INVESTIGASI FRAKSI HAMPA DUA-FASE UDARA-AIR DAN MINYAK PADA PIPA KAPILER KEMIRINGAN 75? TERHADAP SUMBU HORISONTAL

Two-phase flow is part of the simplest multiphase flow which consists of two different phases such as a mixture of solid, liquid, and gas passing through one channel. Applications of two-phase flow are often found in everyday life as well as in industrial processes, for example in micro heat exchangers, condensers, boilers, mining industry, petroleum industry, and in the medical field, namely in the blood circulation of the human body. The purpose of this study is to obtain primary data about the void fraction that occurs in the mini pipe and to determine the effect of the slope of the test section and fluid properties. This study used a test pipe made of acrylic with an inner diameter of 1.6 mm and a length of 160 mm with a slope of 75⁰. The working fluid is air and a mixture of distilled water and coconut oil with a concentration of 350 mg/dl and 500 mg/dl. Superficial velocity of gas (JG) = 0.08 – 74.6 m/s and superficial velocity of liquid (JL) = 0.04 – 4.15 m/s. The flow pattern was observed using a high-speed camera and then the value of the void fraction was obtained using a digital image processing method using the MATLAB R2014a program. The observed flow patterns are plug, slug-annular, annular, and churn. The difference in fluid concentration does not significantly affect the flow pattern and the obtained void fraction. In addition, there is an agreement with previous researchers, but in this study, no bubbly flow pattern was found. This is because the bubbly flow pattern is strongly influenced by the viscosity of the liquid and the superficial velocity of the gas. So that the JG is less stable it will cause a plug flow pattern or elongated bubbly. In addition, there are differences in flow pattern transition lines. The physical properties of the working fluid (viscosity and surface tension) have a great influence on the void fraction and the flow pattern that occurs