WO2007031024A1

WO2007031024A1 - A high performance passive type phase transformation heat sink system and an application thereof

Info

Publication number: WO2007031024A1
Application number: PCT/CN2006/002387
Authority: WO
Inventors: Yaohua Zhao
Original assignee: Sino-Tech Investment Holdings Limited
Priority date: 2005-09-14
Filing date: 2006-09-14
Publication date: 2007-03-22
Also published as: CN1767181A; CN100401508C

Abstract

A high performance passive type phase transformation heat-sink system comprises a micro-flute group evaporator and a condenser, the said micro-flute group evaporator is connected with a capillary pumped loop circuit, the capillary pumped loop circuit is connected to the said condenser. Using the heat-sink system can be of advantage to sufficiently radiate and cool the heater with high heat flow density, thus satisfying the heat-sink requires of high performance chip, super-laser, and optical communication or other electromechanical devices. A phase transformation heat-sink system for desk computer of the invention can satisfy cooling requires of various desk computers by larger heat exchange capability. A phase transformation heat-sink system for notebook computer or the like with the small space of the invention can be of advantage to improve total heat exchange amount.

Description

High-performance passive phase change heat dissipation system and application thereof

The invention relates to a technology for passive phase change heat exchange of a heating working element or component, in particular to a high performance passive phase change heat dissipation system and application thereof, and the specific application comprises a phase change heat dissipation system for a desktop computer and a notebook A cooling system in a small room such as a computer. Background technique

The heat density of the High performance chip is about 60 W/cm ² . This heat flux density is at the same level as the core heat flux of a light water furnace reactor (LWR), but the difference between the heat sink surface temperature and the ambient temperature required by the former is much lower than the latter. The thermal control technology of the computer, that is, the cooling technology requirement, has to satisfy the upper limit temperature (about 100oC) and the ever-increasing heat dissipation heat flux density, which has become an international technical problem.

The cooling capacity of the general-scale air-cooling technology currently in common use is an order of magnitude lower than the heat density of the above-mentioned high-performance chips at a general flow speed (for example, 20 m/s). To enhance the cooling capacity of air cooling technology, there are active methods and passive methods. The passive approach is to refine the heat exchanger flow path to enhance heat transfer performance and increase heat transfer area (such as adding microchannels, etc.). The active methods mainly include increasing the working fluid flow rate and reducing the inlet temperature of the cooling medium. These enhancement methods involve micro-systems and micro-heat transfer problems, such as increasing the micro repowering system (lifting the working fluid flow rate), micro-refrigeration systems (reducing the cooling medium temperature), and micro-fan systems (improving the environment). Convective heat transfer) performance.

The phase change cooling technology of computers is another type of new cooling technology that is being developed and developed that is different from air cooling technology. The theoretical limit of the phase change evaporation heat flux is about two orders of magnitude higher than the current maximum heat flux density of the computer. And the temperature condition satisfies the upper limit temperature of the computer. At present, there are micro-heat pipe technologies (also divided into capillary type, forced vibration type and self-excited oscillation type) and micro-slot group evaporation type heat sink technology. Many national funds and large enterprises have invested in the world. Less funds for development research. However, in general, due to the flow characteristics in the micro-tubes, the ordinary micro-heat pipe technology has encountered a development bottleneck and a critical heat flow restriction problem that cannot be overcome at present, resulting in an inability to effectively increase the total heat transport capacity.

At present, the best passive cooling technology (heat pipe technology) in China has limited heat dissipation capability. For example, the cooling method of domestic desktop computers is mainly fin-and-fan method, technically working on the fin process and fan performance. The cooling system of notebook computers that require small size and high heat dissipation power is basically imported from abroad and the host. It can be said that at home and abroad, LSI cooling issues (including CPU, HDD, FDD and LCD) will be the constraint computer The most important and most urgent factor in performance. At the same time, high-energy lasers, optical communications and other fields have also put forward new requirements for high-power and small-sized heat sinks.

