US20130112377A1

US20130112377A1 - Heat-dissipating device and heat-dissipating system

Info

Publication number: US20130112377A1
Application number: US13/430,617
Authority: US
Inventors: Kai-Shing Yang; Chi-Chuan Wang; Kuo-Hsiang Chien
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2011-11-08
Filing date: 2012-03-26
Publication date: 2013-05-09
Also published as: CN103096689A; TW201319505A

Abstract

A heat-dissipating device and a heat-dissipating system are provided. The heat-dissipating system includes a driver, a heat-exchanger and a heat-dissipating device. The heat-exchanger is communicated to the driver and includes a body, a hydrophobic membrane and a cover. The body has an inlet, an outlet and a channel. Both ends of the channel exposed on a body's surface are respectively communicated to the inlet and the outlet, the inlet and outlet are communicated respectively to the driver and heat-exchanger. The membrane is disposed on the body's surface and covers the channel. The cover combines with the body and has a chamber and an exhaust port. The membrane separates the channel from the chamber communicated to the exhaust port communicated to the heat-exchanger. The driver drives a working fluid to the heat-dissipating device, and the fluid further goes to the heat-exchanger from the heat-dissipating device and then back to the driver.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 100140698, filed on Nov. 8, 2011. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

1. Technical Field
The disclosure generally relates to a heat-dissipating device and a heat-dissipating system, and more particularly, to a heat-dissipating device and a heat-dissipating system able to separate gas and liquid apart.
2. Related Art
Looking at Taiwan's past, present and future development of key industries, no matter the semiconductor industry which long-term led the economic development in Taiwan, or the green energy and energy-saving products which are widely valued by the world due to global warming, soaring oil prices and other factors, such as LED application products (road lamps, vehicle lights, indoor lighting and so on) and high efficiency solar cells, and or the potentially prosperous key industries in future such as cloud computing products, all the products face a challenge of the internally-produced heat. The heat is uneasily to be removed so that the efficiency, the stability and the lifetime of the products are affected and further, the developments of the above-mentioned products and the relevant industries are limited. For the relevant products, the causes to produce high temperature can be divided into two categories, namely, high caloric amount and concentrated heat-source (high heat-density). The influence of the high caloric amount can be explained by using a computer system as an example. Along with the evolution of the IC (integrated circuit) packaging technology and the industrial processes in the development of electronic components, the internal IC packaging density and the operation speed thereof are rapidly increased. However, the high-speed operation frequency and the continuously-reduced circuit line width would make the caloric amount of the electronic components relatively advanced. The statistics has shown that 55% cases of the electronic product's damage are caused by too-high temperature and reducing the temperature of a chip every 10° C. can increase the computing efficiency by 1%-3%, which indicates a significant influence of temperature on the performance, the lifetime and the stability of the related electronic equipments. In this regard, the effective thermal design enables high reliability, great stability and long lifetime for the electronic components and equipments and further overcomes the limitation for developing the high-speed chips.
The real heat-dissipating change sourced from the high heat-density rests in the presence of extreme-high hot spots where the spreading resistance strongly affects the integrated performance of a heat-dissipating module. In addition, in order to increase the light flux, high-power LEDs (light-emitting diodes) are often packaged in array module mode. These light-emitting chips with high-density arrangement further make the heat-dissipating design more difficult. Most of the early cooling of electronic components adopts a natural convection way or a forced convection air-cooling way, where the heat exchange between the heat sink made of copper or aluminum and the electronic components in association with a fan or a heat pipe are used to dissipate heat to outside. Such measure has simpler structure and low cost, but the heat-transferring effect is poor and the issue related to noise is not solved, so that the conventional early measures can not meet the requirement of products with high caloric amount. Therefore, various more effective electronic heat-dissipating means such as thermal electric chips, liquid-cooling method and vapour compression refrigeration and air-conditioning systems have been gradually developed and got applications. Among them, the thermoelectric cooler has a higher cost and the commercial thermoelectric cooler has relatively low efficiency, both which need to input additional energy to cool the heat-source. Although vapour compression cooling system can achieve a lower cooling temperature and can effectively expel the waste-heat of the electronic chip, but such a low-temperature environment is not suitable for electronic components, because when the refrigerant's evaporation temperature is lower than the dew point temperature, condensation phenomenon occurs, and the condensation water vapour will have adverse effects on electronic components and result in component damage and failure, and the products are too expensive.
Currently, the common liquid cooling mean available on the market is an effective way for cooling a system, and in general, they mostly use water as the working fluid and a single-phase liquid mode for operation. In addition, to enhance the cooling capacity of liquid cooling systems, it is often realized by narrowing flowing-channel diameter of the cold plate. Under the high caloric amount situation, micro-channel has superior heat dissipation effect, but the relatively narrow scale of the flowing-channel also requires the pump can provide a very high thrust to drive the working fluid. Meanwhile, the working fluid passing the high temperature area would generate bubbles, which further clogs the flowing-channel, resulting in higher thrust need for the pump to provide. As a result, the liquid cooling scheme has a lower feasibility.

