Gravity independent liquid cooling for electronics
A combined electrohydrodynamic (EHD) and dielectrophoretic (DEP) cooling approach for a processor or similar electronics in a zero gravity environment is beneficial in space exploration. An EHD pumping mechanism is defined by an array of alternating, polarized electrodes surrounding a heat sink coupled to the processor for heat exchange, such as a thermally conductive layer or coating. The array may be circular, rectangular, or any suitable geometry, generally guided by a shape of the heat sink/processor. Cooling fluid is drawn or pumped towards the heat sink by EHD electrodes, and a dielectrophoretic (DEP) electrode disposed above the center of the heat sink extracts the generated vapor bubbles away from the heated surface with a diverging electrical field. One configuration calls for a radial arrangement of EHD electrodes drawing the cooling fluid towards a centrally located heat sink.
1. An electrohydrodynamic cooling device, comprising:
a heat sink coupled to an electronic circuit defining a heat source in a zero-gravity environment;
a cooling fluid in fluidic coupling with the heat sink for heat transfer; and
a dielectrophoretic (DEP) electrode in communication with the heat sink for drawing vapor bubbles in the boiling cooling fluid away from the heat sink.
2. The device of claim 1 further comprising an electrohydrodynamic (EHD) pumping surface engaging the heat sink for transport of the cooling fluid.
3. The device of claim 1 wherein the EHD pumping surface defines a pumping region around the heat sink, the EHD pumping surface directing the cooling fluid towards the heat sink.
4. The device of claim 3 wherein the heat sink is disposed in a centered position in the EHD pumping surface, further comprising EHD electrodes in the surface positioned to direct the cooling fluid towards the heat sink.
5. The device of claim 4 wherein the EHD pumping surface includes the plurality of concentric EHD electrodes for directing the cooling fluid towards the center of the EHD pumping surface.
6. The device of claim 4 wherein the EHD pumping surface includes a linear arrangement of the EHD electrodes for directing the cooling fluid towards an edge of the EHD pumping surface.
7. The device of claim 1 wherein the DEP electrode is disposed adjacent the heat sink and separated by a pumping gap, the pumping gap based on a type of the cooling fluid and an aggregate volume of the bubbles accumulated in a given time.
8. The device of claim 7 wherein the DEP electrode has a planar shape and is disposed on a parallel plane from the EHD pumping surface.
9. The device of claim 7 wherein the DEP electrode has a plurality of parallel conductors, each having a width and separated by the gap from an adjacent parallel conductor, the gap having a size based on a heat flux.
10. A fluidic transport system, comprising:
a set of electrohydrodynamic (EHD) electrodes adapted for disposing a working fluid;
a dielectrophoretic (DEP) electrode surrounded by the EHD electrodes; and
the working fluid in fluidic communication with both the EHD electrodes and the DEP electrode for cooperative transport of the working fluid.
11. A method for cooling electronic circuit, comprising:
combining an electrohydrodynamic (EHD) and dielectrophoretic (DEP) fluid transport mechanism in an absence of gravity;
heating a working fluid from a heat sink thermally coupled to a circuit to be cooled; and
disposing bubbles resulting from boiling of the cooling fluid for drawing heat from the heat sink resulting in cooling of the circuit.
12. The method of claim 11 further comprising:
generating a flow of the working fluid towards the heat sink resulting from forces generated from the EHD fluid transport mechanism;
generating a flow of the working fluid away from the heat sink and between a set of DEP electrodes providing the DEP fluid transport mechanism; and
cycling the working fluid back towards the heat sink in an iterative manner.
13. The method of claim 11 further comprising forming a DEP electrode opposed from the heat sink for imparting dielectrophoretic movement to the bubbles in an absence of gravity induced liquid pressure.
14. The method of claim 13 wherein the DEP electrode generates a DEP field for transport of the vapor bubbles of the working fluid in an absence of buoyancy from the surrounding liquid working fluid.
15. The method of claim 11 further comprising forming an EHD electrode adjacent the heat sink, an EHD pumping mechanism disposed for transporting the working fluid towards the heat sink for boiling into the vapor bubbles.
16. The method of claim 11 further comprising alternating the working fluid between a liquid phase and a gaseous phase between an EHD pumping mechanism and the DEP pumping mechanism in a cyclic manner.
17. A cooling apparatus for an electronic circuit, comprising:
a dielectrophoretic (DEP) electrode including a conductive, planar material having a plurality of parallel portions, each portion defined by a gap between adjacent portions;
a support mechanism for suspending the DEP electrode above a heat source of the electronic circuit, the support mechanism defining a gap between the DEP electrode and the heat source;
a ground connection, the ground connection for coupling the DEP electrode in a non-contacting manner with the electronic circuit;
a fluid medium responsive to the DEP electrode for heat absorption and transport from the electronic circuit;
a voltage source coupled to the DEP electrode for resulting in a flow of the fluid medium for heat conduction and transport; and
an enclosure for encapsulating the electronic circuit and the fluid medium.