SOLDERING OF SADDLES TO LOW EXPANSION ALLOY HEAT PIPES

• US 20040149421A1
• Filed: 01/30/2003
• Published: 08/05/2004
• Est. Priority Date: 01/30/2003
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Wiacek, Chris R., Mahtani, Hiroo H.
• Granted Patent: US 6,810,944 B2
• Time in Patent Office: Days
• US Class Current: 165/41
• CPC Class Codes: B64G 1/506 Heat pipes
• CPC Class Codes: B64G 1/64 Systems for coupling or separating cosmonautic vehicles or parts thereof, e.g. docking arrangements
• CPC Class Codes: F28D 15/0275 Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
• CPC Class Codes: F28D 15/04 with tubes having a capillary structure

Abstract

A heat pipe structure is provided for facilitating temperature stability of heat generating devices residing in a spacecraft. The heat generating structure comprises wall tubing made of a low thermal expansion alloy and a low thermal expansion saddle joined together and embedded into composite panel face sheets or face skins with minimal to no coefficient of thermal expansion (CTE) mismatch. The saddle to composite radiating panel interface employs an adhesive as the joining material. The saddle to heat pipe interface is joined together employing a higher conductivity joining media, such as tin-lead solder, which improves the thermal performance of the heat pipe assembly and minimize the temperature drop across the interface.

Claims

1. A heat pipe structure for cooling heat generating devices in a spacecraft, the heat pipe structure comprising:

a metal alloy heat pipe extending a longitudinal length of a host structure;

a top saddle portion having a joining surface on a first side coupled to at least a portion of a circumference of the metal alloy heat pipe and a generally planar surface on a second side;

a bottom saddle portion having a joining surface on a first side coupled to at least a portion of a circumference of the metal alloy heat pipe and a generally planar surface on a second side;

a top radiating panel sheet coupled to the generally planar surface of the top saddle portion; and

a bottom radiating panel sheet coupled to the generally planar surface of the bottom saddle portion, the metal alloy heat pipe, the top saddle portion and the bottom saddle portion having similar, low coefficient of thermal expansion (CTE).

2. The heat pipe structure of claim 1, the joining surface of the top saddle portion and the joining surface of the bottom saddle portion are soldered to the metal alloy heat pipe, the solder providing a high thermal conductivity interface.

3. The heat pipe structure of claim 1, the metal alloy heat pipe being formed of an iron-nickel based alloy.

4. The heat pipe structure of claim 3, the iron-nickel based alloy having a CTE of about 0.9 parts-per-million per degrees Kelvin (PPM/K) to about 3.6 PPM/K.

5. The heat pipe structure of claim 1, the top saddle portion and the bottom saddle portion being formed from a carbon-carbon material.

6. The heat pipe structure of claim 1, the joining surface of the top saddle portion and the bottom saddle portion being plated and the metal alloy heat pipe being plated with a plating material layer.

7. The heat pipe structure of claim 6, the plating material layer being at least one of nickel and copper.

8. The heat pipe structure of claim 1, the top radiating panel sheet and the bottom radiating panel sheet are formed from a composite material having a low CTE.

9. The heat pipe structure of claim 1, further comprising a plurality of metal alloy heat pipes coupled between corresponding top and bottom saddle portions to form a plurality of heat pipe assemblies, the plurality of heat pipe assemblies being disposed at space apart locations within the heat pipe structure and separated by a core material.

10. A spacecraft comprising the heat pipe structure of claim 1.

11. A heat pipe structure for operating device in a spacecraft, the heat pipe structure comprising:

a plurality of metal alloy heat pipes extending a longitudinal length of a host structure at space apart locations, the plurality of metal alloy heat pipes having a plating layer;

a top saddle portion corresponding to each of the plurality of metal alloy heat pipes, the top saddle having a semi-cylindrical recess that forms a joining surface on a first side, the joining surface having a plating layer soldered to at least a portion of a circumference of the metal alloy pipe and a generally planar surface on a second side;

a bottom saddle portion corresponding to each of the plurality of metal alloy heat pipes, the bottom saddle portion having a semi-cylindrical recess that forms a joining surface on a first side, the joining surface having a plating layer soldered to at least a portion of a circumference of the metal alloy heat pipe and a generally planar surface on a second side;

a top radiating panel skin coupled to the generally planar surfaces of the top saddle portions; and

a bottom radiating panel skin coupled to the generally planar surfaces of the bottom saddle portions, the metal alloy heat pipes, the top saddle portions and the bottom saddle portions having similar, low coefficients of thermal expansion (CTE).

12. The heat pipe structure of claim 11, the plurality of metal alloy heat pipes being formed of an iron-nickel based alloy.

13. The heat pipe structure of claim 12, the iron-nickel based alloy having a CTE of about 0.9 parts-per-million per degrees Kelvin (PPM/K) to about 3.6 PPM/K.

14. The heat pipe structure of claim 11, the top saddle portions and the bottom saddle portions being formed from a carbon-carbon material.

15. The heat pipe structure of claim 11, the plating layers being formed from at least one of nickel and copper.

16. A method for forming a heat pipe structure for cooling operating devices in a spacecraft, the method comprising:

plating a metal alloy heat pipe having a low coefficient of thermal expansion (CTE);

forming a top saddle portion having a semi-cylindrical recess that forms a joining surface on a first side that mates with at least a portion of a circumference of the metal alloy pipe and a generally planar surface on a second side;

forming a bottom saddle portion having a semi-cylindrical recess that forms a joining surface on a first side that mates with at least a portion of a circumference of the metal alloy heat pipe and a generally planar surface on a second side, the top saddle portion and the bottom saddle portion being formed from a material having a similar CTE as the metal alloy heat pipe;

plating the joining surfaces of the top saddle portion and the bottom saddle portion;

soldering the joining surfaces of the top saddle portion and the bottom saddle portion to the metal alloy heat pipe;

coupling a top radiating panel skin to the generally planar surfaces of the top saddle portion; and

coupling a bottom radiating panel skin to the generally planar surfaces of the bottom saddle portion.

17. The method of claim 16, further comprising plating a plurality of metal alloy heat pipes coupled between corresponding top and bottom saddle portions to form a plurality of heat pipe assemblies, and disposing the plurality of heat pipe assemblies at space apart locations within the heat pipe structure and separated by a core material.

18. The method of claim 17, the plurality of metal alloy heat pipes being formed of an iron-nickel based alloy and the top saddle portions and the bottom saddle portions being formed from a carbon-carbon material.

19. The method of claim 18, the iron-nickel based alloy having a CTE of about 0.9 parts-per-million per degrees Kelvin (PPM/K) to about 3.6 PPM/K.

20. The method of claim 16, the plating of the metal alloy heat pipe and the joining interfaces comprising plating a layer of at least one of nickel and copper onto the metal alloy heat pipe and the joining interfaces of the top saddle portion and the bottom saddle portion.