A flat pulsating heat pipe and processing method

Abstract

The present invention provides a flat-plate pulsating heat pipe and a processing method thereof, belonging to the technical field of pulsating heat pipes, comprising a plate body and a pulsating heat pipe flow channel opened inside the plate body, the pulsating heat pipe flow channel being filled with a working medium, the pulsating heat pipe flow channel comprising a plurality of flow enhancing flow channels and flow weakening flow channels, the flow enhancing flow channels and the flow weakening flow channels being arranged alternately, a branch flow channel being provided between adjacent flow enhancing flow channels and flow weakening flow channels, one end of the branch flow channel being connected to the insulating section of the flow enhancing flow channel, and the other end of the branch flow channel being connected to the evaporating section of the flow weakening flow channel, by providing the branch flow channel, bubbles in the evaporating section of the flow weakening flow channel are divided, so that the difference between the flow pressure in the flow enhancing flow channel and the flow pressure in the flow weakening flow channel increases faster, thereby realizing the directional distribution of the working medium flow pressure, breaking the pressure equilibrium state faster, and starting the circulating flow of the working medium in the flat-plate pulsating heat pipe faster, and dissipating the heat more timely.

Description

Technical Field

[0001] The present invention relates to the technical field of pulsating heat pipes, and in particular to a flat plate pulsating heat pipe and a processing method thereof. Background Art

[0002] Heat pipes have a high heat transfer capacity due to their working mechanism of absorbing and releasing latent heat through phase change of the working fluid within them. Flat-plate pulsating heat pipes, among others, do not require a wick structure, making them easy to process and low-cost. Furthermore, the pulsating heat pipe's "gas-liquid plug oscillation" mode facilitates rapid heat transfer between the hot and cold ends. When a certain pressure difference forms between the different tube bundles of a pulsating heat pipe, the original equilibrium state of the working fluid is disrupted, resulting in a periodic circulating flow. The flow conditions within a pulsating heat pipe are directly related to its heat transfer performance: the smoother the working fluid flows within the pulsating heat pipe, the better its heat transfer performance. However, when traditional pulsating heat pipes are in operation, significant gas-liquid conflict occurs between the working fluids in the different tube bundles. This conflict only causes small oscillations in the working fluid. During these small oscillations, the pulsating pressure generated in the evaporation section is significantly dissipated, resulting in a high overall flow resistance and difficulty in circulating the working fluid, leading to poor heat dissipation.

[0003] Chinese patent CN202120357934.6 discloses a battery thermal management system based on a combination of a flat-plate pulsating heat pipe and a liquid cooling system, wherein the liquid cooling system contains a flat-plate pulsating heat pipe, and the flat-plate pulsating heat pipe has a working fluid filling port and one or more stamped rectangular loop channels, the working fluid filling port is connected to the loop channel, and the working fluid filling port is sealed by welding after filling with the working fluid; the flat-plate pulsating heat pipe used in this patent is rectangular as a whole, with a serpentine shape between the pipes, and a condensation section and an evaporation section. This structure has the same problem as the traditional pulsating heat pipe. The working fluid forms bubbles after being heated, but the serpentine pipes are directly connected between the pipes, and there is an obvious gas-liquid conflict problem. The flow pressure is relatively balanced everywhere, and it is difficult to quickly form a pressure difference, breaking the original equilibrium state, resulting in slow startup of the pulsating heat pipe and poor flow effect, affecting the heat dissipation effect of the entire thermal management system.

[0004] Flat-plate pulsating heat pipes have a wide range of applications. In addition to the battery field mentioned above, there is also the electronic chip field. With the miniaturization and integration of electronic chips, the heat flux density of chips is increasing exponentially. Traditional natural cooling and forced air cooling thermal management solutions can no longer meet the growing heat dissipation needs of electronic chips due to low heat transfer limits and large space requirements. For this reason, traditional chip thermal management solutions are prone to problems such as untimely heat dissipation of electronic chips, high operating temperatures, and local hot spots, which seriously endanger the working life of electronic devices. Therefore, based on the application background of electronic chip heat dissipation, when flat-plate pulsating heat pipes are used in electronic chip thermal management, if the flow of pulsating heat pipes can be improved through some technical means to improve their heat transfer performance, then their low cost advantage can be fully utilized without affecting the chip's heat dissipation capacity.

[0005] In summary, the pulsating heat pipe of the prior art has a slow one-way circulation and a poor working fluid flow effect, resulting in insufficient heat exchange capacity. Summary of the Invention

[0006] In order to overcome the above technical problems, the present invention provides a flat pulsating heat pipe to solve the problem that the existing technology takes a long time to circulate, resulting in poor heat exchange effect and failure to dissipate heat to the items that need heat in time.

