Pulsating heat pipe radiator based on micro-channel flat pipes

Abstract

The invention relates to a pulsating heat pipe radiator based on micro-channel flat pipes. The pulsating heat pipe radiator comprises the micro-channel flat pipes. The micro-channel flat pipe is bent for multiple times to form a heat pipe with an arch-shaped bent structure, and the middle part of the heat pipe comprises a plurality of first straight pipe sections which are parallel to one another; the bent section at one end of the heat pipe comprises a second straight pipe section and bent pipe sections connected to the two ends of the second straight pipe section, the end is a heat pipe evaporation end, and the rest part of the heat pipe is a heat pipe condensation end; at the condensation end of the heat pipe, the end parts of the adjacent first straight pipe sections are connected with the third straight pipe sections through the two bent pipe sections, or the end parts of the adjacent first straight pipe sections are directly connected through the bent pipe sections; the condensation end of the heat pipe adopts an air cooling heat dissipation assembly or a liquid cooling heat dissipation assembly to dissipate heat. The invention provides a pulsating heat pipe radiator based on micro-channel flat pipes. The pulsating heat pipe radiator is used for solving the problems that in an existing heat pipe radiating technology, the gravity resistance is weak, the contact area is small, and the radiating effect is poor.

Description

Technical Field

[0001] The invention relates to a pulsating heat pipe radiator based on a microchannel flat tube. Background Art

[0002] As electronic devices develop towards micro-integration, high current and high frequency, the heat generated by the equipment is getting bigger and bigger, and the heat dissipation requirements are becoming more and more severe. If the cooling conditions cannot meet the heat dissipation requirements of the heating components, the resulting temperature accumulation will be fatal to the performance and life of the electronic equipment.

[0003] Traditional heat dissipation and cooling technologies are mainly divided into active heat dissipation and passive heat dissipation. Common active heat dissipation methods include: air cooling, liquid cooling, spray cooling, thermoelectric cooling, etc.; common passive heat dissipation technologies include: fin cooling, heat pipe cooling, VC temperature plate cooling, thermal conductive graphite cooling, etc. Among them, the high thermal conductivity, high temperature uniformity, and high adaptability of heat pipes can well meet the needs of compact heat dissipation space, high heat flux density, less maintenance, and complex and changeable application scenarios of electronic devices, and are widely used in the field of electronic component heat dissipation.

[0004] The working fluid in gravity heat pipes and capillary heat pipes is gas-liquid counter-flow, and the liquid reflux at the condensation end mainly relies on gravity or capillary force. Among them, gravity heat pipes have high requirements for installation angles and weak anti-gravity shape. Capillary heat pipes need to process capillary structures such as sintering and wire mesh grooves inside the heat pipe, and the manufacturing process is complicated. Pulsating heat pipes overcome the shortcomings of the above heat pipes. There is no liquid absorption core, the structure is simpler, and the gas and liquid phases of the working fluid in the pipe flow in the same direction. The heat transfer performance and heat transfer limit are better, the gravity sensitivity is low, and the flexibility is better. It is considered to be a very promising heat transfer element to solve the current limited space high heat flux density heat dissipation. The ordinary pulsating heat pipe structure is formed by serpentine bending of copper tubes. The circular cross-section of the copper tube is in line contact with the heating element. The contact area is small and the heat dissipation capacity is poor, which makes it difficult to meet the heat dissipation requirements. Summary of the invention

[0005] The present invention provides a pulsating heat pipe radiator based on a microchannel flat tube, which is used to solve the problems of weak anti-gravity performance, small contact area, poor heat dissipation effect, etc. existing in the existing heat pipe heat dissipation technology.

