Granular Flow Field in Moving Bed Heat Exchangers: A Continuous Model Approach

Moving Bed Heat Exchangers (MBHX) are a promising option to discharge thermal energy from hot bulk materials, which can be used in solar thermal power plants as heat transfer and storage medium. A precise determination of the flow field in a MBHX is required to predict its thermal performance. This paper presents a continuous model approach, based on the theory of soil mechanics to describe the granular flow inside the heat exchanger. The simulation results are compared to a preceding model and experimental data. For this purpose two different tube bundle geometries are analyzed. The results are evaluated by means of contour plots of the flow field and the velocity magnitude of the granular material at the tube surfaces. The new model captures the flow at the top of the tubes quite well but shows need for further improvement in the lower part of the tubes.