A high-flux heat exchange device based on thermo-chemical reaction assistance

Abstract

The application discloses a high-flux heat exchange device based on a thermo-chemical reaction auxiliary, which comprises a heat exchange chamber and a chemical phase change working medium. The chemical phase change working medium comprises a liquid cooling base fluid and a reversible thermal decomposition solute. The thermal decomposition temperature threshold of the reversible thermal decomposition solute is lower than the physical boiling point of the liquid cooling base fluid under the current environment. When the temperature or pressure of the heat exchange surface reaches the thermal decomposition temperature threshold, the reversible thermal decomposition solute undergoes an endothermic decomposition reaction on the heat exchange surface, rapidly generates a large number of non-condensable bubbles and high-frequency separates, thereby triggering strong local micro-convection disturbance of the fluid and absorbing a large amount of chemical decomposition heat, and finally achieving heat dissipation of the heating element. The application accelerates the transfer of wall heat by using a thermo-chemical reaction, and improves the separation rate of bubbles at the solid-liquid interface, breaks the engineering resistance that bubbles are difficult to nucleate and efficiently separate in traditional boiling heat transfer, and realizes rapid and large absorption and transfer of the combined chemical reaction heat of the solute and the latent heat of vaporization of the base fluid.

Description

Technical Field

[0001] This invention relates to the field of efficient thermal management technology for power equipment, high-power electronic chips and energy storage systems, and specifically to a high-throughput heat exchange device based on thermochemical reaction assistance. Background Technology

[0002] With the rapid development of high-power chips, converter valves, and new energy storage devices, the heat generation and local heat flux density of equipment components have increased dramatically. Traditional single-phase liquid cooling mainly relies on the absorption of sensible heat by the temperature rise of the cooling medium itself, resulting in relatively low heat transfer efficiency and upper limits for heat flux density. Therefore, flow boiling and pool boiling technologies have become mainstream methods for solving high heat flux density heat dissipation due to their advantages such as utilizing the latent heat of vaporization of liquids, high heat transfer efficiency, and small temperature rise of the cooling medium. However, when facing the extreme high heat flux density conditions of modern industry, traditional physical boiling heat transfer technology faces insurmountable limitations in heat transfer limits and reliability.

[0003] The main reason for the limitations of conventional physical boiling heat transfer lies in its inherent phase transition kinetics. First, the boiling of conventional liquids exhibits a significant "boiling initiation hysteresis," meaning that extremely high wall superheat (e.g., pure water often requires a heating surface temperature well above 100°C) is required to generate the first batch of vaporization nuclei. This transient temperature overload can easily cause irreversible thermal damage to sensitive electronic components. Second, under continuous heating at high heat flux density, the rate of bubble generation on the heat exchange surface increases dramatically, often far exceeding the rate at which bubbles detach from the wall. A large number of bubbles that fail to detach in time remain on the heating wall and undergo violent lateral coalescence, eventually forming a heat-insulating gas film covering the heat exchange surface. This gas film causes the boiling mode to deteriorate from efficient nucleus boiling to inefficient film boiling (i.e., a deviation from nucleus boiling), thus completely blocking the wetting and cooling of the heating wall by fresh coolant, leading to a sharp deterioration in local heat transfer, and even causing the equipment to burn out directly. Summary of the Invention

