Abstract:
A fan assembly includes a tubular housing and electrodes which ionize air and cause the air to be filtered and to move through the tubular housing without use of moving parts, such as an impeller, thereby providing air filtration and ventilation without generation of vibrations and acoustic disturbances. An electric potential is applied between a longitudinally-oriented needle electrode and a planar or curved transversely-oriented net electrode disposed within the housing downstream of the needle electrode, thereby forming a longitudinally asymmetric electric field that ionizes and accelerates air molecules toward the net electrode, carrying the air molecules past the net electrode and through the air outlet. The assembly further includes a tubular duct electrode disposed within the housing on the outlet side ofthe net electrode, which collects ionized particles precipitated from the air. A conducting pivot, which is electrically connected to the net electrode, extends coaxially with the tubular duct electrode along at least a portion of the tubular duct electrode in the longitudinal direction and facilitates precipitation of the particles. The duct electrode can be removed and cleaned or replaced.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for moving, filtering and ionizing air. More particularly, the present invention relates to a fan assembly having a tubular housing and electrodes which ionize air and cause the air to be filtered and to move through the tubular housing without use of moving parts, such as an impeller, thereby providing air filtration and ventilation without generation of vibrations and acoustic disturbances. 
     2. Description of the Related Art 
     Conventional fans, ventilation systems and air filtration systems presently used in industrial, commercial and residential applications typically employ an impeller or the like to generate an air flow. The rotary movement of the impeller in such systems causes acoustic disturbances and vibrations, the noise level of which may be excessive for a particular application. For example, it may be desirable to generate a virtually noiseless air flow for industrial applications such as cooling of personnel or equipment, exhausting and/or filtering of air, drying processes, and clean room applications. Noiseless air filtration may also be desirable in residential ventilation and filtration systems. Conventional impeller-based devices are incapable of providing air movement without generating significant noise. Accordingly, there is a need for a system capable of providing noisefree air flow and/or air filtration. 
     Electric fields have been used in a variety of technologies to ionize molecules or to generate a stream of electrons. For example, electrostatic precipitators conventionally use an electrostatic charge to remove particles from an air stream by attracting electrostatically charged particles to an oppositely charged collector. The system disclosed in U.S. Pat. No. 4,518,401 to Pontius et al. is representative of such systems. Specifically, Pontius et al. disclose an electrostatic precipitator comprising a plurality of positively-charged, longitudinally-extending vertical plates and a plurality of negatively-charged, vertically-extending rods interspaced between the plates. As air flows through the precipitator, the electric field formed between the rods and plates causes a corona discharge from the rods which negatively charges particles in the air, which are then drawn to the positively-charged plates and removed from the air. The plates are mechanically rapped periodically, causing the particles to fall into collection hoppers. 
     Other patents disclosing electrostatic precipitators include: U.S. Pat. No. 2,593,869 to Fruth; U.S. Pat. No.2,756,838 to Roberts; U.S. Pat. No.2,778,443 to Yereance; U.S. Pat. No. 3,798,879 to Schmidt-Burbach et al.; U.S. Pat. No. 3,910,778 to Shahgholi et al.; U.S. Pat. No. 5,199,257 to Colletta et al.; U.K. Patent No. 2,229,117 to Colletta; German Patent No. 4410213 to Kogleschatz; and German Patent No. 4400827 to Pechmann. In each of these systems, the air flow through the precipitator is generated by conventional means, and the electric field within the precipitator is generally perpendicular to the direction of flow; consequently, the ionizing action of the precipitator and the shape and orientation of the electric field are not suitable for causing or increasing air flow. 
     Electric fields have been used in conjunction with magnetic fields in ion pumps to form a vacuum by ionizing air molecules and causing the ions to colloid with and be buried within a cathode material. For example, U.S. Pat. No. 4,631,002 to Pierini discloses an ion pump comprising hollow anode elements formed between two cathode plates disposed between opposite poles of a magnet. Other patents disclosing ion pumps include U.S. Pat. No. 4,687,417 to Amboss and U.S. Pat. No. 3,452,923 to Lamont. While such pumps ionize air molecules, they are designed to trap such molecules and thus cannot generate an air flow. 
     Electric fields have also been used in electron beam generators and accelerators to accelerate electrons. For example, U.S. Pat. No. 5,463,268 to Schroeder discloses an electron accelerator which employs a negatively-charged electrode within an acceleration tube and conductive rings to accelerate electrons to a high velocity. U.S. Pat. No. 3,431,455 to Beyer discloses an electron imaging device which directs a beam of electrons onto a surface to form a charge pattern. Such devices typically operate in a vacuum and are not suitable for ionizing and accelerating air molecules or generating an air flow. 
