Wall-to-bed heat transfer in vertical hydraulic transport and in particulate fluidized beds

Abstract

Wall-to-bed heat transfer in hydraulic transport and in particulate fluidized beds of spherical particles was studied. Experiments were performed by spherical glass particles of 0.80-2.98 mm in diameter with water in a 25.4 mm I.D. cooper tube equipped with a steam jacket. In the hydraulic transport runs the Reynolds number varied between 3300 and 20150 (particles of 1.20,1.94 and 2.98 mm in diameter), while in particulate fluidized beds Reynolds number varied between 1960 and 7850 (particles of 0.80, 1.10 and 1.94 mm in diameter). The influence of different parameters as liquid velocity, particles size and voidage on heat transfer in fluidized beds and in hydraulic transport are presented. In our hydraulic transport experiments, the two characteristic flow regimes were observed: "turbulent" and "parallel" flow. Our experimental data show that the heat transfer coefficients in "turbulent" regime are much higher then in "parallel" flow, and the heat transfer coefficients is generally higher while the flow is in fluidized bed. The data for heat transfer in particulate fluidized beds and for vertical hydraulic transport were correlated treating the flowing fluid-particle mixture as a pseudo fluid. New correlation for heat transfer factor in fluidized beds and in vertical hydraulic transport is proposed.