FLOW AND HEAT-TRANSFER IN 2-PHASE FLOW OF NEUTRALLY BUOYANT PARTICLESAND LIQUID

The pressure drop and heat transfer of solid-liquid two-phase flow, in which the ratio of diameter of solid particles to that of a pipe is l arge, were investigated experimentally. The solid particles used were spherical particles whose density is close to that of the liquid. Meas urements were made on friction factor, heat transfer coefficient on th e pipe wail, and on number density of particle distribution in the pip e. The result of visualization of flow indicates that the particles st ay at an equilibrium position for smaller Reynolds numbers and smaller concentration of particles. The equilibrium position of particles app roaches closer to the pipe wall for larger flow rates, and closer to t he pipe axis for smaller pipe diameters. The ratio of the friction fac tor of two-phase flow to that of Poiseuille flow increases gradually w ith increasing Reynolds number in the region of low Reynolds number, a nd increases steeply in the region of high Reynolds number. The ratio of friction factors increases with increasing fraction of the volumetr ic flow rate of the particles, and decreases with increasing ratio of diameter of the particles to that of the pipe. The ratio of heat trans fer coefficient of two-phase flow to that of Poiseuille flow has same tendency as the friction factor.