A reinforced pool boiling heat transfer device providing an electric field based on thermoelectric materials

Abstract

This invention discloses an enhanced boiling heat transfer device based on a thermoelectric material providing an electric field. The hot side of the thermoelectric module is attached to the wall of a heat source, and the cold side of the thermoelectric module is attached to the lower end of a cooling water tank, which contains a refrigerant. The thermoelectric module includes a dielectric layer, a high-temperature resistant thermally conductive ceramic at the cold end, a thermoelectric unit string, and a hot end contact layer, arranged sequentially from the cold end to the hot end. Linear surface electrodes are uniformly arranged on the upper surface of the high-temperature resistant thermally conductive ceramic at the cold end. The thermoelectric unit string consists of P-type and N-type thermoelectric material units arranged at equal intervals and alternately. This invention utilizes a structure that spontaneously generates an electric field based on the thermoelectric effect to induce rapid bubble detachment. It generates an electric field without external power supply to enhance the ability of bubbles to detach from the heat exchange surface, thereby improving the overall boiling heat transfer efficiency. This invention is suitable for applications such as microscale thermal management and high heat flux density heat dissipation.

Description

Technical Field

[0001] This invention belongs to the field of heat transfer enhancement technology, specifically a device that uses an integrated module of thermoelectric material to generate an electric field to enhance heat transfer during pool boiling. Background Technology

[0002] Boiling heat transfer, as a highly efficient phase change heat transfer method, is widely used in many fields such as microelectronic cooling, energy system heat exchange, and thermal management of high heat flux density components. Especially in microscale or high power density applications, improving local heat transfer capacity is a key factor in improving the overall system efficiency and safety. In a typical pool boiling process, the generation, growth, merging, and detachment of bubbles directly determine the effective heat transfer area and time of the heat transfer interface. If bubbles cannot detach in time, they will form a vapor cover layer, leading to local "dry spots," significantly reducing heat transfer efficiency, and even causing system overheating failure. Therefore, how to promote the rapid and stable detachment of bubbles from the heat transfer surface has always been one of the core issues in boiling enhancement technology research.

[0003] In existing technologies, the main methods for enhancing boiling heat transfer include surface structure modification (such as hydrophilic and hydrophobic patterns, micro / nano textures), surface material modification (such as coating with superhydrophobic coatings), and external field effects (such as electrowetting, magnetic fields, and acoustic waves). Among these, enhancement methods based on the electrowetting-on-dielectric (EWOD) mechanism have attracted much attention in recent years due to their ability to directly control the contact angle, reduce pinning forces, and induce rapid bubble detachment. However, traditional electrowetting systems rely on external high-voltage power supplies and complex electrode wiring, making reliable operation in high-temperature, high-humidity, and miniaturized sealed systems difficult, which greatly limits their practicality and integration.

[0004] On the other hand, with the development of thermoelectric material technology, the scheme of generating electricity using the Seebeck effect by utilizing the temperature difference between the hot and cold ends has gradually matured. Thermoelectric materials such as bismuth telluride (Bi2Te3) can stably output milliwatt-level power in medium and low temperature difference environments, possessing good potential for micro-power supply. If thermoelectric energy conversion and electrowetting regulation functions can be integrated into the same structure, local electric field regulation can be achieved through its own heat transfer process without the need for additional power supply, opening up a new, self-driven path for enhancing boiling heat transfer. Summary of the Invention

