CN103429061A - Fasting heat pipe radiator - Google Patents

Abstract

The invention relates to a hollow heat pipe radiator, which comprises a condenser and a heat collector mother board contacted with a heat source, wherein the condenser is positioned on and directly connected with the heat collector mother board, the condenser and the heat collector mother board are both of a hollow structure, the condenser comprises a plurality of hollow fins, the heat collector mother board is provided with two surfaces, one surface of the heat collector mother board is directly contacted with a smooth plane of the heat source, the heat collector is provided with a plurality of blind holes for installing the heat source, the hollow fins and the hollow heat collector mother board are filled with working media of phase change materials for heat dissipation, carbon nano-tubes can be added into the phase change materials to increase the heat conduction capability, the cavities of the hollow fins are mutually communicated with the cavity of the hollow heat collector mother board, the fins and the mother board are of an integral structure formed by integral molding, and a plurality of micro-groove groups are arranged on the radiator, to improve the heat dissipation effect of the heat sink to the heat source, or to adopt a plane or other curved surface for the sake of simplicity without providing the micro-groove group.

Description

Fasting heat pipe radiator

technical field

The invention relates to a new type of high-efficiency radiator, especially suitable for high-power electronic components such as igbt, igct, etc., which generate a large amount of heat but have insufficient heat dissipation capacity and are restricted by space size. And led, tec, cpu, gpu and other devices. This radiator changes the traditional solid fin radiator and adopts hollow fin radiator, and it is supplemented by micro-groove technology, composite nanotechnology, gravity heat pipe technology and many other new technologies, so it is called an empty stomach heat pipe radiator. Compared with the traditional planar gravity heat pipe radiator, its thermal resistance is only about one-fifth of it. Therefore, under the condition of the same volume of heat dissipation, its heat dissipation capacity is increased by about 40% to 95%.

Background technique

As we all know, high-power devices such as switching power supplies, variable frequency power supplies, IGBTs, IGCTs, LEDs, TECs, and GPUs have high energy consumption. Only a very small part of the electrical energy is converted into useful power that can serve human beings, such as the brightness of LEDs. However, most of the energy consumption is turned into heat energy. If the heat is not dissipated, the device will not work properly. Therefore, an efficient heat sink plays a vital role in the performance of high-power devices.

The heat dissipation technologies commonly used in modern times mainly include: natural convection heat dissipation, forced heat dissipation by adding fans, liquid cooling heat dissipation, heat pipe heat dissipation, semiconductor refrigeration heat dissipation, etc. The natural convection heat dissipation method has large thermal resistance and poor heat transfer performance. When the heat density of the device is greater than 0.08W/cm2, this cooling method can no longer meet the actual requirements. Usually have to adopt the way of increasing the size of the heat sink to barely apply. However, the heat dissipation method of adding a fan takes up a lot of space and makes a lot of noise, which often limits its application. The liquid cooling system is complex, and its lifespan is limited by the sealing ring of the water pump. Once the coolant leaks out, the circuit board will be soaked, making it difficult to guarantee reliability. As a high-efficiency heat transfer element, the heat pipe transfers heat quickly. However, due to the large thermal resistance of the fins of the radiator, the heat dissipation capacity cannot keep up with it and it is difficult to achieve good results. The cored heat pipe technology is directly applied to high-power devices. In terms of heat dissipation, there are also disadvantages such as high manufacturing cost, large volume, and difficult processing, which is not conducive to the marketization of products. Semiconductor refrigeration is prone to condensation at the cold end, causing a short circuit on the motherboard, and the cooling efficiency is low and the power consumption is large. Therefore, it is particularly urgent to develop a novel heat sink that can be applied to high-power devices and is moderately priced, small in size, high in efficiency and high in reliability.

