Heat transfer device for composite heat transfer

Abstract

The invention provides a heat transfer device for composite heat transfer, relates to the technical field of heat transfer element improvement, and solves the limitation and problems existing in an existing heat transfer heat pipe technology. The heat transfer device comprises a base plate, a vacuum heat transfer area is defined by the base plate, and a steam channel and a gas-liquid plug chain channel are formed in the preset position of the heat transfer area; the heat transfer area is filled with working medium liquid; capillary core structures are arranged on the pipe wall of the steam channel and the inner wall of the base plate; the pipe wall of the gas-liquid plug chain channel and the base plate are made of metal materials. The advantages of phase change heat transfer and convective heat transfer are combined, and the heat transfer performance of the heat pipe under the low heat load and the high heat load can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of heat transfer element improvement, and in particular to a heat transfer device with composite heat transfer. Background Art

[0002] Heat pipe technology used for heat transfer is often used as a heat dissipation aid to solve space heat dissipation problems. Due to its excellent passive heat transfer characteristics, heat pipe technology has been widely used in space heat dissipation, electronic chip cooling and energy extraction. According to the different heat transfer characteristics and heat transfer principles, as well as the differences in the thermal movement of the working fluid in the pipe and the main heat transfer mechanism, two mainstream and distinctive heat transfer methods can be extracted, namely the phase change heat transfer mechanism and the pulsating flow heat transfer mechanism. Among them, the phase change heat transfer mechanism uses the principle of working fluid evaporation to absorb heat and condensation to release heat to dissipate heat, while the pulsating flow heat transfer mechanism directly uses liquid convection for heat transfer.

[0003] Phase change heat transfer technology is represented by thermosyphon, capillary core heat pipe and loop heat pipe. Phase change heat transfer heat pipe requires that the gas-liquid two-phase channels are isolated from each other, that is, the vapor and liquid do not work in the same channel and path. Because in this type of heat pipe, the gas phase and liquid phase flow in opposite directions, the gas phase flows from the hot end to the cold end, while the liquid phase flows in the opposite direction. Its heat transfer characteristics are mainly manifested in stable and fast startup, sensitive thermal response, stable temperature at each end, and strong heat transfer performance under low heat load. However, due to the limiting effects of boiling limit, capillary limit, viscosity limit, entrainment limit, etc., the low heat transfer limit is the main problem of current phase change heat transfer technology. Pulsating flow heat transfer technology is represented by pulsating heat pipe. The consistent flow channel of gas and liquid in pulsating flow heat transfer heat pipe is one of the reasons for its pulsating flow enhanced heat transfer. Its heat transfer characteristics are mainly manifested in strong heat transfer performance and high ultimate heat flux density, but its main problems are slow startup speed, large startup temperature difference, and large temperature fluctuations at the hot and cold ends. Summary of the invention

[0004] In order to solve the above technical defects, an embodiment of the present application provides a composite heat transfer device.

[0005] An embodiment of the present application provides a composite heat transfer device, comprising: a substrate, the substrate enclosing a vacuum heat transfer zone, a vapor channel and a gas-liquid plug chain channel being arranged at a preset position of the heat transfer zone, the heat transfer zone being filled with a working fluid liquid; a capillary wick structure being arranged on the tube wall of the vapor channel and the inner wall of the substrate; and the tube wall of the gas-liquid plug chain channel and the substrate being made of metal.

[0006] Preferably, the equivalent hydraulic diameter of the steam channel is greater than or equal to a preset pipe diameter threshold, and the equivalent hydraulic diameter of the gas-liquid plug chain channel is less than a preset pipe diameter threshold.

[0007] Preferably, the preset pipe diameter threshold D critical The expression is:

[0008]

[0009] Among them, σ is the surface tension of the working fluid, ρ1, ρ v are the liquid phase density and gas phase density, and g is the gravitational acceleration.

[0010] Preferably, the steam channels and the gas-liquid plug chain channels are arranged alternately.

[0011] Preferably, the cross-section of the steam channel and the cross-section of the gas-liquid plug chain channel are circular, rectangular or elliptical.

[0012] Preferably, the steam channel and the gas-liquid plug chain channel are straight pipes or curved pipes.

[0013] Preferably, the equivalent hydraulic diameters of the cross sections of part or all of the steam channels are the same, and the equivalent hydraulic diameters of the cross sections of part or all of the gas-liquid plug chain channels are the same.

[0014] Preferably, the equivalent hydraulic diameter of the cross section of each of the steam channels and the equivalent hydraulic diameter of the cross section of each of the gas-liquid plug chain channels are smoothly transitioned or section-transitioned.