Therefore, with the rapid development of microelectronics technology, the rapid advancement of various cutting-edge technologies in China, and the practical needs of the defense industry, it is of great practical significance to research and develop the heat dissipation technology of microelectronic devices including computers with independent intellectual property rights. Economic Value. Summary of the invention

The present invention provides a high performance passive phase change heat dissipation system for the deficiencies or defects existing in the prior art. The use of the heat dissipation system facilitates sufficient heat dissipation of the high heat flux heat generating body to meet the heat dissipation requirements of high performance chips, high energy lasers, optical communication or other electromechanical devices.

The present invention also provides a phase change heat dissipation system for a desktop computer that meets the cooling requirements of a next generation desktop computer with a large heat exchange capacity.

The present invention also provides a heat dissipation system for use in a small space such as a notebook computer, which is advantageous for increasing the total heat exchange amount. The general technical idea of the present invention is as follows:

Based on the research status and demand analysis of micro-heat dissipation technology of microelectronics and micro-system devices at home and abroad, a high-performance micro-slot group phase change cooling mode has been developed, which utilizes the capillary pump loop to make the micro-slot group evaporator and condensation The space-isolated structure is designed to improve the heat-dissipating and cooling capacity of high-heat-flow-density heating elements, and to develop high-performance passive cooling elements that meet various small sizes and to meet advanced electronic devices in the next generation of computers and other extreme environments. The cooling system addresses the licensing needs of the military and the thermal issues facing the IT industry.

The technical solution of the present invention is as follows - a high performance passive phase change heat dissipation system, comprising a micro-slot group evaporator and a condenser, wherein: the micro-slot group evaporator is connected with a capillary pump ring line, the capillary pump ring line Connected to the condenser.

The micro-slot group evaporator includes a micro-slot group evaporating heat exchange element, and a dense micro-capillary groove is distributed on the evaporation surface of the evaporating heat-exchange element, and a capillary force generated in the micro-capillary groove can suck the liquid into the groove, thereby The liquid in the tank forms a meniscus evaporation heat transfer near the gas, liquid and solid three-phase contact lines.

The microgroove group surface layer is a Ti0 ₂ material layer or other hydrophilic material layer for superhydrophilic treatment of the micro groove group surface. The micro-capillary groove is a straight groove, the groove width is 0.01-lmm, and the groove depth is 1-4 times of the groove width.

The groove width is 0.1-0.5 mm.

The capillary pumping line includes a vapor delivery line portion and a liquid return line portion, and a one-way valve is disposed in the line.

The outlet end of the liquid return line portion is butted to the microchannel structure, and the microchannel structure is used for the capillary pump loop The reflux liquid in the capillary is driven by the capillary.

The condenser is a naturally cooled condenser, a forced air cooled condenser, a water cooled condenser or a reinforced high efficiency condenser using a polymer grid-like complex membrane.

A phase change heat dissipation system for a desktop computer, comprising: a micro-slot group evaporator and a condenser for heat dissipation of a chip, wherein the micro-slot group evaporator is connected with a capillary pump ring line, the condenser is located on the table top On both sides of the chassis of the computer, the capillary pump ring line is connected to the condenser.

A heat dissipation system for use in a small space such as a notebook computer, comprising: a micro-slot group evaporator and a condenser for cooling the CPU, wherein the micro-slot group evaporator is connected with a capillary pump ring line, the condensation The devices are respectively located on the display backplane layer of the notebook computer and the host backplane layer, and the capillary pump ring pipeline is connected to the condenser, and a hose path is adopted at the rotating shaft of the notebook computer.

The technical effects of the present invention are as follows:

Due to the high-performance passive phase-change heat dissipation system of the present invention, the heat dissipation cooling capability is improved by utilizing a capillary pump ring line to realize spatial isolation of the micro-slot group evaporator and the condenser, so that the heat dissipation system is advantageous for high heat flux density. The heating element is fully cooled and cooled to meet the heat dissipation requirements of high performance chips, high energy lasers, optical communications or other electromechanical devices.

