Heat exchangers, heat exchanger tubes, and additive manufacturing cold spray processes for producing the same

Patent metadata

Field	Value
Publication number	US-2019234697-A1
Application number	US-201815882160-A
Country	US
Kind code	A1
Filing date	Jan 29, 2018
Priority date	Jan 29, 2018
Publication date	Aug 1, 2019
Grant date	—

Abstract

Methods are disclosed for fabricating heat exchangers and Heat Exchanger (HX) tubes, as are heat exchangers fabricated in accordance with such methods. In embodiments, the method includes the steps or processes of obtaining a Non-Equilibrium Alloy (NEA) feedstock powder comprised of an alloy matrix throughout which at least one minority constituent is dispersed. The first minority constituent precipitates from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period. A cold spray process is carried-out to at least partially form the HX tubes from the NEA feedstock powder; and the HX tubes are subsequently installed in the heat exchanger. The HX tubes are exposed to a maximum temperature (T SPRAY_MAX ) during the cold spray process, which is maintained below T CRITICAL to substantially preserve the non-equilibrium state of the NEA feedstock powder through cold spray deposition.

First claim

What is claimed is:

1 . A method for producing a heat exchanger, comprising:
obtaining a Non-Equilibrium (NEA) feedstock powder comprised of an alloy matrix throughout which a first minority constituent is dispersed, the first minority constituent precipitating from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period; and utilizing a cold spray process to at least partially form Heat Exchanger (HX) tubes from the NEA feedstock powder; installing the HX tubes in the heat exchanger; wherein the cold spray process is performed such that: (i) the HX tubes are exposed to a maximum temperature (T SPRAY_MAX ) during the cold spray process, and (ii) T SPRAY_MAX is maintained below T CRITICAL to substantially preserve a non-equilibrium state of the NEA feedstock powder through the cold spray process.

2 . The method of claim 1 wherein installing comprises:
placing the HX tubes in contact with a header structure; and
utilizing a low temperature joint forming process to seal selected interfaces between the HX tubes and the header structure, while maintaining peak temperatures below T CRITICAL .

3 . The method of claim 2 wherein utilizing the low temperature joint forming process comprises utilizing a cold spray process to form circumferential joints at the selected interfaces between the HX tubes and the header structure by local deposition of a second alloy.

4 . The method of claim 3 wherein the second alloy comprises the NEA feedstock powder.

5 . The method of claim 1 wherein HX tubes comprise a first HX tube having an elongated tube body; and
wherein utilizing a cold spray process comprises:
spray depositing the NEA feedstock powder onto outer surfaces of a mandrel to produce at least the elongated tube body of the first HX tube; and
separating the first HX tube from the mandrel after spray depositing.

6 . The method of claim 5 further comprising selecting at least a portion of the mandrel to have a polygonal cross-sectional geometry, as taken in a section plan orthogonal to a longitudinal axis of the mandrel, the polygonal cross-sectional geometry transferred to at least a portion of the elongated tube body spray-deposited onto the outer surfaces of the mandrel.

7 . The method of claim 6 wherein utilizing a cold spray process further comprises:
rotating the mandrel in a first direction by a predetermined angular displacement to position a first side of the mandrel with respect to a nozzle of a cold spray apparatus utilized to deposit the elongated tube body;
after rotating the mandrel, depositing the NEA feedstock powder onto the first side of the mandrel utilizing a sweeping motion during which the nozzle of the cold spray apparatus is moved with respect to the mandrel along the longitudinal axis thereof; and
repeating the steps of rotating and depositing to build-up the elongated tube body over the other sides of the mandrel.

8 . The method of claim 5 further comprising controlling the cold spray process to impart the elongated tube body with an increasing wall thickness when moving toward a terminal end portion of the first HX tube.

9 . The method of claim 5 further comprising controlling the cold spray process to impart the elongated tube body with a terminal thin-walled section at an end of the first HX tube; and
wherein installing comprises:
inserting the terminal thin-walled section of the first HX tube through an opening provided in a header structure; and
after inserting, deforming the terminal thin-walled section to join the first HX tube to the header structure.

10 . The method of claim 5 wherein the spray depositing comprises spray depositing the NEA feedstock powder onto outer surfaces of the mandrel, while concurrently rotating the mandrel about a longitudinal axis thereof.

11 . The method of claim 1 wherein T CRITICAL is less than a melt point of the NEA feedstock powder and greater than 300 degrees Celsius.

12 . The method of claim 1 further comprising selecting the NEA feedstock powder such that:
the NEA feedstock powder is composed predominately of aluminum by weigh percent; and
the first minority constituent is selected from the group consisting of iron and silicon.

13 . The method of claim 1 further comprising selecting the NEA feedstock powder to contain, by weight percent:
between 85 and 90 aluminum;
between 8 and 10 percent iron;
between 1 and 3 percent silicon; and
between 1 and 2 percent vanadium.

14 . The method of claim 1 further comprising, after utilizing the cold spray process, heat treating the HX tubes utilizing an annealing process having a maximum anneal temperature (T ANNEAL_MAX ) less than T CRITICAL .

15 . A method for producing a heat exchanger (HX) tube having an elongated tube body, the method comprising:
producing at least the elongated tube body of the HX tube by depositing a feedstock powder over a mandrel utilizing a cold spray process; and after producing, removing the HX tube from the mandrel.

16 . The method of claim 15 further comprising selecting the feedstock powder to comprise a Non-Equilibrium Alloy (NEA) predominately composed of aluminum, by weight.

17 . The method of claim 16 wherein the NEA feedstock powder comprises an alloy matrix throughout which a first minority constituent is dispersed, the first minority constituent precipitating from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period; and
wherein the HX tubes are exposed to a maximum temperature (T SPRAY_MAX ) during the cold spray process; and
wherein T SPRAY_MAX is maintained below T CRITICAL to preserve, at least in substantial part, a non-equilibrium state of the NEA feedstock powder through the cold spray process.

18 . The method of claim 15 further comprising selecting at least a portion of the mandrel to have a polygonal cross-sectional geometry, as taken in a section plan orthogonal to a longitudinal axis of the mandrel, the polygonal cross-sectional geometry transferred to at least a portion of the elongated tube body spray-deposited onto the outer surfaces of the mandrel.

19 . The method of claim 15 further comprising controlling the cold spray process to impart the elongated tube body with an increasing wall thickness when moving toward a terminal end portion of the first HX tube.

20 . A heat exchanger, comprising:
a header structure; and heat exchanger (HX) tubes joined to the header structure, each HX tube at least partially composed of a spray-deposited Non-Equilibrium Alloy (NEA) material, the NEA material comprising:
an aluminum matrix; and
a first minority constituent dispersed throughout the aluminum matrix and selected from the group consisting of iron and silicon.

Assignees

• Honeywell Int Inc

Inventors

• Chipko Paul
• Piascik James
• Jadidian Bahram
• Kington Harry Lester

Classifications

• B22F5/10 Primary

  of articles with cavities or holes, not otherwise provided for in the preceding subgroups · CPC title

• F28F19/06 Primary

  of metal · CPC title

• C23C24/04

  Impact or kinetic deposition of particles · CPC title

• B22F2301/052

  Aluminium · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title