Premium
Fluidized bed freeboard measurements of heat transfer
Author(s) -
Farag Ihab H.,
Tsai KunYung
Publication year - 1992
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450700408
Subject(s) - freeboard , heat transfer , heat transfer coefficient , mechanics , perpendicular , convection , convective heat transfer , materials science , fluidized bed , thermodynamics , chemistry , geometry , physics , mathematics
Local surface‐to‐suspension heat transfer coefficients in the freeboard of a fluidized bed reactor were measured by a newly designed miniature probe. Four types of plate orientations were used to test directional effects of surface on heat transfer rate. Variations of heat transfer coefficients with radial position are more significant at lower freeboard. For plate parallel both to the axial and radial directions of the column, the heat transfer coefficient ( h ) is higher at the center than at wall. For plate with exposed surface parallel to the axial and perpendicular to the radial directions, the plate gives nearly the same value of h at the center and the wall. At low heights of freeboard, center‐facing surface exhibits higher heat transfer rate than wall‐facing one. The phenomena of higher solids concentration and center to wall movement of particles account for this observation. Variations of heat transfer coefficients with elevation in the freeboard are as much as an order of magnitude, decreasing to gas convection with increasing elevation. These variations are relatively insensitive to the types of plate orientation investigated.