Since the micro-groove group evaporator uses the micro-groove group to evaporate the heat-exchange element, the capillary phenomenon is fully utilized by the dense micro-capillary grooves distributed on the evaporation surface, and the capillary force generated in the micro-groove causes the liquid to be sucked into the micro-groove. The liquid in each tank is attached to a three-phase (gas, liquid, solid) contact line with a small meniscus, and the evaporation of the meniscus has a large local heat transfer coefficient. By designing the optimal size and structure layout, the mechanism of phase change heat and mass transfer and critical heat load in the microchannel is fully revealed. The heat exchange capacity may be higher than or several times the critical thermal load of boiling in the general pool. It has the characteristics of arbitrary heat exchange size and great heat exchange. Therefore, the heat exchange technology may have important application prospects in the future heat dissipation of ultra-microelectronics and micro-system devices and heat dissipation of spacecraft components.

Since the microgroove group surface layer is a Ti0 ₂ material layer or other hydrophilic material layer, the micro-groove group surface is subjected to super-hydrophilic treatment, thereby obtaining a strengthened micro-groove group evaporating heat exchange element.

Since the micro-capillary groove is a straight groove, the groove width is 0.01-lmm, the groove depth is 1-4 times of the groove width; and the groove width can be further increased to 0.1-0.5 MM; this is for the open type micro-slot group evaporation heat transfer surface , can get the best micro-slot size parameters and the best structural design (multi-layer, 'combined micro-groove and external capillary reinforcement structure, etc.).

Since the check valve is provided with a one-way valve, this can fully ensure the one-way flow of the vapor and the liquid, so that the entire CPL circuit, that is, the capillary pump ring line, which is not provided with the liquid pump, is determined by the geometric design of the circuit. Node pressure, which is conducive to the normal operation of the system.

Since the outlet end of the liquid return line portion is docked to the microchannel structure, the microchannel structure is used for the capillary pump loop The reflux liquid in the middle is driven by capillary, that is to say, by using the docking technology of the circuit and the evaporator, not only the liquid returning from the return pipe is continuously replenished into the evaporator, but also an optimal design can be realized, and the liquid connection is added to On the evaporation surface, the influence of gravity on the flow resistance can be overcome, and the negative pressure formed by the capillary force in the micro-groove group can be used to increase the driving force of the liquid return flow.

Since the condenser is a naturally cooled condenser, a forced air-cooled condenser, a water-cooled condenser or a reinforced high-efficiency condenser using a polymer grid-like complex membrane, this facilitates proper configuration according to different working conditions or operating environments. .

Since the phase change heat dissipation system for a desktop computer of the present invention is based on a general inventive concept, the structure design of the microchannel group evaporator and the condenser is spatially separated by the capillary pump ring line to improve the high heat flux density. On the basis of the heat dissipation and cooling of the heating element, the condenser is placed on both sides of the chassis of the desktop computer, and the evaporation evaporation of the evaporator can be applied to the outer walls of both sides of the computer case to generate natural convection heat exchange with the outside air. After the steam is condensed It is recirculated into the evaporator, so that it can meet the cooling requirements of future desktop computers with a large heat exchange capacity without the need of a fan.

Since the heat dissipation system for a small space such as a notebook computer of the present invention is also based on a general inventive concept, the structural design of the micro-slot group evaporator and the condenser is spatially separated by using a capillary pump ring line to improve the height of the structure. Based on the heat dissipation and cooling capacity of the heat flux density heating body, the condenser is placed on the display backplane layer of the notebook computer and the host backplane layer, and a hose path is adopted at the rotating shaft of the notebook computer; this can solve the critical heat flow. Restricting the problem and improving the total heat exchange rate, the test results show that the cooling capacity can reach a heat flux density of 250W / cm ² and a maximum heat transfer capacity of 1000W. Of course, regarding the internal structure design of the evaporator, the horizontal and vertical placement of the chip and the tilting of the chip must be considered. The flow cycle and liquid replenishment will be closely related to the internal structural design of the evaporator. At the same time, CPL hose connection technology is required: The connection between the evaporator and the condenser requires a soft connection due to the rotation axis of the computer display. DRAWINGS

Figure 1 is a schematic diagram of the evaporation of the capillary micro-groove, including the structure diagram and partial enlargement of the evaporating heat exchange element of the micro-groove group. In the figure, Q is the heat flow of the heating element, and the direction of the heat flow is indicated by solid arrows, and the circular and hollow arrows indicate the partial enlarged area and the endothermic evaporation. The partial enlargement map indicates the level of the trough top, the three-phase contact line, the adsorption layer, the meniscus, and the level or position of the evaporating microfluid film.

