Reduced drag combustion pass in a tubular heat exchanger

Patent metadata

Field	Value
Publication number	US-10401055-B2
Application number	US-201715449733-A
Country	US
Kind code	B2
Filing date	Mar 3, 2017
Priority date	Mar 3, 2017
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A heat exchanger tube includes a first pass for at least partially combusting a fuel and the first pass having a modified shape including a minor diameter and major diameter that reduces the external pressure drop of an external fluid flowing across the heat exchanger tube. A HVACR system includes a heat exchanger tube with a first heat exchange pass that at least partially combusts a fuel and has a modified shape. A method of making a heat exchanger including configuring a first heat exchange pass such that the major diameter of modified portion of the first heat exchange pass is oriented towards an incoming direction of the process fluid.

First claim

What is claimed is:

1. A heat exchanger tube, comprising:
a first heat exchange pass including an inlet and being configured as a combustion pass;
one or more subsequent heat exchange passes, one of the one or more subsequent heat exchange passes including an outlet;
one or more bends that fluidly connect two of the heat exchange passes, wherein
the first heat exchange pass has a length extending from the inlet to a first one of the one or more bends, a majority of the length of the first heat exchange pass being modified to form a modified portion that includes a minor diameter and a major diameter, a cross-sectional area of the heat exchanger tube at the minor diameter and the major diameter being at or about the same area as a circular cross-sectional area that has a single diameter based on equally increasing and reducing the minor diameter and the major diameter, respectively.

2. The heat exchanger tube of claim 1 , wherein the minor diameter of the modified portion of the first heat exchange pass has a reduced diameter at or about 10% to at or about 60%.

3. The heat exchanger tube of claim 1 , wherein the minor diameter of the modified portion of the first heat exchange pass has a reduced diameter at or about 15% to at or about 25%.

4. The heat exchanger tube of claim 1 , wherein
the one or more subsequent heat exchange passes includes a second heat exchange pass,
the second heat exchange pass includes a modified portion having a minor diameter and a major diameter and one or more surface features configured to disrupt an internal boundary layer,
the minor diameter of the modified portion of the second heat exchanger pass has a reduced diameter at or about 5% to at or about 100%.

5. The heat exchanger tube of claim 4 , wherein a cross-sectional area of the modified portion of the second heat exchange pass has a reduced cross-sectional area of at least 25%.

6. The heat exchanger tube of claim 4 , wherein
the one or more subsequent heat exchange passes includes a third heat exchange pass,
the third heat exchange pass includes a modified portion having a minor diameter and a major diameter and one or more surface features configured to disrupt an internal boundary layer,
the minor diameter of the modified portion of the third heat exchange pass has a reduced diameter at or about 5% to at about or about 100%.

7. The heat exchanger tube of claim 6 , wherein each of a cross-sectional area of the modified portion of the second heat exchange pass and a cross-sectional area of the modified portion of the third heat exchange pass have a reduced cross-sectional area of least 25%.

8. The heat exchanger tube of claim 6 , wherein the minor diameter of the third heat exchange pass is less than the minor diameter of the second heat exchange pass.

9. The heat exchanger tube of claim 1 , wherein a cross-section of the modified portion of the first heat exchange pass has a shape of an ellipse.

10. A HVACR system for heating air, comprising:
a heat exchanger volume for heating air;
a heat exchanger tube including a first heat exchange pass, a second heat exchange pass, and a bend fluidly connecting the first heat exchange pass to the second heat exchange pass, the heat exchanger tube being located within the heat exchanger volume; and
a blower that blows outer air into the heat exchange volume towards the heat exchanger tube, wherein
the first heat exchange pass includes an inlet and is a combustion pass, and
the first heat exchange pass has a length extending from the inlet to the bend, a majority of the length of the first heat exchange pass being modified to form a modified portion that includes a major diameter and a minor diameter, a cross-sectional area of the heat exchanger tube at the minor diameter and the major diameter being at or about the same area as a circular cross-sectional area that has a single diameter based on equally increasing and reducing the minor diameter and the major diameter, respectively, and
the heat exchanger tube being configured such that the major diameter of the first heat exchange pass is oriented towards an incoming direction of the blowing air.

11. The HVACR system of claim 10 , wherein the minor diameter of the modified portion of the first heat exchange pass has a reduced diameter at or about 10% to at or about 60%.

12. The HVACR system of claim 10 , wherein the minor diameter of the modified portion of the first heat exchange pass has a reduced diameter at or about 15% to at or about 25%.

13. The HVACR system of claim 10 , further comprising:
an air outlet for air to leave the heat exchanger volume, wherein
the blower, a vent, and the heat exchange volume are configured so that the air flows through the heat exchange volume in a direction perpendicular to the heat exchange passes of the heat exchanger tube.

14. The HVACR system of claim 13 , wherein
the second heat exchange pass includes a modified portion having a minor diameter and a major diameter, and
the second heat exchange pass being configured such that the major diameter of the modified portion of the second heat exchange pass is oriented towards an incoming direction of the outer air.

15. The HVACR system of claim 14 , wherein
the heat exchanger tube includes a third heat exchange pass,
the third heat exchange pass includes a modified portion having a minor diameter and a major diameter, and
the third heat exchange pass being configured such that the major diameter of the modified portion of the second heat exchange pass is oriented towards an incoming direction of the outer air.

16. The HVACR system of claim 15 , wherein
each of a cross-sectional area of the modified portion of the second heat exchange pass and a cross-sectional area of the modified portion of the third heat exchange pass has a reduced cross-sectional area of at least 25%.

17. The HVACR system of claim 16 , wherein
the minor diameter of the modified portion of the second heat exchange pass has a reduced diameter at or about 5% to at or about 95% and the minor diameter of the modified portion of the third heat exchange pass has a reduced diameter at or about 5% to at or about 95%, and
the minor diameter of the modified portion of the third heat exchange pass is less than the minor diameter of the modified portion of the second heat exchange pass.

18. The HVACR system of claim 15 , wherein
the second heat exchange pass includes one or more ribs to disrupt an internal boundary layer of the second heat exchange pass, and
the third heat exchange pass includes one or more ribs to disrupt an internal boundary layer of the third heat exchange pass.

19. A method of making a heat exchanger, comprising:
constructing a heat exchanger housing with a heat exchanger volume;
positioning a heat exchanger tube in the heat exchanger volume, the heat exchanger tube including a first heat exchange pass, a second heat exchange pass, and a bend fluidly connecting the first heat exchange pass to the second heat exchange pass, the first heat exchange pass including an inlet and is configured as a combustion pass, the first heat exchange pass having a length extending from the inlet to the bend, a majority of the length of the first heat exchange pass being modified to form a modified portion that includes a major diameter and a minor diameter, a cross-sectional area of the heat exchanger tube at the minor diameter and the major diameter being at or about the same area as a circular cross-sectional area that has a single diameter based on equally increasing and reducin

Assignees

• Trane Int Inc

Inventors

• Kraft Wayne N
• Wagers Nathan
• Bradbury Dennis Scott
• Coley Joshua Brian
• Gowdagiri Sandeep

Classifications

• F28F1/08

  Tubular elements crimped or corrugated in longitudinal section · CPC title

• F28D7/085

  in the form of parallel conduits coupled by bent portions · CPC title

• F24D2220/06

  Heat exchangers · CPC title

• F24H3/087 Primary

  using fluid fuel · CPC title

• F24D5/02

  operating with discharge of hot air into the space or area to be heated · CPC title