[0006] The technical solution of the present invention to solve the above problems is:

[0007] The present invention proposes a pulsating heat pipe radiator based on a microchannel flat tube, which is special in that:

[0008] It comprises a microchannel flat tube; the microchannel flat tube is bent multiple times to form a heat pipe with an arched bent structure, the middle part of the heat pipe comprises a plurality of mutually parallel first straight tube sections; the bent section at one end of the heat pipe comprises a second straight tube section and a bent tube section connected to both ends of the second straight tube section, the end is the heat pipe evaporation end, and the rest of the heat pipe is the heat pipe condensation end; at the heat pipe condensation end, the ends of adjacent first straight tube sections are connected to the third straight tube section through two bent tube sections, or the ends of adjacent first straight tube sections are directly connected through the bent tube section; the heat pipe condensation end adopts air cooling or liquid cooling components for heat dissipation.

[0009] Furthermore, the microchannel flat tube is bent 4n-2 times, where n is a positive integer, to form 2n first straight tube segments 201 and 2n-1 second straight tube segments; when n=1, it is bent twice to form a U-shaped structure; when n≥2, the microchannel flat tube is divided into two forms: equidistant bending and variable-pitch bending; in the equidistant bending mode, the first straight tube segments are evenly spaced; in the variable-pitch bending mode, the first straight tube segments are unevenly spaced.

[0010] Furthermore, the distribution interval of the first straight pipe section follows the alternating rule of "wide-narrow-wide-narrow", and the wide-narrow spacing ratio can be 2:1 or 3:1.

[0011] Furthermore, the interior of the microchannel flat tube contains 2m channels, where m is an integer of 2, 3, etc. Adjacent channels are separated by a central rib, and the central ribs are numbered. The two ends of the flat tube are respectively recorded as end A and end B. At the A end of the flat tube, the central ribs with odd numbers are cut inward to a certain depth on the basis of the original port to form a new end face. At the B end of the flat tube, the central ribs with even numbers are processed in the same way, and the original port is sealed by a hot pressing process; a closed flow channel that can connect adjacent channels in series is finally formed between the original port and the new port.

[0012] Furthermore, at the B end of the microchannel flat tube, the ribs in the head and tail channels maintain a complete shape, and the head and tail channels are connected by U-shaped capillaries or port connectors, ultimately forming a closed flow path in which the head and tail channels are connected and adjacent channels are connected in series.

[0013] Specifically, when a U-shaped capillary is used, the front end of the U-shaped capillary is inserted into the head and tail channels and sealed by brazing; a hole is opened at the lower end of the bending part of the U-shaped capillary to connect the filling tube; the inner diameter of the U-shaped capillary is 1 to 3 times the hydraulic diameter of the microchannel;

[0014] When a port connector is used, the B end of the microchannel flat tube is inserted into the port connector, a through hole is provided inside the port connector, the side wall of the through hole is perforated to connect the head and tail channels, a plugging cap is installed on one side of the through hole and sealed by brazing, and the other side of the through hole is connected to the filling pipe; the inner diameter of the through hole is ≥ the hydraulic diameter of the microchannel.

[0015] Furthermore, the above-mentioned pulsating heat pipe radiator based on microchannel flat tubes also includes an aluminum substrate, and the heat pipe evaporation end is in contact with and connected to the aluminum substrate; the heat pipe evaporation end is connected to the heating element through the aluminum substrate.

[0016] Preferably, when the heating element is installed vertically, the evaporation end of the heat pipe is distributed horizontally, and a chamfered step surface is provided on the side wall of the aluminum substrate, and the chamfer angle α of the chamfered step surface is 5 to 20°; the evaporation end of the heat pipe is in direct contact with the chamfered step surface of the aluminum substrate, or a groove is provided inwardly on the chamfered step surface, and the evaporation end of the heat pipe is inlaid and contacted with the groove.

[0017] Furthermore, when the heating element is installed vertically, the evaporation end of the heat pipe is horizontally distributed, and a groove is directly opened on the side wall of the aluminum substrate, and the evaporation end of the heat pipe is embedded in the groove. Preferably, the groove is arranged obliquely, and after the evaporation end of the heat pipe is embedded in the groove, the condensation end is tilted upward.

