applications due to their low costs, high operating temperatures, and ease of operation. While various analytical and continuum studies are available for analyzing the heat transfer performance of granular flows, they are typically based on assumptions in the near-wall region, particle bed continuum, and effective transport properties such as particle bed flow properties and effective bed thermal conductivity; on the other hand, discrete element method (DEM) based modeling of granular flows can elucidate the particle-scale flow and thermal transport, and is thus an attractive alternative approach. Furthermore, the particle-scale mechanical and flow properties such as sliding and rolling friction coefficients and restitution coefficient between particles are key input parameters for DEM simulations and they may vary at high temperatures. This study aims to develop a DEM model to observe the particle flow and heat transfer characteristics of dense granular flows over a wide range of temperatures (from room temperature up to 800°C) that are typical in TES and TCES applications. The linear-spring dashpot model (LSD) is used to simulate particle collisions via a soft-sphere approach, and for the particle-scale heat transfer, interparticle conduction, particle-fluid-particle conduction, particle convection, and interparticle radiation are considered. The DEM flow and heat transfer model is validated with previously published experimental work for granular flows along an inclined plane. It is then further used to study the effects of sliding and rolling friction coefficients and restitution coefficient on the local particle flow velocity and temperature profiles. A reduction in the magnitude of the streamwise averaged velocity profile can be observed with an increase in the bed temperature. Compared to room temperature (23°C), the particle velocity decreases by 57.10% for 800°C, 31.06% for 600°C, 16.39% for 400°C, and 6.14% for 200°C at the particle outlet, showing the significant effect of the input flow properties at high temperature operation. Effect of interparticle radiation is also significant at high temperatures which is evident by values of particle inlet and outlet temperatures whereby a difference of 0.03°C, 3.04°C, 13.90°C, 38.87°C, and 83.39°C is observed for 23°C, 200°C, 400°C, 600°C, and 800°C respectively. Parametric effects of particle diameter, mass flow rates, plane inclination angle, and interparticle radiation effects are extensively studied to quantify the heat transfer performance in dense granular flows. This work will provide particle-scale insights into thermal transport behavior in granular flows, which can be leveraged to design particle-based heat exchangers and solar receivers and reactors for TES and TCES.

Presenting Author: Like Li Mississippi State University

Presenting Author Biography: Like Li is an Associate Professor in the Mechanical and Aerospace Engineering Department at the University of Central Floria.

Authors:

Ashreet Mishra Mississippi State University
Ouidad Abourazzouk University of Central Florida
Jian Zhao Mississippi State University
Like Li Mississippi State University