Pulsating heat pipe heat exchanger

Abstract

This invention provides a pulsating heat pipe heat exchanger. The condensing end includes a connecting pipe, an upper bend pipe, and the upper part of a straight pipe section. The cooling plate comprises an upper flow channel and a lower flow channel, separated by a partition. The connecting pipe of the condensing end is disposed within the upper flow channel. The straight pipe section of the condensing end is disposed between an upper baffle plate and a lower baffle plate. The upper bend pipe is disposed at the bend of the serpentine flow channel. The inlet and outlet of the upper flow channel are connected to the upper flow channel and are respectively disposed on the left and right sides of the cooling plate. The inlet and outlet of the lower flow channel are also connected to the lower flow channel and are respectively disposed on the left and right sides of the cooling plate. The inlets of the upper and lower flow channels are not located on the same side. This invention provides a heat exchanger with a novel heat exchange structure, which can achieve sufficient heat exchange at the condensing end and improve the heat exchange effect.

Description

Technical Field

[0001] This invention relates to a heat exchanger, and more particularly to a pulsating heat pipe heat exchanger. Background Technology

[0002] Heat pipe technology, a highly efficient phase change heat transfer element, originated in 1963 and was invented by George Grover at Los Alamos National Laboratory in the United States. It makes full use of the principle of heat conduction and the rapid heat transfer properties of phase change media to quickly transfer the heat of the heated object to the outside of the heat source through the heat pipe. Its thermal conductivity exceeds that of any known metal.

[0003] A loop heat pipe (LHP) is a highly efficient heat exchanger that utilizes the pressure difference generated by the phase change of the working fluid to achieve circulating flow and heat transfer. It typically consists of an evaporator, a condenser, a receiver, and steam and liquid lines. Its working principle is as follows: After a heat load is applied to the evaporator, heat is transferred to the capillary wick via thermal conduction through the evaporator's outer shell. The liquid working fluid evaporates on the outer surface of the evaporator capillary wick, simultaneously forming a new gas-liquid interface and capillary force within the micropores of the capillary wick. The generated vapor, driven by capillary force, flows out from the vapor channel into the vapor line and then into the condenser. After entering the condenser, the vapor absorbs the latent and sensible heat of the superheated vapor through convection heat transfer, thus cooling it into a subcooled liquid. The subcooled liquid enters the liquid main through the liquid line to replenish the evaporator capillary wick, and this cycle continues. The circulation of the working fluid is driven by the capillary pressure generated by the evaporator capillary wick, requiring no external power. Because the condensation and evaporation sections are separate, loop heat pipes are widely used in comprehensive energy applications and waste heat recovery.

[0004] Pulsating heat pipes are a novel heat pipe technology that emerged in the early 1990s. The world's first pulsating heat pipe was invented by Japanese engineer Akachi in 1990. It consists of a metal capillary tube bent into a serpentine structure, requiring no internal capillary wick. As a novel heat dissipation and cooling technology, pulsating heat pipes offer advantages such as simple structure, small size, light weight, ease of manufacturing, low cost, and excellent performance. The operating principle and heat transfer characteristics of pulsating heat pipes differ significantly from traditional heat pipes. When a pulsating heat pipe is in operation, it generally consists of three parts: the two ends are the heating and cooling sections, respectively, and the middle section is the adiabatic section, which can also be omitted. The operating principle of a pulsating heat pipe is as follows: When the pipe diameter is sufficiently small, a series of vapor and liquid plugs will form inside the pipe. In the heating section, the liquid film between the vapor bubbles or vapor column and the pipe wall will continuously evaporate due to heating, causing the bubbles to expand and the pressure to increase. Simultaneously, in the cooling section, the vapor bubbles will condense, shrink, and rupture, causing the pressure to drop. This creates a driving pressure difference between the heating and cooling sections, propelling the vapor and liquid plugs to reciprocate between the heating and cooling sections, transferring heat from one end to the other, thus achieving heat transfer or temperature control. It is evident that in a pulsating heat pipe, the phase change of the working fluid mainly provides the driving force for the working fluid; the heat of phase change accounts for a relatively small proportion of the total heat transfer flux in the pulsating heat pipe. The heat pipe primarily relies on the sensible heat change of the working fluid to achieve heat transfer.

