Liquid wick and loop heat pipe device

Abstract

A liquid absorber and a loop heat pipe device includes a first liquid absorber channel, a second liquid absorber channel, and a third liquid absorber channel that are interconnected. The initial pore size of the first liquid absorber channel, the second liquid absorber channel, and the third liquid absorber channel gradually increases, and the initial pore density of the first liquid absorber channel, the second liquid absorber channel, and the third liquid absorber channel gradually decreases. This results in the liquid absorber having a large specific surface area and pore density, which can increase the contact area between the working fluid and the liquid absorber, thereby enhancing the heat transfer efficiency.

Description

Technical Field

[0001] This invention relates to the field of heat and mass transfer technology of loop heat pipes, and particularly to a liquid wick and a loop heat pipe device. Background Technology

[0002] Loop heat pipes utilize the phase change of the working fluid for heat transfer, effectively expanding the heat dissipation surface and solving the heat dissipation problem of high-power devices. They not only offer excellent heat transfer performance but are also lightweight and compact. The phase change process (evaporation and condensation) of the working fluid in the wick achieves heat transfer. When the temperature of the heat source increases, the working fluid evaporates in the wick, and heat is transferred to the condenser with the vapor. Subsequently, the working fluid liquefies in the condenser, releasing heat, and then returns to the evaporator through the capillary action of the wick. This cycle continues, completing the heat transfer process.

[0003] However, the wick is the most crucial component of a loop heat pipe, and its capillary suction performance directly determines the heat transfer performance of the loop heat pipe. Conventional wicks have a constant pore size, resulting in poor capillary suction performance and poor long-distance heat transfer. Further improvements to existing wicks are needed to achieve superior heat transfer capabilities. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a liquid-absorbing core and a loop heat pipe device.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A liquid-absorbing core includes a first liquid-absorbing channel, a second liquid-absorbing channel, and a third liquid-absorbing channel. The pore sizes of the first, second, and third liquid-absorbing channels gradually increase, and the pore densities of the first, second, and third liquid-absorbing channels gradually decrease. The first, second, and third liquid-absorbing channels are made of shape memory polymers, pressure-sensitive materials, or shape memory alloys.

[0007] Furthermore, the first liquid absorption channel has a pore size of 20-200 μm and a pore density of 500-1000 PPI; the second liquid absorption channel has a pore size of 30-300 μm and a pore density of 500-1000 PPI; and the third liquid absorption channel has a pore size of 40-400 μm and a pore density of 500-1000 PPI.

[0008] Furthermore, the shape memory alloy is a CuZnAl shape memory alloy, a NiTi shape memory alloy, or a CuAlNi shape memory alloy.

[0009] Furthermore, the shape memory polymer is a polyurethane-based shape memory polymer, a polyether ester-based shape memory polymer, or a polyimide-based shape memory polymer.

[0010] Furthermore, the pressure-sensitive material is an acrylic pressure-sensitive adhesive, a polyethylene film, or a carbon nanotube pressure-sensitive fiber.

[0011] A loop heat pipe device, characterized in that it includes a liquid wick as described above.

[0012] Furthermore, the system includes an evaporator, a condenser, a steam manifold, and a liquid manifold. The evaporator has a liquid inlet and a gas outlet. The condenser has a gas inlet and a liquid outlet. The two ends of the steam manifold are respectively connected to the liquid inlet and the liquid outlet. The two ends of the liquid manifold are respectively connected to the gas inlet and the gas outlet. The liquid suction core is disposed inside the evaporator. The first liquid suction channel is close to the liquid manifold, and the third liquid suction channel is close to the steam manifold.

[0013] Furthermore, the evaporator, condenser, steam manifold, and liquid manifold are all equipped with shells, which are connected by welding, and each shell is provided with a vacuum of 1×10⁻⁶. -3 pa-1×10 -6 pa.