SUMMARY

The disclosure is directed to a heat-dissipating device able to solve the problem of clogging the channels by bubbles.
The disclosure is directed to a heat-dissipating system able to solve the problem of requiring a high thrust to drive the working fluid in the channels.
The heat-dissipating device of the disclosure includes a body, a hydrophobic membrane and a cover. Both ends of the channel are respectively communicated to the inlet and the outlet, and the channel is exposed on a surface of the body. The hydrophobic membrane is disposed on the surface of the body and covers the channel. The cover combines with the body and has a chamber and an exhaust port, in which the hydrophobic membrane separates the channel from the chamber. The chamber is communicated to the exhaust port.
The heat-dissipating system of the disclosure includes a driver, a heat-exchanger and a heat-dissipating device. The heat-exchanger is communicated to the driver. The heat-dissipating device includes a body, a hydrophobic membrane and a cover. The body has an inlet, an outlet and a channel, in which both ends of the channel are respectively communicated to the inlet and the outlet, the channel is exposed on a surface of the body, the inlet is communicated to the driver and the outlet is communicated to the heat-exchanger. The hydrophobic membrane is disposed on the surface of the body and covers the channel. The cover combines with the body and has a chamber and an exhaust port, in which the hydrophobic membrane separates the channel from the chamber, the chamber is communicated to the exhaust port, the exhaust port is communicated to the heat-exchanger, the driver is for driving a working fluid to the heat-dissipating device and the working fluid further goes to the heat-exchanger from the heat-dissipating device and then back to the driver.
Based on the description above, in the heat-dissipating device and the heat-dissipating system of the disclosure, a hydrophobic membrane is utilized to effectively separate liquid and gas apart, which further ensure smoothly pushing the working fluid to keep a high heat-dissipating efficiency.
Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a schematic diagram of a heat-dissipating system according to an embodiment of the disclosure.

FIG. 2 is an exploded diagram of the heat-dissipating device of FIG. 1.

FIGS. 3 and 4 are schematic diagrams showing channels of other two embodiments.

FIG. 5 includes four photos continuously high-speed captured showing expelled bubbles during conducting heat-dissipating experiments.

FIG. 6 shows the contact angle.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

