Loop heat pipe and electronic equipment using the same

• US 9,696,096 B2
• Filed: 04/25/2013
• Issued: 07/04/2017
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ogata, Susumu, Uchida, Hiroki, Hibino, Seiji
• Primary Examiner(s): Tran, Len
• Assistant Examiner(s): HINCAPIE SERNA, GUSTAVO A
• Application Number:
  US13/870,569
• Publication Number:
  US 20130233521A1
• Time in Patent Office: 1,531 Days
• Field of Search: 16510422, 16510426, 16510427, 16510432, 16510433, 361700
• 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 15/0275 Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
• CPC Class Codes: F28D 15/043 forming loops, e.g. capillary pumped loops
• CPC Class Codes: F28D 2021/0028 for cooling heat generating elements, e.g. for cooling electronic components or electric devices
• 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 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

Abstract

A loop heat pipe includes an evaporator to cause a liquid-phase working fluid to be vaporized by heat from a heat source; a condenser to condense the vaporized working fluid; a circulation path including a liquid line and a vapor line to connect the condenser and the evaporator in a loop; a tank provided on the liquid line and configured to accommodate the liquid-phase working fluid; a connecting line to connect the tank and the evaporator to supply the liquid-phase working fluid to the evaporator; and a bypass line positioned over the connecting line in a direction of gravity and connecting the evaporator and the tank, the bypass line being configured to discharge a vapor bubble produced in the evaporator during operation of the loop heat pipe to the tank.

Claims

1. A loop heat pipe comprising:

an evaporator to cause a liquid-phase working fluid to be vaporized by heat from a heat source;

a condenser to condense the vaporized working fluid;

a circulation path including a liquid line and a vapor line to connect the condenser and the evaporator in a loop;

a tank provided on the liquid line and configured to accommodate the liquid-phase working fluid;

a connecting line to connect the tank and the evaporator to supply the liquid-phase working fluid to the evaporator; and

a bypass line positioned over the connecting line in a direction of gravity and connecting the evaporator and the tank to discharge a vapor bubble produced in the evaporator during operation of the loop heat pipe to the tank,

wherein a porous wick divided into two or more parts is provided inside the evaporator, one part provided on a upper side and another part provided on a lower side of the evaporator along the direction of gravity, and the bypass line positioned over the connecting line in the direction of gravity extends from a vicinity of said one part of the porous wick provided on the upper side of the evaporator to the tank so as to be continuously in fluid communication with the tank.

2. The loop heat pipe according to claim 1, wherein the evaporator is of a flat plate type having a contact face that comes into contact with the heat source, and the evaporator is arranged such that the contact face is parallel to the direction of gravity.

3. The loop heat pipe according to claim 1, wherein an inner diameter of the bypass line is smaller than an inner diameter of the connecting line.

4. The loop heat pipe according to claim 1, wherein the bypass line is made of copper, a copper alloy, aluminum, or an aluminum alloy.

5. The loop heat pipe according to claim 1, wherein two or more of the evaporators are arranged, each of the evaporators being connected to the tank via a corresponding one of the connecting lines and a corresponding one of the bypass lines positioned over the connecting lines.

6. The loop heat pipe according to claim 5, wherein an inner diameter of each of the bypass lines is smaller than an inner diameter of the corresponding one of the connecting lines provided to the respective evaporators.

7. The loop heat pipe according to claim 5, wherein a contact face of each of the evaporators that comes into contact with the heat source is parallel to the direction of gravity.

8. The loop heat pipe according to claim 5, wherein the porous wick divided into two or more parts is provided inside each of the evaporators, the divided parts of the wick being parallel to each other in the direction of gravity.

9. The loop heat pipe according to claim 1, wherein the working fluid is selected from a group of pentane, butane, ammonium, water, ethanol, and acetone.

12. The loop heat pipe according to claim 1, wherein said other part of the porous wick provided on the lower side of the evaporator is positioned below the connecting line that supplies the liquid-phase working fluid to the evaporator.

10. An electronic equipment comprising:

a substrate arranged in a direction of gravity;

an electronic component mounted on the substrate; and

a loop heat pipe to cool the electronic component;

wherein the loop heat pipe includes

an evaporator having a contact face brought into contact with the electronic component, the contact face being parallel to the direction of gravity;

a tank connected to the evaporator via a connecting line and configured to supply a liquid-phase working fluid to the evaporator via the connecting line; and

a bypass line positioned over the connecting line in the direction of gravity and connecting the evaporator and the tank to discharge a vapor bubble produced in the evaporator during operation of the loop heat pipe to the tank,

wherein a porous wick divided into two or more parts is provided inside the evaporator, one part provided on a upper side and another part provided on a lower side of the evaporator along the direction of gravity, and the bypass line positioned over the connecting line in the direction of gravity extends from a vicinity of said one part of the porous wick provided on the upper side of the evaporator to the tank so as to be continuously in fluid communication with the tank.

13. The electronic equipment according to claim 10, wherein said other part of the porous wick provided on the lower side of the evaporator is positioned below the connecting line that supplies the liquid-phase working fluid to the evaporator.

11. An electronic equipment comprising:

a substrate on which two or more electronic components are mounted; and

a loop heat pipe to cool said two or more electronic components;

wherein the loop heat pipe includes

two or more evaporators, each of the evaporators being provided to a corresponding one of the electronic components;

a common tank connected to each of the evaporators via a corresponding connecting line and configured to supply a liquid-phase working fluid to said each of the evaporators; and

two or more bypass lines to connect the common tank and said two or more evaporators, each of the bypass lines being positioned over a corresponding one of the connecting lines in the direction of gravity and connecting the tank and the corresponding evaporator to discharge a vapor bubble produced in the evaporator during operation of the loop heat pipe to the tank,

wherein a porous wick divided into two or more parts is provided inside each of the evaporators, one part provided on a upper side and another part provided on a lower side of associated one of the evaporators along the direction of gravity, and each of the bypass lines positioned over the corresponding one of the connecting lines in the direction of gravity extends from a vicinity of said one part of the porous wick provided on the upper side of the associated evaporator to the tank so as to be continuously in fluid communication with the tank.

14. The electronic equipment according to claim 11 , wherein said other part of the porous wick provided on the lower side of the evaporator is positioned below an associated one of the connecting lines that supplies the liquid-phase working fluid to the evaporator.