[0007] To solve the above technical problems, the technical solution of the present invention is as follows: a flat plate pulsating heat pipe, comprising a plate body and a pulsating heat pipe flow channel opened inside the plate body, wherein the pulsating heat pipe flow channel is filled with a working medium, and the pulsating heat pipe flow channel comprises a plurality of flow enhancement flow channels and flow weakening flow channels, wherein the flow enhancement flow channels and the flow weakening flow channels are arranged alternately.

[0008] The flow enhancement channel includes a flow enhancement channel condensation section, a flow enhancement channel insulation section and a flow enhancement channel evaporation section; the flow weakening channel includes a flow weakening channel condensation section, a flow weakening channel insulation section and a flow weakening channel evaporation section; the flow enhancement channel condensation section and the flow weakening channel condensation section are connected through a condensation end connecting channel; the flow enhancement channel evaporation section and the flow weakening channel evaporation section are connected through an evaporation end connecting channel;

[0009] A branch channel is provided between adjacent flow enhancement channels and flow weakening channels, one end of the branch channel is connected to the adiabatic section of the flow enhancement channel, and the other end of the branch channel is connected to the evaporation section of the flow weakening channel.

[0010] Preferably, the angle between the branch flow channel and the flow enhancement flow channel or the flow weakening flow channel is 30 degrees.

[0011] Preferably, the plate body includes a flow channel substrate and a sealing plate, the pulsating heat pipe flow channel is opened on the flow channel substrate, and the sealing plate is sealed and connected to the flow channel substrate.

[0012] Preferably, the width and depth of the flow enhancing channel and the flow weakening channel are equal.

[0013] Preferably, the width of the flow enhancement channel, the flow weakening channel, and the branch channel is 1-3 mm.

[0014] Preferably, the lengths of the flow weakening flow channel condensation section, the flow weakening flow channel insulation section and the flow weakening flow channel evaporation section are equal, and the lengths of the flow enhancing flow channel condensation section, the flow enhancing flow channel insulation section and the flow enhancing flow channel evaporation section are equal.

[0015] Preferably, the plate is made of copper, and the working medium is a self-wetting fluid.

[0016] Preferably, the self-wetting fluid is a n-heptanol aqueous solution with a mass concentration of 0.1%, the surface tension effect of which can reduce the flow resistance, and the self-wetting effect of which can increase the dry-out limit.

[0017] Preferably, the filling rate of the working fluid is 40%-70%.

[0018] Preferably, the thickness of the flow channel substrate is less than 3 mm.

[0019] Preferably, the distance between the flow enhancing channel and the flow weakening channel is 10-15 mm.

[0020] Preferably, four flow-enhancing flow channels are provided, three flow-weakening flow channels are provided, and six branch flow channels are provided.

[0021] Preferably, a bifurcation is formed at the connection point between the evaporation section of the flow weakening flow channel and the branch flow channel, and the width of the evaporation section of the flow weakening flow channel at the bifurcation is smaller than the width of the branch flow channel at the bifurcation.

[0022] Preferably, the evaporation section of the flow weakening flow channel is provided with a narrow section located at the bifurcation, and the width of the narrow section gradually decreases along the direction from the condensation section of the flow weakening flow channel to the evaporation section of the flow weakening flow channel, and the branch flow channel is provided with a wide section located at the bifurcation, and the width of the wide section gradually increases in the direction close to the narrow section.

[0023] A method for processing a flat plate pulsating heat pipe, comprising the following steps:

[0024] Step 1: groove the flow channel substrate to form a pulsating heat pipe flow channel, and open a liquid injection channel connected to the outside at one end of the pulsating heat pipe flow channel;

[0025] Step 2: Sealing the sealing plate and the flow channel substrate to form a plate body, which is used to enclose the pulsating heat pipe flow channel in the plate body;

[0026] Step 3: vacuuming the pulsating heat pipe flow channel through the liquid injection channel connected to the pulsating heat pipe flow channel, and then filling the working fluid after the vacuuming is completed;

[0027] Step 4: After filling is completed, seal the injection channel;

[0028] Step 5: Perform air tightness test on the flat plate pulsating heat pipe. If the air tightness meets the requirements, the processing is completed.

[0029] Preferably, in the step 2, solder paste is filled between the sealing plate and the flow channel substrate, and the solder paste is located outside the pulsating heat pipe flow channel.

[0030] Preferably, in the step 1, the grooves on the flow channel substrate are formed by milling the grooves.

[0031] An electronic chip thermal management device includes the aforementioned flat plate pulsating heat pipe, wherein one end of the plate body close to the evaporation end connecting flow channel is in close contact with the electronic chip, and one end of the plate body close to the condensation end connecting flow channel is provided with a heat dissipation device.

[0032] Preferably, the heat dissipation device is a fan or heat dissipation fins.