[0015] Preferably, the filling rate of the working fluid in the heat transfer zone is less than 70%.

[0016] The composite heat transfer device provided in the embodiment of the present application realizes efficient heat transfer of heat pipes and is a new type of heat pipe with composite heat transfer characteristics of phase change heat transfer under low heat load and pulsating flow heat transfer under high heat load. The present application combines the advantages of phase change heat transfer and convection heat transfer by reconstructing the structure of the steam channel and the gas-liquid plug chain channel, which can simultaneously improve the heat transfer performance of the heat pipe under low heat load and high heat load. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a heat transfer device for composite heat transfer provided in an embodiment of the present application;

[0018] Figure 2 A schematic structural diagram of a heat transfer device for composite heat transfer provided in another embodiment of the present application;

[0019] Figure 3 A schematic structural diagram of a heat transfer device for composite heat transfer provided in another embodiment of the present application;

[0020] Figure 4 A schematic structural diagram of a heat transfer device for composite heat transfer provided in another embodiment of the present application;

[0021] Figure 5A schematic structural diagram of a heat transfer device for composite heat transfer provided in another embodiment of the present application;

[0022] Figure 6 for Figure 1 Schematic diagram of phase change heat transfer of the heat transfer device of the composite heat transfer under low heat load;

[0023] Figure 7 for Figure 6 A local enlarged view of phase change heat transfer with small heat input under low heat load;

[0024] Figure 8 for Figure 6 A local enlarged view of phase change heat transfer with large heat input under low heat load;

[0025] Fig. 9 for Figure 1 Schematic diagram of phase change heat transfer of the heat transfer device of the composite heat transfer under high heat load;

[0026] Fig.10 for Figure 1 Schematic diagram of the heat transfer device of the composite heat transfer under high heat load, with intermittent fountain boiling in the steam channel and pulsating flow in the gas-liquid plug chain channel synergistic heat transfer;

[0027] Fig.11 for Figure 1 The temperature characteristic curve of the heat pipe heating of the heat transfer device of the composite heat transfer under different liquid filling rates;

[0028] Fig.12 for Figure 1 The influence curve of the heat transfer performance of the heat pipe of the composite heat transfer device when the filling rate is between 19.5% and 67.7%. DETAILED DESCRIPTION

[0029] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0030] like Figures 1 to 5 As shown, an embodiment of the present invention provides a composite heat transfer device, comprising:

[0031] A substrate 1, wherein the substrate encloses a vacuum heat transfer zone, a steam channel 2 and a gas-liquid plug chain channel 3 are arranged at a preset position of the heat transfer zone, and the heat transfer zone is filled with a working fluid liquid;

[0032] The tube wall of the vapor channel and the inner wall of the substrate are provided with a capillary wick structure 4;

[0033] The tube wall of the gas-liquid plug chain channel and the substrate are made of metal.

[0034] In the embodiment of the present invention, the steam channel is a phase change heat transfer heat pipe, and the gas-liquid plug chain channel is a pulsating flow heat transfer heat pipe. The steam channel and the gas-liquid plug chain channel structures are reconstructed in the heat transfer area, and the advantages of the phase change heat transfer type heat pipe and the convection heat transfer type heat pipe are combined to achieve efficient heat pipe heat transfer, phase change heat transfer under low heat load, and pulsating flow heat transfer under high heat load, which can simultaneously improve the heat transfer performance of the heat pipe under low heat load and high heat load.

[0035] In the embodiment of the present invention, the equivalent hydraulic diameter of the steam channel is greater than or equal to a preset pipe diameter threshold, and the equivalent hydraulic diameter of the gas-liquid plug chain channel is less than the preset pipe diameter threshold.

[0036] Because the cross-sectional shapes of the steam channel 2 and the gas-liquid plug chain channel 3 can be circular, elliptical, square, rectangular, regular hexagonal, or even petal-shaped, fan-shaped, etc., considering the influence of the cross-sectional shapes of the steam channel 2 and the gas-liquid plug chain channel 3, in the implementation of the present invention, the "equivalent hydraulic diameter" is used as a measurement parameter of the channel size. The equivalent hydraulic diameter is a theoretical method of converting channels of different cross-sectional shapes into circles. For any shape of a figure, its equivalent hydraulic diameter D = 4*A / P, wherein A is the cross-sectional area, and P is the circumference of the cross section, also called the wet circumference.