[0014] Furthermore, the shell material is copper, aluminum, or stainless steel, and the shell thickness is 0.5mm to 1mm.

[0015] Furthermore, a heat sink is connected to the outside of the evaporator. The heat sink has a planar thermal conductivity of 500 to 2000 W / (m·K) and a thickness of 0.05 mm to 0.6 mm.

[0016] The beneficial effects of this invention are:

[0017] 1. The present invention proposes a liquid suction core, comprising a first liquid suction channel, a second liquid suction channel, and a third liquid suction channel that are interconnected. The initial pore size of the first liquid suction channel, the second liquid suction channel, and the third liquid suction channel gradually increases, and the initial pore density of the first liquid suction channel, the second liquid suction channel, and the third liquid suction channel gradually decreases, so that the liquid suction core has a large specific surface area and pore density, which can increase the contact area between the working fluid and the liquid suction core, effectively improve its capillary suction performance, and thus enhance the heat transfer efficiency.

[0018] 2. The present invention proposes a liquid wick made of shape memory polymer, pressure-sensitive material or shape memory alloy. The liquid wick has intelligent response characteristics such as temperature and pressure. It can automatically adjust the orifice size according to the temperature, pressure and other conditions during the operation of the loop heat pipe, so as to meet the requirements of the loop heat pipe liquid wick for capillary suction force and flow resistance. This allows the liquid wick to always work in the optimal state under different operating conditions, thereby achieving more efficient heat and mass transfer performance and increasing the flexibility of the overall structure. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a liquid-absorbing core according to the present invention;

[0021] Figure 2 This is a schematic diagram of a loop heat pipe device according to the present invention.

[0022] In the diagram, 10 is the liquid suction core; 101 is the first liquid suction channel; 102 is the second liquid suction channel; 103 is the third liquid suction channel; 20 is the loop heat pipe device; 201 is the evaporator; 2011 is the liquid inlet; 2012 is the gas outlet; 202 is the condenser; 2021 is the gas inlet; 2022 is the liquid outlet; 203 is the steam connector; 204 is the liquid connector; and 205 is the heat sink. Detailed Implementation

[0023] The following is combined with Figure 1-2 The present invention will be described in detail below.

[0024] The present invention proposes a liquid-absorbing core 10, comprising a first liquid-absorbing channel 101, a second liquid-absorbing channel 102, and a third liquid-absorbing channel 103 that are interconnected. The pore sizes of the first liquid-absorbing channel 101, the second liquid-absorbing channel 102, and the third liquid-absorbing channel 103 gradually increase, and the pore densities of the first liquid-absorbing channel 101, the second liquid-absorbing channel 102, and the third liquid-absorbing channel 103 gradually decrease. The first liquid-absorbing channel 101, the second liquid-absorbing channel 102, and the third liquid-absorbing channel 103 are made of shape memory polymer, pressure-sensitive material, or shape memory alloy.

[0025] Therefore, compared to a wick 10 with only a constant pore size and pore density, this wick 10 is composed of a first wicking channel 101, a second wicking channel 102, and a third wicking channel 103 with different pore sizes and pore densities. It has a larger specific surface area and pore density, which increases the contact area between the working fluid and the wick 10, thereby enhancing heat transfer efficiency. Furthermore, this wick 10 is made of shape memory polymers, pressure-sensitive materials, or shape memory alloys. The manufactured wick 10 has intelligent response characteristics to temperature and pressure, and can automatically adjust the pore size according to the temperature and pressure conditions during the operation of the loop heat pipe. This meets the requirements of the loop heat pipe wick 10 for capillary suction force and flow resistance, ensuring that the wick 10 always operates in its optimal state under different operating conditions, thereby achieving more efficient heat and mass transfer performance and increasing the flexibility of the overall structure.