[0005] To address the problems existing in the background technology, this invention provides an enhanced pool boiling heat transfer device based on thermoelectric materials to provide an electric field, which belongs to the category of multi-physics field coupling enhanced heat transfer technology. By integrating thermoelectric units, microstructured metal electrode arrays and insulating ceramic multilayer structures, the electric field is directly driven by the temperature difference between the hot end and the cold end during the heat exchange process, thereby realizing the active control of bubble detachment behavior. Compared to existing electrowetting technologies, this invention requires no external power supply, has a more compact structure, higher stability, and greater adaptability, making it particularly suitable for long-term thermal management in confined spaces. The technical solution includes: a thermoelectric module, a positive terminal of the thermoelectric module layer, a cooling water tank, a negative terminal of the thermoelectric module layer, and a voltage switch. The hot side of the thermoelectric module is attached to the heat source wall, and the cold side of the thermoelectric module is attached to the lower end of the cooling water tank, which contains a refrigerant. The thermoelectric module includes: a dielectric layer, a high-temperature resistant thermally conductive ceramic at the cold end, a thermoelectric unit string, and a hot end contact layer, arranged sequentially from the cold end to the hot end. Linear surface electrodes are uniformly arranged on the upper surface of the high-temperature resistant thermally conductive ceramic at the cold end. The thermoelectric unit string consists of P-type and N-type thermoelectric material units arranged in an alternating pattern with equal spacing. Both ends of each P-type and N-type thermoelectric material unit are equipped with Cu blocks, which connect the P-type and N-type thermoelectric material units. One end of the thermoelectric unit string is equipped with the positive terminal of the thermoelectric module layer, and the other end is equipped with the negative terminal of the thermoelectric module layer. Multiple sets of P-type and N-type thermoelectric material units form thermoelectric pairs, with multiple intermediate voltage taps spaced at equal intervals to provide different dynamic voltages. The intermediate voltage taps, the positive terminal of the thermoelectric module layer, and the negative terminal of the thermoelectric module layer are all connected to a voltage switch.

[0006] When the voltage switch is working, it is continuously connected to the negative terminal of the thermoelectric module layer. By connecting different positive terminals of the thermoelectric module layer or intermediate voltage taps, it can achieve graded control of the electrowetting intensity of the cooling water tank. By increasing the local electric field strength applied to the gas-liquid interface, the bubble contact angle of the refrigerant in the cooling water tank is increased, which increases the bubble detachment frequency and reduces the bubble detachment diameter, thereby achieving a stepwise enhancement of the pool boiling heat transfer effect. By decreasing the local electric field strength applied to the gas-liquid interface, the bubble contact angle of the refrigerant in the cooling water tank is reduced, which further reduces the bubble contact angle and enhances the contact line pinning effect, which manifests as a decrease in the bubble detachment frequency and an increase in the bubble detachment diameter, thereby achieving a stepwise weakening of the pool boiling heat transfer enhancement effect.

[0007] The dielectric layer and the coolant are in direct contact.

[0008] When the voltage output provided by the intermediate voltage tap is greater than the dielectric breakdown voltage, the intermediate voltage tap is disconnected from the voltage switch; when the voltage output provided by the intermediate voltage tap is less than the start-up voltage, the intermediate voltage tap is disconnected from the voltage switch.

[0009] The hot end contact layer is made of high thermal conductivity ceramic panel aluminum oxide to ensure efficient heat transfer to the thermoelectric material. The dimensions are 102mm*102mm*0.5mm.

[0010] The cold-end high-temperature resistant thermally conductive ceramic has dimensions of 102mm*102mm*0.5mm, and the surface electrode 10 has dimensions of 100nm*100nm*100mm.

[0011] The surface electrode is a thin metal film made of gold. Periodically arranged linear electrodes are formed on the surface of the cold-end alumina high thermal conductivity ceramic panel module using photolithography. The electrode spacing is preferably 1 mm.

[0012] The dielectric layer uses a Teflon coating, which is spin-coated onto the surface electrode and the alumina high thermal conductivity ceramic panel using spin-coating technology. The spin-coating thickness is between 300nm and 500nm.

[0013] The beneficial effects of this invention are as follows:

[0014] 1. A structure that spontaneously generates an electric field based on the thermoelectric effect to induce rapid bubble detachment. It can generate an electric field without the need for external power supply to enhance the ability of bubbles to detach from the heat exchange surface, thereby improving the overall boiling heat transfer efficiency. It is suitable for applications such as microscale thermal management and high heat flux density heat dissipation.

