Flat plate pulsating heat pipe applicable at various angles and method of manufacturing same

Patent metadata

Field	Value
Publication number	US-10264707-B2
Application number	US-201515518814-A
Country	US
Kind code	B2
Filing date	May 22, 2015
Priority date	Oct 14, 2014
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

Disclosed is a flat plate pulsating heat pipe (FP-PHP) serving as a power-free high efficiency heat transfer system for small electronic devices such as mobile phones and laptop computers. The FP-PHP is manufactured using MEMS technology and configured to have a single-turn loop or a multi-turn loop, each having a single diameter channel or a dual diameter channel. Further, since a working fluid used in a flat plate pulsating heat pipe exhibits different characteristics according to the main working temperature, provided is a flat plate pulsating heat pipe which includes a working fluid having optimum efficiency in the main working temperature. In addition, the flat plate pulsating heat pipe applicable at various installation angles, of the present invention which is for achieving the above purpose, includes: a silicon lower wafer plate having a rectangular shape; a capillary tube comprising a channel which has a constant depth on the upper surface of the silicon wafer lower plate and is formed in the form of a straight line along the longitudinal direction of the silicon wafer lower plate, wherein the channel forms a closed loop which is bent at both ends of the silicon wafer lower plate and is connected; a wafer upper plate which is coupled on top of the silicon wafer lower plate and seals the capillary tube; and a working fluid filled inside the capillary tube, wherein the capillary tube is made of a combination of a dual-diameter tube including a pair of channels having different widths and a single diameter tube including a pair of channels having the same width.

First claim

The invention claimed is:

1. A flat plate pulsating heat pipe comprising:
a silicon lower wafer plate having a rectangular shape;
a capillary tube formed in an upper portion of the silicon lower wafer plate and shaped to bend at positions near respective ends of the silicon lower wafer plate to form a closed loop;
an upper wafer plate bonded onto the silicon lower wafer plate to seal the capillary tube;
a working fluid in the capillary tube;
an evaporator provided to an end portion of the capillary tube in a longitudinal direction of the silicon lower wafer plate and located near an external heat source installed outside the silicon lower wafer plate; and
a condenser that is provided to an opposite end portion of the capillary tube in the longitudinal direction of the silicon lower wafer plate and at which the working fluid heated by the external heat source radiates heat outside the capillary tube,
wherein the capillary tube has a larger diameter in a portion from the evaporator to the condenser and a smaller diameter in a portion from the condenser to the evaporator, and
performance of the flat plate pulsating heat pipe is represented by the following figure of merit (M PHP ):

M
PHP

=

Maximim
⁢

⁢
driving
⁢

⁢
pressure

Frictional
⁢

⁢
pressure
⁢

⁢
drop

=

ρ
1

⁢

h
fg

⁢

σ
⁡

(

1

w
2

-

1

w
1

)

μ
1

⁡

[

(

1
-
x

)

2

⁢

(

1
+

h

w
1

)

4

⁢

Φ
L
2

+

(

1
+

h

w
2

)

4

]

where ρ 1 is density of liquid phase of working fluid, h fg is latent heat of vaporization, σ is surface tension, w 1 is width of larger channel, w 2 is width of smaller channel, μ 1 is viscosity coefficient of liquid phase of working fluid, x is vapor mass quality (mass of vapor with respect to mass of entire working fluid), h is height (depth) of channel, Φ 2 L is frictional multiplier (pressure difference required for two-phase flow/pressure difference required for liquid flow with same massflow rate).

2. The flat plate pulsating heat pipe according to claim 1 , wherein the capillary tube has a single-turn loop shape.

3. The flat plate pulsating heat pipe according to claim 1 , wherein the capillary tube has a multi-turn loop shape.

4. The flat plate pulsating heat pipe according to claim 1 , wherein FC-72 is used as the working fluid when a main operating temperature of the evaporator is 100° C. or lower but ethanol is used as the working fluid when the main operating temperature of the evaporator is higher than 100° C.

5. The flat plate pulsating heat pipe according to claim 1 , wherein the figure of merit (M PHP ) of the flat plate pulsating heat pipe is 10 12 kg/(m·s)(W/m 3 ) or higher.

6. The flat plate pulsating heat pipe according to claim 1 , wherein a thickness of the flat plate pulsating heat pipe is 2 mm or less.

7. The flat plate pulsating heat pipe according to claim 1 , further comprising two through-holes provided to respective side surfaces of the silicon lower wafer plate, the two through-holes communicating with the capillary tube and used such that the working fluid is charged into and discharged from the capillary tube through the two through-holes.

8. A flat plate pulsating heat pipe comprising:
a silicon lower wafer plate having a rectangular shape;
a capillary tube including a channel formed to have a predetermined depth in an upper portion of the silicon lower wafer plate, the channel linearly extending in a longitudinal direction of the silicon lower wafer plate and bending at positions near respective ends of the silicon lower wafer plate, thereby forming a closed loop;
an upper wafer plate bonded to the silicon lower wafer plate to seal the capillary tube; and
a working fluid in the capillary tube,
wherein the capillary tube is a combination of a dual diameter channel including a pair of channels with respectively different

Assignees

• Korea Advanced Inst Sci & Tech

Inventors

• Kim Sung Jin
• Kwon Gi Hwan

Classifications

• H05K7/20318

  Condensers · CPC title

• H05K7/20309

  Evaporators · CPC title

• F28F13/10

  by imparting a pulsating motion to the flow, e.g. by sonic vibration · CPC title

• F28D2015/0225

  Microheat pipes · CPC title

• F28D15/043

  forming loops, e.g. capillary pumped loops · CPC title