[0037] In the embodiment of the present invention, the preset pipe diameter threshold D critical The expression is:

[0038]

[0039] Among them, σ is the surface tension of the working fluid, ρ1, ρ v are the liquid phase density and gas phase density, and g is the gravitational acceleration.

[0040] In the embodiment of the present invention, in order to realize the combination of phase change heat transfer type heat pipe and convection heat transfer type heat pipe, the phase change heat transfer heat pipe and the pulsating flow heat transfer heat pipe are limited in the pipe diameter size. The following formula reflects the limitation of the pipe diameter size:

[0041]

[0042] When the equivalent hydraulic diameter of the channel is greater than or equal to D critical When the equivalent hydraulic diameter of the channel is less than D critical When the heat pipe is heated, the surface tension will cause the liquid to suspend freely in the tube, forming a liquid plug, and the heat pipe works in a pulsating flow heat transfer mode.

[0043] In the embodiment of the present invention, some heat transfer zones with equivalent hydraulic diameters greater than D are arranged simultaneously in the same heat transfer zone. critical The vapor passage is less than D critical The gas-liquid plug chain channel can realize efficient operation of phase change heat transfer and pulsating flow heat transfer in the same heat transfer zone, so as to complement the transfer of high and low heat loads.

[0044] In the embodiment of the present invention, a steam channel and a gas-liquid plug chain channel are simultaneously arranged in the heat transfer zone, and the arrangement of the steam channel and the gas-liquid plug chain channel is not limited, and can be regular or irregular. The number of steam channels can be one or more, and the number of gas-liquid plug chain channels can be one or more, and the number of steam channels and the number of gas-liquid plug chain channels can be the same or different. When the number of steam channels and the number of gas-liquid plug chain channels are both multiple, the equivalent hydraulic diameter of each steam channel can be the same or different, and the equivalent hydraulic diameter of each gas-liquid plug chain channel can be the same or different. The cross-sectional shape of each steam channel can be the same or different, and the cross-sectional shape of each gas-liquid plug chain channel can be the same or different. The cross-sectional shapes at different positions of the same steam channel can be the same or different, and the cross-sectional shapes at different positions of the same gas-liquid plug chain channel can be the same or different. The cross-sectional shapes of different shapes in the same steam channel can be smoothly transitioned or section-transitioned, and the cross-sectional shapes of different shapes in the same gas-liquid plug chain channel can be smoothly transitioned or section-transitioned.

[0045] like Figure 1 As shown in the structural schematic diagram of the heat transfer device of the composite heat transfer, the steam channel 2 and the gas-liquid plug chain channel 3 are arranged alternately.

[0046] like Figure 2 As shown in the structural schematic diagram of the heat transfer device of the composite heat transfer, the gas-liquid plug chain channel is arranged at a position close to the central area of ​​the heat transfer zone, and the steam channel is arranged at a position away from the central area of ​​the heat transfer zone, that is, at the two side edges of the heat transfer zone.

[0047] like Figure 3 As shown in the structural schematic diagram of the heat transfer device of the composite heat transfer, the gas-liquid plug chain channel and the steam channel are arranged at intervals, wherein, from left to right in the heat transfer zone, they are arranged in sequence: a steam channel or multiple adjacent steam channels → a gas-liquid plug chain channel or multiple adjacent gas-liquid plug chain channels → a steam channel or multiple adjacent steam channels → a gas-liquid plug chain channel or multiple adjacent gas-liquid plug chain channels → a steam channel or multiple adjacent steam channels.

[0048] like Figure 4As shown in the structural schematic diagram of the heat transfer device of the composite heat transfer, the gas-liquid plug chain channel is arranged on one side of the heat transfer zone, and the steam channel is arranged on the other side of the heat transfer zone, wherein the equivalent hydraulic diameters of the multiple steam channels can be the same or different, and the equivalent hydraulic diameters of the multiple gas-liquid plug chain channels can be the same or different. Figure 4 The equivalent hydraulic diameters of the multiple steam channels shown in the figure are different, the equivalent hydraulic diameters of the multiple gas-liquid plug chain channels are also different, and the equivalent hydraulic diameters decrease successively.

[0049] In the embodiment of the present invention, the cross-section of the steam channel and the cross-section of the gas-liquid plug chain channel are circular, rectangular or elliptical.

[0050] In the embodiment of the present invention, the steam channel and the gas-liquid plug chain channel are straight tubes or curved tubes.

[0051] like Figure 5 As shown, the steam channel and the gas-liquid plug chain channel in the heat transfer zone are both S-shaped.