At present, the heat dissipation methods that are widely used are: A, the finned radiator shown in Figure 1, mainly extrudes high thermal conductivity materials (such as aluminum profiles or copper) to form fins 4, and then the fins pass through the natural convection of the air Dissipate the heat from the heat source 1, or increase the forced air cooling measures to improve the heat dissipation effect. B, Planar heat pipe radiator as shown in Figure 2. The fins are made of solid metal materials such as copper and aluminum, and are integrated with the hollow planar heat pipe base plate. In the process of the above-mentioned heat sink exporting heat, the contact thermal resistance 2 is relatively large, and the temperature of the heating element is often more than ten degrees Celsius or even tens of degrees Celsius higher than the temperature of the fins. It is hoped that the temperature that the semiconductor PN junction can withstand is not higher than 65°C. It is generally believed internationally that for every 5°C increase above this temperature, the life of the device will be doubled, and the reliability will be significantly reduced. Therefore, people wish to develop a high-efficiency radiator that neither increases the size of the radiator nor increases the weight of the radiator.

Contents of the invention

In order to improve the heat dissipation effect of the radiator on high-power devices, the applicant invented a radiator with empty stomach heat pipes through years of research. The radiator includes a condenser and a heat collector motherboard in contact with the heat source. The condenser is located on the heat extractor motherboard and is directly connected to it. It is characterized in that both the condenser and the motherboard of the heat collector are hollow structures, and the condenser includes a plurality of hollow fins. The motherboard of the heat extractor has two surfaces, one of which is a smooth plane directly in contact with the heat source, and a plurality of blind holes for installing the heat source are arranged on the heat extractor. The other surface is a surface in the shape of a plane or a microgroove, and the plurality of hollow fins and the cavity of the heat collector motherboard are filled with working fluid for phase change heat dissipation.

The plurality of hollow fin cavities are integrated with the cavity of the heat collector motherboard. The motherboard of the heat collector is provided with a plurality of microgrooves compatible with the hollow fins, the hollow fins are accommodated in the accommodation grooves, and the bottom of the side walls of the hollow fins are respectively connected to the side walls of the motherboard accommodation grooves. connected. Wherein the working fluid of the heat dissipation is a phase change material, carbon nanotubes can also be added in the phase change material in order to further improve the heat dissipation effect; the phase change material includes distilled water, methanol, acetone, HFC refrigerant, calcium chloride, nitric acid Calcium, manganese nitrate, sodium sulfate and other working fluids, choose one or a combination of them according to actual requirements. Wherein, the bottom of the heat extractor motherboard includes a plurality of microgrooves formed by machining, profile extrusion, etching, forging and other techniques, or flat or other curved surfaces. The materials of the fins and the motherboard include aluminum, copper and other metal materials with high thermal conductivity or non-metallic materials with high thermal conductivity. The heat sources include high-power LEDs, TECs, IGBTs, IGCTs, and other electronic components of various specifications and models, as well as other chips that need to dissipate heat, such as cpu, gpu, etc. The number and size of the fins are not particularly limited, and can be set according to actual cooling requirements.

The invention also provides a method for manufacturing the empty stomach heat pipe radiator.

The method includes the following steps: the first step: selecting a high thermal conductivity material to make a condenser of multiple hollow fin groups of the radiator and a hollow heat collector motherboard, and connecting the condenser and the heat collector motherboard Form an integral structure by welding or bonding or other methods. And lead out a small pipeline that is convenient for cleaning, vacuuming, and filling working fluid. The condenser and the motherboard can also be integrated by die-casting with a special mold or other methods at one time. Step 2: Clean and passivate the inner wall of the finned condenser and the hollow cavity of the motherboard of the heat collector. Step 3: Vacuum the hollow cavity of the finned condenser and the heat extractor motherboard. Step 4: Fill the hollow cavity of the finned condenser and the motherboard of the heat extractor with working fluid. Step 5: Carry out anodic oxidation, electrophoretic painting or other metal surface protection treatment measures on the outer surface of the radiator. The working fluid can also add a phase change material containing carbon nanotubes.