[0018] Furthermore, when the heating element is installed vertically, the evaporation end of the heat pipe is vertically distributed, the second straight pipe section of the evaporation end of the heat pipe is in direct contact with the aluminum substrate, and the condensation end is tilted upward by a certain angle β, and the value range of β is 0 to 45°.

[0019] Advantages of the present invention:

[0020] 1) The pulsating heat pipe radiator proposed in the present invention can increase the plane area of ​​the evaporation end after multiple bends, so as to form direct surface contact with the heating plane, increase the contact area, and enhance heat dissipation;

[0021] 2) The channel connection processing method provided by the present invention has a simple processing technology on the one hand, and can connect the internal channels of the microchannel flat tube in series end to end to form a closed flow path, which is beneficial to enhance the pulsation performance of the working medium in the tube and enhance the heat dissipation effect;

[0022] 3) The connection method between the heat pipe radiator and the aluminum substrate provided by the present invention provides a feasible heat dissipation solution for vertically distributed heating elements, ensuring efficient heat dissipation of the heat pipe radiator when used vertically at the evaporation end. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of a pulsating heat pipe radiator based on microchannel flat tubes;

[0024] Figure 2 It is a structural diagram of an embodiment of microchannel flat tube arch equidistant bending;

[0025] Figure 3 It is a structural diagram of an embodiment of a microchannel flat tube arch variable pitch bending;

[0026] Figure 4 It is a structural diagram of another embodiment of a microchannel flat tube arch variable pitch bending;

[0027] Figure 5 It is a diagram of the connection method of adjacent channels in a flat tube;

[0028] Figure 6 This is a structural diagram of an embodiment of connecting the head and tail channels of a flat tube;

[0029] Figure 7 This is another structural diagram of an embodiment of connecting the end and end channels of a flat tube;

[0030] Figure 8 It is a structural diagram of an embodiment of a bow-shaped heat pipe radiator when the evaporation end is horizontally distributed;

[0031] Fig. 9 is a structural diagram of another embodiment of a bow-shaped heat pipe radiator when the evaporation end is horizontally distributed;

[0032] Fig.10 is a structural diagram of another embodiment of a bow-shaped heat pipe radiator when the evaporation end is horizontally distributed;

[0033] Fig.11 It is a structural diagram of an embodiment of a bow-shaped heat pipe radiator when the evaporation end is vertically distributed.

[0034] In the figure:

[0035] Pulsating heat pipe radiator 1, microchannel flat tube 2, fin 3, first straight tube section 201, second straight tube section 202, third straight tube section 203, curved tube section 204, U-shaped capillary tube 4, port connector 5, connecting tube 6, filling tube 7, aluminum substrate 8. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0037] See also Figure 1-Figure 4 The present invention proposes a pulsating heat pipe radiator based on a microchannel flat tube, including a microchannel flat tube 2; the microchannel flat tube 2 is bent multiple times to form a heat pipe with an arched bending structure, and the middle part of the heat pipe includes a plurality of mutually parallel first straight tube sections 201.

[0038] The bent section at one end of the heat pipe includes a second straight pipe section 202 and a bent pipe section 204 connected to both ends of the second straight pipe section 202. This end is the evaporation end of the heat pipe, and the rest of the heat pipe is the condensation end of the heat pipe. At the condensation end of the heat pipe, the end of the adjacent first straight pipe section 201 is connected to the third straight pipe section 203 through two bent pipe sections 204, or the ends of the adjacent first straight pipe sections 201 are directly connected through the bent pipe section 204. The condensation end of the heat pipe adopts air cooling or liquid cooling components for heat dissipation.

[0039] The outer plane of the second straight pipe section 202 of the heat pipe evaporation end is in direct or indirect contact with the heating element to dissipate heat from the heating element. When the heat pipe evaporation end forms direct surface contact with the heating element, the contact gap is filled with thermal conductive interface materials such as silicone grease and silica gel.