[0015] 2. By introducing a thermoelectric self-powered electrowetting mechanism, an electrowetting electric field can be locally generated on the heat exchange surface without the need for external power electrodes. Compared with traditional electrowetting solutions, this invention has a simpler structure, higher stability, stronger controllability, and greater engineering adaptability and practicality.

[0016] 3. The voltage switch can select the required level to change the local electric field intensity applied to the gas-liquid interface, thereby changing the bubble contact angle. Due to the contact line pinning effect, this manifests as a change in the bubble detachment frequency and the bubble detachment diameter, thus achieving different pool boiling heat transfer effects. Attached Figure Description

[0017] Figure 1 This is a cross-sectional schematic diagram of the overall structure of an embodiment of the enhanced pool boiling heat transfer device based on a thermoelectric material to provide an electric field, showing the overall interlayer structure of the invention from the hot end to the cold end.

[0018] Figure 2 This is a schematic diagram of the thermoelectric unit array structure in an embodiment of the present invention, illustrating the series arrangement of thermoelectric pairs (n-type / p-type) on a two-dimensional plane;

[0019] Figure 3This is a schematic diagram of a thermoelectric unit array structure with a segmented plug-in structure in an embodiment of the present invention, illustrating the series arrangement of thermoelectric pairs (n-type / p-type) on a two-dimensional plane and the setting of voltage taps;

[0020] Figure 4 This is a schematic diagram of the cold-end thermally conductive ceramic structure in an embodiment of the present invention, showing the three-dimensional configuration of the cold-end channel and the ceramic substrate;

[0021] Figure 5 This is a schematic diagram of the metal wire electrode arrangement in an embodiment of the present invention, showing the spatial region between the periodically alternating electrodes and the range of electric field action.

[0022] Among them, 1-positive terminal of thermoelectric module layer, 2-negative terminal of thermoelectric module layer, 3-Cu block, 4-cold end high temperature resistant thermally conductive ceramic, 5-P-type thermoelectric material unit, 6-N-type thermoelectric material unit, 7-cavity, 8-hot end high temperature resistant thermally conductive ceramic, 9-dielectric layer, 10-linear surface electrode, 11-positive terminal of surface electrode, 12-negative terminal of surface electrode, 13-cooling water tank, 14-voltage switcher. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings.

[0024] like Figures 1-5 The embodiment of the present invention shown includes: a thermoelectric module, a positive terminal 1 of the thermoelectric module layer, a negative terminal 2 of the thermoelectric module layer, and a voltage switch 14. The thermoelectric module includes: a dielectric layer 9, a high-temperature resistant thermally conductive ceramic 4 at the cold end, a thermoelectric unit string, and a hot end contact layer 8, arranged sequentially from cold end to hot end. A linear surface electrode 10 is uniformly disposed on the upper surface of the high-temperature resistant thermally conductive ceramic 4 at the cold end. The thermoelectric unit string consists of P-type thermoelectric material units 5 and N-type thermoelectric material units 6 arranged at equal intervals and staggered. Cu blocks 3 are installed at both ends of both the P-type thermoelectric material units 5 and N-type thermoelectric material units 6. Thermoelectric material unit 5 and N-type thermoelectric material unit 6 are connected by Cu block 3; one end of the thermoelectric unit string is equipped with the positive terminal 1 of the thermoelectric module layer, and the other end is equipped with the negative terminal 2 of the thermoelectric module layer; multiple thermoelectric pairs composed of multiple sets of P-type thermoelectric material units 5 and N-type thermoelectric material units 6 are connected in series to form a regular array-type thermoelectric power generation structure; in the middle of the thermoelectric unit string, multiple intermediate voltage taps 15 are provided with equal number of thermoelectric pairs to provide different dynamic voltages; the intermediate voltage taps 15, the positive terminal 1 of the thermoelectric module layer, and the negative terminal 2 of the thermoelectric module layer are all connected to the voltage switch 14;

[0025] When the voltage switch 14 is working, it is continuously connected to the negative terminal of the thermoelectric module layer. By connecting different positive terminals 1 or intermediate voltage taps 15 of the thermoelectric module layer, it can achieve graded control of the electrowetting intensity of the cooling water tank 13. By increasing the local electric field intensity applied to the gas-liquid interface (with a larger voltage) to increase the bubble contact angle of the refrigerant in the cooling water tank 13, the bubble detachment frequency increases and the bubble detachment diameter decreases, thereby achieving a stepwise enhancement of the pool boiling heat transfer enhancement effect. By decreasing the local electric field intensity applied to the gas-liquid interface (with a smaller voltage) to decrease the bubble contact angle of the refrigerant in the cooling water tank 13, the bubble contact angle decreases further and the contact line pinning effect increases, which manifests as a decrease in the bubble detachment frequency and an increase in the bubble detachment diameter, thereby achieving a stepwise weakening of the pool boiling heat transfer enhancement effect.

[0026] The thermoelectric module is encapsulated as a single piece, with the hot side of the module attached to the heat source wall and the cold side attached to the lower end of the cooling water tank. Its overall thickness does not exceed 3 mm, and its size can be optimized to balance heat dissipation performance and size limitations, making it suitable for microelectronic systems and enclosed heat transfer applications.

[0027] In this embodiment, the dielectric layer 9 is in direct contact with the coolant, so the cavity for containing the coolant includes a cooling water tank 13 and the dielectric layer 9.

[0028] In this embodiment, when the voltage output provided by the intermediate voltage tap is greater than the dielectric breakdown voltage, the intermediate voltage tap is disconnected from the voltage switch 14; when the voltage output provided by the intermediate voltage tap is less than the start-up voltage, the intermediate voltage tap is disconnected from the voltage switch 14.

[0029] In this embodiment, to achieve graded adjustment of the output voltage, a segmented plug-in structure is adopted in the series direction of the thermoelectric unit strings. The voltage switch 14 selects different external terminals as output terminals to obtain multiple output voltages with different amplitudes, thereby achieving different bubble detachment enhancement effects. It is used to switch between multiple voltage taps according to operating parameters, ensuring that the output voltage applied to the surface electrode structure is within a preset safe and effective range. Specifically, the voltage switch 14 forms 16 voltage levels, that is, a set of external terminals is set every 8 rows of thermoelectric pairs along the array length direction, and the voltage interval between adjacent levels is approximately... The voltage switch is composed of a segmented plug-in structure and its corresponding external terminals.

[0030] Figure 2The diagram shows the structure of the thermoelectric unit in this invention. This thermoelectric unit consists of several pairs of n-type and p-type thermoelectric materials connected in series. Each thermoelectric unit has the same size, preferably 0.5 mm × 0.5 mm × 0.8 mm, and is arranged at equal intervals along the horizontal and vertical directions of the module (with a cavity 7). The horizontal spacing is 0.5 mm, and the vertical spacing is 0.25 mm, forming a uniform array. The selected thermoelectric material is Bi₂Te₃, which possesses high thermoelectric performance, as well as good machinability and thermal stability.

[0031] The electrical energy generation of the thermoelectric unit is based on the Seebeck effect. When a temperature difference exists between the hot and cold ends of the thermoelectric material, charge carriers diffuse and migrate from the high-temperature end to the low-temperature end under the influence of thermal driving force, causing charge accumulation at both ends and thus forming a voltage output in the external circuit. In this embodiment, multiple P-type thermoelectric material units 5 and N-type thermoelectric material units 6 are arranged in an alternating S-shape series connection along a predetermined direction, forming a high-density thermoelectric pair array, integrating 6400 thermoelectric pairs N within an effective area of ​​100 mm × 100 mm. The output voltage of the thermoelectric array is determined by the temperature difference between its hot and cold ends, and its open-circuit voltage satisfies… The hot end is heated by a heating platform located below the thermoelectric array, and its temperature can be controlled by adjusting the heating power. The cold end is in direct contact with a pool of coolant and is in a pool boiling heat exchange state, utilizing the latent heat of vaporization of the coolant for efficient heat dissipation. The temperature of the cold end is limited by the saturated boiling temperature of the coolant and its operating conditions. By adjusting the heating power of the hot end and the pool boiling conditions of the cold end, the temperature difference between the hot and cold ends can be changed within the allowable operating range, thereby achieving continuous adjustment of the output voltage. Furthermore, the thermoelectric array is provided with a segmented plug-in structure along its series direction, with voltage taps between adjacent segments led out through external terminals. Different plug-in nodes are selected as output terminals (e.g., ...). Figure 3 It can obtain output voltages of different amplitudes under the same temperature difference conditions, realizing multi-level voltage regulation. By combining temperature difference regulation with segmented plug-in structure, flexible, stable and controllable adjustment of thermoelectric output voltage can be achieved over a wide range, providing continuous and adjustable electric field driving capability for subsequent surface electrode structures.

[0032] A hot-end contact layer is located at the bottom of the module to absorb and conduct heat from external heat sources to the thermoelectric material above. This layer is made of alumina (Al2O3) ceramic plate, 0.5 mm thick, with a thermal conductivity of approximately 25 W / m·K, exhibiting good high-temperature stability, electrical insulation, and thermal coupling characteristics. To reduce interfacial thermal resistance, the surface of this layer is laser-polished and can be pre-coated with a thin metal interface film to enhance thermal coupling with the thermoelectric material. In practical applications, the ceramic plate can be fixed to the hot surface using silver paste, thermally conductive silicone, or vacuum pressing to achieve an efficient and stable thermal connection.

[0033] The cold-end heat dissipation layer is located above the thermoelectric material, with a structure symmetrical to the hot-end, and is also made of alumina ceramic plate. The difference lies in that the upper surface of this ceramic plate has an array of microchannel structures formed using micro-nano fabrication technology, such as... Figure 4 As shown. Each channel has a cross-sectional dimension of 100nm*100nm and a length of 100mm. One channel is created at 1mm intervals along the width of the ceramic substrate, periodically distributed on the module surface. These channels are filled with a highly conductive metallic material, Au (gold), to construct... Figure 5 The periodic alternating electrode array shown.

[0034] The electrode fabrication process is as follows: First, positive photoresist is spin-coated onto the ceramic surface and exposed to ultraviolet light through a mask. After development, an opening pattern of linear channels is formed. Then, reactive ion etching (RIE) or laser direct writing technology is used to etch trenches of corresponding depths on the ceramic substrate surface. After removing the photoresist, a gold layer is deposited over the entire surface using magnetron sputtering or electron beam evaporation, ensuring that it fully fills the trenches. Finally, wet etching (such as with a KI / I2 solution) is used to remove excess metal from the ceramic plane, retaining the Au conductive lines within the channels to form a periodic metal electrode structure. This process combines high resolution with good batch consistency, making it suitable for mass production.

[0035] The resulting Au linear electrode array has alternating positive and negative electrodes, each connected to the output terminal of the thermoelectric array. Driven by a 50V DC voltage, a uniform transverse electric field is formed between the electrodes, with a field strength reaching 40–60 V / mm. This electric field provides stable electrowetting in the liquid bubble growth region on the module surface. Specifically, the electric field influences the contact angle between the liquid and solid (i.e., the Lippmann-Young mechanism), forming an electrowetting zone at the bubble, inducing contact line contraction, and weakening the bubble pinning effect, thereby significantly increasing the bubble detachment frequency and shortening the residence time.

[0036] The operating principle and process of this invention are as follows: First, inject sufficient coolant into the cooling water tank 13, and then seal the cooling water tank; apply thermal grease evenly to the surface of the high-temperature resistant thermally conductive ceramic at the hot end, and then place it on the heating surface to ensure that the two surfaces are in close contact. The thermal grease is used to fill the tiny gaps and uneven surfaces between the surface of the high-temperature thermally conductive ceramic and the heating surface, thereby reducing air gaps and thermal resistance and improving heat transfer efficiency.

[0037] In actual operation, heat is transferred from the high-temperature resistant thermally conductive ceramic 8 at the hot end to the P-type thermoelectric material unit 5 and the N-type thermoelectric material unit 6, and then from the P-type thermoelectric material unit 5 and the N-type thermoelectric material unit 6 to the high-temperature resistant thermally conductive ceramic at the cold end. Coolant (such as HFE7100) is adsorbed onto the surface of the cold end module to cool it, resulting in a large temperature difference between the two ends of the thermoelectric unit, thus generating an electric field between the two linear electrodes 10. As the heat flux density increases, the temperature exceeds the boiling point of the refrigerant, and the refrigerant begins to boil. At this time, the large temperature difference between the two ends of the thermoelectric unit generates a sufficiently large electric field between the two linear electrodes 10. This causes the initial bubbles to increase their contact angle and redistribute the interfacial tension under the influence of the local electric field, creating more favorable mechanical conditions for detachment. Experiments have shown that under the structure of this invention, the bubble detachment diameter decreases and the detachment frequency increases, exhibiting excellent heat transfer enhancement capabilities.

[0038] Furthermore, thanks to the etching-filling process used in the aforementioned electrode structure, this thermoelectric module can achieve self-powered local electric field generation without a high-voltage external power supply, significantly simplifying the peripheral control system. The entire module is manufactured using MEMS-compatible processes, exhibiting excellent on-chip integrability. It can be tailored and combined according to specific application requirements, with single-chip areas ranging from 20 mm² to 100 cm², suitable for various engineering needs ranging from microchip cooling to high-power heat dissipation modules.

[0039] Meanwhile, to ensure long-term stable operation, the modules are bonded together using a multi-layer thermoforming structure, supplemented by edge ceramic encapsulation. A titanium / gold adhesion layer system is used at the electrode-ceramic interface to improve metal adhesion, and inorganic adhesives are added at the thermoelectric material-ceramic interface to prevent peeling. The entire encapsulation structure showed no interlayer separation or performance degradation after thermal cycling testing, demonstrating excellent engineering stability.

[0040] In this embodiment, the thermoelectric material selected is a Bi2Te3-based thermoelectric material with a Seebeck coefficient. It is located in the range of 160 to 220 μV / K. In each thermoelectric pair, the geometric dimensions of the n-type and p-type thermoelectric materials are both 0.5 mm × 0.5 mm × 0.8 mm, the lateral spacing between adjacent thermoelectric pairs is 0.5 mm, and the longitudinal spacing is 0.25 mm.

[0041] On a planar substrate with dimensions of 100 mm × 100 mm, multiple thermocouples are uniformly arranged in a matrix, with 50 thermocouples arranged in each row along the horizontal direction, for a total of 128 rows. Adjacent rows are electrically connected in series through a metal interconnection structure, thus forming an overall thermoelectric array containing N = 6400 thermocouples.

[0042] When there is a temperature difference between the cold end and the hot end of the thermoelectric array At this time, the thermoelectric potentials generated by each thermocouple are superimposed sequentially, forming an output voltage across the array, whose open-circuit voltage satisfies:

[0043]

[0044] By adjusting the operating temperature of the bottom heating platform, the temperature difference between the hot and cold ends can be controlled, thereby obtaining output voltages of different amplitudes. Preferably, the maximum operating temperature of the hot end is not higher than 250 ℃, and the temperature of the cold end is not lower than 0 ℃. Under the condition that the temperature difference between the hot and cold ends is about 40 K, the thermoelectric array can stably output a DC voltage of about 50 V.

[0045] In this embodiment, taking a 300 nm Teflon dielectric layer as an example, the minimum applied voltage must not be lower than the startup voltage of 15V under this dielectric layer thickness, and the maximum voltage must not exceed the breakdown voltage of 65V under this dielectric layer thickness. When the temperature difference between the hot and cold ends... The open-circuit voltage generated at that time is The voltage interval between each adjacent gear is To achieve a significant electrowetting control effect in the cooling water tank, the output voltage applied to the surface electrode structure should preferably be no less than the starting voltage of 15V. This means the voltage switch should be adjusted to a setting greater than the fourth level (18.75V). Furthermore, when the voltage output provided by the intermediate voltage tap is less than the starting voltage, that intermediate voltage tap should be disconnected from the voltage switch 14 (e.g., ...). Figure 3 (As shown).

[0046] Meanwhile, to avoid dielectric layer breakdown, the output voltage is preferably no higher than the breakdown voltage of 65 V. That is, the voltage switch should be adjusted to a level lower than the 13th setting (60.9375 V), and when the voltage output provided by the intermediate voltage tap exceeds the dielectric layer breakdown voltage, that intermediate voltage tap is disconnected from the voltage switch 14. Therefore, by selecting different voltage outputs between the 4th and 13th settings, graded control of the electrowetting intensity can be achieved within the safe operating range. For example, when the temperature difference between the hot and cold ends... The open-circuit voltage generated at that time is The voltage interval between each adjacent gear is To achieve a significant electrowetting control effect in the cooling water tank, the output voltage applied to the surface electrode structure should preferably be no less than the starting voltage of 15V, meaning the voltage switch should be adjusted to a setting greater than level 5 (15.625V). Simultaneously, since the open-circuit voltage is lower than the breakdown voltage, the voltage can be increased to level 16 for full-load operation. Therefore, by selecting different voltage outputs between levels 5 and 16, graded control of the electrowetting intensity can be achieved within the safe operating range.

[0047] In particular, within the voltage regulation range mentioned above, as the selected gear increases, the local electric field strength applied to the gas-liquid interface gradually increases, which further increases the bubble contact angle and weakens the contact line pinning effect. This results in an increase in the bubble detachment frequency and a decrease in the bubble detachment diameter, thereby achieving a stepwise enhancement of the pool boiling heat transfer effect.

[0048] The hot-end contact layer is preferably made of alumina ceramic panel with high thermal conductivity to ensure efficient heat transfer to the thermoelectric material. The panel has dimensions of 102mm*102mm*0.5mm.

[0049] The cold-end heat dissipation layer includes an alumina high thermal conductivity ceramic panel and an electrode arrangement channel. The alumina high thermal conductivity ceramic panel has dimensions of 102mm*102mm*0.5mm (length*width*height), and the surface electrode 10 has dimensions of 100nm*100nm*100mm (length*width*height). The surface electrode 10 is a metal thin film made of gold, and periodically arranged linear electrodes are formed on the surface of the cold-end alumina high thermal conductivity ceramic panel module using photolithography. The electrode spacing is preferably 1mm.

[0050] The dielectric layer uses a Teflon coating, which is spin-coated onto the surface electrode and the alumina high thermal conductivity ceramic panel using spin-coating technology. The spin-coating thickness is between 300nm and 500nm.

[0051] The electric field acts in the space between the electrodes, forming a local transverse electric field that acts on the bubbles during boiling. This induces changes in the contact angle and interface depinning, thereby enhancing the bubble detachment behavior.