[0033] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0034] 1. By setting up branch flow channels, the bubbles in the evaporation section of the flow weakening flow channel are divided, so that the flow pressure difference between the flow enhancement flow channel and the flow weakening flow channel increases faster, achieving directional distribution of the working fluid flow pressure, breaking the pressure equilibrium state more quickly, and making the working fluid circulation flow in the flat pulsating heat pipe start faster and dissipate heat more timely; it also increases the flow frequency and improves the heat exchange effect.

[0035] 2. The bifurcation weakens the width of the evaporation section and the branch channel by changing part of the flow, so that more bubbles are divided into the branch channel and then enter the flow enhancement channel, achieving a faster break of the pressure balance state and a faster unidirectional circulation flow of the working fluid.

[0036] 3. The flat-plate pulsating heat pipe of the present application has a fast heat dissipation startup and a small overall size, can be better used for heat dissipation of electronic chips, has a low processing cost, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the flat-plate pulsating heat pipe structure of the present invention;

[0038] Figure 2 This is a schematic diagram of the internal pulsating heat pipe flow path structure of the flat-plate pulsating heat pipe of the present invention;

[0039] Figure 3This is a schematic diagram of the main structure of the pulsating heat pipe flow path inside the flat-plate pulsating heat pipe of the present invention;

[0040] Figure 4 for Figure 3 Enlarged view of point B in the middle;

[0041] Figure 5 Schematic diagram of bubble distribution at the bifurcation;

[0042] Figure 6 Schematic diagram of working medium flow during stagnation period;

[0043] Figure 7 It is a schematic diagram of the working medium flow direction during the circulation period;

[0044] Figure 8 This is a schematic diagram of the internal pulsating heat pipe flow channel grooves of the flat pulsating heat pipe in the processing state of the present invention;

[0045] Figure 9 for Figure 8 Enlarged view of point A in the middle;

[0046] Figure 10 Schematic diagram of the electronic chip thermal management device and electronic chip assembly structure of the present invention;

[0047] Among them: 1. Plate body; 2. Pulsating heat pipe flow channel; 3. Flow enhancement flow channel; 4. Flow weakening flow channel; 5. Condensation end connecting flow channel; 6. Evaporation end connecting flow channel; 7. Branch flow channel; 8. Fork mouth; 9. Narrow mouth section; 10. Wide mouth section; 11. Liquid injection channel; 12. Heat dissipation device; 100. Electronic chip; 101. Flow channel substrate; 102. Sealing plate; 301. Flow enhancement flow channel condensation section; 302. Flow enhancement flow channel insulation section; 303. Flow enhancement flow channel evaporation section; 401. Flow weakening flow channel condensation section; 402. Flow weakening flow channel insulation section; 403. Flow weakening flow channel evaporation section. DETAILED DESCRIPTION

[0048] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the present embodiment, some components of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of the actual product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the accompanying drawings. In the description of the present invention, it should be understood that the terms "left side," "right side," "upper," "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. "First," "second," etc., do not indicate the importance of components and are therefore not to be construed as limiting the present invention. In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," "fixed," etc. should be understood broadly. For example, they can mean fixed connection, detachable connection, or integration; they can mean mechanical connection, electrical connection, or communication with each other; they can mean direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components, unless otherwise expressly limited. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of the present invention.

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0050] First, let's explain the operating principle of an ordinary pulsating heat pipe: When an ordinary pulsating heat pipe works, due to the small diameter of the pipe, the working fluid forms a randomly spaced gas-liquid plug after being filled in; when the working fluid in the evaporation section is heated, new small bubbles are generated on the surface of the evaporation section due to vaporization nucleation, and merge with the original gas plug to increase the volume of the gas plug. At this time, the overall pressure of the working fluid in the evaporation section increases and is greater than the pressure in the condensation section. However, despite the pressure difference between the hot and cold ends, the working fluid in the evaporation section cannot move to the condensation section at the same time, and the working fluid needs to flow back in the condensation section to form flow. The channels of an ordinary pulsating heat pipe are simple parallel channels. The evaporation sections of adjacent channels all generate upward flow pressure. A slight upward movement of the working fluid will cause a conflict in the flow direction, and there will be a small oscillation for a period of time. The heat transfer effect of small oscillations is generally poor. Only after a period of heating or when the power is further increased, the accumulated heat between the channels causes the temperature difference between the hot and cold ends to become larger, and the occasional pressure imbalance between adjacent channels increases, triggering a unidirectional circulation flow. In other words, one channel between adjacent channels overcomes the other. It can be understood that when the heating power is low or the time is short, there is a small oscillation between adjacent channels, with one channel increasing while the other decreases. The more accumulated heat is, the more conducive it is to breaking this balance, which means that the high-temperature gas-liquid plug at the bottom flows to the top, and the low-temperature gas-liquid plug at the top flows to the bottom. Therefore, only then can there be a significant heat transfer effect. The heat accumulation stage before the unidirectional circulation is defined as the stagnation period. At this time, there is no flow and very little heat exchange. To be more precise, there is also a small oscillation period. At this time, the working fluid between adjacent channels oscillates slightly up and down, with one increasing while the other decreases. There is a certain heat transfer effect, but it is not significant. When sufficient heat is accumulated, a unidirectional circulation flow occurs, and the heat transfer effect is obvious. However, due to the successful heat transfer of the working fluid, the imbalance of internal pressure is reduced, and it will return to the stagnation stage. So the cycle is stagnation-small oscillation-one-way cycle-stagnation-small oscillation-one-way cycle.

