Heat transfer coefficient in three-phase vertical upflows of gas-liquid-fine solid particles system.

Abstract

Heat transfer characteristics between the inner tube wall and fluid of air-water-fine glass spheres three-phase vertical upflow were investigated using three kinds of glass spheres and two tubes under the following operating conditions: gas velocity (UG) = 80 - 900cm/s, slurry velocity (UL) = 30- 160cm/s, and solid particles concentration in slurry (CS) = 5 - 54 wt % for DT = 15-mm tube; and UG = 15 - 305 cm/s, UL = 8 - 62 cm/s, and CS = 0.2 - 57 wt % for DT = 27-mm tube. The following results were obtained.1) The heat transfer coefficients of three-phase vertical upflow exhibit larger values than those of gas-liquid twophase vertical upflow in the range of 0-40 wt % solid concentration.2) Monotonous small increases of the heat transfer coefficient with increase of both gas and slurry velocities were observed over the whole range of experimental conditions.3) A new empirical correlation of heat transfer coefficient was proposed to fit all data obtained in this work within 30%.