[0040] Specifically, see Figure 1 When the heat pipe condensation end adopts air cooling, the surface of the heat pipe condensation end is provided with fins 3. The form of the fins 3 includes but is not limited to folded fins, serrated fins, and insert fins.

[0041] When liquid cooling is used, the first straight pipe section 201 of the condensing end is fitted with the liquid cooling plate, or the condensing end is entirely extended into the interior of a box filled with cooling fluid.

[0042] As an embodiment of the present invention, the microchannel flat tube 2 is bent 4n-2 times (n is an integer of 1, 2, 3...) to form 2n first straight tube segments 201 and 2n-1 second straight tube segments 202; specifically, when n=1, it is bent twice to form a U-shaped structure; when n≥2, optionally, the bow-shaped bending structure has two forms: equidistant bending and variable pitch bending.

[0043] Specifically, Figure 2 An embodiment of an equidistant bending of an arched bending structure is shown, wherein the first straight tube sections 201 are evenly spaced.

[0044] Figure 3 An embodiment of a variable pitch bending of an arched bending structure is shown, wherein the first straight pipe sections 201 are distributed at uneven intervals.

[0045] Specifically, the distribution interval of the first straight pipe section 201 follows the alternating rule of "wide-narrow-wide-narrow", and the width-narrow spacing ratio can be 2:1 or 3:1, which shortens the distance between the first straight pipe sections of adjacent condensation ends, which is beneficial to reducing the flow resistance of the working fluid in the pipe, enhancing the pulsation effect of the working fluid in the adjacent pipe sections, and thereby improving the heat dissipation capacity of the pulsating heat pipe. Figure 4 Another preferred embodiment of the variable pitch bend is shown. Figure 3In this embodiment, the third straight pipe section 203 is eliminated at the condensation end, and a curved pipe section 204 is used to directly connect to the first straight pipe section 201, forming a "concave"-shaped structure at the condensation end of the heat pipe. On the one hand, the distance between the first straight pipe sections adjacent to the condensation end is shortened, which is beneficial to reducing the flow resistance of the working medium and enhancing the pulsation effect. On the other hand, under the same installation space, compared with Figure 3 The "concave"-shaped structure can obtain more first straight pipe sections, which helps to increase the heat exchange area at the condensation end and enhance the heat dissipation effect of the heat pipe.

[0046] In some embodiments of the present invention, see Figure 5 The microchannel flat tube 2 contains 2m channels inside, where m is an integer of 2, 3, etc. Adjacent channels are separated by middle ribs, which are numbered. The two ends of the flat tube are respectively recorded as end A and end B. At end A of the flat tube, the middle ribs numbered with odd numbers are cut inward to a certain depth on the basis of the original port to form a new end face. At end B of the flat tube, the middle ribs numbered with even numbers are processed in the same way, and the original port is sealed by a hot pressing process; a closed flow channel that can connect adjacent channels in series is finally formed between the original port and the new port. Preferably, the inward cutting depth of the middle ribs in the channel is about 1 to 5 times the hydraulic diameter of the microchannel, which is conducive to port welding.

[0047] In some embodiments of the present invention, see Figure 6 and Figure 7 At the B end of the microchannel flat tube 2, the ribs in the head and tail channels maintain a complete shape, and the head and tail channels are connected by a U-shaped capillary 4 or a port connector 5, ultimately forming a closed flow path in which the head and tail channels are connected and adjacent channels are connected in series.

[0048] Specifically, see Figure 6 The front end of the U-shaped capillary 4 is inserted into the head and tail channels and sealed by brazing; a hole is opened at the lower end of the bending part of the U-shaped capillary 4 to connect the filling tube 7; the U-shaped capillary has a certain preferred inner diameter, and studies have found that its inner diameter is optimally 1 to 3 times the hydraulic diameter of the microchannel.