[0004] To address the issues of low upper limit of heat flux density in single-phase liquid cooling and "boiling lag" (requiring extremely high wall superheat) and easy agglomeration of bubbles forming an insulating gas film in pure water boiling cooling, which leads to deterioration of heat transfer, this invention provides a high-flux heat exchange device based on thermochemical reaction assistance. This device introduces easily decomposable chemical solutes under specific operating conditions into the cooling base liquid, and, in conjunction with the microstructure control of the heat exchange surface, while maintaining the minimalist system architecture, utilizes a three-level synergistic mechanism of latent heat of chemical decomposition, providing dense physical vaporization nuclei, and inducing non-boiling volatilization of the base liquid. This significantly breaks through the engineering bottleneck of slow bubble detachment in homogeneous chemical reactions, and improves the flow field stability and ultimate heat flux density under extreme heat loads.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a high-throughput heat exchange device based on thermochemical reaction assistance, comprising: A chemical phase change working fluid, which fills or circulates within a heat exchange chamber, the chemical phase change working fluid comprising a liquid cooling base fluid and a solute, the solute comprising a reversibly thermally decomposable solute, and the thermal decomposition temperature threshold of the reversibly thermally decomposable solute being lower than the physical boiling point of the liquid cooling base fluid under the current environment; The heat exchange chamber includes a heat exchange surface. The outer side of the heat exchange surface is used for thermally conducting and connecting external heating elements. When the temperature or pressure of the heat exchange surface reaches the thermal decomposition temperature threshold, the reversible thermally decomposed solute undergoes an endothermic decomposition reaction on the heat exchange surface, rapidly generating a large number of non-condensable bubbles that detach at high frequency, thereby triggering strong local micro-convective disturbances in the fluid and absorbing a large amount of chemical decomposition heat, ultimately achieving heat dissipation for the heating elements.

[0006] Preferably, the reversible thermally decomposable solute is a substance with high heat of reaction, and the liquid cooling base liquid is a medium with high latent heat of vaporization.

[0007] Preferably, the solute further includes a surfactant used to inhibit bubble coalescence.

[0008] Preferably, an artificial vaporization core area is provided on the inner side of the heat exchange surface to increase the number of bubble attachment points and accelerate bubble peeling.

[0009] Preferably, the artificial vaporization core region includes a microstructured surface.

[0010] Preferably, the microstructure surface includes one or more combinations of machined microgrooves, laser-etched micropores, sintered porous layers of metal powder, or inorganic coatings with micro- and nano-pores.

[0011] Preferably, a catalytic medium layer that promotes the acceleration of chemical reactions is attached to the surface of the microstructure. The catalytic medium layer is used to accelerate the dehydration rate of reversible thermally decomposable solutes at the solid-liquid interface.

[0012] Preferably, the catalytic medium layer can also be arranged alternately with the microstructure surface to form an artificial vaporization core region.

[0013] Preferably, the device is further equipped with a pressure regulation and control system, which is connected to the inlet end of the heat exchange chamber; the system can actively establish a negative pressure suction state in the heat exchange chamber according to the temperature feedback of the heating element, thereby forcibly accelerating the precipitation and expansion of chemical bubbles by reducing the local environmental pressure.

[0014] Preferably, the device further includes a working fluid concentration dynamic adjustment loop, which includes a concentration sensor, a high-concentration replenishment tank and a low-concentration dilution tank; when the heating element is in a high power consumption stage, the loop injects a high-concentration working fluid into the heat exchange chamber to store heat dissipation capacity; when the device is in a low power consumption stage, a low-concentration working fluid is injected in a timely manner to flush the hot end, so as to prevent a large amount of gas from accumulating and hindering the contact between the heat sink and the liquid.

[0015] Preferably, the exhaust port of the heat exchange chamber is connected to the condensation recovery module through a pipe. The condensation recovery module is located at the low-temperature heat dissipation end and is used to cool and pressurize the mixed bubbles that are discharged after absorbing heat, so that they are re-dissolved and merged to release heat. The condensed working fluid is returned to the heat exchange chamber through a capillary reflux component or a micro water pump.

[0016] Advantages of this invention: Compared with the prior art, the present invention has the following significant advantages: 1. This invention utilizes the synergistic effect of chemical phase change and physical evaporation. Under basic operating conditions, the device can meet the cooling requirements of conventional standby heat generation simply by relying on decomposition endothermic heat generation; while under extremely high load conditions, the combination of chemical decomposition and base liquid evaporation will significantly increase the heat flux density. Overall, it breaks through the performance limits of traditional pure physical boiling. According to engineering scaling analysis, the exhaust heat flux density can cover a wide range from approximately 0.2 W / cm² to 125 W / cm², adaptively meeting the various heat dissipation requirements of high-power electronic components from low load to extreme full load.

