Oscillating heat pipe OHP optimal heating power obtaining method

Abstract

The invention discloses a method for acquiring the optimal heating power of an oscillating heat pipe OHP. The method comprises the following steps: acquiring multiple pieces of fluctuation information of corresponding pressure in the oscillating heat pipe OHP along with time change under multiple heating powers; each piece of fluctuation information comprises first data used for representing the pressure disorder degree and second data used for representing the oscillation intensity; target fluctuation information is determined from the multiple pieces of fluctuation information, the disorder degree and oscillation intensity corresponding to the target fluctuation information meet preset rules, and the heating power corresponding to the target fluctuation information is the optimal heating power. According to the method, the pressure oscillation amplitude is quantized by introducing the oscillation intensity, the pressure oscillation period is quantized by introducing the oscillation disorder degree, and then the optimal heating power can be quickly determined by comparing and analyzing the pressure disorder degree and the oscillation intensity.

Description

Technical Field

[0001] This invention relates to the field of cryogenic technology, and in particular to a method for obtaining the optimal heating power of an oscillating heat pipe (OHP). Background Technology

[0002] Low-temperature superconductivity is crucial for next-generation high-tech applications such as controlled nuclear fusion particle accelerators, magnetic levitation trains, and quantum computers. However, the heat transfer rate in the 4K region limits the improvement of low-temperature superconducting performance. Copper is currently a commonly used heat transfer material in low-temperature superconducting systems.

[0003] In the 4K region, the thermal conductivity of copper is only 400–800 W·m. -1 ·K -1 Furthermore, the large temperature difference between the two ends of the cryogenic system results in a slow cooling rate and delayed temperature fluctuations. Cryogenic oscillating heat pipes (Oscillating Heat Pipes, OHP) are a new type of high-efficiency heat transfer element. Due to phase change heat transfer and convective heat transfer, they possess high heat transfer performance. Specifically, the effective thermal conductivity (ETC) of helium-based oscillating heat pipes (OHP) is two orders of magnitude higher than that of copper, reaching as high as 4000-16000 W·m. -1 ·K -1 Therefore, one of the research prospects for low-temperature superconducting systems is to explore the application of oscillating heat pipes (OHP) in low-temperature superconductivity.

[0004] From an intuitive analysis, the existence of the highest effective thermal conductivity point is reasonable. Too low a heating power is insufficient to stimulate the behavior of the oscillating heat pipe (OHP); conversely, too high a heating power causes the OHP to dry out, preventing gas-liquid two-phase heat transfer. Therefore, there exists an optimal heating power that maximizes the thermal conductivity of the OHP, and obtaining this optimal heating power is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to obtain the optimal heating power and to provide a method for obtaining the optimal heating power of an oscillating heat pipe (OHP).

[0006] A method for obtaining the optimal heating power of an oscillating heat pipe (OHP) includes:

[0007] Multiple fluctuation information of pressure change over time inside the oscillating heat pipe OHP under multiple heating powers is obtained; each fluctuation information includes first data to characterize the degree of pressure disorder and second data to characterize the oscillation intensity; the degree of disorder represents the dispersion of the absolute value of the difference between adjacent periods;

[0008] The target fluctuation information is determined from multiple fluctuation information, and the disorder level and oscillation intensity corresponding to the target fluctuation information conform to the preset rules. The heating power corresponding to the target fluctuation information is the optimal heating power.

[0009] The method described above, further, the preset rule is:

[0010] Among the multiple fluctuation information, multiple first data corresponding to the multiple fluctuation information are compared. When the maximum value and the second largest value of the first data exceed the set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information.

[0011] When the maximum and second largest values ​​of the first data are within a set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the target fluctuation information.

[0012] Furthermore, as described above, the degree of disorder conforms to the formula:

[0013]

[0014] Where ΔT i Indicates the pressure fluctuation cycle. This represents the average value of the pressure fluctuation cycle, where n represents the total number of cycles.

[0015] Furthermore, as described above, the oscillation intensity satisfies the following formula:

[0016]

[0017] In the formula: E is the oscillation intensity, W; T sample ρ is the sampling time of the dynamic pressure signal, in seconds; ρ is the density of liquid helium, in kg / m³. 3 c is the speed of sound, m / s; S is the cross-sectional area of ​​the pipe, m. 2 ;P i For pressure fluctuation amplitude, Pa; Δt i The pressure fluctuation period is s.