Figure 2 is a schematic view of the structure of the evaporation plate, including micro-capillary grooves on the evaporation surface, which are distributed longitudinally and laterally.

Figure 3 shows the forced air cooling desktop CPU heat sink.

Figure 4 is a cooling system diagram of a water-cooled external condenser. The cooling water and capillary pump ring are shown.

Figure 5 is a diagram of a naturally cooled heat dissipation system. The figure shows the microslot group evaporator, the capillary pump ring line and the external cold The connection status of the condenser.

Figure 6 is a schematic diagram of the cooling system of the notebook computer. The figure shows the status of the notebook's display backplane and the host backplane as the heat sink.

The reference numerals are listed below:

1-micro-groove group evaporative heat exchange element; 11-micro-cylinder trough; 11A-vertical trough; 11B-transverse trough; 2' - evaporation plate; 2- micro-slot group evaporator; 3-condenser; 3 '-water-cooled Condenser; 4-liquid (evaporant); 5-fan; 6-CPU chip; 6' - heating element; 10-CPL capillary pump ring; 20- CPL steam part; 30- CPL liquid part. detailed description

The invention will be further described in detail below with reference to the accompanying drawings.

Regarding the micro-groove group evaporating heat exchange element in the present invention - the micro-groove group evaporating heat exchange element generally refers to engraving a dense fine straight groove on a plate of any size, and the capillary force generated in the micro-slot causes the liquid to be sucked into the micro-groove Inside. The liquid in each tank has a slight meniscus near the three-phase (gas, liquid, solid) contact line, and the evaporation of the meniscus has a great local heat transfer coefficient. By designing the optimal size and structural layout, the amount of heat exchange may be higher than or several times the critical thermal load of boiling in the general pool. And it has the characteristics of arbitrary heat exchange size and great heat exchange. Therefore, the heat exchange technology may have important application prospects in the future heat dissipation of ultra-microelectronics and micro-system devices and heat dissipation of spacecraft components. The innovations can be summarized as follows: Developed a new generation of high-performance cooling technology, the most advanced application technology in the relevant fields in the world; different from the conventional micro-cooling system, which is large in size and cannot meet the requirements of modern technology. Technology can lay the foundation for future micro-cold system technology. The key technologies used in the following are: revealing the mechanism of phase change heat and mass transfer and critical heat load in the micro-slot; for the open heat transfer surface of the micro-slot group, the optimal micro-slot size parameters and optimal structural design are obtained ( Multi-layer, combined micro-groove and external capillary reinforcement structure, etc.) For different liquid working fluids, the micro-groove group surface is super-hydrophilic treated with Ti0 ₂ material or other hydrophilic materials to obtain enhanced micro-groove group evaporation Thermal component.

The schematic diagram of the capillary microchannel evaporation shown in Fig. 1 includes a structural diagram and a partial enlargement diagram of the microgroove group evaporating heat exchange element 1. In the figure, Q is the heat flow of the heating element, and the direction of the heat flow is indicated by solid arrows; the circular ring and the hollow arrow indicate the partial enlarged area and the endothermic evaporation; the figure also shows the shape of the liquid distribution in the micro-capillary groove 11. The partial enlargement map indicates the level or position of the top of the tank, the three-phase contact line, the adsorption layer, the meniscus, and the evaporating micro-liquid film. The capillary force generated in the micro-capillary groove 11 allows the liquid to be sucked into the tank, so that the liquid in the tank forms a meniscus evaporation heat exchange in the vicinity of the gas, liquid, and solid three-phase contact line. '