[0005] Currently, when pulsating heat pipes dissipate heat through condensation, the condenser end has a bend and a connecting pipe linking the two outermost pipes. This causes a non-counter-current heat exchange problem when the fluid passes through the condenser end, meaning the heat exchange effect is not optimal. Therefore, improvements are needed to achieve the best heat exchange performance. Summary of the Invention

[0006] In order to overcome the defects and shortcomings of the existing technology, the present invention provides a heat exchanger with a novel heat exchange structure, which can achieve sufficient heat exchange at the condensing end and improve the heat exchange effect.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A pulsating heat pipe heat exchanger includes a pulsating heat pipe and a cooling plate. The pulsating heat pipe includes an evaporating end and a condensing end, with the condensing end disposed within the cooling plate for heat exchange with a fluid within the cooling plate. The pulsating heat pipe includes straight pipe sections, an upper bend, a lower bend, and connecting pipes. Multiple straight pipe sections are provided. The upper and lower bends are respectively located at the upper and lower parts of the straight pipe sections to connect adjacent straight pipe sections. The connecting pipes are located above the upper bends, connecting the upper ends of the leftmost and left and right straight pipe sections. The straight pipe sections, upper bends, lower bends, and connecting pipes form a continuous loop. The condensing end includes the connecting pipe, the upper bend, and the upper part of the straight pipe sections. The cooling plate includes an upper flow channel and a lower flow channel, separated by a partition. The lower flow channel includes an upper baffle extending downward from the upper part of the partition and a lower baffle extending upward from the lower wall of the cooling plate. The upper and lower baffles are spaced apart, thus forming a serpentine flow channel. The connecting pipe at the condensing end is located in the upper flow channel, with a straight section between the upper and lower baffles, and an upper bend located at the bend of the serpentine flow channel. The inlet and outlet of the upper flow channel are connected to the upper flow channel and are located on the left and right sides of the cooling plate, respectively. The inlet and outlet of the lower flow channel are also connected to the lower flow channel and are located on the left and right sides of the cooling plate, respectively. The inlets of the upper and lower flow channels are not located on the same side. As an improvement, the flow path of the fluid in the upper flow channel is opposite to the flow direction of the fluid in the connecting pipe.

[0008] As an improvement, the baffle is a heat conductor, allowing the fluids in the upper and lower channels to exchange heat through the baffle.

[0009] As an improvement, the loop heat pipe, consisting of straight sections, upper bends, lower bends, and connecting pipes, is manufactured as a single unit.

[0010] As an improvement, the straight pipe section, upper bend, lower bend and connecting pipe are manufactured separately and then connected to form a complete structure.

[0011] As an improvement, the partition plate includes a parallel portion parallel to the lower wall of the cooling plate and a vertical portion perpendicular to the lower wall of the cooling plate. The parallel portion includes a first parallel portion, a second parallel portion, and a third parallel portion, and the vertical portion includes a first vertical portion and a second vertical portion. The left end of the first parallel portion is connected to the left side wall of the cooling plate, the lower end of the first vertical portion is connected to the right end of the first parallel portion, the left end of the second parallel portion is connected to the upper end of the first vertical portion, the upper end of the second vertical portion is connected to the right end of the second parallel portion, the left end of the third parallel portion is connected to the upper end of the second vertical portion, and the right end of the third parallel portion is connected to the right side wall of the cooling plate.

[0012] As an improvement, the left end of the first parallel section is located at the lower middle of the left side wall of the cooling plate, and the right end of the third parallel section is located at the lower middle of the right side wall.

[0013] As an improvement, the partition plate is a symmetrical structure along the middle of the lower wall of the cooling plate.

