G-Jitter Effects on Bubble Dynamics and Heat Transfer In Electrowetting Induced Pool Boiling

In pool boiling under low-gravity conditions, the lack of adequate buoyancy force results in vapor bubbles adhering to the heated surface. This phenomenon severely deteriorates the heat transfer rate by forming an insulating vapor layer that impedes the efficient transfer of thermal energy. The challenge is further compounded under g-jitter conditions, where the fluctuating gravity induces complex bubble dynamics and alters the heat transfer characteristics. In the present study, a comprehensive numerical investigation is conducted using the phase-field method, which enables precise tracking of the liquid-vapor interface, coupled with a dynamic contact angle model. The simulations reveal distinct bubble behaviors under conditions with and without g-jitter. Specifically, the hydrodynamics of bubble in pool boiling under fluctuating gravity with elevated amplitude and frequency exhibit frequent variations in both the base radius and height of the bubble. These parameters influence the timing and mechanics of bubble detachment, leading to significant variations in local heat flux distribution. Irrespective of the specific g-jitter characteristics, the overall heat transfer rate from the heated surface is observed to be considerably lower compared to terrestrial gravity conditions. This reduction is attributed to the inability of the bubbles to escape effectively from the surface, resulting in prolonged residence times and thermal insulation. To mitigate these adverse effects, the present work proposes the integration of the electrowetting technique with pool boiling systems. Electrowetting exploits the principle of altering the wettability of a surface by applying an electric field, thereby enhancing liquid rewetting and promoting bubble detachment. This approach offers an on-chip solution to address the heat transfer degradation associated with g-jitter, enabling more efficient thermal management in low-gravity environments. By dynamically controlling the contact angle and bubble motion, electrowetting facilitates improved heat transfer performance, making it a promising strategy for advanced thermal systems in space applications.