[0026] In this embodiment, the pore size of the first liquid absorption channel 101 is 20-200 μm and the pore density is 500-1000 PPI; the pore size of the second liquid absorption channel 102 is 30-300 μm and the pore density is 500-1000 PPI; and the pore size of the third liquid absorption channel 103 is 40-400 μm and the pore density is 500-1000 PPI.

[0027] In this embodiment, the shape memory alloy is a CuZnAl shape memory alloy, a NiTi shape memory alloy, or a CuAlNi shape memory alloy. The shape memory polymer is a polyurethane-based shape memory polymer, a polyether ester-based shape memory polymer, or a polyimide-based shape memory polymer. The pressure-sensitive material is an acrylic pressure-sensitive adhesive, a polyethylene film, or a carbon nanotube pressure-sensitive fiber.

[0028] In this embodiment, the liquid absorption core 10 is manufactured by 4D printing technology. Its laser scanning power ranges from 10W to 1000W, and its laser scanning speed ranges from 1mm / s to 100mm / s. The scanning path includes one or more of transverse scanning, spiral scanning, and interlayer scanning.

[0029] In this embodiment, CuZnAl shape memory alloy is used as the printing material, and 3D modeling software is used to design the specific structure of the liquid absorption core 10, specifically:

[0030] The parameters of each segment of the suction core 10 are as follows: the pore size of the first suction channel 101 is 20 μm, and the pore density is 634 PPI; the pore size of the second suction channel 102 is 30 μm, and the pore density is 508 PPI; the pore size of the third suction channel 103 is 40 μm, and the pore density is 508 PPI. In other embodiments, the opening type of the first suction channel 101, the second suction channel 102, and the third suction channel 103 can be elliptical, square, or polygonal.

[0031] The printing parameters are as follows: laser scanning power 300W, laser scanning speed 1mm / s, processing path direction moves from the first liquid suction channel 101 to the third liquid suction channel 103, and the thickness direction is filled layer by layer.

[0032] The liquid-absorbing core 10 proposed in this invention increases the pore size of each liquid-absorbing channel under low heat flux density and low temperature conditions, promoting rapid fluid adsorption and flow to reduce flow resistance and increase the adsorption rate of the liquid. Furthermore, the pore sizes converge to the same range, reducing the fluid resistance differences caused by different pore sizes. Under high heat flux density and high temperature conditions, the pore size of each liquid-absorbing channel decreases, increasing the surface tension between the liquid and the core material, making it easier for the liquid to be attracted into the core material, thereby improving capillary suction. Simultaneously, increasing the pore size distribution range of the liquid-absorbing core 10 within a certain range can improve the uniformity and efficiency of capillary suction, increase the contribution of different pore sizes to the capillary action, and optimize the liquid absorption effect.

[0033] The present invention also proposes a loop heat pipe device 20, including the liquid absorber 10 as described above. Specifically, the loop heat pipe device 20 includes an evaporator 201, a condenser 202, a steam connector 203, and a liquid connector 204. The evaporator 201 is provided with a liquid inlet 2011 and a gas outlet 2012. The condenser 202 includes a gas inlet 2021 and a liquid outlet 2022. The two ends of the steam connector 203 are respectively connected to the liquid inlet 2011 and the liquid outlet 2022. The two ends of the liquid connector 204 are respectively connected to the gas inlet 2021 and the gas outlet 2012. The liquid absorber 10 is disposed inside the evaporator 201, and the first liquid absorber channel 101 is close to the liquid connector 204, and the third liquid absorber channel 103 is close to the steam connector 203.

