Significant Differences in the Value of the Void Fraction in Various Types of Low-Viscosity Two-Phase Flow Patterns in Capillary Tubes with a Particular Slope

Abstract

A two-phase flow is the simplest form of multi-phase flow. Two-phase flow has basic parameters, including flow behavior, flow pattern, void fraction, pressure gradient, or pressure drop. The development and application of fluid flow in small channels (mini and micro) are in the Micro Electromechanical System (MEMS). In general, the application of two-phase flow can be found in various applications in the industrial world, such as boilers, cores, and steam generators in nuclear reactors, petroleum transportation, electronic cooling, and different other types of chemical reactors. One of the most common challenges is void fractions and flow patterns in horizontal and vertical pipelines. The purpose of this study was to find out the significant difference in the characteristic value of fundamental parameters, primarily void fractions and flow patterns that occur in capillary pipes with a slope of 15o to horizontal. The fraction value and shape of this flow pattern are essential because it determines the pressure drop value, which means determining the level of danger that can occur if the pressure drop value reaches the extreme value. The fluid used a mixture of air-water and glycerin with 0, 10, 20, and 30% concentrations. To determine the void fraction is used digital image processing method with MATLAB R2014a application. A 1200 fps high-speed camera and 640 x 480-pixel resolution are used for video shooting. The experiment was conducted at superficial gas (JG) velocities of 0.025 - 66.3 m/s and superficial fluid velocities (JG) intervals of 0.033 – 4.935 m/s. The experiment results showed a significant difference between the void fraction value for the bubbly flow pattern and the churn flow pattern, which has not been widely discussed in previous studies. The analysis concluded that the higher the velocity of superficial gases, the void fraction value increases. This increase in the void fraction is why there is a significant change in flow patterns from bubble flow patterns to churn. In addition, it was also found that the increased viscosity of the fluid significantly affected changes in flow patterns, incredibly bubbly and plug, but its velocity decreased. It is also the result that the higher homogeneous void fraction (β) value affects the increase in the length of bubbly flow patterns and plugs.