The structure of the microgroove group evaporating heat exchange element 1 shown in Fig. 2 includes micro-capillary grooves 11 on the evaporation surface, which are distributed in the longitudinal direction and the lateral direction, that is, the vertical grooves 11A and the lateral grooves 11B. The micro-capillary groove is a straight groove, the groove width is 0.01-lmm, and the groove depth is The groove width is 1-4 times; and the groove width may further preferably be 0.1 to 0.5 mm. Of course, the micro-capillary grooves can also be non-straight grooves. As shown in FIG. 3, the forced air-cooled desktop CPU cooler is shown in the figure, and the forced air cooling of the condenser 3 by the fan of the conventional configuration is shown, including the CPU chip 6, the micro-slot group evaporating heat exchange element 1 and The position of the capillary groove, the evaporation plate 2', the condensing portion, that is, the condenser 3, the fan 5, and the liquid 4. The condenser 3 is forcedly air-cooled by the fan 5 to further improve the heat exchange capability of the system.

Regarding the CPL system in the present invention, that is, the capillary pump ring system:

CPL technology has been applied to the heat dissipation problem of spacecraft. Since the heat generated by the internal components of the spacecraft must be brought to the surface away from the heat generating body for heat exchange and cooling, the heat generated by the heat generating body of the evaporator is carried by the steam through the steam line to the cooling portion, and is condensed to become a liquid and a liquid passage. Go back to the evaporator. The driving force of the fluid circulation is generated by the capillary force on the evaporator. However, the heat transfer density of the heating element on the general spacecraft is not very high, and the surface of the evaporator can be driven by a very fine groove (or hole) structure to achieve a large capillary driving force. At present, the maximum heat flux density of the evaporator in the CPL system is small. The main reason is that the current CPL can only form the evaporation surface and the capillary micro-groove (or pore) as a single structure, and it is difficult to achieve high evaporation heat flux density and high capillary driving force at the same time, so the critical heat flux density is low.

For a cooling system of a relatively large desktop computer, the evaporating component and the condensing component can be made in one piece, so that the CPL system can be disregarded. However, for notebook computer cooling with small space and high heat flux density, it is the consensus of most people to bring heat to the back of the computer display. When the steam and condensed liquid share a loop (heat pipe type), the total change will be greatly limited. Thermal critical mass. This research will develop a new type of CPL system to achieve a high heat flow transmission system. The innovations can be summarized as follows: The new CPL system with a number of new technologies can be applied to both normal gravity and microgravity conditions; the micro-slot evaporation surface and the liquid capillary drive structure are designed separately to achieve the high critical heat flux density of the evaporator. The key technologies used are: Steam delivery line and liquid circuit design. Since the liquid pump is not installed in the entire CPL circuit, the geometric design of the circuit will determine the pressure of each node in the circuit system to determine whether it is operating normally. One-way valve setting technology, in order to fully ensure the one-way flow of vapor and liquid, a check valve is arranged in the pipeline. The connection between the circuit and the evaporator, the liquid returned by the return pipe must be continuously replenished into the evaporator. The best design is to add the liquid connection to the evaporation surface, so as to overcome the influence of gravity on the flow resistance, and at the same time The negative pressure formed by the capillary force in the microgroove group increases the driving force of the liquid reflux.

Regarding the enhanced micro-condenser in the present invention - since the heat of evaporation must pass through the condensing heat exchanger, the steam is condensed into a liquid and then recycled to the evaporator, the development of a high-efficiency condenser will also become important. This patent emits a low energy surface that sustains droplet condensation for a long period of time, thereby constituting a condenser that matches the power of the microturbine. The innovations can be summarized as follows: This study first proposed a model of a mesh-like 髙 molecular film, which forms a large-area high-strength coordination bond with a metal substrate, and the stability is greatly enhanced compared with the conventional small-molecular complex film. Not only can it effectively extend the service life, but it can also form in a regular grid. High density nucleation center. The key technologies used are: preparation of polymer grid-like complex membranes and their application in enhanced micro condensers; microscopic mechanism of condensation process and enhanced control conditions; development of high-efficiency condensers.

