Liquid atomization process

• US 6,119,953 A
• Filed: 04/21/1999
• Issued: 09/19/2000
• Est. Priority Date: 05/13/1996
• Status: Expired due to Term

• Current Assignee: Universidad de Sevilla
• Original Assignee: Aradigm Corporation
• Inventors: Barrero Ripoll, Antonio, Ganan-Calvo, Alfonso
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Ganey, Steven J.
• Application Number:
  US09/171,518
• Time in Patent Office: 517 Days
• Field of Search: 239/8, 239/290, 239/291, 239/418, 239/419, 239/423, 239/424, 239/338, 239/346, 261/76, 261/78.1, 261/78.2, 261/115, 261/116, 128/200.14, 128/200.21, 128/203.12, 222/420, 73/864.81
• US Class Current: 239/8
• CPC Class Codes: B05B 1/02 designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shapeB05B1/26, B05B1/28, B05B1/34 take precedence
• CPC Class Codes: B05B 7/0475 with means for deflecting the peripheral gas flow towards the central liquid flow B05B7/0458 takes precedence
• CPC Class Codes: B05B 7/061 with several liquid outlets discharging one or several liquids
• CPC Class Codes: B05B 7/065 an inner gas outlet being surrounded by an annular adjacent liquid outlet
• CPC Class Codes: B05B 7/066 with an inner liquid outlet surrounded by at least one annular gas outlet
• CPC Class Codes: B05B 7/0884 the outlet orifices for jets constituted by a liquid or a mixture containing a liquid being aligned
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: F02M 43/04 Injectors peculiar thereto
• CPC Class Codes: F02M 67/10 Injectors peculiar thereto, e.g. valve less type
• CPC Class Codes: F02M 69/047 injectors with air chambers, e.g. communicating with atmosphere for aerating the nozzles F02M69/325 takes precedence
• CPC Class Codes: F23D 11/106 medium and fuel meeting at the burner outlet

Abstract

The object of the present invention is a liquid atomization procedure that uses appropriate geometric parameters and physical properties to ensure that the liquid to be atomized is discharged as a continuous, steady capillary microjet through a suitable orifice. The procedure relies on the microwithdrawal effect undergone by a liquid-gas interface when the gas is withdrawn from a point (orifice) near the liquid surface. The invented procedure is applicable to any mechanism involving homogeneous atomization of liquids (particularly electronic fuel injection).

Claims

1. A method of creating an aerosol, comprising:

forcing a liquid through a channel of a feeding source in a manner which causes the liquid to be expelled from an exit opening;

forcing a gas through a pressure chamber in a manner which causes the gas to exit the pressure chamber from an opening positioned in front of a flow path of liquid expelled from the exit opening of the feeding source;

wherein a stable liquid-gas interface is maintained and the liquid forms a stable capillary jet between the feeding source exit opening and the opening of the pressure chamber;

wherein fluctuations in dynamic forces exerted by the gas do not exceed the surface tension forces on surface of the liquid in the pressure chamber; and

allowing the microjet to exit the pressure chamber opening and split into drops by effects of instability.

2. The method of claim 1, wherein the liquid has a viscosity in a range of from about 10^-4 to about 1 kg/m/sec.

3. The method of claim 1, wherein the liquid has a viscosity in a range of from about 0.3×

10³¹ 3 to about 5×

10^-2 kg/m/sec.

4. The method of claim 1, wherein the liquid is forced through the channel at a rate in a range of about 1 nl/sec to about 100 μ

l/sec.

5. The method of claim 1, wherein the liquid is forced through the channel at a rate in a range of about 0.01 to about 10 μ

l/sec.

6. The method of claim 1, wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 50 m/sec to about 2000 m/sec.

7. The method of claim 1, wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 100 to 500 m/sec.

8. The method of claim 1, wherein the liquid is expelled from a circular exit opening having a diameter of less than about 0.4 mm and wherein the opening in the pressure chamber is circular and positioned directly in front of the exit opening of the feeding source and has a diameter of less than 0.25 mm and wherein the exit opening of the feeding source is positioned at a point of less than about 0.5 mm from the opening of the pressure chamber.

9. The method of claim 8, wherein the liquid is expelled from a circular exit opening having a diameter in a range of from about 0.1 mm to about 0.4 mm, the pressure chamber exit opening has a diameter in a range of about 0.1 mm to 0.25 mm and the exit opening of the feeding source is positioned at a point in a range of about 0.2 mm to about 0.5 mm from the exit opening of the pressure chamber.

10. A method of creating an aerosol, comprising:

feeding liquid through a feeding source to an outlet;

feeding gas through an orifice positioned in front of the feeding source outlet in a direction parallel to a direction of flow out of the feeding source outlet;

wherein the feeding of liquid and feeding of gas are each at a rate relative to each other so as to maintain a stable capillary microjet of liquid which exits the orifice and forms aerosolized particles;

wherein fluctuations in dynamic forces exerted by the gas do not exceed the surface tension forces on surfaces of the liquid;

wherein gas from the pressure chamber surrounds liquid exiting the feeding source outlet which is drawn into the orifice concentrically; and

allowing the microjet to exit the pressure chamber orifice and split into drops by effects of instability.

11. The method of claim 10, wherein gas is forced into an area around the feeding source outlet at a pressure in the range of 100 to 2000 mBar above atmospheric pressure.

12. The method of claim 10, wherein the liquid has a viscosity in the range of from 10^-4 to 1 kg/m/sec.

13. The method of claim 10, wherein the aerosolized particles formed are uniform in size to the extent of having a relative size standard deviation of 10 to 30%.