In the hollow heat pipe radiator of the present invention, without increasing the size and weight of the radiator, the hollow fin condenser and the hollow heat collector motherboard are formed into an integrated structure with interconnected cavities. Micro-grooves are arranged on the bottom of the heater motherboard to further improve the heat dissipation capacity of the gravity-cooled phase-change medium filled in the cavity, thereby improving the heat dissipation efficiency of high-power devices.

Description of drawings

Figure 1: Common radiator;

Figure 2: Planar heat pipe radiator;

Figure 3: Schematic diagram of the basic working principle of the gravity heat pipe;

Figure 4: Gravity heat pipe radiator;

Figure 5: Fasting heat pipe radiator;

Figure 6: Conical fin hollow heat pipe radiator;

Figure 7: Rectangular fin hollow heat pipe radiator;

Figure 8: Circular fin hollow heat pipe radiator;

Figure 9: Curves of the effect of input power on the surface temperature of LEDs assembled with three different heat sinks;

Figure 10: Curves of the influence of ambient temperature on the surface temperature of LEDs assembled with three different heat sinks;

Figure 11: Schematic diagram of the manufacturing method of the fasting heat pipe radiator;

Fig. 12-Fig. 16: Finished pictures of an empty stomach heat pipe radiator.

1: Heat source, 2: Thermal contact resistance, 3: Motherboard, 4: Fin, 5: Working fluid, 6: Storage tank, 3-1: Evaporation section, 3-2: Thermal insulation section, 3-3: Condensation section , 3-4: shell, 3-5: exothermic, 3-6: steam, 3-7: reflux liquid, 3-8: endothermic, 11-1: microgrooves, 11-2: for Vacuum, filled with working fluid pipeline.

specific embodiment

Firstly, the fasting heat pipe radiator of the present invention is introduced in combination with the specification and accompanying drawings. The basic working principle of the radiator is shown in Figure 3, it is a high-efficiency planar gravity heat pipe radiator relying on gravity to return liquid, and the heat transfer direction is irreversible. The working medium of the gravity heat pipe is accumulated at the bottom of the heat pipe shell 3-4, the evaporation section 3-1 is in the lower half of the heat pipe, the condensation section 3-3 is in the upper half of the heat pipe, and the heat insulation section 3-2 is in the middle. The working fluid evaporates after absorbing the heat supplied by the heat source through heat absorption 3-8 in the evaporation section. The steam 3-6 flows upwards, and after passing through the adiabatic section, the latent heat of vaporization is handed over to the cold source to release heat 3-5 in the condensation section, thereby condensing into a liquid. The condensate forms the reflux liquid 3-7 due to the action of gravity, and the reflux liquid 3-7 flows back to the lower half evaporation section to complete a working cycle. With the continuous circulation of the working fluid, the heat from the heat source in the lower half is continuously transferred to the cold source in the upper half.

The applicant has developed a novel heat pipe radiator based on the above principles. In one embodiment, the novel heat pipe radiator is a planar gravity heat pipe radiator as shown in FIG. 4 . The gravity heat pipe radiator includes N hollow fins 4 and a heat collector motherboard 3 in contact with the heat source 1 . Among them, the hollow fins made of high thermal conductivity materials are filled with thermal conductivity working fluids including phase change materials, such as distilled water, methanol, acetone, HFC refrigerants, calcium chloride, calcium nitrate, manganese nitrate, sodium sulfate and other working fluids. one or more of them. In order to further improve the heat dissipation efficiency, carbon nanotubes can be added to the phase change material. In the motherboard 3, there are N accommodation grooves 6 adapted to the hollow fins, the hollow fins are accommodated in the accommodation grooves, the side walls and the bottom of the hollow fins 4 are respectively in contact with the side walls and the bottom of the accommodation grooves, There is a larger heat dissipation contact area. Compared with the ordinary finned radiators shown in Figures 1 and 2, the fasting heat pipe radiator can not only rely on the fins 4 to dissipate heat from the heat source 1 in the process of heat dissipation, but more importantly, the hollow fins The working medium 5 inside the chip undergoes a phase change during the heat dissipation process, so it can take away more heat than the ordinary planar heat pipe radiator that only relies on fins for heat dissipation, with higher temperature and lower heat transfer temperature difference. Therefore, the cooling capacity of the fasting heat pipe radiator is better than that of the ordinary flat heat pipe radiator.

