Direct impact aerosol sampling by electrostatic precipitation
The present disclosure provides apparatuses for collecting aerosol samples by ionizing an air sample at different degrees. An air flow is generated through a cavity in which at least one corona wire is disposed and electrically charged to form a corona therearound. At least one grounded sample collection plate is provided downstream of the at least one corona wire so that aerosol ions generated within the corona are deposited on the at least one grounded sample collection plate. A plurality of aerosol samples ionized to different degrees can be generated. The at least one corona wire may be perpendicular to the direction of the flow, or may be parallel to the direction of the flow. The apparatus can include a serial connection of a plurality of stages such that each stage is capable of generating at least one aerosol sample, and the air flow passes through the plurality of stages serially.
1. An electrostatic aerosol sampling apparatus comprising:
a chamber including a cavity configured to allow an air flow therethrough;
at least one corona wire located within said cavity;
at least one grounded sample collection plate disposed downstream of a portion of said at least one corona wire;
a high voltage application circuitry configured to generate a corona between said at least one corona wire and said at least one grounded sample collection plate; and
at least one means for inducing an air flow through said cavity; wherein said cavity includes:
a cylindrical cavity portion in which said at least one corona wire is disposed; and
a conical cavity portion adjoining said cylindrical cavity portion and having an increasing horizontal cross-sectional area that increases with distance from said at least one corona wire, wherein said at least one grounded sample collection plate is located on a wall of said cavity located at a base of said conical cavity.
2. The electrostatic aerosol sampling apparatus of claim 1 , further comprising:
another chamber including another cavity therein and cascaded to said chamber such that said air flow enters said another chamber after exiting said chamber;
at least another corona wire located within said another cavity; and
at least another grounded sample collection plate disposed downstream of a portion of said at least another corona wire.
3. The electrostatic aerosol sampling apparatus of claim 1 , wherein said at least one grounded sample collection plate is downstream of an entirety of said at least one corona wire.
4. The electrostatic aerosol sampling apparatus of claim 1 , wherein a direction of said air flow at said at least one corona wire is substantially perpendicular to a surface of said at least one grounded sample collection plate on which aerosols in said air flow impinge.
5. The electrostatic aerosol sampling apparatus of claim 1 , wherein a direction of said air flow at said at least one corona wire is substantially perpendicular to a lengthwise direction of said at least one corona wire.
6. The electrostatic aerosol sampling apparatus of claim 1 , wherein said at least one grounded sample collection plate is mounted on a wall of said cavity, wherein said wall includes a plurality of holes that allow passage of said air flow therethrough.
7. The electrostatic aerosol sampling apparatus of Claim 1 , wherein said at least one grounded sample collection plate is located at a center region of said base of said conical cavity portion, and a plurality of holes is located between said center region and a periphery of said base of said conical cavity portion.
8. The electrostatic aerosol sampling apparatus of Claim 1 , wherein said cavity further includes another conical cavity portion located upstream of said cylindrical cavity portion and having an increasing horizontal cross-sectional area that increases with distance from said at least one corona wire.
9. The electrostatic aerosol sampling apparatus of Claim 1 , wherein said at least one corona wire intersects an axis of symmetry of said cylindrical cavity portion at a right angle.
10. The electrostatic aerosol sampling apparatus of claim 1 , wherein a portion of said at least one grounded sample collection plate is upstream of said at least one corona wire.
11. The electrostatic aerosol sampling apparatus of claim 1 , wherein a direction of said air flow at said at least one corona wire is substantially parallel to a lengthwise direction of said at least one corona wire.
12. The electrostatic aerosol sampling apparatus of claim 1 , wherein said at least one grounded sample collection plate is a plurality of grounded sample collection plates that includes:
a first grounded sample collection plate located on a first portion of a wall of said cavity; and
a second grounded sample collection plate located on a second portion of said wall of said cavity and downstream of said first grounded sample collection plate.
13. The electrostatic aerosol sampling apparatus of claim 12 , wherein said second portion is recessed farther away from said at least one corona wire than said first portion is from said at least one corona wire.
14. The electrostatic aerosol sampling apparatus of claim 13 , wherein said at least one corona wire is parallel to said first and second grounded sample collection plates.
15. The electrostatic aerosol sampling apparatus of claim 1 , wherein one of said at least one grounded sample collection plate is located within an air outlet channel attached to said cavity.
16. The electrostatic aerosol sampling apparatus of claim 1 , wherein said at least one means for inducing said air flow comprises a drone or a fan.
17. A method of collecting at least one aerosol sample comprising:
providing an electrostatic aerosol sampling apparatus comprising:
a chamber including a cavity configured to allow an air flow therethrough
at least one corona wire located within said cavity;
a plurality of grounded sample collection plates disposed downstream of a portion of said at least one corona wire;
a high voltage application circuitry configured to generate a corona between said at least one corona wire and said at least one grounded sample collection plate; and
at least one means for inducing an air flow through said cavity; and
inducing accumulation of an aerosol material on said at plurality of grounded sample collection plates by causing air to pass through said cavity employing said at least one means for inducing said air flow while a corona is present between said at least one corona wire and each of said at least one grounded sample collection plate, wherein said method further comprises collecting a plurality of aerosol samples including different materials caused by different degrees of ionization of materials in said air flow.
18. The method of claim 17 , wherein said electrostatic aerosol sampling apparatus further comprises:
another chamber including another cavity therein and cascaded to said chamber through an air outlet channel of said chamber;
at least another corona wire located within said another cavity; and
at least another grounded sample collection plate disposed downstream of a portion of said at least another corona wire,
wherein said method further comprises collecting a plurality of aerosol samples in said chamber and in said another chamber.
19. The method of claim 17 , wherein said cavity includes:
a cylindrical cavity portion in which said at least one corona wire is disposed; and
a conical cavity portion adjoining said cylindrical cavity portion and having an increasing horizontal cross-sectional area that increases with distance from said at least one corona wire, wherein said at least one grounded sample collection plate is located on a wall of said cavity located at a base of said conical cavity.