[0014] As an improvement, the thermal conductivity of the partition plate varies at different locations, with the thermal conductivity of the second parallel section being less than that of the vertical section, and the thermal conductivity of the vertical section being less than that of the first and third parallel sections.

[0015] As an improvement, a first fluid flows in the first flow channel and a second fluid flows in the second flow channel. The first fluid and the second fluid are different fluids.

[0016] As an improvement, the heat absorption capacity of the fluid in the upper flow channel is less than that of the fluid in the lower flow channel.

[0017] Compared with the prior art, the present invention has the following advantages: Because pulsating heat pipes circulate when heated, the flow direction can be uncertain due to differing heating directions. This invention addresses this by using a cooling plate comprising an upper and lower flow channel separated by a partition. The inlets of the upper and lower flow channels are not located on the same side, allowing for independent heat exchange in each channel. This ensures sufficient heat exchange regardless of the flow direction within the heat pipe. If the flow direction of the upper and lower flow channels is opposite to the flow direction of the fluid inside the heat pipe, counter-current flow provides the best heat exchange effect. If the flow direction of the upper and lower flow channels is the same as the flow direction of the fluid inside the heat pipe, heat exchange between the two fluids can be achieved through heat conduction between the partitions. This compensates for the problem of insufficient heat exchange caused by excessive temperature differences due to co-current flow, resulting in more efficient heat exchange. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the pulsating heat pipe structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the cooling plate of the present invention; Figure 3 This is a schematic diagram of the placement of the pulsating heat pipe of the present invention; Figure 4 This is a schematic diagram of the assembled structure of the pulsating heat pipe of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] Unless otherwise specified, in this article, " / " represents division, and "×" and "*" represent multiplication when formulas are involved.

[0021] It should be noted that, unless otherwise specified, the directional terms "up," "down," "left," and "right" in this invention do not represent actual directions, but are merely for convenience of expression. The four terms "up," "down," "left," and "right" respectively represent... Figure 1The pulsating heat pipe has four positions: "up", "down", "left", and "right".

[0022] Figure 1-4 A pulsating heat pipe heat exchanger is demonstrated. For example... Figure 1 As shown, the heat exchanger includes a pulsating heat pipe 1 and a cooling plate 2, wherein the pulsating heat pipe 1 includes an evaporating end 11 and a condensing end 13. Figure 3 As shown, the condenser end 13 is disposed inside the cooling plate 2 and exchanges heat with the fluid inside the cooling plate 2; the pulsating heat pipe 1 includes a straight pipe section 14, an upper bend pipe 15, a lower bend pipe 16 and a connecting pipe 17. Multiple straight pipe sections 14 are provided. Upper bends 15 and lower bends 16 are respectively located at the upper and lower ends of the straight pipe sections 14 to connect adjacent straight pipe sections 14. A connecting pipe 17 is located above the upper bend 15, connecting the upper ends of the leftmost and left and right straight pipe sections. The straight pipe sections 14, upper bends 15, lower bends 16, and connecting pipe 17 form a continuous loop. The condensing end 13 includes the connecting pipe 17, the upper bend 15, and the upper part of the straight pipe sections 14. The cooling plate 2 includes an upper flow channel 21 and a lower flow channel 22, separated by a partition 23. The lower flow channel 22 includes an upper baffle 24 extending downward from the upper part of the partition and a lower baffle 25 extending upward from the lower wall of the cooling plate. The upper baffle 24 and lower baffle 25 are spaced apart, thus forming a serpentine flow channel in the lower flow channel. The connecting pipe 17 of the condensing end 11 is located within the upper flow channel 21. At least a portion of the straight pipe section of the condensing end 13 (e.g., Figure 3 The straight pipe section shown in the middle position is set between the upper baffle 24 and the lower baffle 25, and the upper bend pipe 15 is set at the bend position of the serpentine flow channel; the inlet 3 and outlet 4 of the upper flow channel are connected to the upper flow channel and are respectively set on the left and right sides of the cooling plate, and the inlet 5 and outlet 6 of the lower flow channel are connected to the lower flow channel and are respectively set on the left and right sides of the cooling plate.

[0023] This invention sets up two flow channels, upper and lower, with a baffle structure in the lower flow channel. This allows the heat exchange tube sections at different positions of the condensation end of the pulsating heat pipe to be adapted to the flow channel shape, ensuring that the heat exchange fluid is in full contact with the heat exchange tube sections and improving the heat exchange effect.

[0024] This invention, by setting up upper and lower flow channels, allows the upper and lower flow channels to heat different fluids respectively, thereby outputting fluids at various temperatures to meet the needs of diverse output fluids and different users.

[0025] In this invention, the inlet and outlet of the first and second flow channels are located on opposite sides of the cooling plate. This is because when the heat pipe evaporator absorbs heat, the circulation direction of the fluid within the heat pipe may change depending on the amount of heat absorbed at different locations. By positioning the inlet and outlet of the upper and lower flow channels on opposite sides, the positions of the inlet and outlet can be determined based on the actual fluid flow direction within the heat pipe. In other words, the positions of the inlet and outlet can be varied as needed to meet different heat exchange requirements. For example, to maximize heat exchange, the fluid can flow counter-currently to the heat pipe section. Alternatively, to avoid excessively high output temperatures, the fluid in the upper flow channel can flow in the same direction as the fluid within the heat pipe, while the fluid in the lower flow channel can flow counter-currently, thus transferring the less heat exchanged by the upper fluid to the lower flow channel.

[0026] As an improvement, the inlet 3 of the upper flow channel and the inlet 5 of the lower flow channel are not located on the same side of the cooling plate, so that the outlet 4 of the upper flow channel and the outlet 6 of the lower flow channel are not located on the same side of the cooling plate.

[0027] As an improvement, the flow path of the fluid in the upper channel is opposite to the flow direction of the fluid in the connecting pipe. Similarly, the flow path of the fluid in the lower channel is opposite to the flow direction of the fluid in the upper bend. This design allows the fluid to flow in the opposite direction to the fluid flow path within the heat pipe, thereby maximizing heat exchange.

[0028] As an improvement, the baffle acts as a heat conductor, allowing heat exchange between the fluids in the upper and lower flow channels. By installing the heat-conducting baffle, heat exchange between the fluids in the upper and lower flow channels can be achieved, resulting in heat complementarity between the two channels. This allows the higher-temperature fluid in one channel to transfer heat to the lower-temperature fluid, which then cools down and absorbs heat from the heat pipe, maximizing heat exchange. Through the complementary heat conduction of the baffle, optimal heat exchange performance can be achieved regardless of whether the flow is co-current or counter-current.

[0029] As an improvement, the pulsating heat pipe, consisting of straight sections, upper bends, lower bends, and connecting pipes, is manufactured as a single unit. This integrated manufacturing process simplifies the production process.

[0030] As an improvement, straight pipe sections, upper bends, lower bends, and connecting pipes are manufactured separately and then joined together. Heat pipes can also be manufactured separately and then welded together.

[0031] As an improvement, such as Figure 2As shown, the partition plate includes a parallel portion parallel to the lower wall of the cooling plate and a vertical portion perpendicular to the lower wall of the cooling plate. The parallel portion includes a first parallel portion 231, a second parallel portion 233, and a third parallel portion 235. The vertical portion includes a first vertical portion 232 and a second vertical portion 234. The left end of the first parallel portion connects to the left side wall of the cooling plate, the lower end of the first vertical portion connects to the right end of the first parallel portion, the left end of the second parallel portion connects to the upper end of the first vertical portion, the upper end of the second vertical portion connects to the right end of the second parallel portion, the left end of the third parallel portion connects to the upper end of the second vertical portion, and the right end of the third parallel portion connects to the right side wall of the cooling plate. This structure allows the heat pipe to fit perfectly with the fluid flow channel, achieving optimal heat exchange. Furthermore, this structure allows the upper parts of the leftmost and rightmost straight pipe sections to also exchange heat within the upper flow channel, increasing the heat exchange area of ​​the upper flow channel and reducing the difference in heat exchange area between the upper and lower flow channels, further improving the uniformity of heat exchange.

[0032] As an improvement, the left end of the first parallel section is located at the lower middle of the left side wall of the cooling plate, and the right end of the third parallel section is located at the lower middle of the right side wall. Because the area of ​​the heat pipe in the lower flow channel is larger than that in the upper flow channel, the above structure maximizes the heat exchange area of ​​the fluid in the upper flow channel and maximizes the fluid path, thereby achieving a relatively balanced heat exchange between the upper and lower sections.

[0033] As an improvement, the partition plate is a symmetrical structure along the middle of the lower wall of the cooling plate.

[0034] As an improvement, the thermal conductivity of the partition plate varies at different locations. The thermal conductivity of the second parallel section is greater than that of the vertical section, and the thermal conductivity of the vertical section is greater than that of the first and third parallel sections. This is because when the inlet 3 of the upper flow channel and the inlet 5 of the lower flow channel are not located on the same side of the cooling plate, the positions of the first and third parallel sections are the outlet and inlet of the upper and lower flow channels, respectively, or the inlet and outlet of the upper and lower flow channels. In this case, the temperature difference between the two is the largest, resulting in the best heat exchange effect. This is because increasing the thermal conductivity at the intermediate position enhances the heat exchange effect, achieving overall heat exchange balance and thus further optimizing the heat exchange performance.

[0035] As an improvement, a first fluid flows through the first flow channel, and a second fluid flows through the second flow channel; the first and second fluids are different fluids. By using different fluids, diverse needs can be met, satisfying different heating requirements. This allows a single heat exchanger to heat multiple fluids.

[0036] As an improvement, the heat absorption capacity of the fluid in the upper flow channel is less than that of the fluid in the lower flow channel. Because the heat exchange area in the upper part is smaller, the difference in heat absorption capacity of the fluid satisfies the difference in heat exchange volume caused by the different heat exchange areas, thereby achieving overall heat exchange balance between the upper and lower heat pipes.

[0037] As an improvement, the evaporator end is thermally connected to a heat source, which can be waste heat from the flue gas.

[0038] As an improvement, the heat source is the heat spreader 7, such as... Figure 4 As shown, a phase change material is placed inside the heat spreader. After the heat spreader absorbs heat, the phase change material vaporizes. The vaporized phase change material transfers heat to the evaporator end, condenses after heat transfer, and then absorbs heat again, thus forming a cycle.

[0039] Pulsating heat pipes have strong bending capabilities and can be appropriately modified according to the space inside the cooling plate, making reasonable use of the internal space of the cooling plate.

[0040] The evaporation section of the pulsating heat pipe absorbs heat from the heat source, and the working fluid inside the pipe vaporizes to produce steam, which is then transferred to the condensation section of the pulsating heat pipe to release heat. The condensation section of the pulsating heat pipe fully contacts the cooling fluid in the cooling plate, thereby carrying away the heat from the pulsating heat pipe. The condensed working fluid returns to the evaporation section for the next cycle.

[0041] As an improvement, the pulsating heat pipe includes an adiabatic section 12 located between the evaporation and condensation sections. A capillary copper tube of the required diameter and total length is selected according to the application requirements and then bent. The condensation section uses water cooling, with the heat pipe transferring heat from the condensation section through direct contact with the cooling water. Because of the pulsating heat pipe's good flexibility, in practical applications, a customized pulsating heat pipe can be made to match the application requirements. A liquid filling port is reserved in the adiabatic section of the pulsating heat pipe. The pulsating heat pipe is first evacuated and then filled with liquid. After filling, the liquid filling port is sealed by soldering, completing the manufacturing of the entire pulsating heat pipe. The working fluid of the pulsating heat pipe can be selected according to the operating temperature, including a single solution of water or ethanol, or a mixture of multiple fluids.

[0042] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A pulsating heat pipe heat exchanger, the heat exchanger comprising a pulsating heat pipe and a cooling plate, the pulsating heat pipe comprising an evaporating end and a condensing end, the condensing end being disposed within the cooling plate for heat exchange with a fluid within the cooling plate; the pulsating heat pipe comprising a straight pipe section, an upper bend, a lower bend, and a connecting pipe, wherein multiple straight pipe sections are provided, the upper bend and lower bend are respectively disposed at the upper and lower parts of the straight pipe sections for connecting adjacent straight pipe sections, the connecting pipe is located at the upper part of the upper bend and connects the upper ends of the leftmost and left and right straight pipe sections, the straight pipe sections, the upper bend, the lower bend, and the connecting pipe form a continuous loop; the condensing end comprising the connecting pipe, the upper bend, and the upper part of the straight pipe section, characterized in that, The cooling plate includes an upper flow channel and a lower flow channel, which are separated by a partition. The lower flow channel includes an upper baffle extending downward from the upper part of the partition and a lower baffle extending upward from the lower wall of the cooling plate. The upper and lower baffles are spaced apart, thus forming a serpentine flow channel. The connecting pipe at the condensing end is located in the upper flow channel, and the straight pipe section at the condensing end is located between the upper and lower baffles. The upper bend is located at the bend of the serpentine flow channel. The inlet and outlet of the upper flow channel are connected to the upper flow channel and are located on the left and right sides of the cooling plate, respectively. The inlet and outlet of the lower flow channel are connected to the lower flow channel and are located on the left and right sides of the cooling plate, respectively. The inlet of the upper flow channel and the inlet of the lower flow channel are not located on the same side.

2. The heat exchanger as described in claim 1, characterized in that, The baffle is a heat conductor, and the fluids in the upper and lower channels can exchange heat through the baffle.

3. The heat exchanger as described in claim 1, characterized in that, The loop heat pipe, consisting of straight pipe sections, upper bends, lower bends, and connecting pipes, is manufactured as a single unit.

4. The heat exchanger as described in claim 1, characterized in that, Straight pipe sections, upper bends, lower bends, and connecting pipes are manufactured separately and then connected to form a complete structure.

5. The heat exchanger as described in claim 1, characterized in that, The partition plate includes a parallel portion parallel to the lower wall of the cooling plate and a vertical portion perpendicular to the lower wall of the cooling plate. The parallel portion includes a first parallel portion, a second parallel portion, and a third parallel portion. The vertical portion includes a first vertical portion and a second vertical portion. The left end of the first parallel portion is connected to the left side wall of the cooling plate, the lower end of the first vertical portion is connected to the right end of the first parallel portion, the left end of the second parallel portion is connected to the upper end of the first vertical portion, the upper end of the second vertical portion is connected to the right end of the second parallel portion, the left end of the third parallel portion is connected to the upper end of the second vertical portion, and the right end of the third parallel portion is connected to the right side wall of the cooling plate.

6. The heat exchanger as described in claim 5, characterized in that, The left end of the first parallel section is located in the lower middle part of the left side wall of the cooling plate, and the right end of the third parallel section is located in the lower middle part of the right side wall.

7. The heat exchanger as described in claim 5, characterized in that, The evaporator end is connected to a heat source, which is a heat spreader plate. A phase change material is installed inside the heat spreader plate. After the heat spreader plate absorbs heat, the phase change material vaporizes. The vaporized phase change material transfers heat to the evaporator end, and then condenses and absorbs heat again, thus forming a cycle.

8. The heat exchanger as described in claim 5, characterized in that, The thermal conductivity of the partition plate varies at different locations. The thermal conductivity of the second parallel section is less than that of the vertical section, and the thermal conductivity of the vertical section is less than that of the first and third parallel sections.

9. The heat exchanger as claimed in claim 1, characterized in that, The first fluid flows through the first flow channel, and the second fluid flows through the second flow channel. The first fluid and the second fluid are different fluids.

10. The heat exchanger as claimed in claim 9, characterized in that, The heat absorption capacity of the fluid in the upper flow channel is less than that of the fluid in the lower flow channel.

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