In order to improve the integration of the radiator and the heat source (that is to say, without increasing the size of the radiator) and further improve the heat dissipation capacity of the new heat pipe radiator, the applicant invented the fasting heat pipe radiator, the fasting heat pipe radiator Concentrated micro-groove technology, heat pipe technology, nanotechnology, low thermal resistance technology.

The hollow heat pipe radiator is illustrated in conjunction with accompanying drawings 5 and 11 of the specification. The empty stomach heat pipe radiator includes a heat collector motherboard 3 , a working fluid 5 including a phase change medium material, and condenser fins 4 . The heat taker motherboard 3 has two surfaces, one of which directly contacts the smooth plane of the heat source 1, where the heat source can be a high-power device such as LED, TEC, IGBT, IGCT, or a cpu, gpu chip. The heat extractor motherboard 3 is made of copper, aluminum or other metal materials, and blind holes are provided on the heat extractor to facilitate the installation of heat sources. In order to increase the contact area between the heat extractor motherboard and the working medium, several microgroove groups 11-1 are formed on the other surface of the heat extractor motherboard using microgroove technology. The phase change material depends on the actual temperature requirement of the heat source 1 . The condenser has a hollow fin structure of N groups. The specific geometric shape of the inner surface of the hollow fin 4 is not particularly limited, and can be triangular cone, rectangle, circle or any other suitable shape, as shown in the accompanying drawings 6-8 shown. Wherein accompanying drawing 6 is a tapered fin, accompanying drawing 7 is a rectangular fin, accompanying drawing 8 is a circular fin, and its outer surface is then designed into various shapes of fins. The belly of the fin is hollow, so its thermal resistance is significantly lower than that of ordinary fin-type radiators.

Compared with the planar gravity heat pipe radiator, the hollow heat collector motherboard 3 and the entire hollow condenser fin 4 of the hollow heat pipe radiator are integrally formed to form a whole, and the fins and the cavity of the motherboard are connected together. , as shown in Figure 5. There are also receiving slots 6 for receiving fins 4 in the heat collector motherboard 3 as shown in FIG. 4 . The contact area between the working medium liquid inside the fasting heat pipe radiator and the inner surface of the tube wall is much larger than the contact area between the working medium liquid inside the gravity heat pipe radiator and the inner surface of the tube wall, so the heat that can be taken away is larger than that of the gravity heat pipe radiator There is more heat, the surface temperature is higher, and the heat transfer temperature difference is larger, so the heat dissipation capacity of the fasting heat pipe radiator is stronger than that of the planar gravity heat pipe radiator.

comparative example

In order to illustrate that the fasting heat pipe radiator of the present invention has higher heat dissipation efficiency, the fasting heat pipe radiator in FIG. 5 is now compared with the common radiator and the planar heat pipe radiator in FIGS. 1 and 2 .