[0052] In the embodiment of the present invention, the equivalent hydraulic diameters of the cross sections of part or all of the steam channels are the same, and the equivalent hydraulic diameters of the cross sections of part or all of the gas-liquid plug chain channels are the same.

[0053] Among them, the equivalent hydraulic diameters at different positions of the same steam channel can be the same, such as a straight cylinder or a curved pipe, but the equivalent hydraulic diameter at each position is the same, or they can be different, such as a wedge shape or a cone shape. The equivalent hydraulic diameters at different positions of the same gas-liquid plug chain channel can be the same, such as a straight cylinder or a curved pipe, but the equivalent hydraulic diameter at each position is the same, or they can be different, such as a wedge shape or a cone shape.

[0054] When the equivalent hydraulic diameters at different positions of the same steam channel are different, or the shapes of the cross sections at different positions of the same steam channel are different, when the equivalent hydraulic diameters at different positions of the same gas-liquid plug chain channel are different, or the shapes of the cross sections at different positions of the same gas-liquid plug chain channel are different, the equivalent hydraulic diameter of the cross section of each of the steam channel and the equivalent hydraulic diameter of the cross section of each of the gas-liquid plug chain channel have a smooth transition or a cross-sectional transition.

[0055] Combine the following Figures 6 to 10 Explain the heat transfer mechanism of the heat transfer device of composite heat transfer.

[0056] (1) Phase change heat transfer under low heat load

[0057] refer to Figures 6 to 8In the low heat load stage, the heat transfer is completed by the gas-liquid phase change cycle in the large tube during the phase change heat transfer stage. In this stage, the liquid plug in the small and medium tubes is almost stagnant, and the entire heat pipe is quite quiet. The phase change heat transfer stage is a low heat input process, which can be clearly divided into two states. Figure 7 As shown in the figure, when the input heat is small, the liquid condensed and refluxed from the cold end is difficult to form a complete liquid film on the tube wall, but flows back to the hot end in the form of small droplets adhering to the wall. As the input heat increases, the droplet reflux rate gradually increases and eventually forms a complete liquid film on the tube wall. Figure 8 As shown, when the input heat is large, the droplet reflux volume forms a complete liquid film. Due to the stable circulation of the working fluid, the heat pipe performance will be significantly improved.

[0058] (2) Pulsating flow heat transfer under high heat load

[0059] refer to Figures 9 and 10 After the input heat load is sufficient to drive the pulsating motion of the liquid plug, the composite heat pipe enters the pulsating flow stage. At this time, heat is transferred simultaneously by the intermittent fountain boiling in the large tube and the pulsating flow in the small tube.

[0060] Combine the following Figure 11-12 Explain the change of thermal resistance of composite heat pipe under increasing heat load

[0061] like Fig.11 As shown, Fig.11 for Figure 1 The heat transfer device of the composite heat transfer shown in FIG. 1 shows the temperature signal of the hot end at different filling rates over time, where: Fig.11 (a) is a comparison chart of all filling rates used in the experiment. Fig.11 (b) is a comparison chart of liquid filling rate less than 47.6%, and (c) is a comparison chart of liquid filling rate greater than 47.6%. In the figure, the green circle and the red circle have the same meaning, but are distinguished in different figures, representing the instantaneous hot end temperature change of the heat pipe when it changes from pure phase change heat transfer to pulsating flow heat transfer.

[0062] from Fig.11 It can be seen that with the increase of filling rate, the pulsating flow transition temperature shows a trend of first increasing and then decreasing with the filling rate, and the filling rate of 47.6% is a turning point.

[0063] Fig.12 The change curve of thermal resistance under different filling rates is shown in the figure. Thermal resistance is a parameter for comparing the heat transfer performance of heat pipes. The smaller the value, the better the performance. Fig.12It is shown in the figure that when the filling rate is less than 47.6%, the thermal resistance decreases as the filling rate decreases. This shows that the heat transfer performance of the heat pipe with a lower filling rate is better in this case. At this time, the phase change heat transfer mode of the working fluid in the large tube plays a dominant role, and the lower the filling rate, the more conducive it is to the establishment of phase change heat transfer. When the filling rate is greater than 47.6%, the thermal resistance decreases as the filling rate decreases. At this time, the internal disturbance of the working fluid in the large tube is obvious, indicating that the natural convection heat transfer of the liquid plays an enhanced heat transfer role in the heat pipe with a high filling rate. When the input heat is sufficient to drive the pulsating heat transfer mode to change, the performance of each heat pipe has changed significantly. The lower the filling rate, the better the heat transfer performance of the heat pipe is the general trend. And the thermal resistance curve of the heat pipe less than 47.6% presents an 'S' shape. When the filling rate is higher than this, the thermal resistance curve after the pulsation is formed is approximately linear. For the heat pipe with a filling rate of 47.6%, its thermal resistance curve is like a combination of the two.