     While the above patents establish that electric fields have been used to ionize air molecules and particles and to accelerate electrons, electric fields have not been exploited in the generation of an air flow, such as that produced by conventional impeller fans. In particular, it has not been demonstrated that a significant volume of air can be moved through a chamber from an air inlet to an air outlet by applying an electrostatic field to the air within the chamber. Further, conventional electrostatic precipitators used in ventilation systems do not enhance or increase air flow. Thus, fans that employ an electric field as a means of moving air are unknown. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to produce an air flow using a fan assembly having no moving parts. 
     It is another object of the present invention to produce an air flow by applying an asymmetric electric field to a volume of air. 
     It is a further object of the present invention to provide a fan assembly that is virtually noiseless and free of vibrations while producing an air flow. 
     Another object of the present invention is to filter particles from an air stream flowing through a fan assembly. 
     Yet another object of the present invention is to ionize air molecules flowing through a fan assembly. 
     A further object of the present invention is to move air in a highly energy efficient manner. 
     The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto. 
     According to the present invention, air is moved, ionized and filtered by means of an electric field within a fan assembly having no moving parts. The system includes a tubular housing which draws air in through a flared inlet end and exhausts filtered air through an outlet end. Within the housing is a needle electrode which extends longitudinally. A net electrode is disposed within the housing on the outlet side of the needle electrode and extends in a transverse direction. The net electrode can be planar or curved to present a concave surface to the needle electrode. An electric potential on the order of tens of thousands of volts is applied between the needle and net electrodes to form an electric field therebetween. The combination of the longitudinally oriented needle electrode and the transversely oriented net electrode and their relative arrangement creates an electric field that is asymmetric in the longitudinal direction and that tends to ionize and accelerate air molecules toward the net electrode, carrying the air molecules past the net electrode and through the air outlet. 
     The voltage applied across the electrodes is a function of the space between the electrodes and is sufficient to produce a corona effect which ionizes air molecules in the field without causing discharge in the air or arcing between the electrodes. The spacing between the electrodes must be small enough to form an electric field of sufficient strength to ionize air molecules in a concentration sufficient to produce a significant air flow. However, the distance between the electrodes must be large enough that the ions generated are predominantly negative (in the case where the net electrode is positively charged), such that a large majority of the ions will be attracted to and accelerate toward the net electrode. 
     The overall length of the housing, the distance between the inlet end and the electrodes, and the distance between the electrodes are generally proportional to (i.e., scale with) a transverse linear dimension (e.g., the diameter) of the housing. 
     The system further includes a tubular duct electrode disposed within the housing on the outlet side of the net electrode, which collects ionized particles precipitated from the air. A conducting pivot, which is electrically connected to the net electrode, extends coaxially with the tubular duct electrode along at least a portion of the tubular duct electrode in the longitudinal direction and facilitates precipitation ofthe particles. The duct electrode can be removed and cleaned or replaced. 
     The system of the present invention can be used to provide air filtration, ionization and ventilation for enclosed spaces, on the order oftens of cubic meters, in which acoustical disturbances are not desirable, such as in transport cabins, harvesting and lifting machines, office buildings and factories, industrial exhaust systems, and in residential applications. 
     The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, particularly when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components. 
     The disclosures of all of the above patents are incorporated herein by reference in their entirety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a system for moving and filtering air according to an exemplary embodiment of the present invention. 
     FIG. 2 is a side view in cross-section of the system shown in FIG. 1 with a flat net electrode. 