Heat sink thermal resistance = contact thermal resistance R ₁ + heat dissipation motherboard thermal resistance R₂ + fin thermal resistance R₃. In general, R ₁ =10% R total, R ₂ =10% R _total , fin thermal resistance = 80% R _total . It can be seen that the thermal resistance of the fins becomes the biggest factor affecting the heat dissipation efficiency of the radiator, and the structure of the fins directly determines the size of its thermal resistance. As can be seen from the above: R _1a = R _1b = R _1c ; R _2a > R _2b > R _2c ; R _3a > R _3b > R _3c ; and the applicant obtained according to a large amount of experimental data analysis: R _3c = R _3b 1/4= R _3a 1/6; Among them: R _1a is the contact thermal resistance of the ordinary heat sink in Figure 1, R _1b is the contact thermal resistance of the common planar heat pipe radiator in Figure 2, and R _1c is the fasting resistance in Figure 5 Contact thermal resistance of the heat pipe radiator; R _2a is the thermal resistance of the common radiator motherboard in Figure 1; R _2b is the thermal resistance of the common planar heat pipe radiator motherboard in Figure 2; R _2c is the empty stomach heat pipe radiator in Figure 5 The thermal resistance of the motherboard; R _3a is the thermal resistance of the common radiator fin in Figure 1; R _3b is the thermal resistance of the common planar heat pipe radiator fin in Figure 2; R _3c is the empty stomach heat pipe radiator fin in Figure 5 thermal resistance.

The applicant applied the radiators in attached drawings 1, 2, and 5 to dissipate heat from high-power LEDs through specific experiments, and installed high-power LED lamps with three radiators shown in attached drawings 1, 2, and 5 respectively. Under the ambient temperature and different input power conditions, the corresponding surface temperature test results are shown in Figure 9-10. It can be seen from Figure 9 that when the ambient temperature is set to 30°C, the temperature of the contact surface between the ordinary heat sink and the high-power LED lamp in Figure 1 is higher under different input powers, and the fasting heat pipe in Figure 5 The temperature of the contact surface between the radiator and the high-power LED lamp is low, while the temperature of the contact surface of the planar heat pipe radiator in Figure 2 is in between; the surface temperature of the LED lamp increases with the increase of the heating power of the LED lamp. However, the surface temperature of LED lamps using different radiators rises to different degrees. The temperature rise of the contact surface of the fasting heat pipe radiator in Figure 5 is small, while the temperature rise of the common radiator in Figure 1 is larger with the contact surface, and the temperature of the contact surface of the flat heat pipe radiator in Figure 4 is between the two; That is, the heat dissipation effect of the fasting heat pipe radiator is better.

It can be seen from Figure 10 that when the input power of the high-power LED lamp is set to 14W, as the ambient temperature increases, the surface temperature of the high-power LED lamp also rises, and the surface temperature increase of the LED lamp with different radiators Basically the same. Under the same ambient temperature, the temperature of the contact surface between the ordinary radiator and the LED lamp in Fig. 1 is higher, the temperature of the contact surface of the fasting heat pipe radiator and the LED lamp in Fig. 5 is lower, and the plane in Fig. 4 Heat pipe radiators are somewhere in between. Therefore, the fasting heat pipe radiator can make high-power LED work at a lower temperature, and has better adaptability to changes in ambient temperature.

The manufacturing method of the fasting heat pipe radiator of the present invention will now be described in detail in conjunction with accompanying drawing 11 of the specification. First, select materials with high thermal conductivity such as aluminum or copper to process the hollow fin condenser and the hollow heat collector motherboard of the radiator, and then weld or bond the condenser and the heat collector motherboard with other methods. The method is to form an integrated structure, and lead out a pipeline 11-2 that is convenient for cleaning, vacuuming, and filling the working fluid. It is also possible to use special mold die-casting or similar methods to make the condenser fins and the motherboard into one at one time; especially It should be noted that, in order to further improve the heat dissipation capacity, it is better to use microgroove technology to arrange a plurality of microgroove groups 11-1 on the heat collector motherboard, and the number or size of the fins in the fin condenser can be adjusted according to the actual situation. The need depends on the size of the space, and then use high-pressure liquid to clean the hollow cavity of the finned condenser and the motherboard of the heat extractor, and passivate it, then evacuate it, and then inject an appropriate amount of working fluid, preferably mixed with A certain amount of carbon nanotube material to improve heat dissipation. Finally, the outer surface of the radiator is anodized, electrophoretic painted or other protective measures are taken to produce the finished product of the fasting heat pipe radiator of the present invention as shown in Figures 12-16.

