Comparison of Empirical Expression and Experimental Findings in the Flow of Low Density Spherical Capsule Train with Pressure Gradient Expressions Developed for the Flow Of Slurry

摘要

Design parameters (i.e. power of pumps, number of pumps, diameter of capsule, diameter of pipe, geometry of pipe, etc.) of pipelines in which capsules flow can be developed if the pressure drops (ΔP)m caused by the two-phase flow are known. Therefore designers are in need of a general pattern to calculate the pressure drops. Slurry flow mechanism is different from capsule flow mechanism, so that expressions for pressure gradient of slurry flows cannot be used for capsule flows. In the experimental part of this study, pressure drops that occur in the flow of low density (s=0.87) spherical capsule (d=0.08m) train with water inside horizontal pipes (D=0.1m) were found out at 5-30% capsule transport concentrations, and the capsule flow mechanism was observed in Plexiglas pipes installed in the experimental equipment. After conducting a dimensional analysis and arriving at conclusions by using the experimental findings and observations, an empirical expression developed to calculate the pressure drops of the flow of a low density spherical capsule train was presented. Four different flow regimes were defined in the slurry flow, and pressure gradient equations defined for symmetric and asymmetric suspension flows which minimize the pressure drops were reviewed. Differences and similarities between the capsule flow mechanism and the slurry flow mechanism were found out by using the experimental findings. Experimental variables (i.e. bulk velocity, diameter of particle-or capsule, diameter of pipe, concentration of particle, density of particle, etc.) were applied to the pressure gradient expressions developed for slurry flows, so that the pressure gradients calculated for a concentration by 5% were compared with the experimental findings and with the mathematical model developed. It was noticed that the pressure gradient expressions of the slurry flows have not simulated the experimental results. However, comparison of the empirical expression developed for the pressure drops of the spherical capsule train flow (2.5x10~4