[0017] 2. This invention advances the trigger point for high-throughput heat exchange to before the boiling of the base liquid (e.g., 60℃~80℃ in an NH4HCO3 aqueous solution cooling system). The early non-condensable bubbles generated by thermal decomposition directly adhere to the heat exchange wall surface, serving as ready-made vaporization nuclei for the phase change of the base liquid. This allows the system to transition to the intense nucleation boiling stage without any delay and with extreme smoothness, completely eliminating the risk of temperature overload at the initial stage of boiling.

[0018] 3. The solute-containing solution used in this invention, compared to a pure single-component working fluid, can induce a specific concentration distribution of solute molecules or ions at the gas-liquid interface to a certain extent. This distribution significantly alters the local surface tension, creating steric hindrance and repulsive forces when adjacent bubbles approach each other, inhibiting lateral bubble coalescence, and allowing bubbles to maintain a high-frequency, small state and rapidly detach from the wall. This greatly delays the occurrence of deviating from nucleus boiling (DNB) crisis, ensuring the long-term stable operation of the device under extreme conditions.

[0019] 4. The device of this invention has a simple structure, is easy to manufacture, and is highly adaptable, providing an innovative solution for efficient and compact thermal management of high-power electronic chips, converter valves, and new energy storage equipment. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the flow boiling system structure according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the flow boiling system structure according to Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the pool boiling heat exchange device according to Embodiment 3 of the present invention.

[0021] 1. Chemical phase change working fluid; 2. Heat exchange chamber; 3. Heat exchange surface; 4. Heating element; 5. External fluid drive pump; 6. Condenser; 7. Concentration sensor; 8. Working fluid concentration dynamic adjustment circulation loop; 9. V-groove microstructure; 10. Heat spreader; 11. Working fluid replenishment pipeline; 12. Working fluid suction pipeline. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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 accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0023] This invention provides a high-throughput heat exchange device based on thermochemical reaction assistance, comprising a heat exchange chamber 2 filled or circulated with a chemical phase change working fluid 1. The chemical phase change working fluid 1 comprises a liquid cooling base liquid and a solute, wherein the solute includes a reversibly thermally decomposable solute, and the thermal decomposition temperature threshold of the reversibly thermally decomposable solute is lower than the physical boiling point of the liquid cooling base liquid under the current environment. At least one side of the heat exchange chamber 2 is a heat exchange surface 3, the outer side of which is used for thermally conductive connection to an external heating element 4. When the temperature or pressure of the heat exchange surface 3 reaches the thermal decomposition temperature threshold, the reversibly thermally decomposable solute undergoes an endothermic decomposition reaction on the heat exchange surface 3, rapidly generating a large number of non-condensable bubbles that detach at high frequency, thereby inducing strong local micro-convective disturbances in the fluid and absorbing a large amount of chemical decomposition heat, ultimately achieving heat dissipation for the heating element 4.

[0024] The efficient heat transfer process of the device involves a three-stage progressive physical mechanism: First, the reversibly thermally decomposed solute undergoes a chemical decomposition reaction on the heat exchange surface 3, directly absorbing a large amount of latent heat of chemical decomposition; second, the non-condensable gas produced by decomposition forms microbubbles on the heat exchange surface 3, providing dense physical vaporization nuclei for the subsequent boiling of the liquid cooling base liquid; finally, the vapor partial pressure inside the generated bubbles is extremely low, causing the liquid cooling base liquid to undergo violent volatilization in a non-boiling state at the gas-liquid interface, further absorbing the latent heat of volatilization and accelerating the expansion and release of the bubbles.

[0025] As a preferred embodiment of the present invention, the reversible thermally decomposable solute is a substance with a high heat of reaction, such as ammonium bicarbonate or sodium bicarbonate; the liquid cooling base liquid is a medium with a high latent heat of vaporization, such as pure water or an aqueous solution containing antifreeze additives.

