An experimental determination of pressure drops in the flow of low density spherical capsule train inside horizontal pipes

An experimental investigation was carried out to determine pressure drops of the flow of a two-phase mixture of spherical ice capsules and water inside the pipelines of cooling systems. Instead of ice capsules, spherical capsules made of polypropylene material whose density (870 kg/m3) is similar to that of ice were used in the experiments. Flow behavior of the said spherical capsules, 0.08 m outer diameter, was observed in the measuring section inside plexiglass pipes, 0.1 m inner diameter and 6 m in length; pressure drops were measured on the 4 m section. The investigation was carried out in the 1.2 × 104 < Re < 1.5 × 105 range and under transport concentration (Ctr) by 5–30%.Dimensional analysis was conducted to find out the dimensionless numbers of the physical event; variation of the pressure gradient occurring in the spherical capsule train–water flow inside a horizontal pipe versus bulk velocity and concentration was shown. Pressure gradients of the capsule–water flow and of the slurry flow were compared with each other. Reasons why the pressure gradient occurring in the two-phase capsule flow is higher than that of the single-phase water flow at the same velocity were investigated; effects of the increase of concentration and bulk velocity upon pressure gradients were examined.