[0051] Example 1:

[0052] like Figure 1-7 As shown, a flat plate pulsating heat pipe includes a plate body 1 and a pulsating heat pipe flow channel 2 opened inside the plate body 1. The pulsating heat pipe flow channel 2 is filled with a working medium. The pulsating heat pipe flow channel 2 includes a plurality of flow enhancement flow channels 3 and flow weakening flow channels 4. The flow enhancement flow channels 3 and the flow weakening flow channels 4 are arranged alternately.

[0053] The flow enhancement channel 3 includes a flow enhancement channel condensation section 301, a flow enhancement channel insulation section 302, and a flow enhancement channel evaporation section 303. The flow weakening channel 4 includes a flow weakening channel condensation section 401, a flow weakening channel insulation section 402, and a flow weakening channel evaporation section 403. The flow enhancement channel condensation section 301 and the flow weakening channel condensation section 401 are connected through a condensation end connecting channel 5. The flow enhancement channel evaporation section 303 and the flow weakening channel evaporation section 403 are connected through an evaporation end connecting channel 6.

[0054] A branch channel 7 is provided between the adjacent flow enhancement channel 3 and flow weakening channel 4 , one end of the branch channel 7 is connected to the flow enhancement channel insulation section 302 , and the other end of the branch channel 7 is connected to the flow weakening channel evaporation section 403 .

[0055] In combination with the operating principle of the aforementioned ordinary pulsating heat pipe, the flat plate pulsating heat pipe of this embodiment is explained. The flat plate pulsating heat pipe of the present application includes a plate body 1 and a pulsating heat pipe flow channel 2 arranged inside. The material of the plate body 1 has excellent thermal conductivity, and those skilled in the art can choose a well-known material. The working fluid inside the pulsating heat pipe flow channel 2 is similar, wherein the flow enhancement flow channel 3 and the flow weakening flow channel 4 are alternately distributed, that is, a plurality of flow enhancement flow channels 3 are arranged, and a flow weakening flow channel 4 is arranged between adjacent flow enhancement flow channels 3, that is, a one-by-one arrangement is made, so that adjacent flow enhancement flow channels 3 and flow weakening flow channels 4 form a cycle, and a plurality of groups of alternately arranged flow enhancement flow channels 3 and flow weakening flow channels 4 form multiple cycles. The flow enhancement flow channels 3 and the flow weakening flow channels 4 both include the basic structure of the pulsating heat pipe, that is, they are interconnected. The condensation section, insulation section and evaporation section, the ends of the condensation section away from the insulation section are connected through the condensation end connecting channel 5, and the ends of the evaporation section away from the insulation section are connected through the evaporation end connecting channel 6, so that the flow enhancement channel 3 and the flow weakening channel 4 are connected, the working fluid absorbs heat in the evaporation section, passes through the insulation section and enters the condensation section to dissipate heat, and then returns to the evaporation section to absorb heat again, repeating the above process, absorbing heat from external objects for heat dissipation. The characteristic of this flat-plate pulsating heat pipe is that a branch channel 7 is provided, and its two ends are respectively connected to the flow weakening channel insulation section 302 and the flow weakening channel evaporation section 403, that is, an inclined channel is formed to connect the adjacent flow enhancement channel 3 and flow weakening channel 4, and the two adjacent branch channels 7 form a V-shaped structure or an inverted V-shaped structure, which distributes the evaporation pressure of the flow weakening channel 4 to the flow enhancement channel 3.

[0056] The specific operation process is as follows:

[0057] refer to Figure 5-6, first is the stagnation period, at this time the circulation flow has not yet been formed, when the working medium in the flow enhancement flow channel evaporation section 303, the flow weakening flow channel evaporation section 403 and the evaporation end connecting flow channel 6 begins to absorb external heat, the working medium evaporates after absorbing heat, and bubbles are generated and flow in the direction of the flow enhancement flow channel insulation section 302 and the flow weakening flow channel insulation section 402 respectively. At this time, the bubbles in the flow enhancement flow channel evaporation section 303 pass through the flow enhancement flow channel insulation section 302 and enter the flow enhancement flow channel evaporation section 303. At this time, the flow pressure of the working medium increases, and the working medium is easy to flow upward; the bubbles in the flow weakening flow channel evaporation section 403 first pass through the connection between the branch flow channel 7 and the flow weakening flow channel evaporation section 403, and the bubbles will be divided, part of which enters the branch flow channel 7 and then enters the flow weakening flow channel insulation section 302 of the adjacent flow enhancement flow channel 3, and part continues to enter the flow weakening flow channel evaporation section 4 03 flows toward the flow weakening flow channel insulation section 302 and enters the flow weakening flow channel condensation section 401. At this time, in addition to the flow pressure generated by the flow enhancing flow channel evaporation section 303 in the flow enhancing flow channel itself, which makes the working medium flow upward, the bubbles supplemented by the branch flow channel 7 enter the flow enhancing flow channel insulation section 302, so that the flow pressure of the flow enhancing flow channel 3 is enhanced, and the working medium flows upward faster. For the flow weakening flow channel 4, the flow pressure inside it is relatively weakened. Therefore, the flow pressure inside the entire pulsating heat pipe flow channel 2 presents a state of alternating distribution of flow pressure "strong-weak" with the alternating arrangement of the flow enhancing flow channel 3 and the flow weakening flow channel 4, which is more conducive to breaking the pressure balance state in the pulsating heat pipe flow channel 2, faster getting out of the stagnation period, entering the circulating flow period, making the flat-plate pulsating heat pipe start faster, and at the same time, the flow frequency increases and the heat exchange effect is better.

[0058] refer to Figure 7 After the branch channel 7 continues to distribute the flow pressure, the gradually increasing pressure imbalance between the flow enhancement channel 3 and the flow weakening channel 4 triggers a one-way circulation. The specific flow direction of the working medium is: the working medium in the flow enhancement channel 3 flows from the flow enhancement channel evaporation section 303 to the flow enhancement channel condensation section 301, and at the same time, the working medium in the flow weakening channel 4 flows from the flow weakening channel condensation section 401 to the flow weakening channel evaporation section 403. Since it is an overall circulating flow, the flow rates of the flow enhancement channel 3 and the flow weakening channel 4 are close at this time, while the movement direction of the bubbles in the branch channel 7 is relatively uncertain at this time, because the flow at the bifurcation where the two ends of the branch channel 7 are connected is at a higher speed, and the instantaneous pressure at both ends of the branch channel 7 is reduced, making the direction of the working medium movement uncertain.

[0059] Since the unidirectional circulation flow is triggered, the low-temperature working medium in the condensation section 401 of the flow weakening flow channel flows to the evaporation section 403 of the flow weakening flow channel, reducing the superheat of the working medium there, slowing down the bubble generation speed, and alleviating the conflict with the flow direction of the working medium in the flow weakening flow channel 4 at this time. Through the circulation flow of the flow-enhancing channel evaporation section 303 - the flow-enhancing channel adiabatic section 302 - the flow-enhancing channel condensation section 301 - the condensation end connecting channel 5 - the flow-weakening channel condensation section 401 - the flow-weakening channel adiabatic section 402 - the flow-weakening channel evaporation section 403 - the evaporation end connecting channel 6 - the flow-enhancing channel evaporation section 303, the evaporation section is cooled, the condensation section obtains heat, and the heat exchange is completed. The pressure difference between the hot and cold ends decreases, and the flow enters the stagnation period again. The working fluid in the flow-enhancing channel evaporation section 303, the flow-weakening channel evaporation section 403, and the evaporation end connecting channel 6 begins to absorb external heat to cool the object, and then enters the circulation flow period again for working fluid heat exchange. The condensation section dissipates heat, and the above cycle is repeated. The branch channel 7 is provided to distribute the driving force of the working fluid flow, better promote one-way circulation, strengthen the flow of the working fluid, enter the circulation flow period faster, and improve the heat transfer effect.

[0060] In a further embodiment, the plate body 1 includes a flow channel substrate 101 and a sealing plate 102, the pulsating heat pipe flow channel 2 is opened on the flow channel substrate 101, and the sealing plate 102 is sealed and connected to the flow channel substrate 101. By setting the flow channel substrate 101 and the sealing plate 102, one is used to groove to form the pulsating heat pipe flow channel 2, and the other is used to seal the pulsating heat pipe flow channel 2, which is convenient for production and processing.

[0061] In a further embodiment, the width and depth of the flow enhancement channel 3 and the flow weakening channel 4 are equal, and the width and depth are the same, so that the conditions of adjacent flow enhancement channels 3 and flow weakening channels 4 are basically the same, which makes it easier for the channel pressure to tend to an unbalanced state.

[0062] In a further embodiment, the width of the flow enhancement channel 3, the flow weakening channel 4, and the branch channel 7 is 1-3 mm. Too small a channel width will increase the channel resistance. 1-3 mm is suitable for general working fluids and has a wider range of applications.

[0063] In a further embodiment, the lengths of the flow weakening flow channel condensation section 401, the flow weakening flow channel insulation section 402 and the flow weakening flow channel evaporation section 403 are equal, and the lengths of the flow enhancing flow channel condensation section 301, the flow enhancing flow channel insulation section 302 and the flow enhancing flow channel evaporation section 303 are equal.