[0026] As a preferred embodiment of the present invention, an appropriate amount of surfactant may be added to the solute. The surfactant is used to reduce the gas-liquid interfacial tension, inhibit the aggregation behavior of bubbles on the heat exchange surface 3, and maintain the rapid detachment of high-frequency small bubbles. The surfactant may be sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Triton X-100, or Tween-80. Sodium dodecyl sulfate uses electrostatic repulsion to prevent the aggregation of bubbles and maintain the high-frequency detachment of bubbles. Sodium dodecylbenzene sulfonate, on the one hand, inhibits bubble aggregation through electrostatic repulsion, and on the other hand, increases the surface hydrophilicity of the heat exchange surface 3, thereby enhancing the activation surface of the chemical decomposition reaction and promoting the endothermic reaction. Triton X-100 or Tween-80: both are nonionic surfactants that prevent bubble aggregation through molecular steric hindrance effect, while enhancing the wettability of the heat exchange surface 3 and improving the bubble nucleation and detachment process.

[0027] As a preferred embodiment of the present invention, the inner side of the heat exchange surface 3 is partially or entirely processed with an artificial vaporization core area to increase the bubble attachment points and accelerate bubble peeling.

[0028] As a preferred embodiment of the present invention, the artificial vaporization core region includes a microstructured surface, which includes one or more combinations of machined microgrooves, laser-etched micropores, sintered porous layers of metal powder, or inorganic coatings with micro-nano pores.

[0029] Preferably, a catalytic medium layer (such as titanium dioxide, zinc oxide, etc.) that promotes the acceleration of chemical reactions is attached to the surface of the microstructure. This layer is used to reduce the activation energy of the reaction at the solid-liquid interface and to directionally accelerate the decomposition, gas production, and stripping rate of the solute at specific locations.

[0030] Of course, the catalytic medium layer can also be arranged alternately with the microstructure surface to form an artificial vaporization core region.

[0031] Example 1 The high-throughput heat exchanger based on thermochemical reaction assistance is an active flow boiling system that forms a complete fluid circulation loop, suitable for industrial-grade heat exchange scenarios with extreme thermal shock and requiring long-term continuous operation. The system includes the aforementioned heat exchange chamber 2, a pressure regulation and control system, and a condensation recovery module. The heat exchange chamber 2 contains the aforementioned chemical phase change working fluid 1, the pressure regulation and control system includes an external fluid-driven pump 5, and the condensation recovery module includes a condenser.

[0032] See Figure 1 The exhaust port and air inlet of the heat exchange chamber 2 are connected to the condenser via pipes, forming a closed fluid circulation loop. The condenser is located at the low-temperature heat dissipation end, and an external fluid drive pump 5 is installed on the air inlet pipe. The bottom surface of the inner side of the heat exchange chamber 2 serves as the heat exchange surface 3, and the outer side of its bottom surface is connected to the external heating element 4 via a heat spreader 10. The operating temperature is 100 degrees Celsius at normal pressure. The chemical phase change cooling medium circulating in the chamber is an aqueous solution of ammonium bicarbonate within a specified mass fraction range.

[0033] During operation, when heat exchange surface 3 is subjected to extreme thermal loads and its local temperature reaches the decomposition threshold of ammonium bicarbonate, the external fluid-driven pump 5 is activated. This forces the chemical phase change cooling medium to flow rapidly through heat exchange surface 3, causing the ammonium bicarbonate to decompose and generate tiny bubbles. The vaporization nuclei generated at this time cause the water solute to rapidly evaporate without boiling at the gas-liquid interface. The bubbles expand rapidly and are forcibly stripped from the wall surface under the shear force of the fluid (the already condensed medium in the condenser) provided by the external fluid-driven pump 5. Subsequently, the gas-liquid mixture carrying a large amount of latent heat and gas is transported to the downstream condenser. At the low-temperature condensation end, the gas redissolves in the liquid cooling base fluid and combines to release heat, completely restoring the initial cooling liquid state, thus completing the closed-loop zero-consumption cycle of the system.

