The size of bubbles leaving a three-phase fluidized bed containing low density particles was investigated photographically with a video camera. The influence of gas and liquid flow rates, size and density of solid particles on the size of bubbles was also studied. The size of the bubbles is almost independent of gas velocity, but decreases with increasing liquid velocity. The bubble coalescence tends to occur in the bed rather than the bubble column. The size of bubbles can be roughly estimated from the bubble size in the bubble column, physical properties of the particles, and operating conditions.
The purpose of this report is to discuss pressure drop characteristics in a flexible and/or collapsible tube where the flow area and the shape change depending on a transmural pressure across the tube wall. Single-and two-phase pressure drop and void fraction were measured in a vertical tube under various external pressure conditions. The results of numerical simulation agreed with the experimental results.