[0018] The method described above, further comprising the method for determining the target fluctuation information from multiple fluctuation information sources, includes:

[0019] Identify suboptimal volatility information from multiple volatility data points;

[0020] Expanding from both sides of the heating power corresponding to the suboptimal fluctuation information, multiple updated heating powers are selected respectively;

[0021] Obtain multiple updated fluctuation information of the pressure change over time inside the oscillating heat pipe OHP corresponding to the multiple updated heating powers;

[0022] The target fluctuation information is determined from the plurality of updated fluctuation information.

[0023] The method described above, further comprising the method for determining the target fluctuation information from multiple fluctuation information sources, includes:

[0024] First fluctuation information is determined from multiple fluctuation information; multiple first data corresponding to multiple fluctuation information are compared; when the maximum value and the second largest value of the first data exceed a set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information; when the maximum value and the second largest value of the first data are within the set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the first fluctuation information.

[0025] Expanding from both sides of the heating power corresponding to the first fluctuation information, select multiple heating powers respectively, and obtain multiple updated fluctuation information corresponding to the multiple updated heating powers;

[0026] The first fluctuation information is determined from the plurality of updated fluctuation information;

[0027] When the first fluctuation information conforms to the preset rule, the heating power corresponding to the first fluctuation information is determined to be the optimal heating power;

[0028] If the first fluctuation information does not conform to the preset rule, then return to the execution: determine the first fluctuation information from multiple fluctuation information.

[0029] The method described above, further comprising, before obtaining multiple fluctuations in the pressure over time inside the oscillating heat pipe OHP under multiple heating powers, the following steps:

[0030] The oscillating heat pipe OHP is constructed by building a physical platform and establishing an experimental device for the oscillating heat pipe OHP, and / or the oscillating heat pipe OHP is constructed and established in simulation software.

[0031] The method described above, further includes

[0032] An oscillating heat pipe (OHP) is prepared, comprising alternating condensation, adiabatic, and evaporation sections.

[0033] An experimental setup for an oscillating heat pipe (OHP) is established. A refrigeration unit, a cooling unit, a heating unit, a gas supply unit, a vacuum pump unit, and a measurement unit are prepared. The oscillating heat pipe (OHP) is placed in the refrigeration unit. The condensing section is fixed to the cooling unit, and the evaporating section is fixed to the heating unit. A vacuum is created inside and outside the oscillating heat pipe (OHP) using the vacuum pump unit. Experimental gas is filled into the oscillating heat pipe (OHP) using the gas supply unit. A first pressure sensor for measuring the pressure inside the oscillating heat pipe (OHP) is installed at its port.

[0034] The method described above, further comprising, when installing the first pressure sensor for measuring the pressure inside the OHP oscillating heat pipe at the port, also includes:

[0035] A third pressure sensor is installed in the vacuum pump unit, wherein the third pressure sensor is located on the pipeline between the vacuum pump and the vacuum chamber of the vacuum pump unit;

[0036] A first temperature sensor is installed on the cooling unit in the condensation section, and a second temperature sensor is installed on the heating unit in the evaporation section.

[0037] The method described above, further, involves constructing an oscillating heat pipe OHP and establishing an experimental setup for the oscillating heat pipe OHP in simulation software, including:

[0038] Draw a 3D model of the oscillating heat pipe OHP and mesh it;

[0039] Set boundary conditions and set monitoring points on the oscillating heat pipe OHP, wherein the boundary conditions include; the monitoring points include a first pressure sensor set at the input end of the oscillating heat pipe OHP;

[0040] Based on different heating powers, the pressure fluctuation information inside the oscillating heat pipe OHP is obtained by measuring the first pressure sensor.

[0041] The beneficial effects of this invention are as follows: This application quantifies the pressure oscillation amplitude by introducing oscillation intensity and quantifies the pressure oscillation period by introducing oscillation disorder. Then, by comparing and analyzing the pressure oscillation intensity and disorder, the optimal heating power can be quickly determined. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating a method for obtaining the optimal heating power of an oscillating heat pipe (OHP) according to an embodiment of the present invention.

[0043] Figure 2(a) shows the pressure fluctuation distribution under different heating powers inside the oscillating heat pipe OHP with a filling rate of 48%.

[0044] Figure 2(b) is a magnified view of the pressure fluctuation of the shrimp with a heating power of 0.131W in Figure 2(a).

[0045] Figure 3 The graph shows the relationship between oscillation intensity, disorder, effective thermal conductivity (ETC), and heating power through experiments.

[0046] Figure 4 This is a schematic diagram of the experimental setup for an oscillating heat pipe (OHP) in a physical device.

[0047] Figure 5A comparison of the results of constructing an oscillating heat pipe OHP in simulation software and on a physical platform, and establishing an experimental setup for an oscillating heat pipe OHP.