[0034] In this embodiment, the liquid suction core 10 divides the evaporator 201 into a gas collecting chamber and a liquid storage chamber. The gas collecting chamber is connected to the gas outlet 2012, and the liquid storage chamber is connected to the liquid inlet 2011. The first liquid suction channel 101, the second liquid suction channel 102, and the third liquid suction channel 103 are connected to the liquid storage chamber. The heat transfer principle is as follows: heat is conducted to the wall of the evaporator 201 by the heat sink 205. The working fluid in the liquid suction core 10 inside the evaporator 201 is evaporated and vaporized. The vapor working fluid enters and collects in the gas collecting chamber. Under a small pressure difference, it flows into the steam connecting pipe 203. After reaching the condenser 202, it releases heat and condenses into liquid. The liquid working fluid then flows back to the evaporator 201 through the liquid connecting pipe 204. This cycle is repeated to achieve heat dissipation. The working fluid is one of water, a mixture of ethylene glycol and water, or ammonium, with a liquid filling rate of 70%.

[0035] In this embodiment, the evaporator 201, condenser 202, steam manifold 203, and liquid manifold 204 are all equipped with shells. These shells are connected by welding to ensure the required internal vacuum level for operation. Specifically, the shells are equipped with a vacuum level of 1×10⁻⁶.-3 pa-1×10 -6 pa, the shell material is copper, aluminum or stainless steel, and the shell thickness is 0.5mm to 1mm.

[0036] In this embodiment, a heat sink 205 is also connected to the outside of the evaporator 201. The thermal conductivity of the heat sink 205 is 500 to 2000 W / (m·K), and its thickness is 0.05 mm to 0.6 mm.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand and implement the present invention. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A loop heat pipe device, characterized in that, The device includes an evaporator, a condenser, a steam manifold, and a liquid manifold. The evaporator has a liquid inlet and a gas outlet. The condenser has a gas inlet and a liquid outlet. The two ends of the liquid manifold are connected to the liquid inlet and the liquid outlet, respectively. The two ends of the steam manifold are connected to the gas inlet and the gas outlet, respectively. The device also includes a liquid suction core disposed inside the evaporator. The liquid-absorbing core includes a first liquid-absorbing channel, a second liquid-absorbing channel, and a third liquid-absorbing channel that are interconnected. The pore sizes of the first, second, and third liquid-absorbing channels gradually increase, and the pore densities of the first, second, and third liquid-absorbing channels gradually decrease. The first, second, and third liquid-absorbing channels are made of shape memory polymers, pressure-sensitive materials, or shape memory alloys. The first liquid-absorbing channel is located near the liquid connector, and the third liquid-absorbing channel is located near the vapor connector.

2. The loop heat pipe device as described in claim 1, characterized in that, The first liquid absorption channel has a pore size of 20-200 μm and a pore density of 500-1000 PPI; the second liquid absorption channel has a pore size of 30-300 μm and a pore density of 500-1000 PPI; and the third liquid absorption channel has a pore size of 40-400 μm and a pore density of 500-1000 PPI.

3. The loop heat pipe device as described in claim 2, characterized in that, The shape memory alloy is CuZnAl shape memory alloy, NiTi shape memory alloy, or CuAlNi shape memory alloy.

4. A loop heat pipe device as described in claim 2, characterized in that, The shape memory polymer is a polyurethane-based shape memory polymer, a polyether ester-based shape memory polymer, or a polyimide-based shape memory polymer.

5. A loop heat pipe device as described in claim 2, characterized in that, The pressure-sensitive material is acrylic pressure-sensitive adhesive, polyethylene film, or carbon nanotube pressure-sensitive fiber.

6. A loop heat pipe device as described in any one of claims 1-5, characterized in that, The evaporator, condenser, steam manifold, and liquid manifold are all equipped with a shell, which is connected by welding, and the vacuum degree inside the shell is 1×10⁻⁶. -3 pa~1×10 -6 pa.

7. A loop heat pipe device as described in claim 6, characterized in that, The shell material is copper, aluminum or stainless steel, and the shell thickness is 0.5mm to 1mm.

8. A loop heat pipe device as described in claim 1, characterized in that, A heat sink is also connected to the outside of the evaporator. The heat sink has a planar thermal conductivity of 500 to 2000 W / (m·K) and a thickness of 0.05 mm to 0.6 mm.

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