The manufacturing process of the fasting heat pipe radiator of the present invention is more complicated than that of conventional planar heat pipe radiators, but it greatly reduces the fin thermal resistance of existing radiators; its heat dissipation capacity is 40%-95% higher than that of ordinary planar heat pipe radiators of the same size ; Within the limit heat flux density, it has unparalleled heat dissipation performance in the industry, and has better adaptability to changes in ambient temperature. It can be expected from the above conclusions that the novel hollow heat pipe radiator will be widely used with high cost performance, stable and efficient heat transfer performance.

Claims (10)

1. a heat-pipe radiator on an empty stomach, comprise condenser and the heat collector motherboard contacted with thermal source, described condenser is positioned on the heat collector motherboard and directly connects with it, it is characterized in that: described condenser and heat collector motherboard are hollow structure, and described condenser comprises the fin of a plurality of hollows, described heat collector motherboard has two surfaces, the smooth flat in one of them surperficial direct contact heat source, and on heat collector, be provided with for a plurality of blind holes of thermal source are installed, be filled with the working medium for phase-change heat in the heat collector motherboard of the fin of the plurality of hollow and hollow.

2. radiator as claimed in claim 1, is characterized in that: the mutual UNICOM of cavity of the fin cavity of the plurality of hollow and the heat collector motherboard of hollow, the overall structure that wherein this fin and heat collector motherboard are formed in one and form.

3. radiator as claimed in claim 1, it is characterized in that: be provided with a plurality of holding tanks that adapt with hollow fin in described heat collector motherboard, hollow fin is incorporated in this holding tank, and the sidewall of hollow fin contacts with bottom with the sidewall of this motherboard holding tank respectively with bottom.

4. described radiator as arbitrary as claim 1-3, it is characterized in that: the working medium of wherein said heat radiation comprises phase-change material.

5. radiator as claimed in claim 4, it is characterized in that: the working medium of described heat radiation also comprises CNT (carbon nano-tube).

6. radiator as claimed in claim 4, it is characterized in that: described phase-change material comprises any one in distilled water, methyl alcohol, acetone, HFC cold-producing medium, calcium chloride, calcium nitrate, sodium sulphate and manganese nitrate.

7. radiator as claimed in claim 2 is characterized in that: wherein said heat collector motherboard bottom comprises having a plurality of microflutes that utilize the microflute technology to form, or the curved surface of plane or other shapes.

8. radiator as claimed in claim 4, it is characterized in that: the material of described fin and motherboard comprises aluminium, copper and other thermal conductive metallic materials and heat conduction nonmetallic materials, described thermal source comprises high-power LED, TEC, IGBT, IGCT, and all heating elements that need heat radiation in addition, heat radiation need to limit according to reality for described fin number and size.

9. manufacture the method for heat-pipe radiator on an empty stomach for one kind, it is characterized in that: said method comprising the steps of:

The first step: select high thermal conductivity materials to form a plurality of hollow fin condensers of radiator and the heat collector motherboard of hollow, by condenser and the heat collector structure that forms as one, and draw one and be convenient to cleaning, vacuumize the pipeline of tank working medium;

Second step: the cavity to fin condenser inwall and heat collector motherboard hollow is cleaned, and it is carried out to passivation;

The 3rd step: the cavity of fin condenser and heat collector motherboard hollow is evacuated;

The 4th step: fill with working medium in the cavity of fin condenser and heat collector motherboard hollow;

The 5th step: the radiator outer surface is carried out to anodic oxidation or electrophoretic coating processing.

10. the method for heat-pipe radiator on an empty stomach of manufacturing as claimed in claim 9, it is characterized in that: the heat collector motherboard cavity of the plurality of hollow fin cavity and hollow is interconnected, this fin and motherboard are structure as a whole, the form as one technique of structure of described condenser and heat collector template comprises welding, bonding, or utilizes extraordinary die casting to become one structure.

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