Studying the characteristics of bubble motion in pool boiling in microgravity conditions under the influence of a magnetic field

Pool boiling of a paramagnetic liquid in two identical tanks was created under microgravity conditions to study the characteristic behavior of bubbles under influence of a magnetic field. The main objective of this research project was to study the Kelvin force effect on bubbles in microgravity conditions. In addition, characteristics of bubble motion in pool boiling in microgravity condition with and without the influence of a magnetic field were studied. The reduced gravity conditions or microgravity conditions demonstrate the behavior in outer space environments. Parabolic path of an aircraft was used to create microgravity conditions for a period of 20-30 seconds. Two cylindrical tanks were used for the boiling process. One had a permanent magnet in the bottom and the other one was kept as reference to allow the comparison analysis of bubble motion with and without magnetic field. MnCl₂ was dissolved in distilled water to make a paramagnetic liquid, and that paramagnetic liquid was used to conduct pool boiling process. The pool boiling process was continued inside the tanks throughout the parabolic maneuver of the aircraft. Boiling process was captured on video simultaneously from three different angles to study the characteristics of bubble motion during the microgravity conditions. Frame by frame analysis the video clips was used to carry out image processing techniques to determine characteristic data of the bubble images. MatLab Image Processing Toolbox was used to analyze the image data of each frame that was captured from videos. During this investigation of bubble motion, two main studies were conducted. First, the characteristics of a single bubble were studied, such as: center of the bubble, shape of the bubble (maximum radius and minimum radius in vertical and horizontal direction), vertical and horizontal displacement of the center of the single bubble, rate of change of the position of the bubble coordinates and the vertical component of t- he selected single bubble velocity. As the strength of the magnetic field reduces, the influence of the magnetic field on bubbles was weakened along the vertical axis of the tank. That phenomenon was visualized by comparing the radius of a bubble in the bottom, middle and the top of the tank. Data gathered from the image processing technique of bubble frames relevant to bubble motion was graphically demonstrated. This research was partially funded by the NASA- WV Space Grant Consortium and West Virginia University Mechanical and Aerospace Engineering Department.