Electrohydrodynamic pumping of vapour refrigerant bubbles in a two-phase natural circulation heat transport loop

The objective of this work is to develop an enhanced two-phase thermal transport loop. In this work, an Electrohydrodynamic (EHD) device, namely an ion-drag pump is analyzed to enhance the performance of a Natural Circulation Loop (NCL). The benefit of these EHD devices is that they require no moving parts and substantial weight savings when compared with classical pumps. The enhancement can be twofold: 1) single-phase liquid pumping and 2) two-phase flow control. When the NCL is working in a subcooled off-design point, bubbles are generated due to a pressure drop. The control of bubbly flow is desired to optimize the system when it returns to the design-point operation. In a dielectric fluid such as R134a, the dielectrophoretic force on an induced dipole such as a vapor bubble can be dominant depends on the bubble diameter. When alpha approximate to 0 (r(b) < r(cr)) - the bubbles will follow the fluid streamlines and when alpha > 0 (r(b) > r(cr)) - the bubbles follow the trajectory defined by an analytical model based on a force balance between buoyancy, dielectrophoresis, and friction drag.