[0034] Example 2 See Figure 2 Based on Embodiment 1, this embodiment further includes a dynamic working fluid concentration adjustment loop 8, which specifically comprises a concentration sensor 7, a high-concentration replenishment tank, and a low-concentration dilution tank. The concentration sensor 7 is installed inside the heat exchange chamber 2 to measure the working fluid concentration in the heat exchange chamber 2 in real time. The high-concentration replenishment tank and the low-concentration dilution tank are connected to the heat exchange chamber 2 via a working fluid inlet pipe 11 and a working fluid suction pipe 12, respectively. When the heating element 4 is in a high-power consumption stage, a low-concentration working fluid is drawn through the working fluid suction pipe 12 and a high-concentration working fluid is injected into the heat exchange chamber 2 through the working fluid inlet pipe 11 to reserve heat dissipation capacity. When the device is in a low-power consumption stage, a high-concentration working fluid is drawn in a timely manner and a low-concentration working fluid is injected to flush the hot end, preventing a large amount of gas from accumulating and hindering the contact between the heat sink and the liquid. The working fluid flow can be achieved through a small auxiliary pump and a matching injection device.

[0035] Example 3 Thermochemical reaction-assisted high-throughput heat exchangers are pool boiling heat exchangers that do not require a circulation loop. They are suitable for maintenance-free, space-constrained, or lightweight heat exchange scenarios with strict noise requirements. See also Figure 3 The heat exchange chamber 2 of this device is a closed chamber with a heat exchange surface 3 at the bottom and a V-shaped groove microstructure 9 on the surface. A metal oxide catalyst coating is also attached to the microstructure. The chamber contains an aqueous medium containing dissolved sodium bicarbonate and surfactant.

[0036] Under boiling conditions, the catalyst coating significantly lowers the reaction threshold for solute decomposition, accelerating the gas production rate. Sodium bicarbonate preferentially aggregates and decomposes at the wall microstructure to form microbubbles, followed by intense non-boiling volatilization from the water-based liquid into the bubble interior at the gas-liquid interface. Surfactants are directionally adsorbed at the gas-liquid interface, significantly reducing the surface tension. This makes it difficult for the densely generated chemical bubbles on heat exchange surface 3 to adsorb and coalesce into a large-area gas film, instead maintaining a small and independent morphology. Due to the small volume of individual bubbles, under the combined action of buoyancy and the expansion force of non-boiling volatilization of the internal base liquid, they can continuously detach from heat exchange surface 3 at a very high frequency and float upwards. The detachment of the high-frequency microbubble cluster not only smoothly carries away the latent heat of decomposition and volatilization, but also spontaneously triggers strong natural convection in the static chamber, rapidly displacing the high-temperature medium at the bottom.

[0037] In this embodiment, sodium bicarbonate decomposes into carbon dioxide at the hot end and escapes to the cold end, such as the gas-liquid interface of a boiling pool. At this temperature, the carbon dioxide encounters sodium carbonate in the solute at the interface and recombines. In particular, in some extreme operating conditions that require efficient recombination, spraying, atomization, or other methods can be used to facilitate this recombination.

[0038] In summary, the device proposed in this invention involves the decomposition of solute in the cooling base liquid, which absorbs heat and releases gas. Specifically, under specific conditions (such as a certain temperature or pressure), the solute decomposes on the heat exchange wall surface corresponding to the heating element, absorbing heat and rapidly generating a large number of bubbles on the surface. This invention utilizes thermochemical reactions to significantly accelerate heat transfer across the wall surface and increase the bubble detachment rate at the solid-liquid interface. It overcomes the engineering resistance of traditional boiling heat transfer, which is difficult for bubbles to nucleate and detach efficiently. Even at temperatures significantly lower than the boiling point of the coolant (such as 60℃~80℃ in an NH4HCO3 aqueous solution cooling system), it achieves rapid and large-scale absorption and transfer of the heat of solute chemical reaction combined with the latent heat of vaporization of the base liquid. Engineering scaling analysis verifies that the heat flux density of this device can adaptively transition from basic heat transfer to extreme bursts, with exhaust heat flux density roughly covering the range of 0.2 W / cm² to 125 W / cm², perfectly meeting the heat dissipation requirements of current high-power industrial electronic components.

