Curved classifiers and classification methods

Patent metadata

Field	Value
Publication number	US-10845288-B2
Application number	US-201615768574-A
Country	US
Kind code	B2
Filing date	Nov 11, 2016
Priority date	Nov 13, 2015
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A particle electrical mobility classifier is provided for the classification of particles (e.g., particles less than 1 μιη in size) based on their electrical mobility. The particle classification zone is curved. In an exemplary embodiment, two metal concentric cylinders, separated by an annular insulation spacer, establish a particle classification zone. A DC electrical field is supplied by the cylinders in the circular classification zone. An example classifier can be operated in different modes such as: (1) as a particle precipitator; (2) as a particle electrical mobility separator, and (3) as a differential mobility classifier. The curved classification zone results in a particle classifier having an extended particle sizing range as compared to their counterparts in classical configurations. The curve of the classification channel (in the flow direction) may be in any of several configurations (e.g., circular, wavy, spiral, or helical).

First claim

We claim:

1. A particle electrical mobility classifier, comprising:
a curved classification channel which extends circumferentially about a longitudinal axis of the particle mobility classifier, wherein the curved classification channel is formed by curved inner and outer wall parts spaced apart from one another and having electrically conductive surfaces spaced apart to create an electric field therebetween, and wherein the curved classification channel is configured to conduct aerosol particles within the curved inner and outer wall parts along at least one flow path selected from the group consisting of annular, spiral, wavy, and helical;
an aerosol flow inlet port configured to admit a polydisperse aerosol flow to the curved classification channel at a non-zero angle with respect to a line tangent to the classification channel, wherein the non-zero angle is not a 90° angle;
a sheath flow inlet port configured to admit a sheath flow to the curved classification channel; and
at least one outlet port from the curved classification channel configured for output of classified particles,
wherein the curved classification channel, the aerosol inlet port, the sheath flow inlet port, and the at least one outlet port are configured together to conduct flow in an angular direction by which aerosol particles in the flow rotate about the longitudinal axis of the classifier while in a classification zone of the curved classification channel.

2. The classifier of claim 1 , further comprising a voltage source electrically coupled to the inner and outer wall parts of the curved classification channel, the coupling configured such that the inner wall part and outer wall part are oppositely polarized creating the electric field in the classification zone.

3. The classifier of claim 1 , wherein the non-zero angle is less than 90°.

4. The classifier of claim 1 , further comprising one or more additional ports for inflow or outflow of one or more of aerosol particles and sheath flow.

5. The classifier of claim 1 , wherein the classification channel is continuously curved for an entire length of a classification zone while a cross section of the classification channel remains unchanged.

6. A method for classifying aerosol particles based on mobility, comprising:
providing a particle electrical mobility classifier according to claim 1 ;
admitting a polydisperse aerosol to the curved classification channel of the classifier, wherein the curved classification channel has inner and outer wall parts forming at least one configuration selected from the group consisting of annular, spiral, wavy, and helical;
admitting a sheath flow to the curved classification channel;
directing a total flow such that aerosol particles in the total flow travel in an angular path and rotate about a longitudinal axis of the classifier while traveling within the inner and outer wall parts in a classification zone of the classification channel; and
obtaining classified particles from the classification channel.

7. The method of claim 6 , wherein the polydisperse aerosol flow is admitted at a first position and the classified particles are obtained at a second position, and the first and second positions are oriented with respect to another such that only particles which travel in the angular path while in the classification zone reach the second position.

8. The method of claim 7 , wherein the polydisperse aerosol is admitted via an aerosol flow inlet port arranged at the first position, the sheath flow is admitted via a sheath flow inlet port, and the classified particles are obtained with one or more outlets, at least one outlet of which is arranged at the second position.

9. The method of claim 6 , wherein the sheath flow is admitted to the curved classification channel at a position and in a direction that urges aerosol particles in an angular path through a classification zone of the classification channel.

10. The method of claim 6 , further comprising a step of selecting a particle size or size range for classification by setting or adjusting one or more of the total flow rate and an applied voltage, wherein the classified particles obtained are of the selected particle size or size range.

11. The classifier of claim 1 , wherein the sheath flow inlet port is arranged upstream of the aerosol flow inlet port.

12. The classifier of claim 1 , wherein a distance between the inner wall and the outer wall is ⅛ inch or less.

Assignees

• Univ Virginia Commonwealth

Inventors

• Chen Daren
• Liu Qiaoling

Classifications

• G01N2015/0038

  Investigating nanoparticles · CPC title

• G01N15/0266 Primary

  with electrical classification · CPC title

• G01N2015/0046

  in gas, e.g. smoke · CPC title

• B03C3/36

  Controlling flow of gases or vapour · CPC title

• B03C3/15

  Centrifugal forces · CPC title