     FIG. 3 is a side view in cross-section of the system shown in FIG. 1 with a curved net electrode. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A perspective view and a side sectional view of an assembly  10  for moving and filtering air according to an exemplary embodiment of the present invention are respectively illustrated in FIGS. 1 and 2. Assembly  10  includes a hollow, elongated, tubular housing  12  through which air flows from an open inlet  14  to an open outlet  16 . Inlet  14  and outlet  16  may be covered by a protective mesh, grid or the like. In this context, the term “tubular” does not imply any particular cross-sectional shape. Tubular housing  12  can be formed from any conventional non-conducting material including, but not limited to, a polymer. In the exemplary embodiment, tubular housing  12  has a substantially circular cross-section perpendicular to the longitudinal direction (i.e., the direction of air flow), with the inlet end comprising a confuser  18  which flares toward inlet  14  to improve the air flow dynamics of air flowing into tubular housing  12 . Between confuser  18  and outlet  16 , tubular housing  12  is substantially cylindrical (i.e., with a substantially constant inner diameter). 
     While assembly  10  of the exemplary embodiment is shown with a circular cross-section and a cylindrical shape, the tubular housing may have other cross-sectional shapes which provide acceptable air flow, and the exemplary embodiment is not to be construed as limiting the invention to only substantially circular cross-sections or cylindrical shapes. For example, tubular housing  12  can have a cross-sectional shape that is elliptical, rectangular, square, polygonal, etc. 
     The cross-sectional dimensions of housing  12  are principal parameters in determining the air flow volume through housing  12 , and most of the important dimensions of assembly  10  are proportional to (i.e., scale with) the cross-sectional dimensions of housing  12 . Accordingly, most dimensions and distances relating to cylindrical housing  12  of the exemplary embodiment are described with respect to the inner diameter D T  of the tubular portion of housing  12 . More generally, it will be understood that these dimensions and distances are proportional to an inner, linear, cross-sectional dimension of the housing, where the cross-sectional shape of the housing can be other than circular. In the exemplary embodiment, the overall length L H  of housing  12  in the longitudinal direction, inclusive of confuser  18 , is preferably in the range between 2.5 to 4 times the inner diameter D T  of the tubular portion of housing  12 , and is more preferably approximately 3 times the diameter D T . 
     For convenience, assembly  10  is shown in the figures as a stand-alone unit having a base  19  with a flat bottom for resting on a flat surface, such as a table top or floor. It will be understood, however, that the system of the present invention need not be a stand-alone unit. For example, the system can be integrated directly into a ventilation or air filtration system, such as within a duct of such a system. 
     Confuser  18  reduces the aerodynamic resistance of the air being drawn into housing  12  through inlet  14  and increases the air flow rate and the length of the air jet exhausted from outlet  16 . It has been experimentally determined that the volume and rate of air flow through housing  12  is very sensitive to the geometry of confuser  18 , and ajudiciously selected confuser geometry can increase the exit velocity of air from outlet  16  by 20% to 30% relative to a non-confuser (i.e., non-flared) configuration. The inner diameter D c  of confuser  18  at inlet  14  (i.e., the maximum diameter of confuser  18 ) is preferably in the range between 1.0 and 1.5 times the inner diameter D T  of confuser  18  at its inward longitudinal end (i.e., the inner diameter ofthe tubular portion of housing  12  and the minimum confuser diameter), and more preferably between 1.2 and 1.4 times the inner diameter D T  of the tubular portion of housing  12 . More generally (for all cross-sectional shapes), the cross-sectional area an inlet  14  is preferably in the range between 1.4 to 2.0 times the cross-sectional area at the inward end of confuser  18 . The length L 1  of confuser  18  in the longitudinal direction is preferably in the range between 0.1 and 0.5 times the inner diameter D T  of the tubular portion of housing  12 , and more preferably in the range between 0.1 and 0.25 times the inner diameter D T  (or a linear cross-sectional dimension, for non-circular cross-sections). 
     An electrically conductive needle electrode  20 , in the shape of a wire or a thin rod, is disposed within housing  12  inward of confuser  18 . More specifically, needle electrode  20  includes a transverse portion which extends radially from housing  12  to a central longitudinal axis therein, and a longitudinal portion which is bent at approximately 90° with respect to the transverse portion. The longitudinal portion of needle electrode  20  lies along the longitudinal axis and extends inward of the transverse portion, terminating at a pointed tip. Needle electrode  20  is electrically isolated from housing  12 . The distance L 2  from the tip of needle electrode  20  to inlet  14  is preferably in the range between 0.7 and 1.5 times the inner diameter D T , and more preferably in the range between 1.0 and 1.5 times D T . While the needle electrode of the exemplary embodiment lies along the longitudinal axis, it will be understood that the needle electrode of the present invention need not lie directly along the axis or extend strictly parallel thereto. As used herein the terms “longitudinal direction” and “extending longitudinally” require an orientation generally extending along the path between inlet  14  and outlet  16 , but do not require an orientation strictly parallel to the longitudinal axis of housing  12 . 