Claims

1. A heat transfer device for enhanced pool boiling based on an electric field provided by thermoelectric materials, characterized in that, include: The thermoelectric module includes a thermoelectric module layer positive terminal (1), a cooling water tank (13), a thermoelectric module layer negative terminal (2), and a voltage switch (14). The hot side of the thermoelectric module is attached to the heat source wall, and the cold side of the thermoelectric module is attached to the lower end of the cooling water tank (13). The cooling water tank is filled with a refrigerant. The thermoelectric module includes a dielectric layer (9), a cold-end high-temperature resistant thermally conductive ceramic (4), a thermoelectric unit string, and a hot-end contact layer (8) arranged sequentially from the cold end to the hot end. A linear surface electrode (10) is uniformly arranged on the upper surface of the cold-end high-temperature resistant thermally conductive ceramic (4). The thermoelectric unit string is composed of P-type thermoelectric material units (5) and N-type thermoelectric material units (6) arranged at equal intervals. Both ends of the material unit (5) and the N-type thermoelectric material unit (6) are equipped with Cu blocks (3), and the P-type thermoelectric material unit (5) and the N-type thermoelectric material unit (6) are connected by Cu blocks (3); one end of the thermoelectric unit string is equipped with a positive terminal (1) of the thermoelectric module layer, and the other end is equipped with a negative terminal (2) of the thermoelectric module layer; the P-type thermoelectric material unit (5) and the N-type thermoelectric material unit (6) form a thermoelectric pair; in the middle of the thermoelectric unit string, multiple intermediate voltage taps (15) are provided with equal numbers of thermoelectric pairs to provide different dynamic voltages; the intermediate voltage taps (15), the positive terminal (1) of the thermoelectric module layer and the negative terminal (2) of the thermoelectric module layer are all connected to the voltage switch (14); When the voltage switch (14) is working, it is continuously connected to the negative terminal of the thermoelectric module layer. By connecting different positive terminals (1) or intermediate voltage taps (15) of the thermoelectric module layer, the electrowetting intensity of the cooling water tank (13) can be graded and controlled. By increasing the local electric field intensity applied to the gas-liquid interface, the bubble contact angle of the refrigerant in the cooling water tank (13) is increased, which increases the bubble detachment frequency and reduces the bubble detachment diameter, thereby achieving a gradual enhancement of the pool boiling heat transfer enhancement effect. By decreasing the local electric field intensity applied to the gas-liquid interface, the bubble contact angle of the refrigerant in the cooling water tank (13) is reduced, which further reduces the bubble contact angle and enhances the contact line pinning effect, which manifests as a decrease in the bubble detachment frequency and an increase in the bubble detachment diameter, thereby achieving a gradual weakening of the pool boiling heat transfer enhancement effect.

2. The enhanced pool boiling heat transfer device based on an electric field provided by thermoelectric materials according to claim 1, characterized in that... The dielectric layer (9) and the coolant in the cooling water tank (13) are in direct contact.

3. A heat transfer device for enhanced pool boiling based on an electric field provided by a thermoelectric material, as described in claim 1 or 2, characterized in that... When the voltage output provided by the intermediate voltage tap is greater than the dielectric breakdown voltage, the intermediate voltage tap is disconnected from the voltage switch (14); when the voltage output provided by the intermediate voltage tap is less than the start-up voltage, the intermediate voltage tap is disconnected from the voltage switch (14).

4. The enhanced pool boiling heat transfer device based on an electric field provided by thermoelectric materials according to claim 1, characterized in that... The hot end contact layer is made of high thermal conductivity ceramic panel aluminum oxide to ensure efficient heat transfer to the thermoelectric material. The dimensions are 102mm*102mm*0.5mm.

5. The enhanced pool boiling heat transfer device based on an electric field provided by thermoelectric materials according to claim 1, characterized in that... The cold end high temperature resistant thermal conductive ceramic (4) has a length, width and height of 102mm*102mm*0.5mm, and the surface electrode 10 has a length, width and height of 100nm*100nm*100mm.

6. The enhanced pool boiling heat transfer device based on an electric field provided by thermoelectric materials according to claim 5, characterized in that... The surface electrode (10) is a metal thin film made of gold. It is formed by photolithography on the surface of the cold-end alumina high thermal conductivity ceramic panel module with periodically arranged linear electrodes. The electrode spacing is preferably 1 mm.

7. A heat transfer device for enhanced pool boiling based on an electric field provided by a thermoelectric material, as described in claim 1 or 2, characterized in that... The dielectric layer uses a Teflon coating, which is spin-coated onto the surface electrode and the alumina high thermal conductivity ceramic panel using spin-coating technology. The spin-coating thickness is between 300nm and 500nm.

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