"Solid conduction effects and design criteria in moving bed heat exchangers"

J.A. Almendros-Ibáñez (1) , A. Soria-Verdugo (2) , U. Ruiz-Rivas (2) , D. Santana (2)

1 Section of Solar and Energy E_ciency
2 Thermal and Fluid Engineering Department

This work presents a theoretical study of the energetic performance of a Moving Bed Heat Exchanger (MBHE), which consists on a ow of solid particles moving down that recovers heat from a gas ow percolating the solids in cross ow. In order to defne the solid conduction effects, two solutions for the MBHE energy equations have been studied: an analytical solution considering only convection heat transfer (and neglecting solid conduction) and a numerical solution with the solid conductivity retained in the equations. In a second part, the power requirements of a MBHE (to pump the gas and to raise the down-owing particles) are confronted with the heat transferred considering the variation of design parameters, such as gas and solids velocities, solids particle diameter or MBHE dimensions. The numerical results show that solid conductivity reduces the global effciency of the heat exchanger. Therefore, a selection criterium for the solids can be established, in which their thermal conductivity should be minimized to avoid conduction through the solid phase, but to a limit in order to ensure that temperature differences inside an individual solid particle remain small.Regarding the other energy interactions involved in the system, these are at least one order of magnitude lower than the heat exchanged. Nevertheless, for a proper analysis of the system the effciency of the devices used to pump the gas and to raise the particles and the relative costs of the different energy forms present in the system should be taken into account

Mots clés: Moving Bed Heat Exchanger; Heat transfer; Biot number; Packed bed

Domaines: Thermique [physics.class-ph]; Thermique [physics.class-ph]

J.A. Almendros-Ibáñez, A. Soria-Verdugo, U. Ruiz-Rivas, D. Santana. "Solid conduction effects and design criteria in moving bed heat exchangers". Applied Thermal Engineering, 2011, 31 (6-7), pp.1200. ⟨10.1016/j.applthermaleng.2010.12.021⟩. ⟨hal-00723970⟩