Systems and methods for thermally actuated flow control

Patent metadata

Field	Value
Publication number	US-10393287-B2
Application number	US-201615555120-A
Country	US
Kind code	B2
Filing date	Mar 2, 2016
Priority date	Mar 2, 2015
Publication date	Aug 27, 2019
Grant date	Aug 27, 2019

Abstract

Various implementations provide an inherently safer design feature for microchannel reactors that provides temperature control at the individual channel level. This approach relies on bimetallic strips embedded within the combustion channel, forming a thermally-actuated “valve”. Bimetallic strips convert a temperature change into a mechanical displacement. Heating the strip increases its deflection and thereby restricts flow in the combustion channels, which consequently reduces the rate of heat generation. The thermally-actuated valve is not limited to use in microchannel reactors and may be used in other structures for which thermally actuated flow control is desired, according to some implementations.

First claim

The invention claimed is:

1. A thermally actuated flow control system disposed within a reactor, the control system comprising:
a first linear array of bimetallic strips disposed on a first wall of a channel; and
a second linear array of bimetallic strips disposed on a second wall of the channel, the first and second walls being opposite and in a facing relationship with each other relative to a fluid flow path through the channel,
wherein:
the first wall and/or the second wall comprises a catalyst layer, the catalyst layer enabling a combustible reaction of a fuel flowing through the channel,
each bimetallic strip comprises a fixed end and a free end,
the fixed ends of the bimetallic strips in the first array are coupled to the first wall,
the fixed ends of the bimetallic strips in the second array are coupled to the second wall,
each bimetallic strip comprises a first metal strip having a first thermal expansion coefficient and a second metal strip having a second thermal expansion coefficient, the first and second metal strips being fixedly coupled together, and the first thermal expansion coefficient being higher than the second thermal expansion coefficient, wherein the first metal strip is coupled to the wall, and the second metal strip extends towards the fluid flow path through the channel, and
a deflection of the free ends of the bimetallic strips first array away from the first wall and the free ends of the bimetallic strips of the second array away from the second wall increases as a temperature of the fuel flowing through the channel increases, which decreases a flowrate of the fuel flowing through the channel and reduces the rate of heat generation by the combustion reaction, and the deflection of the free ends of the bimetallic strips of the first array and the second array decreases as the temperature of the fuel flowing through the channel decreases, which increases the flowrate of the fuel flowing through the channel and increases the rate of heat generation by the combustion reaction.

2. The thermally actuated flow control system of claim 1 , wherein the first thermal expansion coefficient is about 5% to about 40% less than the second thermal expansion coefficient.

3. The thermally actuated flow control system of claim 2 , wherein the first thermal expansion coefficient is about 33% less than the second thermal expansion coefficient.

4. The thermally actuated flow control system of claim 1 , wherein the first metal strip and the second metal strip each have a melting temperature that is higher than about 1000° C.

5. The thermally actuated flow control system of claim 1 , wherein the fixed ends are directly coupled to the channel walls.

6. The thermally actuated flow control system of claim 1 , wherein a length of each bimetallic strip is at least ten times longer than a thickness of each bimetallic strip, the length being measured in the axial flow direction between the fixed end and the free end, and the thickness of each bimetallic strip comprising a thickness of the first metal strip and the second metal strip.

7. The thermally actuated flow control system of claim 6 , wherein the length of each bimetallic strip is at least ten times longer than a width of each bimetallic strip, the width being measured in a direction that is orthogonal to the length direction and thickness direction.

8. The thermally actuated flow control system of claim 7 , wherein the width of each bimetallic strip is between about 5 and about 10 times greater than the thickness of each bimetallic strip.

9. The thermally actuated flow control system of claim 1 , wherein a length of each bimetallic strip is at least ten times longer than a width of each bimetallic strip, the length being measured in the axial flow direction between the fixed end and the free end, and the width being a distance between opposite edges of the strip that extend between the fixed end and free end, the edges being perpendicular to the direction of flow through the channel.

10. The thermally actuated flow control system of claim 1 , wherein a distance between the first and second walls is at least around ten times longer than a thickness of each bimetallic strip, the thickness of each bimetallic strip comprising a thickness of the first metal strip and the second metal strip.

11. The thermally actuated flow control system of claim 10 , wherein the distance between the first and second walls is around twenty times longer than the thickness of each bimetallic strip.

12. The thermally actuated flow control system of claim 1 , wherein a thickness of the first metal strip is at least 1/10 th of a thickness of the bimetallic strip.

13. The thermally actuated flow control system of claim 1 , wherein a thickness of the second metal strip is at least 1/10 th of a thickness of the bimetallic strip.

14. The thermally actuated flow control system of claim 1 , wherein the free ends of the bimetallic strips in the first array are aligned with the free ends of the bimetallic strips in the second array within a plane that bisects the first and second walls and is perpendicular to the flow path through the channel.

15. The thermally actuated flow control system of claim 1 , wherein the first and second arrays of bimetallic strips are disposed centrally along a length of the channel.

16. The thermally actuated flow control system of claim 1 , wherein the first and second arrays of bimetallic strips are disposed adjacent to a portion of the channel where the largest temperature changes are expected to occur.

17. The thermally actuated flow control system of claim 1 , wherein a length of each bimetallic strip is selected such that a distance between the free ends of the first array and the free ends of the second array is at least about 5% of a height of the channel at a maximum expected temperature for the fuel, the length being measured in the axial flow direction between the fixed end and the free end of each bimetallic strip.

18. The thermally actuated flow control system of claim 1 , wherein the reactor is a microchannel reactor.

19. The thermally actuated flow control system of claim 1 , wherein the channel is defined by at least two parallel plates.

20. The thermally actuated flow control system of claim 1 , wherein the channel is defined by an inner wall of a conduit.

21. The thermally actuated flow control system of claim 20 , wherein a width of each bimetallic strip is between about 1/60th and about ⅙th of a circumference of the channel, and a distance between edges of adjacent bimetallic strips is between about 1/60th and about ⅙th of the circumference of the channel, wherein edges of each bimetallic strip extend between the fixed and free ends of each bimetallic strip, and the edges are perpendicular to the direction of flow through the channel.

22. The thermally actuated flow control system of claim 20 , wherein the free ends of the bimetallic strips deflect towards a central axis of the conduit.

23. The thermally actuated flow control system of claim 1 , wherein a device is coupled to an external surface of the first or the second wall, and the deflection of the bimetallic strips in response to the temperature of the fuel flowing through the channel controls the amount of heat transferred through the first or the second wall to the device.

24. The thermally actuated flow control system of claim 1 , wherein a length of each bimetallic strips is selected such that the free ends of

Assignees

• Univ Texas

Inventors

• Baldea Michael
• Pattison Richard
• Donahue Melissa
• Gupta Akash

Classifications

• F16K31/002

  actuated by temperature variation (thermo-electric F16K31/025) · CPC title

• B01J2219/00876

  Insulation elements · CPC title

• B01J2219/00855

  Surface features · CPC title

• B01J2219/00835

  Comprising catalytically active material · CPC title

• B01J2219/0086

  Dimensions of the flow channels · CPC title