FIG. 1 is a schematic diagram of a heat-dissipating system according to an embodiment of the disclosure and FIG. 2 is an exploded diagram of the heat-dissipating device of FIG. 1. Referring to FIGS. 1 and 2, a heat-dissipating system 100 of the embodiment includes a driver 110, a heat-exchanger 120 and a heat-dissipating device 200. The heat-exchanger 120 is communicated to the driver 110. In more details, a working fluid 50 flows from the driver 110 to the heat-dissipating device 200. After the working fluid 50 takes heat away from the heat-dissipating device 200 to get warmed, the working fluid 50 flows to the heat-exchanger 120 to conduct heat-exchanging with the ambient environment. Thereafter, the working fluid 50 flows back to the driver 110 from the heat-exchanger 120 so as to complete one cycle. The heat-dissipating system 100 of the embodiment is, for example, the one to form closed cycle.
The heat-dissipating device 200 includes a body 210, a hydrophobic membrane 220 and a cover 230. The body 210 has an inlet 212, an outlet 214 and a channel 216. Both ends of the channel 216 are respectively communicated to an inlet 212 and an outlet 214. The channel 216 is exposed on the surface of the body 210. In other words, if solely observing the body 210, the bottom of the channel 216 can be directly seen from the surface of the body 210 where no any other structures cover the channel 216. The inlet 212 is communicated to the driver 110 and the outlet 214 is communicated to the heat-exchanger 120. The working fluid 50 enters the channel 216 from the driver 110 via the inlet 212, and then, enters the heat-exchanger 120 from the channel 216 via the outlet 214. The hydrophobic membrane 220 is disposed on the surface of the body 210 and covers the channel 216. The hydrophobicity of the hydrophobic membrane 220 makes the working fluid 50 unable to pass through the hydrophobic membrane 220, but gas can pass through the hydrophobic membrane 220.
The cover 230 is combined with the body 210 and has a chamber 232 and an exhaust port 234. The hydrophobic membrane 220 separates the channel 216 from a chamber 232, while the chamber 232 is communicated to the exhaust port 234. The exhaust port 234 is communicated to the heat-exchanger 120. The body 210 is configured for contacting a heat-source 60, which can be, for example, an LED, a chip, a solar energy or other components requiring heat-dissipating. The heat of the heat-source 60 is transferred to the surface of the body 210, and then, to the working fluid 50 in the channel 216. During the working fluid 50 is being warmed, the heat is brought away from the body 210 to achieve heat-dissipating purpose. The working fluid 50 can be even converted from liquid state to vapour state, and during the liquid-vapour conversion, more heat would be brought away. In addition, the working fluid 50 in vapour state after the conversion can quickly pass through the hydrophobic membrane 220 to enter the chamber 232 and flow to the heat-exchanger 120 from the exhaust port 234. In this way, it can avoid the working fluid 50 in vapour state in the channel 216 from forming bubbles to block the flowing of the working fluid 50, which ensure the working fluid 50 smoothly and ceaselessly cycling and bringing away heat to get the optimum heat-dissipating efficiency. The working fluid in vapour state 50 after cooling would be converted back to liquid state again.
The driver 110 is configured for providing a driving force to drive the working fluid 50 to the heat-dissipating device 200. Then, the working fluid 50 flows to the heat-exchanger 120 from the heat-dissipating device 200 and back to the driver 110.
The heat-dissipating device 200 of the embodiment further includes a supporting plate 240 disposed between the body 210 and the cover 230 and the supporting plate 240 fixes the hydrophobic membrane 220 on the surface of the body 210. The supporting plate 240 has a plurality of ventilation ports 242. The working fluid in vapour state 50 can quickly pass through the hydrophobic membrane 220 and the ventilation ports 242 to enter the chamber 232. The major function of the supporting plate 240 is for avoiding the hydrophobic membrane 220 from being peeled off from the surface of the body 210 and thereby avoiding the working fluid in liquid state 50 from entering the chamber 232. However, if the hydrophobic membrane 220 were appropriately fixed, the supporting plate 240 can be saved.
The hydrophobicity of the hydrophobic membrane 220 in the embodiment is explained in more details as follows. The contact angle θ between the hydrophobic membrane 220 and the working fluid 50 in the channel 216 is between 90° and 180°. Referring to FIG. 6, it shows the contact angle. The contact angle θ is the angle formed at the contact interface of the solid surface and liquid/gas. As shown in FIG. 6, the contact angle θ is a system formed by the interaction of three different interfaces. In general, the contact angle θ plays a constraint for a shape of a droplet defined from Young-Laplace equation, wherein the droplet is on an unit of lateral solid surface. The measurement of contact angle θ can be finished by a contact angle protractor. The contact angle θ is not limited to the liquid/gas interface, it is applicable to interface between two liquid or between two vapor. Generally speaking, if a droplet on a solid surface strongly forced by force of the solid surface (such as water and a strongly hydrophilic surface of a solid), the droplet will be completely flatly attached to the surface of the solid, and the contact angle θ is about 0°. With non-hydrophilic solid, the contact angle θ is larger, to about 90°. In many highly hydrophilic surfaces, contact angle θ of water droplet is about 0° to 30°. If the surface of a solid is hydrophobic, the contact angle θ is larger than 90°. For the high hydrophobic surface, the contact angle θ of water droplet can be as high as 150° or even 180°. On this surface, the water droplets only stay on, not really infiltrate to the surface. It is to be called super-hydrophobic. We can observe it on the appropriate fluoride treated (Teflon coating) surface, and it can be called the lotus effect. This super hydrophobic phenomenon on the surface of new material bases on the same principle as the principle founded on the lotus leaf surface (leaf with many small protrusions), and even honey has a super hydrophobic phenomenon on the surface of the new material. The contact angle θ provide information of force between the surface and the liquid. But sometimes, the contact angle θ may not refer to the angle from the interface between liquid/gas to the liquid, but refers to the angle from the interface between liquid/gas to the gas. The above interpreted angles are complementary angles. The channel 216 of the embodiment is a continuous S-shape. FIGS. 3 and 4 are schematic diagrams showing channels of other two embodiments. In the embodiment of FIG. 3, the channel 316 branches in multiple times from the inlet 312 to the outlet 314. The channel 316 repeatedly branches from the inlet 312 and reaches the middle position, and then the multiple branches merge one by one and converge finally at the outlet 314. In the embodiment of FIG. 4, the channel 416 includes a plurality of parallel branches.
FIG. 5 includes four real photos continuously high-speed captured showing expelled bubbles during conducting heat-dissipating experiments based on the channel of FIG. 4. It is obvious from FIG. 5 that the area R10 is almost occupied by bubbles (marked with oblique lines) at the beginning (0 sec.), but the area occupied by the bubbles is noticeably shrunk after 0.04 sec. and after 0.08 sec. Further, after 0.12 sec. the area R10 occupied by the bubbles is shrunk roughly to a half. It can be seen the heat-dissipating device of the disclosure is certainly helpful to quickly expel the gas from the channel via the hydrophobic membrane.
Referring to FIG. 1 again, the heat-dissipating system 100 of the embodiment can further include a filter 130 disposed between the driver 110 and the inlet 212. The filter 130 is configured for filtering possible impurities in the working fluid 50. The heat-dissipating system 100 of the embodiment can further include a one-way valve 140 disposed between the exhaust port 234 and the heat-exchanger 120. The one-way valve 140 can avoid the working fluid in liquid/vapour state 50 from being refluxed to enter the chamber 232. The heat-dissipating system 100 of the embodiment further includes a reservoir 150 disposed between the heat-exchanger 120 and the driver 110 for storing the working fluid 50 and thereby to adjust the amount of the working fluid 50 flowing cyclically in the whole system. The heat-exchanger 120 of the embodiment has a fan 122 to advance the efficiency of the heat-exchanging between the heat-exchanger 120 and the ambient environment so as to quickly cool the working fluid 50. The driver 110 of the embodiment is a pump, but other fauns of driver are allowed.
In summary, in the heat-dissipating device and the heat-dissipating system of the disclosure, a hydrophobic membrane is utilized to quickly expel gas from the channel to the chamber so as to reduce the probability of that the clogged channel by bubbles makes the working fluid unable to smoothly flow, which further ensure the working fluid ceaselessly getting cycles to keep a high heat-dissipating efficiency.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.