     An electrically conductive net or mesh electrode  22  is disposed within housing  12  at a distance L 3  from inlet  14  that is greater than the distance L 2  from the tip of needle electrode  20  to inlet  14 . Net electrode  22  extends transversely across substantially all of the interior cross-sectional area of housing  12 . In the embodiment shown in FIG. 2, net electrode  22  has a substantially flat or planar disc shape with a diameter that is slightly less than the inner diameter D T  of housing  12 . Net electrode  22  is electrically isolated from housing  12 . The distance L 3  is preferably in the range between 1.3 and 2 times the inner diameter D T . 
     According to another embodiment shown in FIG. 3, a net electrode  24  is curved. For example, net electrode is in the shape of a portion of a sphere or an ellipsoid. Specifically, net electrode  24  presents a concave surface to needle electrode  22 , with the center of net electrode  24  projecting toward outlet  16  and being displaced from the peripheral edge of net electrode  24  in the longitudinal direction by a distance L 4 . The distance L 4  is preferably in the range between 0.1 and 0.4 times the inner diameter D T  of housing  12 , and more preferably in the range between 0.1 and 0.3 times the inner diameter D T  of housing  12 . For a spherical net electrode, the radius of curvature ρ is preferably in the range between 0.3 and 0.8 times the inner diameter D T  of housing  12 , and more preferably in the range between 0.6 and 0.8 times diameter D T . It should be noted that, in the case of the curved net eletrode  24 , the distance L 3  is measured from inlet  14  to the transverse plane in which the peripheral edge of net electrode  24  lies (i.e., the shortest distance between net electrode  24  and the inlet plane). 
     A negative terminal of a power supply  26  is electrically connected to needle electrode  20 , and a positive terminal of power supply  26  is electrically connected to net electrode  22  (or  24 ). Power supply  26  comprises a transformer system, which may include several transformer stages, that steps up a voltage from an external power source to a high voltage required by assembly  10 . In general, the potential difference between needle electrode  20  and net electrode  22  (or 24) is maintained at a level producing a field strength below a field strength at which discharge in the air takes place (approximately 35 kV/cm), e.g., approximately ¾ ths of this value. Thus, the potential difference between the electrodes is a function of the distance between the electrodes, and the distance between the electrodes is determined by the potential difference U therebetween and the electrode geometries. In accordance with the present invention, the mean electric field strength E is preferably in the range between 5 to 35 kV/cm, and the distance L between the electrodes is generally proportional to U/E. The optimal magnitude of the electric field E is determined as function of a number of parameters, including the electrode geometry and air humidity. For example, where the electrodes are separated by several centimeters, a potential difference between needle electrode  20  and net electrode  22  (or  24 ) in the range between 15 kV and 35 kV can be formed by application of the negative and positive terminals of power supply  26  to electrodes  20  and  22  (or  24 ), respectively. 
     As shown in FIGS. 2 and 3, where assembly  10  is a stand-alone unit, power source  26  can be contained within base  19 , with electrodes  20  and  22  (or  24 ) extending through housing  12  into base  19  to electrically connect with power source  26 . The power consumption of assembly  10  is comparable to that of a conventional fan producing a similar flow volume and rate and is on the order of 10 Watts for an air flow rate of approximately 3 to 4 m/s and a flow volume of approximately 0.35 to 0.47 cubic meters/minute. 
     In operation, the electric potential between negative needle electrode  20  and positive electrode  22  (or  24 ) forms an electric field of sufficient strength to ionize air molecules (e.g., O 2 , N 2 , H 2 O) entering housing  12  though inlet  14 . The concentration of air ions is on the order of at least 100 per cm 3 . Due to the longitudinal asymmetry of the electric field formed by longitudinally oriented needle electrode  20  and transversely oriented net electrode  22  (or  24 ), negatively charged air ions tend to accelerate toward positively charged net electrode  22  (or  24 ) and pass through housing  12  and exit at outlet  16 , thereby producing an electronic wind. More particularly, the flow of the negatively charged ions causes a concurrent flow of neutral air molecules through housing  12 . 
     In order to produce a significant air flow, it is necessary to have a predomination of negatively charged air ions over positively charged air ions. The relative position of electrodes  20  and  22  (or  24 ) determines the strength and shape of the electric field and the energy of ionization. When the relative distance between electrodes  20  and  22  (or  24 ) is too great, the concentration of generated air ions is insufficient to produce significant air flow. When the relative distance between the electrodes is too small, the concentration of air ions is high, but the predomination of negative air ions over positive air ions is insufficient. It has been determined by the present inventors that, at the spacing given above, there is sufficient ionization (air ion concentration) and the necessary predomination of negative air ions to produce a significant electronic wind. By comparison, planar net electrode  22  provides a greater outlet air jet length than curved net eletrode  24 , while curved net electrode  24  provides more uniform ionization than planar net electrode  22 . The overall length L of housing  12  affects the length of the air flow jet at outlet  16  as is determined by the spacing between electrodes  20  and  22  (or  24 ). 
