Gas-flammability sensing systems and methods

Patent metadata

Field	Value
Publication number	US-10532822-B2
Application number	US-201715415673-A
Country	US
Kind code	B2
Filing date	Jan 25, 2017
Priority date	Jan 25, 2017
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

Gas-flammability sensing systems and methods may be used to determine the flammability of gas mixtures in measurement volumes such as a fuel tank (e.g., an aircraft fuel tank). Gas-flammability sensing systems include a test cell structured to receive a gas sample, a heater in thermal communication with the test cell, and a gas meter configured to measure a physical property of the gas sample within the test cell related to the combustion state of the gas sample. The heater is configured to heat the gas sample to an elevated temperature less than the autoignition temperature of the gas sample. Methods of determining the flammability of a gas sample include collecting the gas sample, heating the gas sample to the elevated temperature, measuring the physical property of the gas sample after heating, and determining the flammability of a gas sample based upon the measured physical property.

First claim

The invention claimed is:

1. A gas-flammability sensing system comprising:
an inlet;
an outlet;
a test cell fluidically connected to the inlet and the outlet, the test cell structured to receive a gas sample through the inlet and to discharge the gas sample through the outlet;
a heater in thermal communication with the test cell, wherein the heater is positioned and configured to heat the gas sample within the test cell to between 50° C. and 500° C.; and
a gas meter configured to measure a physical property of the gas sample within the test cell related to a combustion state of the gas sample in the test cell;
wherein the gas sample includes a combustion fuel, wherein the test cell has a sample thickness for the gas sample that is configured to quench a propagating flame front in the gas sample and is less than a quenching distance of a mixture of the combustion fuel and air.

2. The gas-flammability sensing system of claim 1 , wherein the gas meter is an electrical meter configured to measure an electrical property of the gas sample within the test cell related to the combustion state of the gas sample in the test cell.

3. The gas-flammability sensing system of claim 2 , wherein the electrical property includes at least one of resistivity and permittivity.

4. The gas-flammability sensing system of claim 2 , wherein the test cell includes a plurality of electrodes and defines a probed region for the gas sample that is between at least two of the plurality of electrodes.

5. The gas-flammability sensing system of claim 4 , wherein the at least two of the plurality of electrodes are plate electrodes that each have a surface with an area that is at least 10 times a squared value of a distance between the plate electrodes.

6. The gas-flammability sensing system of claim 4 , wherein the at least two of the plurality of electrodes are arranged concentrically and wherein a length of the at least two of the plurality of electrodes is at least 10 times a sample thickness of a probed region of the test cell between the at least two of the plurality of electrodes.

7. The gas-flammability sensing system of claim 1 , wherein the gas meter is an optical meter configured to measure an optical property of the gas sample within the test cell related to a combustion state of the gas sample in the test cell, wherein the optical property includes at least one of absorbance, transmittance, scattering, luminescence emission, and fluorescence emission.

8. The gas-flammability sensing system of claim 1 , wherein the gas meter is a gas density meter configured to measure a density of the gas sample within the test cell.

9. The gas-flammability sensing system of claim 1 , wherein the heater is positioned and configured to heat the gas sample within the test cell to at most 150° C.

10. The gas-flammability sensing system of claim 1 , wherein the inlet is fluidically connected to a measurement volume to sample gas contents of the measurement volume, wherein the measurement volume is a ullage space of a fuel tank.

11. The gas-flammability sensing system of claim 1 , further comprising:
an inlet channel that connects the inlet to a test cell inlet of the test cell; and
a flame arrester within the inlet channel.

12. The gas-flammability sensing system of claim 1 , further comprising a pump in fluidic communication with the test cell and configured to pump the gas sample, the pump being configured to draw the gas sample from the inlet to the test cell.

13. An aircraft comprising:
a fuel tank with a ullage space; and
the gas-flammability sensing system of claim 1 positioned and configured to measure a flammability of gas in the ullage space of the fuel tank.

14. The aircraft of claim 13 , further comprising a fuel tank inerting system and a controller, wherein the fuel tank inerting system is configured to supply inert gas into the ullage space of the fuel tank, and wherein the controller is programmed to control the amount of inert gas supplied to the ullage space based upon the flammability of the gas in the ullage space.

15. The gas-flammability sensing system of claim 1 , further comprising a fuel tank with a ullage space, wherein the inlet is in fluidic communication with the ullage space of the fuel tank.

16. The gas-flammability sensing system of claim 15 , further comprising a fuel tank inerting system and a controller, wherein the fuel tank inerting system is configured to supply inert gas into the ullage space of the fuel tank, and wherein the controller is programmed to control the amount of inert gas supplied to the ullage space based upon the flammability of the gas in the ullage space.

17. The gas-flammability sensing system of claim 15 , wherein the fuel tank is an aircraft fuel tank.

18. The gas-flammability sensing system of claim 15 , wherein the gas-flammability sensing system is structured for continuous sampling of gas contents from the ullage space.

19. The gas-flammability sensing system of claim 1 , wherein the test cell has a probed region with a sample thickness for the gas sample that is at most 10 mm.

20. The gas-flammability sensing system of claim 1 , wherein the gas-flammability sensing system includes no ignition sources.

21. A gas-flammability sensing system comprising:
an inlet;
an outlet;
a test cell fluidically connected to the inlet and the outlet, the test cell structured to receive a gas sample through the inlet and to discharge the gas sample through the outlet;
a heater in thermal communication with the test cell, wherein the heater is positioned and configured to heat the gas sample within the test cell to between 50° C. and 500° C.;
a gas meter configured to measure a physical property of the gas sample within the test cell related to a combustion state of the gas sample in the test cell; and
a fuel tank with a ullage space, wherein the inlet is in fluidic communication with the ullage space of the fuel tank.

22. The gas-flammability sensing system of claim 21 , wherein the gas meter is an electrical meter configured to measure an electrical property of the gas sample within the test cell related to the combustion state of the gas sample in the test cell.

23. The gas-flammability sensing system of claim 22 , wherein the electrical property includes at least one of resistivity and permittivity.

24. The gas-flammability sensing system of claim 22 , wherein the test cell includes a plurality of electrodes and defines a probed region for the gas sample that is between at least two of the plurality of electrodes.

25. The gas-flammability sensing system of claim 24 , wherein the at least two of the plurality of electrodes are plate electrodes that each have a surface with an area that is at least 10 times a squared value of a distance between the plate electrodes.

26. The gas-flammability sensing system of claim 24 , wherein the at least two of the plurality of electrodes are arranged concentrically and wherein a length of the at least two of the plurality of electrodes is at least 10 times a sample thickness of a probed region of the test cell between the at least two of the plurality of electrodes.

27. The gas-flammability sensing system of claim 21 , wherein the gas meter is an optical meter configured to measure an optical property of the gas sample within the test cell related to a combustion state of the gas sample in the test cell, wherein the optical pro

Assignees

• Boeing Co

Inventors

• Kwon Eddie
• Damazo Jason Scott
• Boettcher Philipp Andreas
• Sweet William J
• Housen Kevin Richard

Classifications

• G01N2027/222

  for analysing gases · CPC title

• G01N27/226

  Construction of measuring vessels; Electrodes therefor · CPC title

• G01N21/532

  with measurement of scattering and transmission · CPC title

• G01N21/645

  Specially adapted constructive features of fluorimeters · CPC title

• G01N21/85

  Investigating moving fluids or granular solids · CPC title