Electrostatic precipitator pre-filter for electrohydrodynamic fluid mover

Abstract

Electrostatic precipitation is performed upstream of collector electrode surfaces toward which a downstream EHD fluid mover accelerates fluid flow. In this way, the upstream electrostatic precipitator (ESP) acts as a pre-filter (with low flow-impedance) and can reduce accumulation of otherwise detrimental materials on downstream electrodes and/or arcing. In some cases, pre-filtering by an upstream electrostatic precipitator may also reduce accumulation of otherwise detrimental materials on downstream heat transfer surfaces and/or ozone catalytic or reactive surfaces/materials. In some embodiments, an EHD fluid mover with an ESP pre-filter is used in a thermal management system to dissipate heat generated by a thermal source.

1 . An apparatus comprising:
 a fluid flow path;   an electrohydrodynamic (EHD) fluid mover introduced in the fluid flow path and operable to motivate fluid flow therealong; and   an electrostatic precipitator preceding the EHD fluid mover in the fluid flow path, the electrostatic precipitator operable to prevent a substantial amount of particulate matter otherwise entrained in the fluid flow from reaching at least collector electrode surfaces of the EHD fluid mover.   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 heat transfer surfaces introduced in the fluid flow path downstream of the electrostatic precipitator to transfer heat to or from the fluid flow.   
     
     
         3 . The apparatus of  claim 2 ,
 wherein at least a substantial portion of the heat transfer surfaces are downstream of an emitter electrode of the EHD fluid mover.   
     
     
         4 . The apparatus of  claim 2 ,
 wherein at least a substantial portion of the heat transfer surfaces are downstream of the collector electrode surfaces of the EHD fluid mover.   
     
     
         5 . The apparatus of  claim 3 ,
 wherein, during operation, at least a leading portion of the heat transfer surfaces constitute the collector electrode surfaces of the EHD fluid mover.   
     
     
         6 . The apparatus of  claim 1 ,
 the EHD fluid mover configured to generate, when energized, net ion flow in a primary direction; and   the electrostatic precipitator configured to generate, when energized, ion flow in directions substantially unaligned with the primary direction.   
     
     
         7 . The apparatus of  claim 1 ,
 wherein collector electrode surfaces of the EHD fluid mover and of the electrostatic precipitator are respectively positioned such that, when energized, magnitude of ion current to collector surfaces of the EHD fluid mover substantially exceeds that to the collector surfaces of the electrostatic precipitator.   
     
     
         8 . The apparatus of  claim 1 ,
 wherein collector electrode surfaces of the EHD fluid mover and of the electrostatic precipitator are respectively coupled between supply voltages such that, when energized, magnitude of ion current to collector surfaces of the EHD fluid mover substantially exceeds that to the collector surfaces of the electrostatic precipitator.   
     
     
         9 . The apparatus of  claim 1 ,
 wherein ion current to respective collector electrode surfaces of the EHD fluid mover and of the electrostatic precipitator is from one or more emitter electrodes energized to positive high voltage; and   wherein the collector electrode surfaces of the EHD fluid mover and the collector electrode surfaces of the electrostatic precipitator are each coupled to ground.   
     
     
         10 . The apparatus of  claim 1 ,
 wherein ion current to respective collector electrode surfaces of the EHD fluid mover and of the electrostatic precipitator is from one or more emitter electrodes energized to positive high voltage;   wherein the collector electrode surfaces of the EHD fluid mover are coupled to ground; and   wherein the collector electrode surfaces of the electrostatic precipitator are coupled to provide an operating voltage off of ground.   
     
     
         11 . The apparatus of  claim 10 ,
 wherein the operating voltage for the collector electrode surfaces of the electrostatic precipitator is variable and thereby accommodates accumulation of particulate matter thereon.   
     
     
         12 . The apparatus of  claim 1 , further comprising:
 at least some emitter electrode surfaces that exhibit surface features sized or shaped to, when energized, generate ions through a corona discharge effect.   
     
     
         13 . The apparatus of  claim 1 ,
 wherein collector electrode surfaces of the EHD fluid mover and of the electrostatic precipitator are coupled to ground.   
     
     
         14 . The apparatus of  claim 1 ,
 the EHD fluid mover and electrostatic precipitator having separate emitter electrode surfaces,   wherein the emitter electrode surfaces of the EHD fluid mover are positioned relative to the collector electrode surfaces thereof to, when energized, generate a net ion flow in substantial alignment with a direction of the motivated fluid flow, and   wherein the emitter electrode surfaces of the electrostatic precipitator are positioned relative to collector electrode surfaces of the electrostatic precipitator to, when energized, generate a substantial majority of ion flows in one or more directions that are substantially orthogonal to the motivated fluid flow.   
     
     
         15 . The apparatus of  claim 14 , further comprising:
 one or more repelling electrodes, wherein at least some of the surfaces thereof are positioned between the emitter electrode surfaces of the EHD fluid mover and upstream collector electrode surfaces of the electrostatic precipitator.   
     
     
         16 . The apparatus of  claim 15 ,
 wherein at least some of surfaces of the one or more repelling electrodes are positioned between the emitter electrode surfaces of the electrostatic precipitator and downstream collector electrode surfaces of the EHD fluid mover.   
     
     
         17 . The apparatus of  claim 1 ,
 the electrostatic fluid mover and electrostatic precipitator sharing at least one emitter electrode,   wherein, when energized, magnitude of ion current from the emitter electrode to collector surfaces of the EHD fluid mover substantially exceeds that to collector surfaces of the electrostatic precipitator.   
     
     
         18 . The apparatus of  claim 17 ,
 wherein ion current to the collector surfaces of the EHD fluid mover is at least 10 times greater than that to the collector surfaces of the electrostatic precipitator.   
     
     
         19 . A method comprising:
 motivating fluid flow using an electrohydrodynamic (EHD) fluid mover introduced in a fluid flow path; and   upstream of the electrohydrodynamic (EHD) fluid mover, electrostatically precipitating from the fluid flow a substantial amount of particulate matter otherwise entrained therein and thereby preventing the electrostatically precipitated particulate matter from reaching collector electrode surfaces of the EHD fluid mover.   
     
     
         20 . The method of  claim 19 , further comprising:
 transferring heat to or from the fluid flow using heat transfer surfaces introduced in the fluid flow path downstream of the electrostatic precipitating.   
     
     
         21 . The method of  claim 19 , further comprising:
 energizing at least a first emitter electrode to generate ions that, in a first portion of an electric field, are driven toward collection surfaces of the electrohydrodynamic (EHD) fluid mover; and   energizing at least a second emitter electrode, upstream of the first emitter electrode, to generate ions that, in a second portion of the electric field, are driven toward collection surfaces of an electrostatic precipitator.   
     
     
         22 . The method of  claim 21 , further comprising:
 repelling at least some of the ions generated at the first emitter electrode away from paths toward collection surfaces of an electrostatic precipitator.   
     
     
         23 . The method of  claim 19 , further comprising:
 energizing a shared emitter electrode to generate ions that, in a first portion of an electric field, are driven toward collection surfaces of the electrohydrodynamic (EHD) fluid mover and which, in a second portion of the electric field, are driven toward collection surfaces of an electrostatic precipitator.   
     
     
         24 . The method of  claim 23 ,
 wherein positioning of the respective collection surfaces of the EHD fluid mover and of the electrostatic precipitator, relative to the shared emitter electrode, is such that when the shared emitter is energized, magnitude of ion current to the collection surfaces of the EHD fluid mover substantially exceeds that to the collection surfaces of the electrostatic precipitator.   
     
     
         25 . The method of  claim 23 , further comprising:
 coupling respective collection surfaces of the EHD fluid mover and of the electrostatic precipitator between supply voltages such that, when the shared emitter is energized, magnitude of ion current to collection surfaces of the EHD fluid mover substantially exceeds that to the collection surfaces of the electrostatic precipitator.   
     
     
         26 . An apparatus comprising:
 an enclosure;   a thermal management assembly for use transferring heat to or from one or more devices within the enclosure, the thermal management assembly defining a flow path for conveyance of air between ventilated boundary portions of the enclosure, the thermal management assembly including an electrohydrodynamic (EHD) fluid mover introduced in the flow path and operable to motivate air flow past heat transfer surfaces thermally coupled to the one or more devices within the enclosure; and   an electrostatic precipitator preceding the EHD fluid mover in the flow path, the electrostatic precipitator operable to prevent a substantial amount of particulate matter otherwise entrained in the air flow from reaching the EHD fluid mover.   
     
     
         27 . The apparatus of  claim 26 , further comprising:
 a repelling electrode between an emitter electrode of the EHD fluid mover and collection surfaces of the electrostatic precipitator.   
     
     
         28 . The apparatus of  claim 26 , further comprising:
 a collector electrode of the electrostatic precipitator formed and positioned at an inlet one of the ventilation boundaries to allow the air flow to transit therethrough.   
     
     
         29 . The apparatus of  claim 26 ,
 configured to cool the one or more devices; and   embodied as one or more of a handheld mobile phone or personal digital assistant; a laptop, netbook, pad-type or desktop computer; a digital book reader, media player or gaming device; and a projector, television or video display panel.   
     
     
         30 . The apparatus of  claim 26 , configured to provide ambient heating or cooling in a volume external to the enclosure.