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Research Papers: Multiphase Flows

# Effect of Capsule Density and Concentration on Pressure Drops of Spherical Capsule Train Conveyed by Water

[+] Author and Article Information
Deniz Ulusarslan

Department of Mechanical Engineering, Yıldız Technical University, 34349 Istanbul, Turkeyulusars@yildiz.edu.tr

J. Fluids Eng 132(1), 011304 (Jan 12, 2010) (6 pages) doi:10.1115/1.4000738 History: Received March 27, 2009; Revised November 12, 2009; Published January 12, 2010; Online January 12, 2010

## Abstract

This experimental investigation concerns the hydraulic transport of a spherical capsule train, whose density is equal to that of water (relative density; $s=1$), in horizontal pipes. In a system where the carrier fluid is water, pressure drops of two phase flow and capsule velocities were measured at 0.2–1.0 m/s bulk velocities and 5–20% capsule transport concentrations. The results found were compared with the pressure gradient (pressure drops per unit length) ratios $((ΔP/L)m/(ΔP/L)w)$ measured for less dense capsules. The capsule velocity and the velocity ratio $(Vc/Vb)$ increased with increasing the bulk velocity. As concentration increases, the pressure gradient of the capsule-water mixture increases. For all concentrations, the pressure gradient ratio decreases (getting closer to 1) with increasing bulk velocity. This result is similar to that of capsules with less relative density. However, the pressure gradient ratio of the capsule flow with less density is higher than that of capsules with equal density at constant transport concentrations. The reason for this difference is that the capsules with a density equal to that of water move along the axis of the pipe for a longer time. When capsules with equal density are used, the mass flow rate will remain the same, but energy consumption will decrease.

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## Figures

Figure 1

Schematic diagram of distance between capsules

Figure 2

Relation between bulk velocity and capsule velocity

Figure 3

Variation in velocity ratio with bulk velocity

Figure 4

Relation between the velocity ratio and Re number of mixture

Figure 5

Relation between (ΔP/L)m and Re number of mixture based on experiments

Figure 6

Variation in pressure gradient ratio with bulk velocity and concentration

Figure 7

Comparison of pressure gradient ratios for different capsule density

Figure 8

Darcy–Weisbach friction factor versus Reynolds number of mixture

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