     Needle electrode  20  emits charged particles (electrons). The electrons move to the net electrode  22  (or  24 ) and ionize the air molecules in this region, forming a mixture of positive and negative ions and free electrons. Slow moving ions are neutralized on the net electrode  22  (or  24 ). 
     A portion of the electrons is also neutralized; however, some electrons having a high speed slip past the net electrode  22  (or  24 ). The energy of these electrons is not enough to ionize the air molecules by the blow. That is why they give part of their energy to the air molecules carrying them away but are themselves slowed down. The slow electrons stick to the oxygen molecules, forming negative ions. 
     As shown in FIGS. 2 and 3, a cylindrical duct electrode  28 , having an outer diameter that is less than the inner diameter D T  of housing  12 , is concentrically arranged within housing  12  on an outlet side of net electrode  22  (or  24 ). Duct electrode  28  attracts and collects ionized particles, such as dust and particulate matter in the air flow passing through housing  12 . Duct electrode  28  can be a metallic cylinder or a metallic cylinder with a thin, removable porous cover. Duct cathode  28  is preferably grounded for electro-safety reasons. The length L 5  of duct electrode  28  in the longitudinal direction is preferably in the range between 0.3 and 0.5 times the length L H  of housing  12 . The distance L 6  from inlet  14  to the near end of duct electrode  28  (i.e., the longitudinal end further from outlet  16 ) is preferably in the range between 2 and 2.5 times the inner diameter D T  of housing  12 . 
     Duct electrode  28  can be removed from housing  12  to dispose of particles collected thereon. For example, housing  12  can be opened at outlet  16  for removal of duct electrode  28 . Alternatively, housing  12  can be formed of two cylindrical segments which are detachably joined in the vicinity of duct electrode  28  and which can be separated to remove duct electrode  28  for cleaning or replacement. In the case where duct electrode  28  includes a porous cover for collecting particles, the porous cover can be removed from the metallic cylinder for cleaning or replacement with a new cover. 
     An electrically conductive pivot  30  in the shape of a wire or thin rod, and electrically connected to the net electrode  22  (or  24 ), extends along the longitudinal center axis of housing  12  from the surface of net electrode  22  (or  24 ) toward outlet  16 . Specifically, conducting pivot  30  extends coaxially through the center of the space surrounded by duct electrode  28  and terminates within duct electrode  28  toward the outlet end thereof. The length L 7  of pivot  30  is preferably in the range between 1.0 and 1.1 times the inner diameter D T  of housing  12  and more preferably approximately 1.05 times D T , When power is applied to electrodes  20  and  22  (or  24 ), pivot  30  is at the same potential as electrode  22  (or  24 ). 
     Pivot  30  promotes precipitation of particles onto the walls of duct electrode  28 . More specifically, pivot  30  is connected to positively charged net electrode  22  (or  24 ); thus, a radial electric field is formed between pivot  30  and duct electrode  28  which is held at a lower potential (ground). In this configuration, pivot  30  serves as an anode and duct electrode  28  serves as a cathode, causing positively charged particles to move toward and adhere to duct electrode  28  due to the radial electric field. The particles adhere to duct electrode  28  and lose their electric charge so that duct electrode  28  operates as a dust particle collector. Pivot  30  need not be a wire or thin rod and can have other longitudinally extending aerodynamic shapes, including, but not limited to, a cylinder. 
     In certain applications, such as those within the microelectronic industry and in the field of processing micro-patterns (e.g., in clean rooms), it is desirable to filter particles from an air stream while generating a relatively small air flow volume with a minimum of air turbulence. For such applications, it is desirable to apply the positive terminal of power supply  26  to needle electrode  20  and the negative terminal of power supply  26  to the net electrode  22  (or  24 ). This arrangement still causes air to flow through housing  12  from inlet  14  to outlet  16  due to the asymmetric electric field, and results in filtration of dust particles and the like comparable to that achieved in the negative ionization system. However, because the mass of the positively charged ions is greater than that of negatively charged ions, the positive ions exiting housing  12  have less kinetic energy and produce less air flow volume and velocity. 
     By way of a non-limiting example, assembly  10  shown in the figures can have the following parameters: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Inner Diameter D T  of Housing 12 
                 50 mm 
               