[0064] In a further embodiment, the plate 1 is made of copper, which has excellent thermal conductivity and facilitates heat exchange with other objects. The working fluid is a self-wetting fluid, which has the advantage of low flow resistance when running in a pulsating heat pipe.

[0065] In a further embodiment, the filling rate of the working fluid is 40%-70%.

[0066] In a further embodiment, the thickness of the flow channel substrate 101 is less than 3 mm, which reduces the overall volume and can adapt to narrow spaces for heat transfer.

[0067] In a further embodiment, the spacing between the flow enhancement channel 3 and the flow weakening channel 4 is 10-15 mm, so as to ensure that the branch channel 7 has sufficient lateral distance to distribute the channel driving force.

[0068] In a further embodiment, there are 4 flow enhancement channels 3, 3 flow weakening channels 4, and 6 branch channels 7. A sufficient number of channels are set to better start the cycle. The specific number can be set according to the contact area of ​​the object to be dissipated heat.

[0069] Example 2:

[0070] refer to Figure 1-7 The flow weakening channel evaporation section 403 is connected to the branch channel 7 to form a bifurcation 8, and the width of the flow weakening channel evaporation section 403 at the bifurcation 8 is smaller than the width of the branch channel 7 at the bifurcation 8.

[0071] like Figure 1-7 As shown, the function of the branch flow channel 7 is to divide the bubbles generated by the evaporation section 403 of the flow weakening flow channel, thereby adjusting the flow pressure inside the flow enhancing flow channel 3 and the flow weakening flow channel 4, and distributing the flow pressure, that is, achieving the directional distribution of the driving force of the working medium flow.

[0072] The connection point between the flow weakening channel evaporation section 403 and the branch channel 7 is a bifurcation 8. When the bubbles generated by the flow weakening channel evaporation section 403 flow to the bifurcation 8, if the width of the end of the branch channel 7 that crosses and connects with the flow weakening channel evaporation section 403 is equal to the width of the flow weakening channel evaporation section 403, the bubbles tend to be evenly distributed to the three channels. When the opening width of the end of the branch channel 7 is made larger, the width of the flow weakening channel evaporation section 403 is smaller, and the widths of the flow weakening channel 4 and the branch channel 7 outside the position of the bifurcation 8 remain unchanged, at this time, when the bubbles flow to the bifurcation 8, more bubbles tend to flow into the branch channel 7, and then flow into the flow enhancing channel 3, so as to better realize the directional distribution of the working medium flow driving force, so that the flow pressure between the flow enhancing channel 3 and the flow weakening channel 4 can achieve an unbalanced state faster, thereby entering the circulation flow faster.

[0073] In a further embodiment, the flow weakening flow channel evaporation section 403 is provided with a narrow mouth section 9 located at the fork 8, and the width of the narrow mouth section 9 gradually decreases along the direction from the flow weakening flow channel condensation section 401 to the flow weakening flow channel evaporation section 403, and the branch flow channel 7 is provided with a wide mouth section 10 located at the fork 8, and the width of the wide mouth section 10 gradually increases in the direction close to the narrow mouth section 8. When the bubbles flow toward the fork 8, the inlet width of the narrow mouth section 9 of the flow weakening flow channel evaporation section 403 suddenly becomes smaller, and the part of the bubbles entering the flow weakening flow channel evaporation section 403 is smaller. Since the width of the wide mouth section 10 at the inlet is large, more parts are divided and flow to the branch flow channel 7 to enter the flow enhancement flow channel insulation section 302, thereby more stably achieving the distribution of bubbles, and accelerating the progress of the flow pressure imbalance in the flow channel.

[0074] Example 3:

[0075] refer to Figure 1-9 A method for processing a flat plate pulsating heat pipe, comprising the following steps:

[0076] Step 1: groove the channel substrate 101 to form a pulsating heat pipe channel 2, and open a liquid injection channel 11 connected to the outside at one end of the pulsating heat pipe channel 2, groove the flow enhancement channel 3 and the flow weakening channel 4, the condensation end connecting channel 5, the evaporation end connecting channel 6, and the branch channel 7, and open a liquid injection channel 11 at the condensation end connecting channel 5 or the evaporation end connecting channel 6, and connect the outside with the condensation end connecting channel 5 or the evaporation end connecting channel 6 through the liquid injection channel 11, and then connect the pulsating heat pipe channel 2.

[0077] Step 2: Sealingly connecting the sealing plate 102 and the flow channel substrate 101 to form a plate body 1, which is used to enclose the pulsating heat pipe flow channel 2 in the plate body 1;

[0078] Step 3: Evacuate the pulsating heat pipe channel 2 through the liquid injection channel 11 connected to the pulsating heat pipe channel 2. After the vacuuming is completed, fill the channel with the working fluid. Technical means well known to those skilled in the art will not be described in detail. The process can be carried out according to the vacuum degree and the liquid filling rate.