Claims

What is claimed is:

1. A heat-dissipating device, comprising:

a body, having an inlet, an outlet and a channel, wherein both ends of the channel are respectively communicated to the inlet and the outlet, and the channel is exposed on a surface of the body;

a hydrophobic membrane, disposed on a surface of the body and covering the channel; and

a cover, combining with the body and having a chamber and an exhaust port, wherein the hydrophobic membrane separates the channel from the chamber, and the chamber is communicated to the exhaust port.

2. The heat-dissipating device as claimed in claim 1, further comprising a supporting plate disposed between the body and the cover and fixing the hydrophobic membrane onto the surface of the body, wherein the supporting plate has a plurality of ventilation ports.

3. The heat-dissipating device as claimed in claim 1, wherein a contact angle between the hydrophobic membrane and a working fluid in the channel is between 90° and 180°.

4. The heat-dissipating device as claimed in claim 1, wherein the channel is a continuous S-shape.

5. The heat-dissipating device as claimed in claim 1, wherein the channel branches in multiple times from both the inlet and the outlet to the middle.

6. The heat-dissipating device as claimed in claim 1, wherein the channel comprises a plurality of parallel branches.

7. A heat-dissipating system, comprising:

a driver;

a heat-exchanger, communicated to the driver;

a heat-dissipating device, comprising:

a body, having an inlet, an outlet and a channel, wherein both ends of the channel are respectively communicated to the inlet and the outlet, the channel is exposed on a surface of the body, the inlet is communicated to the driver and the outlet is communicated to the heat-exchanger;

a hydrophobic membrane, disposed on the surface of the body and covering the channel; and

a cover, combining with the body and having a chamber and an exhaust port, wherein the hydrophobic membrane separates the channel from the chamber, the chamber is communicated to the exhaust port, the exhaust port is communicated to the heat-exchanger, the driver is for driving a working fluid to the heat-dissipating device and the working fluid further goes to the heat-exchanger from the heat-dissipating device and then back to the driver.

8. The heat-dissipating system as claimed in claim 7, wherein the heat-dissipating device further comprises a supporting plate disposed between the body and the cover and fixing the hydrophobic membrane onto the surface of the body, the supporting plate has a plurality of ventilation ports.

9. The heat-dissipating system as claimed in claim 7, wherein a contact angle between the hydrophobic membrane and the working fluid in the channel is between 90° and 180°.

10. The heat-dissipating system as claimed in claim 7, wherein the channel is a continuous S-shape.

11. The heat-dissipating system as claimed in claim 7, wherein the channel branches in multiple times from both the inlet and the outlet to the middle.

12. The heat-dissipating system as claimed in claim 7, wherein the channel comprises a plurality of parallel branches.

13. The heat-dissipating system as claimed in claim 7, further comprising a filter disposed between the driver and the inlet.

14. The heat-dissipating system as claimed in claim 7, further comprising a one-way valve disposed between the exhaust port and the heat-exchanger.

15. The heat-dissipating system as claimed in claim 7, further comprising a reservoir disposed between the heat-exchanger and the driver for storing the working fluid.

16. The heat-dissipating system as claimed in claim 7, wherein the heat-exchanger has a fan.

17. The heat-dissipating system as claimed in claim 7, wherein the driver is a pump.