Efficiency Analysis of an Air-Sand Heat Exchanger for selected operating conditions based on CFD-DEM Simulation

Air-Sand Heat Exchanger enable direct contact heat transfer between a fluid and a bulk solids. In simplified numerical simulations the interaction is described solely with Computational Fluid Dynamics as flow through a porous media. This approach neglects the impact of the fluid flow on the particle arrangement and resulting effects on the particle flow, which are important factors for the heat transfer. To overcome this inaccuracy a numerical simulation with Computational Fluid Dynamics to describe the continuum body of the fluid, and with the Discrete Element Method to describe the single particle based bulk solids was set-up. With this coupled simulation the fluid-particle interaction could be described and it showed that it cannot be neglected when setting the operating conditions, as the fluid-particle interaction and the possibly resulting effects pinning, blistering, and blocking have a major impact on the heat transfer effciency.