MULTI-GAS FLOW DEVICE

• US 20100030388A1
• Filed: 10/13/2009
• Published: 02/04/2010
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Chiun Wang, John M. Lull, William S. Valentine
• Original Assignee: Chiun Wang, John M. Lull, William S. Valentine
• Inventors: Wang, Chiun, Valentine, William S., Lull, John M.
• Granted Patent: US 8,068,999 B2
• Time in Patent Office: Days
• US Class Current: 700/282
• CPC Class Codes: G01F 1/363 with electrical or electro-mechanical indication G01F1/37 and G01F1/38 take precedence
• CPC Class Codes: G01F 5/005 by measuring pressure or differential pressure, created by the use of flow constriction
• CPC Class Codes: Y10T 137/2496 Self-proportioning or correlating systems
• CPC Class Codes: Y10T 137/877 With flow control means for branched passages

Abstract

A system and method of characterizing or controlling a flow of a fluid is provided that involves a sensor conduit and a bypass. A plurality of fluids may be utilized in the flow control device based on characteristic information of the device generated during calibration thereof. The characteristic information, in turn is based on a dimensionless parameters, such as adjusted dynamic pressure and adjusted Reynolds number.

Claims

1. A method of determining a flow rate of a fluid comprising:

providing a flow sensor comprising a bypass with a plurality of bypass tubes, a sensor conduit in fluid communication with the bypass;

generating a measured signal representative of a flow rate of a fluid through the sensor conduit;

accessing characteristic information generated during calibration of the flow sensor at a plurality of flow rates with at least one calibration fluid, the characteristic information including a plurality of first dimensionless parameters based on a dynamic pressure of each of the plurality of flow rates and a corresponding plurality of second dimensionless parameters based on a Reynolds number of each of the plurality of flow rates; and

generating a representation of the flow rate of the fluid through the flow sensor based at least partially on the measured signal and on the characteristic information.

2. The method of claim 1, wherein the characteristic information is at least partially defined by a characteristic function:

3. The method of claim 2, wherein the fluid is not any of the calibration fluids utilized during calibration of the flow sensor.

4. The method of claim 2, wherein the characteristic function is based at least partially on a bypass bias function defined by the relationship.

5. A method of controlling a flow rate of a fluid through a flow controller comprising a control valve and a flow sensor, the flow sensor having a bypass that includes a plurality of bypass tubes, and a sensor conduit fluidly connected to the bypass, the method comprising

generating a measured signal representative of a flow rate of the fluid through the sensor conduit;

generating a representation of the flow rate of the fluid through the flow sensor based at least partially on the measured signal, one or more sensor attributes, one or more fluid properties, and a characteristic function according to the relationship;

6. The method of claim 5, wherein the characteristic function is further based on a bypass bias function, F_B, defined by the relationship:

7. The method of claim 5, wherein the fluid is not a calibration fluid utilized to generate the characteristic function.

8. A method of generating a characteristic function for a flow sensor having a bypass that includes a plurality of bypass tubes, comprising:

measuring a plurality of flow rates of a calibration fluid flowing through the flow sensor;

generating a plurality of adjusted dynamic pressure attributes corresponding to each of the plurality of measured flow rates of the calibration fluid; and

generating the characteristic function based at least partially on the plurality of adjusted dynamic pressure attributes and at least one physical attribute of the flow sensor.

9. The method of claim 8, wherein the act of generating the plurality of adjusted dynamic pressure attributes comprises measuring a pressure differential across the flow sensor for each of the plurality of flow rates and generating a plurality of dynamic pressure values for each of the plurality of flow rates.

10. The method of claim 9, wherein the act of generating the plurality of adjusted dynamic pressure attributes, (Np)_i, comprises calculating, for each of the plurality of flow rates, the function:

11. The method of claim 10, further comprising generating a plurality of adjusted flow attributes corresponding to each of the plurality measured flow rates of the calibration fluid.

12. The method of claim 11, wherein the act of generating the plurality of adjusted flow attributes, (Nf)_i, comprises calculating, for each of the plurality of flow rates, the function:

13. The method of claim 8, further comprising measuring a plurality of output values corresponding to the plurality of flow rates of the calibration fluid.

14. The method of claim 13, further comprising generating a calibration curve based on the plurality of output values and the characteristic function.

15. The method of claim 8, wherein the characteristic function is defined by the relationship:

16. A method of generating a calibration curve for a flow sensor that includes at least one bypass tube, comprising;

introducing a calibration gas into the flow sensor at a plurality of flow rates;

determining a first dimensionless parameter based at least partially on a dynamic pressure value of the calibration gas flowing through the bypass for each of the plurality of flow rates;

determining second dimensionless parameter based at least partially on a diameter to length aspect ratio of the bypass for each of the plurality of flow rates; and

mapping the first dimensionless parameter as a function of the second dimensionless parameter.

17. The method of claim 16, wherein the first dimensionless parameter is defined by the ratio of the product of one half of the density of the calibration gas and the square of the mean flow velocity to the measured overall pressure differential.

18. The method of claim 17, wherein the second dimensionless parameter is defined by a product of the Reynolds number of the calibration gas flowing through the bypass and the aspect ratio of the bypass.

19. The method of claim 18, further comprising.

determining a plurality of first and second dimensionless numbers corresponding to each of the plurality of flow rates;

and

mapping each of the corresponding first and second dimensionless numbers to generate a calibration curve.

20. The method of claim 19, further comprising generating a bypass bias function based on the plurality of corresponding first and second dimensionless numbers.

21. A computer readable medium encoded with a program for execution on at least one processor, the program, when executed on the at least one processor, performing a method of regulating a flow of fluid through a flow controller that includes a flow sensor having a sensor conduit and a bypass having a plurality of bypass tubes, and a control valve fluidly connected to the flow sensor, the method comprising:

receiving, as an input, a sensor output value representative of a flow rate of the fluid through the sensor conduit;

generating a representation of the flow rate of the fluid through the flow sensor based at least partially on the sensor output value, one or more flow sensor attributes, one or more fluid properties, and a characteristic function represented by the relationship;

22. The method of claim 21, wherein the characteristic function is further based on a bypass bias function, F_B, defined by the relationship: