Maintaining thermal uniformity in micro-channel cold plates with two-phase flows

• US 8,797,741 B2
• Filed: 10/21/2010
• Issued: 08/05/2014
• Est. Priority Date: 10/21/2010
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Altman, David H.
• Primary Examiner(s): THOMAS, BRADLEY H
• Application Number:
  US12/909,347
• Publication Number:
  US 20120097374A1
• Time in Patent Office: 1,384 Days
• Field of Search: 361/702, 361/704, 361/711, 361/719, 361/720, 165/80.2, 165/80.4, 165/104.33, 298/900.3
• US Class Current: 361/702
• CPC Class Codes: F28D 15/0266 with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers F28D15/043 takes precedence
• CPC Class Codes: F28D 2021/0029 Heat sinks
• CPC Class Codes: F28F 2260/02 having microchannels
• CPC Class Codes: F28F 3/12 Elements constructed in the shape of a hollow panel, e.g. with channels F28D1/02, F28D1/03 take precedence
• CPC Class Codes: F28F 9/026 with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
• CPC Class Codes: H01L 23/427 Cooling by change of state, e.g. use of heat pipes by liquefied gas H01L23/445
• CPC Class Codes: H01L 23/473 by flowing liquids H01L23/4332, H01L23/4338 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 29/4935 Heat exchanger or boiler making

Abstract

A cold plate system including, in one embodiment, first and second flow paths extending from a common inlet to a common outlet, wherein the first and second flow paths enable two-phase coolant flow under pressure through micro-channels for cooling heat loads on the cold plate system, first and second orifices disposed in the first flow path on an inlet side of the first flow path, and a third orifice spaced from a fourth orifice, the third and fourth orifices disposed in the second flow path on an inlet side of the second flow path, wherein the first and second orifices in the first flow path and the third and fourth orifices in the second flow path minimize a difference in mass flow rate between the first and second flow paths when the first and second flow paths are exposed to different heat loads.

Claims

1. A cold plate system, comprising:

a common inlet and a common outlet;

first and second flow paths being hydraulically parallel between the common inlet and the common outlet, wherein the first and second flow paths enable two-phase coolant flow under pressure through micro-channels for cooling heat loads on the cold plate system;

the first flow path having a first inlet coupled to the common inlet, a first outlet coupled to the common outlet, and first and second orifices located between the first inlet and the first outlet, wherein the first orifice is spaced from the second orifice in the first flow path, the first and second orifices disposed in the first flow path on an inlet side of the first flow path, wherein the first and second orifices each protrude into the first flow path to reduce a cross-sectional area of the first flow path for constricting flow of the coolant;

a third orifice spaced from a fourth orifice, the third and fourth orifices disposed in the second flow path on an inlet side of the second flow path;

wherein the first and second orifices in the first flow path and the third and fourth orifices in the second flow path minimize a difference in mass flow rate between the first and second flow paths when the first and second flow paths are exposed to different heat loads; and

a first card slot aligned with the first flow path to cool a first circuit card assembly seated in the first card slot and a second card slot aligned with the second flow path to cool a second circuit card assembly.

2. The system according to claim 1, wherein the cold plate system is passive.

3. The system according to claim 1, wherein for a selected temperature and pressure, the first orifice is sized to not cause flashing of the liquid coolant and the second orifice is sized to flash subcooled liquid coolant to a two-phase flow.

4. The system according to claim 1, further including a further orifice in the first flow path.

5. The system according to claim 1, wherein the second orifice is located at an inlet to a micro-channel.

6. The system according to claim 1, further including a slot for coupling the cold plate system to a circuit card.

7. The system according to claim 6, wherein the circuit card forms a part of a radar system.

8. The system according to claim 6, wherein the circuit card forms a part of a computer.

9. The system according to claim 1, wherein the first and second orifices are spaced to minimize the difference in mass flow rate between the first and second flow paths when the first and second flow paths are exposed to different heat loads.

10. A cold plate system, comprising:

a first flow path;

a first orifice disposed in the first flow path, the first orifice having a fluid inlet and a fluid outlet into a region, wherein the first orifice protrudes into the first flow path to reduce a cross-sectional area of the first flow path for constricting flow of coolant;

a second orifice disposed at an inlet of a first micro-channel coupled to the region, wherein the second orifice has a cross-sectional area less than the inlet of the first micro-channel to constrict flow of the coolant;

a third orifice disposed at an inlet of a second micro-channel coupled to the region, wherein the third orifice has a cross-sectional area less than the inlet of the second micro-channel to constrict flow of the coolant;

wherein the first flow path and the first and second micro-channels enable two-phase coolant flow under pressure through the first and second micro-channels to minimize a difference in mass flow rate between the first and second micro-channels when the first and second flow micro-channels are exposed to different heat loads; and

a first card slot aligned with the first flow path to cool a first circuit card assembly seated in the first card slot and a second card slot aligned with the second flow path to cool a second circuit card assembly.

11. The system according to claim 10, wherein the first and second micro-channels are sized to generate flashing bubbles to maximize cooling for a selected pressure and temperature.

12. The system according to claim 10, wherein the first and second micro-channels are hydraulically parallel.

13. The system according to claim 10, wherein the system is passive.

14. The system according to claim 10, farther including a slot for coupling the cold plate system to circuit card.

15. A cold plate system, comprising:

first and second flow paths extending from a common inlet to a common outlet, the first and second flow paths being hydraulically parallel, wherein the first and second flow paths enable two-phase coolant flow under pressure through micro-channels for cooling heat loads on the cold plate system;

a first orifice spaced from a second orifice, the first and second orifices disposed in the first flow path on an inlet side of the first flow path, wherein the first and second orifices each protrude into the first flow path to reduce a cross-sectional area of the first flow path for constricting flow of the coolant;

wherein the first flow path is configured to cool a first heat load and the second flow path is configured to cool a second heat load, Which is less than the first heat load, wherein the first and second orifices in the first flow path minimize a difference in mass flow rate between the first and second flow paths, wherein the first flow path has a first inlet coupled to the common inlet, a first outlet coupled to the common outlet, and first and second orifices located between the first inlet and the first outlet, wherein the first orifice is spaced from the second orifice in the first flow path; and

a first card slot aligned with the first flow path to cool a first circuit card assembly seated in the first card slot and a second card slot aligned with the second flow to cool a second circuit card assembly

16. The cold plate system according to claim 15, wherein the cold plate system is passive.

17. The cold plate system according to claim 15, further including a slot for coupling the cold plate system to a circuit card.

18. A method, comprising:

providing a common inlet and a common outlet;

providing first, second and third flow paths being hydraulically parallel between the common inlet and the common outlet, wherein the first, second, and third flow paths enable two-phase coolant flow under pressure through micro-channels for cooling heat loads on the cold plate system;

wherein the first flow path has a first inlet coupled to the common inlet, a first outlet coupled to the common outlet, and first and second orifices located between the first inlet and the first outlet, wherein the first orifice is spaced from the second orifice in the first flow path, the first and second orifices disposed in the first flow path on an inlet side of the first flow path, wherein the first and second orifices each protrude into the first flow path to reduce a cross-sectional area of the first flow path for constricting flow of the coolant; and

providing a third orifice spaced from a fourth orifice, the third and fourth orifices disposed in the second flow path on an inlet side of the second flow path;

providing a fifth orifice spaced from a sixth orifice, the fifth and sixth orifices disposed in the third flow path on an inlet side of the third flow path;

wherein the first, second, third, fourth, fifth, and sixth orifices in the first, second, and third flow paths minimize a difference in mass flow rate between the first, second, and third paths when the first, second, and third flow paths are exposed to different heat loads,

configuring the first, second, and third flow paths and the coolant for a given first heat load for the first path, second heat load for the second path, and third heat load for the third path such that the first heat load being greater than the second and third heat loads increases mass flow rates in the second and third flow paths to induce flashing across the third orifice in the second flow path and the fifth orifice in the third flow path, which increases pressure drops across the third and fourth orifices in the second flow path and the fifth and sixth orifices in the third flaw path.

19. The method according to claim 18, further including sizing the first orifice such that under nominal balanced flow conditions a given pressure drop will not cause flashing.

20. The method according to claim 19, further including sizing the second orifice to flash subcooled coolant to a two-phase flow.