RT Journal Article
T1 Experimental evaluation of the convection heat transfer coefficient of large particles moving freely in a fluidized bed reactor
A1 García Gutiérrez, Luis Miguel
A1 Hernández Jiménez, Fernando
A1 Cano Pleite, Eduardo
A1 Soria Verdugo, Antonio
AB Heat transfer is a key aspect in the performance of fluidized bed reactors. In particular, the dense phase heat transfer coefficient, which determines the heat exchanged between the bed and fuel particles, is of special relevance. This work presents a study on the heat transfer that occur when introducing pelletized particles of dry ice in a fluidized bed. The convection heat transfer coefficient is experimentally evaluated by means of the sublimation of dry ice particles using a novel methodology, which consists in a measurement system based on a macro-TGA fluidized bed and the corresponding evaluation of the acquired data. The system is capable of measuring the real time mass of the fluidized bed, which is a direct measure of the mass loss of the dry ice particles. The evaluation of such measurements allows to determine the convection heat transfer coefficient between the dry ice particles and the bed. Fixed and fluidized bed regimes, varying the excess gas velocity from -0.03 m/s up to 0.35 m/s, were tested for two different bed materials, namely Ballotini glass beads and alumina. The results of the sublimation and heat transfer coefficients are in good agreement with values reported in the literature, confirming the reliability of the experimental and postprocessing methodologies. In general, higher gas velocities enhance the dry ice particles mixing in the bed up to a limit in which the sublimation and convection heat transfer coefficients do not further increase. Additionally, the influence of the buoyancy behaviour of the dry ice particles in the bed on the convection heat transfer coefficient is discussed. The convection heat transfer coefficient decreases substantially if the dry ice particles present a flotsam behaviour and the gas velocity is not sufficiently high to ensure a proper circulation of the particles in the whole bed.
PB Elsevier
SN 0017-9310
YR 2020
FD 2020-06
LK https://hdl.handle.net/10016/32476
UL https://hdl.handle.net/10016/32476
LA eng
DS e-Archivo
RD 1 sept. 2024