《A single particle model for surface-to-bed heat transfer in fluidized beds》.pdf

Available online at Powder Technology 187 (2008) 68 – 78 /locate/powtec A single particle model for surface-to-bed heat transfer in fluidized beds Francesco Di Natale ⁎, Amedeo Lancia, Roberto Nigro Dipartimento di Ingegneria Chimica, Università di Napoli “Federico II ” P.le Tecchio, 80, 80125 Napoli, Italy Received 12 March 2007; received in revised form 8 November 2007; accepted 17 January 2008 Available online 2 February 2008 Abstract This paper presents a semi empirical single particle model for the description of heat transfer coefficient between a submerged surface and a fluidized bed. The model is applied to several experimental data and gives a satisfactory description of the effect of pressure, temperature and bed material properties on the heat transfer coefficient either in bubbling or slugging fluidized beds. The model considers the averaged surface void fraction as the only regression parameter for the description of experimental data. Surface void fraction results to be a function of Archimedes number and minimum fluidization bed voidage and its value is consistent with the numerical and experimental data reported in literature. © 2008 Elsevier B.V. All rights reserved. Keywords: Fluidized beds; Heat transfer model; Surface void fraction 1. Introduction have been carried out. The main objective of these studies was the description of heat transfer coefficient for immersed tube Fluidized gr