[0079] Step 4: After the filling is completed, the liquid injection channel 11 is blocked; the blocking can seal the pulsating heat pipe flow channel 2. A blocking agent can be used for permanent blocking, or a detachable blocking member can be used to achieve a sealing effect. Those skilled in the art can choose existing technology to process it.

[0080] Step 5: Test the flat plate pulsating heat pipe for airtightness. If it meets the requirements, the process is complete. You can place it directly in water to observe whether there are bubbles, or you can use an instrument to test it.

[0081] In a further embodiment, in step 2, solder paste is filled between the sealing plate 102 and the flow channel substrate 101, and the solder paste is located outside the pulsating heat pipe flow channel 2.

[0082] In a further embodiment, in step 1, the grooves on the flow channel substrate 101 are formed by milling the grooves.

[0083] In a further embodiment, the grooves may be formed without using surface treatment technology, thus saving costs.

[0084] Example 4:

[0085] This embodiment processes and produces a certain specification of flat plate pulsating heat pipe.

[0086] Step 1: groove the copper channel substrate 101 with a thickness of 2.5mm, a width of 100mm and a length of 158mm to form a pulsating heat pipe channel 2, wherein the groove depth of the pulsating heat pipe channel 2 is 2mm, the width of the flow enhancement channel 3, the flow weakening channel 4, the condensation end connecting channel 5, and the evaporation end connecting channel 6 are all 2mm, the width of the branch channel 7 is 1.5mm, the flow enhancement channel 3 is opened with 4 channels, the flow weakening channel 4 is opened with 3 channels, the flow enhancement channel 3 and the flow weakening channel 4 are arranged alternately, the condensation end connecting channel 5, the evaporation end connecting channel 6, the flow enhancement channel 3 at both ends are all 4mm away from the edge of the channel substrate 101, and the flow enhancement channel 3 is 1.5mm wide. The distance between the flow channel 3 and the flow weakening flow channel 4 is 13 mm. The lengths of the flow enhancing flow channel condensation section 301, the flow enhancing flow channel insulation section 302, the flow enhancing flow channel evaporation section 303, the flow weakening flow channel condensation section 401, the flow weakening flow channel insulation section 402, and the flow weakening flow channel evaporation section 403 are all equal. The flow enhancing flow channel insulation section 302 is connected to the branch flow channel 7 at a position 60 mm away from the evaporation end connecting flow channel 6. The flow weakening flow channel evaporation section 403 is connected to the other end of the branch flow channel 7 at a position 15 mm away from the evaporation end connecting flow channel 6. An injection channel 11 connected to the outside is opened at one end of the pulsating heat pipe flow channel 2. The diameter of the injection channel 11 is 1.5 mm.

[0087] Step 2: Seal and press the sealing plate 102 (0.5 mm thick, same length and width dimensions, and same material) with the flow channel substrate 101 to form a plate body 1 with a thickness of 3 mm, a width of 100 mm, and a length of 150 mm, which is used to enclose the pulsating heat pipe flow channel 2 within the plate body 1;

[0088] Step 3: Vacuum the pulsating heat pipe flow channel 2 through the liquid injection channel 11 connected to the pulsating heat pipe flow channel 2, and then fill it with self-wetting fluid with a filling rate of 60%;

[0089] Step 4: After filling is completed, solder paste is used to seal the liquid injection channel 11;

[0090] Step 5: Perform air tightness test on the flat plate pulsating heat pipe. If the air tightness meets the requirements, the processing is completed.

[0091] Example 5:

[0092] refer to Figure 10 A heat management device for electronic chips includes the flat pulsating heat pipe of the aforementioned embodiment. The end of the plate 1, near the evaporation-end connecting channel 6, is in close contact with the electronic chip. A heat sink 12 is provided at the end of the plate 1, near the condensation-end connecting channel 5. The area of ​​the evaporation section can be adjusted based on the area of ​​the electronic chip 100 to provide better coverage.

[0093] It is specifically used in the thermal management of the electronic chip 100. The corresponding positions of the flow enhancement channel evaporation section 303, the flow weakening channel evaporation section 403, and the evaporation end connecting channel 6 in the plate body 1 are in close contact with the electronic chip 100, and the working fluid absorbs heat. Then the heat is circulated and conducted to the flow enhancement channel condensation section 301, the flow weakening channel condensation section 401, and the condensation end connecting channel 5. The heat dissipation device 12 dissipates the heat absorbed by the working fluid to complete the heat exchange. Since the flat-plate pulsating heat pipe of the present application has a small overall volume, it starts faster and enters the circulating flow heat conduction of the working fluid faster, and the flow and heat transfer effects are better, which is more conducive to the timely heat dissipation of the electronic chip 100. When the electronic chip 100 starts to heat up, the heat dissipation of the flat-plate pulsating heat pipe can be started faster, which is more conducive to protecting the electronic chip 100 and improving its service life.