               
                 Inner Diameter D C  of Confuser 18 at Inlet Opening 
                 75 mm 
               
               
                 Longitudinal Length L H  of housing 12, 
                 150 mm 
               
               
                 Including Confuser 18 
               
               
                 Longitudinal Length L 1  of Confuser 
                 20 mm 
               
               
                 Distance L 2  from Confuser Inlet 14 to Tip of 
                 50 mm 
               
               
                 Needle Electrode 20 
               
               
                 Distance L 3  from Confuser Inlet 14 to Flat 
                 65 mm 
               
               
                 Net Electrode 22 
               
               
                 Radius of Curvature ρ of Spherical Net 24 
                 32.5 mm 
               
               
                 Maximum Longitudinal Displacement L4 of Spherical 
                 10 mm 
               
               
                 Net 24 
               
               
                 Longitudinal Length L 5  of Duct Electrode 
                 50 mm 
               
               
                 Distance L 6  from Confuser Inlet 14 to Duct 
                 100 mm 
               
               
                 Electrode 28 
               
               
                 Longitudinal Length L 7  of Pivot 30 
                 52.5 mm 
               
               
                 Electric Field Strength U 
                 22 kV 
               
               
                 Power Consumption P 
                 10 W 
               
               
                 Air Flow Volume V 
                 376.8 dm 3/min 
               
               
                   
                 (=13.3 ft 3/min) 
               
               
                 Air Flow Rate v 
                 3.2 m/s 
               
               
                   
               
             
          
         
       
     
     It is to be understood that these dimensions and parameters are provided by way of example only and are not in any way limiting on the scope of the invention. 
     The apparatus for moving, filtering and ionizing air described herein can serve as an elementary cell in an array of cells arranged to move parallel columns of air. More specifically, multiple cells can be positioned side-by-side with their respective longitudinal axes aligned substantially in parallel, such that the cells move air in substantially the same direction. By way of non-limiting example, an array of apparatuses can be arranged side-by-side to form a panel having a cross-section of 1×1 square meter in the transverse direction (perpendicular to the direction of air flow) and 20 cm in the longitudinal direction (the direction of air flow). Each cell can have a distinct tubular housing abutted against adjacent cells, or adjacent cells can share common longitudinal housing sections, with individual cells having a square, rectangular or hexagonal cross-section. Such an array could function as a noiseless ceiling fan to ventilate a room. 
     The system of the present invention can be used to provide air filtration, ventilation and ionization for enclosed spaces, on the order of tens of cubic meters, in which acoustical disturbances are not desirable, such as in transport cabins, harvesting and lifting machines, office buildings and factories, industrial exhaust systems, and in residential applications. The system power requirements are comparable to those of a conventional fan producing the same air flow rate and volume. For example, the exemplary system having the above parameters produced an air flow of approximately 13.3 cubic feet/minute using approximately 10 Watts of power. 
     While the system described in the exemplary embodiment includes a single needle electrode, more than one needle electrode can be used. For example, two adjacent needle electrodes terminating at the same distance from the inlet can be used to increase the output of the system. Thus, the “needle electrode” can comprise a plurality of needle electrode elements. 
     Having described preferred embodiments of a new and improved method and apparatus for moving ionized air, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention as defined by the appended claims.