The water-cooled external condenser heat dissipation system shown in Fig. 4 shows the micro-groove group evaporating heat exchange element 1 and its capillary micro-groove, the steam portion 20 in the CPL, the water-cooled condenser 3', and the liquid in the CPL. Part 30, the position of the microgroove evaporator 2, the heating element 6'.

The natural cooling type heat dissipation system shown in Fig. 5 shows the position of the naturally cooled condenser 3, the CPL, that is, the capillary pump ring line 10, and the micro-slot group evaporator 2 (heat absorber). The micro-slot group evaporator 2 is connected to the capillary pump ring line 10, and the capillary pump ring line 10 is connected to the condenser 3.

The notebook cooling system shown in Figure 6 shows the position of the heat sink, heat pipe, heat chip, high performance heat sink, and power supply. As can be seen from the figure, this embodiment uses the display backplane layer of the notebook computer and the host backplane layer as the heat dissipation surface, that is, the condenser 3. The high-performance heat sink is a micro-slot group evaporator with a micro-slot group evaporative heat exchange element 1. The heat generating chip is the CPU chip 6 and the like. The heat pipe is the capillary pump ring line 10 . The microgroove evaporator is connected to the condenser 3 via the capillary pump loop 10 and uses a hose path at the rotating shaft of the notebook.

It should be noted that the above-described embodiments may enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way. Accordingly, the present invention has been described in detail herein with reference to the drawings and the embodiments of the invention The technical solutions and their improvements should be covered by the scope of protection of the present invention.

Claims

Rights request

A high-performance passive phase change heat dissipation system, comprising a micro-slot group evaporator and a condenser, wherein: the micro-slot group evaporator is connected with a hair pump ring line, the capillary pump ring line and the condenser Connected.

2 . The high performance passive phase change heat dissipation system according to claim 1 , wherein the micro-slot group evaporator comprises a micro-slot group evaporating heat exchange element, and the evaporation surface of the evaporating heat-exchange element is densely distributed. The micro-capillary groove, the capillary force generated in the micro-capillary groove, enables the liquid to be sucked into the groove, so that the liquid in the groove forms a meniscus evaporation heat exchange near the gas, liquid and solid three-phase contact line.

The high-performance passive phase-change heat dissipation system according to claim 2, wherein the micro-groove group surface layer is a Ti0 ₂ material layer or other hydrophilic material layer, and is used for super-family of the micro-groove group surface. Water treatment.

The high-performance passive phase change heat dissipation system according to claim 2, wherein the micro-capillary groove is a straight groove, the groove width is 0.01-lmm, and the groove depth is 1-4 times of the groove width.

The high performance passive phase change heat dissipation system according to claim 4, wherein the groove width is 0.1 - 0.5 mm, and the groove depth is 2 - 3 times the groove width.

6. The high performance passive phase change heat dissipation system according to claim 1, wherein the capillary pump ring line comprises a vapor delivery line portion and a liquid return line portion, and a one-way is provided in the pipeline. valve.

The high performance passive phase change heat dissipation system according to claim 6, wherein the outlet end of the liquid return line portion is butted to the microchannel structure, and the microchannel structure is used in the capillary pump ring line. The reflux liquid is driven by a capillary.

8. The helium performance passive phase change heat dissipation system according to claim 1, wherein the condenser is a natural cooling condenser, a forced air cooling condenser or a water cooled condenser.

9. A phase change heat dissipation system for a desktop computer, comprising: a micro-slot group evaporator and a condenser for heat dissipation of a chip, wherein the flask group evaporator is connected with a capillary pump ring line, the condenser Located on either side of the chassis of the desktop computer, the capillary pump ring line is connected to the condenser.

10. A heat dissipation system for use in a small space such as a notebook computer, comprising: a micro-slot group evaporator and a condenser for cooling heat of the CPU, wherein the micro-slot group evaporator is connected with a capillary pump ring line, The condensers are respectively located on the display backplane layer of the notebook computer and the host backplane layer, and the capillary pump loop line is connected to the condenser, and a hose path is adopted at the rotating shaft of the notebook computer.