[0094] In a further embodiment, the heat dissipation device 12 is a fan or heat dissipation fins, which dissipates the heat absorbed by the working medium more quickly, thereby facilitating the flow and heat transfer of the working medium.

[0095] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A flat plate pulsating heat pipe, characterized in that: The invention comprises a plate body (1) and a pulsating heat pipe flow channel (2) provided inside the plate body (1), wherein the pulsating heat pipe flow channel (2) is filled with a working medium, and the pulsating heat pipe flow channel (2) comprises a plurality of flow enhancing flow channels (3) and flow weakening flow channels (4), wherein the flow enhancing flow channels (3) and the flow weakening flow channels (4) are arranged alternately. The flow enhancement channel (3) comprises a flow enhancement channel condensation section (301), a flow enhancement channel insulation section (302) and a flow enhancement channel evaporation section (303); the flow weakening channel (4) comprises a flow weakening channel condensation section (401), a flow weakening channel insulation section (402) and a flow weakening channel evaporation section (403); the flow enhancement channel condensation section (301) and the flow weakening channel condensation section (401) are connected via a condensation end connecting channel (5); the flow enhancement channel evaporation section (303) and the flow weakening channel evaporation section (403) are connected via an evaporation end connecting channel (6); A branch flow channel (7) is provided between adjacent flow enhancement flow channels (3) and flow weakening flow channels (4), one end of the branch flow channel (7) being connected to the flow enhancement flow channel insulation section (302), and the other end of the branch flow channel (7) being connected to the flow weakening flow channel evaporation section (403).

2. The flat plate pulsating heat pipe according to claim 1, characterized in that: The plate body (1) comprises a flow channel substrate (101) and a sealing plate (102); the pulsating heat pipe flow channel (2) is provided on the flow channel substrate (101); and the sealing plate (102) is sealed and connected to the flow channel substrate (101).

3. The flat plate pulsating heat pipe according to claim 1, characterized in that: The width and depth of the flow enhancing flow channel (3) and the flow weakening flow channel (4) are equal.

4. The flat plate pulsating heat pipe according to claim 1, characterized in that: The material of the plate body (1) is copper, and the working medium is a self-wetting fluid.

5. The flat plate pulsating heat pipe according to claim 1, characterized in that: There are four flow-enhancing flow channels (3), four flow-weakening flow channels (4), and six branch flow channels (7).

6. A flat plate pulsating heat pipe according to any one of claims 1 to 5, characterized in that: A bifurcation (8) is formed at the point where the flow weakening channel evaporation section (403) is connected to the branch channel (7), and the width of the flow weakening channel evaporation section (403) at the bifurcation (8) is smaller than the width of the branch channel (7) at the bifurcation (8).

7. The flat plate pulsating heat pipe according to claim 6, characterized in that: The flow weakening channel evaporation section (403) is provided with a narrow section (9) located at the bifurcation (8), and the width of the narrow section (9) gradually decreases in the direction from the flow weakening channel condensation section (401) to the flow weakening channel evaporation section (403); the branch channel (7) is provided with a wide section (10) located at the bifurcation (8), and the width of the wide section (10) gradually increases in the direction close to the narrow section (9).

8. A method for processing a flat plate pulsating heat pipe, comprising processing the flat plate pulsating heat pipe according to any one of claims 1 to 7, characterized in that: The following steps are included: Step 1: groove the flow channel substrate (101) to form a pulsating heat pipe flow channel (2), and provide a liquid injection channel (11) communicating with the outside at one end of the pulsating heat pipe flow channel (2); Step 2: Sealing the sealing plate (102) and the flow channel substrate (101) to form a plate body (1), which is used to enclose the pulsating heat pipe flow channel (2) in the plate body (1); Step 3: vacuuming the pulsating heat pipe flow channel (2) through the liquid injection channel (11) connected to the pulsating heat pipe flow channel (2), and then filling the working fluid after the vacuuming is completed; Step 4: After filling is completed, the injection channel (11) is blocked; Step 5: Perform air tightness test on the flat plate pulsating heat pipe. If the air tightness meets the requirements, the processing is completed.

9. The method for processing a flat-plate pulsating heat pipe according to claim 8, characterized in that: In the second step, solder paste is filled between the sealing plate (102) and the flow channel substrate (101), and the solder paste is located outside the pulsating heat pipe flow channel (2).

10. An electronic chip thermal management device, characterized in that: It comprises a flat plate pulsating heat pipe as described in any one of claims 1 to 7, wherein one end of the plate body (1) close to the evaporation end connecting flow channel (6) is in close contact with the electronic chip, and one end of the plate body (1) close to the condensation end connecting flow channel (5) is provided with a heat dissipation device (12).

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