[0039] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the scope of protection of the present invention.

Claims

1. A high-throughput heat exchanger based on thermochemical reaction assistance, characterized in that, include: A chemical phase change working fluid (1) is filled or circulated in a heat exchange chamber (2). The chemical phase change working fluid (1) comprises a liquid cooling base liquid and a solute. The solute includes a reversibly thermally decomposable solute, and the thermal decomposition temperature threshold of the reversibly thermally decomposable solute is lower than the physical boiling point of the liquid cooling base liquid under the current environment. The heat exchange chamber (2) includes a heat exchange surface (3). The outer side of the heat exchange surface (3) is used to conduct heat to connect the external heating element (4). When the temperature or pressure of the heat exchange surface (3) reaches the thermal decomposition temperature threshold, the reversible thermally decomposed solute undergoes an endothermic decomposition reaction on the heat exchange surface (3), rapidly generating a large number of non-condensable bubbles that detach at high frequency, thereby triggering strong local micro-convective disturbances in the fluid and absorbing a large amount of chemical decomposition heat, ultimately achieving heat dissipation for the heating element (4).

2. The apparatus according to claim 1, characterized in that: The reversible thermally decomposable solute is a substance with high heat of reaction, and the liquid cooling base liquid is a medium with high latent heat of vaporization.

3. The apparatus according to claim 1, characterized in that: The solute also includes a surfactant, which is used to inhibit bubble coalescence.

4. The apparatus according to claim 1, characterized in that: The heat exchange surface (3) has an artificial vaporization core area on its inner side, which is used to increase the bubble attachment points and accelerate bubble peeling.

5. The apparatus according to claim 4, characterized in that: The artificial vaporization core region includes a microstructured surface and / or a catalytic medium layer that promotes the acceleration of chemical reactions. The catalytic medium layer is used to accelerate the dehydration rate of reversible thermally decomposed solutes at the solid-liquid interface.

6. The apparatus according to claim 5, characterized in that: The catalytic medium layer is attached to the surface of the microstructure, or the catalytic medium layer and the microstructure surface are arranged alternately.

7. The apparatus according to claim 6, characterized in that: The microstructure surface includes one or more combinations of machined microgrooves, laser-etched micropores, sintered porous layers of metal powder, or inorganic coatings with micro- and nano-pores.

8. The apparatus according to any one of claims 1-7, characterized in that: The device is also equipped with a pressure regulation and control system, which is connected to the inlet end of the heat exchange chamber (2). The system can actively establish a negative pressure suction state in the heat exchange chamber (2) based on the temperature feedback of the heating element (4), thereby forcibly accelerating the precipitation and expansion of chemical bubbles by reducing the local environmental pressure.

9. The apparatus according to claim 8, characterized in that: The device also includes a working fluid concentration dynamic adjustment loop (8), which includes a concentration sensor (7), a high-concentration replenishment tank and a low-concentration dilution tank; when the heating element (4) is in the high power consumption stage, the loop injects a high-concentration working fluid into the heat exchange chamber (2) to store heat dissipation capacity; when the device is in the low power consumption stage, a low-concentration working fluid is injected in time to flush the hot end to prevent a large amount of gas from accumulating and hindering the contact between the heat sink and the liquid.

10. The apparatus according to claim 8, characterized in that: The exhaust port of the heat exchange chamber (2) is connected to the condensation recovery module through a pipe. The condensation recovery module is located at the low temperature heat dissipation end and is used to cool and pressurize the mixed bubbles that are discharged after absorbing heat, so that they are re-dissolved and merged to release heat. The condensed working fluid is returned to the heat exchange chamber (2) through a capillary reflux component or a micro water pump.

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