[0049] See also Figure 7 The B end of the microchannel flat tube 2 is inserted into the port connector 5. A through hole is provided inside the port connector 5. The side wall of the through hole is perforated to connect the head and tail channels. A plugging cap is installed on one side of the through hole and sealed by brazing. The other side of the through hole is connected to the filling pipe 7. The inner diameter of the through hole is ≥ the hydraulic diameter of the microchannel. Preferably, the port connector 5 can be in the form of a connecting pipe 6. The side wall of the connecting pipe is perforated to insert the head and tail channels. The inner diameter of the connecting pipe is 1 to 3 times the hydraulic diameter of the channel. The connecting pipe is installed on one side of the connecting pipe and the filling pipe 7 is connected, and the other side is sealed by hot pressing.

[0050] In some embodiments of the present invention, the above-mentioned pulsating heat pipe radiator based on microchannel flat tubes further includes an aluminum substrate 8, and the heat pipe evaporation end and the heating element can be connected through the aluminum substrate 8. The heat pipe evaporation end can be in direct contact with the aluminum substrate 8, and the contact surface is connected by gluing or welding.

[0051] As a preferred embodiment, see Fig.10 A groove can be provided on the side wall of the aluminum substrate 8, and the evaporation end of the heat pipe is inlaid with the groove, wherein the groove should cover the second straight pipe section 202 and the curved pipe section 204, and the groove depth ≥ the thickness of the flat pipe + the arc radius of the curved pipe section. More preferably, the groove is arranged obliquely, and after the evaporation end of the heat pipe is inlaid with the groove, the condensation end is inclined upward, and the inclination angle is 5 to 20 degrees.

[0052] In some embodiments of the present invention, see Figure 8 When the heating element is installed vertically, the heat pipe evaporation end of the pulsating heat pipe radiator 1 is horizontally distributed, and the contact surface between the heat pipe evaporation end and the aluminum substrate 8 is a beveled step surface. Preferably, the bevel angle α of the beveled step surface is 5 to 20°, which is optimal, which is conducive to the radiator to obtain faster thermal response and better heat dissipation performance. More preferably, see Fig. 9 A groove is formed inwardly on the beveled step surface, and the evaporation end of the heat pipe is inlaid and contacted with the groove.

[0053] In some embodiments of the present invention, see Fig.11 When the heating element is installed vertically, the heat pipe evaporation end of the pulsating heat pipe radiator 1 is vertically distributed, and the second straight pipe section 202 of the heat pipe evaporation end is in direct contact with the aluminum substrate 8. In order to obtain a faster thermal response speed, the condensation end can be tilted upward at a certain angle β, and the value range of β is 0 to 45°.

[0054] The above descriptions are merely embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related system fields, are also included in the protection scope of the present invention.

Claims

1. A pulsating heat pipe radiator based on microchannel flat tubes, characterized in that: It comprises a microchannel flat tube (2), wherein the microchannel flat tube (2) is bent multiple times to form a heat pipe with an arcuate bent structure, and the middle part of the heat pipe comprises a plurality of mutually parallel first straight tube sections (201); The bent section at one end of the heat pipe comprises a second straight pipe section (202) and a bent pipe section (204) connected to both ends of the second straight pipe section (202); the end is the evaporation end of the heat pipe, and the rest of the heat pipe is the condensation end of the heat pipe; At the condensation end of the heat pipe, the ends of the adjacent first straight pipe sections (201) are connected to the third straight pipe section (203) via two curved pipe sections (204), or the ends of the adjacent first straight pipe sections (201) are directly connected via the curved pipe sections (204); The heat pipe condensation end adopts air cooling or liquid cooling components to dissipate heat.

2. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 1 is characterized in that: The microchannel flat tube (2) is bent 4n-2 times, where n is a positive integer, to form 2n first straight tube sections (201) and 2n-1 second straight tube sections (202); when n=1, the tube is bent twice to form a U-shaped structure; when n≥2, the microchannel flat tube (2) is divided into two forms: equidistant bending and variable-pitch bending; in the equidistant bending mode, the first straight tube sections (201) are evenly spaced; in the variable-pitch bending mode, the first straight tube sections (201) are unevenly spaced.

3. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 2 is characterized in that: In the variable pitch bending mode, the distribution interval of the first straight pipe section (201) follows the alternating rule of "wide-narrow-wide-narrow".

4. A pulsating heat pipe radiator based on microchannel flat tubes according to any one of claims 1 to 3, characterized in that: The microchannel flat tube (2) contains 2m channels inside, where m is an integer of 2, 3, etc. Adjacent channels are separated by middle ribs, which are numbered. The two ends of the flat tube are respectively marked as end A and end B. At the end A of the flat tube, the middle ribs with odd numbers are cut inward to a certain depth based on the original port to form a new end face. At the end B of the flat tube, the middle ribs with even numbers are processed in the same way, and the original port is sealed by a hot pressing process; a closed flow channel that can connect adjacent channels in series is finally formed between the original port and the new port.

5. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 4 is characterized in that: At the B end of the microchannel flat tube (2), the ribs in the head and tail channels are kept intact, and the head and tail channels are connected by a U-shaped capillary (4) or a port connector (5), ultimately forming a closed flow path in which the head and tail channels are connected and adjacent channels are connected in series; When a U-shaped capillary tube (4) is used, the front end of the U-shaped capillary tube (4) is inserted into the head and tail channels and sealed by brazing; a hole is opened at the lower end of the bent portion of the U-shaped capillary tube (4) and connected to a filling tube (7); the inner diameter of the U-shaped capillary tube is 1 to 3 times the hydraulic diameter of the microchannel; When the port connector (5) is used, the B end of the microchannel flat tube (2) is inserted into the port connector (5), a through hole is provided inside the port connector (5), the side wall of the through hole is perforated to connect the head and tail channels, a plugging cap is installed on one side of the through hole and sealed by brazing, and the other side of the through hole is connected to the filling pipe (7); the inner diameter of the through hole is ≥ the hydraulic diameter of the microchannel.

6. A pulsating heat pipe radiator based on microchannel flat tubes according to any one of claims 1 to 3, characterized in that: It also comprises an aluminum substrate (8), and the evaporation end of the heat pipe is in contact with and connected to the aluminum substrate (8); the evaporation end of the heat pipe is connected to the heating element via the aluminum substrate (8).

7. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 6 is characterized in that: When the heating element is installed vertically, the evaporation end of the heat pipe is distributed horizontally, and a chamfered step surface is provided on the side wall of the aluminum substrate (8), and the chamfering angle α of the chamfered step surface is 5 to 20°; The evaporation end of the heat pipe is in direct contact with the beveled step surface of the aluminum substrate (8), or the beveled step surface is provided with a groove inwardly, and the evaporation end of the heat pipe is in embedded contact with the groove.

8. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 6, characterized in that: When the heating element is installed vertically, the evaporation end of the heat pipe is distributed horizontally, and a groove is directly opened on the side wall of the aluminum substrate (8), and the evaporation end of the heat pipe is inlaid and contacted with the groove.

9. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 8, characterized in that: The groove is arranged obliquely, and after the evaporation end of the heat pipe is embedded and in contact with the groove, the condensation end is inclined upward.

10. The pulsating heat pipe radiator based on microchannel flat tubes according to claim 6, characterized in that: When the heating element is installed vertically, the evaporation end of the heat pipe is distributed vertically, the second straight pipe section (202) of the evaporation end of the heat pipe is in direct contact with the aluminum substrate (8), and the condensation end is tilted upward at a certain angle β, and the value range of β is 0 to 45°.

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