[0064] The various techniques described herein may be implemented in combination with hardware or software, or a combination thereof. Thus, the method and apparatus of the present invention, or some aspects or parts of the method and apparatus of the present invention may be in the form of program codes (i.e., instructions) embedded in a tangible medium, such as a removable hard disk, a USB flash drive, a floppy disk, a CD-ROM, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by the machine, the machine becomes a device for practicing the present invention.

[0065] In the case where the program code is executed on a programmable computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The memory is configured to store the program code; the processor is configured to execute the method of the present invention according to the instructions in the program code stored in the memory.

[0066] By way of example and not limitation, readable media include readable storage media and communication media. Readable storage media stores information such as computer readable instructions, data structures, program modules or other data. Communication media generally embody computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and include any information transfer medium. Any combination of the above is also included within the scope of readable media.

[0067] In the description provided herein, algorithms and displays are not inherently related to any particular computer, virtual system or other device. Various general purpose systems can also be used together with examples of the present invention. According to the above description, it is obvious that the structure required for constructing such systems. In addition, the present invention is not directed to any specific programming language either. It should be understood that various programming languages ​​can be utilized to implement the content of the present invention described herein, and the above description of specific languages ​​is for disclosing preferred embodiments of the present invention.

[0068] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0069] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim.

[0070] Those skilled in the art will appreciate that the modules or units or components of the devices in the examples disclosed herein may be arranged in the devices described in the embodiment, or alternatively may be located in one or more devices different from the devices in the examples. The modules in the foregoing examples may be combined into one module or may be divided into multiple submodules.

[0071] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and in addition they may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0072] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present invention and to form different embodiments.

[0073] In addition, some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the functions. Therefore, a processor with necessary instructions for implementing the method or method elements forms a device for implementing the method or method elements. In addition, the elements described herein of the device embodiments are examples of devices for implementing the functions performed by the elements for the purpose of implementing the invention.

[0074] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0075] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is primarily selected for readability and instructional purposes, rather than for explaining or limiting the subject matter of the present invention.

Claims

1. A composite heat transfer device, characterized in that: include: A substrate, wherein the substrate encloses a vacuum heat transfer zone, a steam channel and a gas-liquid plug chain channel are arranged at a preset position of the heat transfer zone, and the heat transfer zone is filled with a working fluid liquid; The tube wall of the vapor channel and the inner wall of the substrate are provided with a capillary wick structure; The tube wall of the gas-liquid plug chain channel and the substrate are made of metal.

2. The heat transfer device according to claim 1, characterized in that: The equivalent hydraulic diameter of the steam channel is greater than or equal to a preset pipe diameter threshold, and the equivalent hydraulic diameter of the gas-liquid plug chain channel is less than the preset pipe diameter threshold.

3. The heat transfer device according to claim 2, characterized in that: Preset pipe diameter threshold D critical The expression is: Among them, σ is the surface tension of the working fluid, ρ1, ρ v are the liquid phase density and gas phase density, and g is the gravitational acceleration.

4. The heat transfer device according to claim 1 or 2, characterized in that: The steam channels and the gas-liquid plug chain channels are arranged alternately.

5. The heat transfer device according to claim 1 or 2, characterized in that: The cross-section of the steam channel and the cross-section of the gas-liquid plug chain channel are circular, rectangular or elliptical.

6. The heat transfer device according to claim 1 or 2, characterized in that: The steam channel and the gas-liquid plug chain channel are straight tube-shaped pipes or curved tubes.

7. The heat transfer device according to claim 1 or 2, characterized in that: The equivalent hydraulic diameters of the cross sections of part or all of the steam channels are the same, and the equivalent hydraulic diameters of the cross sections of part or all of the gas-liquid plug chain channels are the same.

8. The heat transfer device according to claim 1 or 2, characterized in that: The equivalent hydraulic diameter of the cross section of each of the steam channels and the equivalent hydraulic diameter of the cross section of each of the gas-liquid plug chain channels have a smooth transition or a section transition.

9. The heat transfer device according to claim 1 or 2, characterized in that: The filling rate of the working fluid in the heat transfer area is less than 70%.

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