[0048] Figure 6 To compare the dynamic pressure measured in simulation software and physical platform when constructing an oscillating heat pipe OHP and establishing an experimental setup for oscillating heat pipe OHP. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0050] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] Cryogenic systems are crucial for achieving cryogenic superconductivity in next-generation large-scale scientific facilities. Taking the currently common liquid helium system as an example, its applications include particle accelerators, controlled nuclear fusion devices, and high magnetic field equipment. However, the thermal conductivity of copper, a commonly used material in liquid helium systems, is only about 400 to 800 W·m in the 4K region. -1 ·K -1 The low thermal conductivity leads to many drawbacks, such as large temperature differences between the two ends, delayed temperature fluctuations, and limited improvement in the cooling performance of superconducting magnets.

[0053] Therefore, a novel heat transfer element—the oscillating heat pipe (OHP)—is introduced. An OHP typically consists of one or more curved channels filled with a working fluid, such as refrigerant, water, or ethanol. Heat transfer is achieved through convection, phase change, and oscillation. These channels can be circular, rectangular, or other shapes, and their dimensions are generally on the order of millimeters to centimeters. The two ends of each channel are connected to a heat source and a heat sink, respectively, forming a closed loop.

[0054] Specifically, the structure of the oscillating heat pipe OHP includes a condensing section, an adiabatic section, and an evaporating section. The condensing and evaporating sections are welded to two copper plates. This ensures uniform cooling in the condensing section and uniform heating in the evaporator section. Between the condensing and evaporating sections is an adiabatic section made of 316 stainless steel tubing. The working principle is as follows: when a heat source heats one end of the oscillating heat pipe, the working fluid inside evaporates into steam in the evaporating section, and the steam quickly flows to the lower-temperature region. During this process, due to the density difference between the steam and liquid, as well as capillary action and gravity, the working fluid oscillates within the pipe. The steam condenses into liquid at the condenser end, releasing heat, and then the liquid flows back to the evaporating section under capillary action, thus continuously transferring heat from the heat source to the heat sink. In the 4K region, its maximum effective thermal conductivity can be one to two orders of magnitude higher than copper, reaching as high as 4000-16000 W·m. -1 ·K -1 .

[0055] The heat transfer process of an oscillating heat pipe involves the interaction of various physical phenomena, including complex fluid flow, phase change, and heat conduction. By studying its maximum effective thermal conductivity, we can delve into the intrinsic mechanisms and interrelationships of these physical processes, thereby verifying existing heat transfer theories and providing important experimental evidence and theoretical support for further refining these theories.

[0056] Currently, research on the maximum effective thermal conductivity is relatively lacking. There are three main theories: the sensitive / latent heat transfer theory, the maximum frequency theory, and the steady-state unidirectional flow theory.

[0057] (a) Sensitive / latent heat transfer theory; explaining that phase change heat transfer (latent heat) is the main heat transfer mechanism of oscillating heat pipes (OHP). Jung, Joa, and others studied the heat transfer mechanism of oscillating heat pipes (OHP). The results showed that the higher the latent heat transfer rate, the higher the effective thermal conductivity.

[0058] (b) Maximum Frequency Theory: High oscillation frequency promotes heat transfer in oscillating heat pipes (OHPs). Sagar et al. used Fast Fourier Transform (FFT) to analyze the deterministic behavior of the optimal phase of an oscillating heat pipe (OHP) in the frequency range of 0.62-1.56 Hz. The results show that the effective thermal conductivity is highest when the oscillation frequency is at its maximum.

[0059] (c) Steady-state unidirectional flow theory. Results show that steady-state continuous unidirectional flow circulation promotes heat transfer in the oscillating heat pipe (OHP). Handka et al. experimentally observed four different quasi-steady-state two-phase flow patterns. Results indicate that the quasi-steady-state continuous unidirectional flow circulation corresponds to the best heat transfer performance, while the intermittent bidirectional flow circulation corresponds to the poorest heat transfer performance.

[0060] In summary, the mechanism for the highest effective thermal conductivity remains insufficient in two aspects: Firstly, relevant research has not given enough attention to the highest thermal conductivity, which remains at the level of macroscopic performance testing such as effective thermal conductivity; secondly, existing research mainly focuses on the averaging and comparative analysis of its internal phase transition and oscillatory behavior parameters from a statistical perspective. However, research on microscopic parameters such as the amplitude and frequency distribution of the internal oscillation process is relatively lacking.

[0061] According to the inventors, the existence of oscillation behavior is the biggest difference between the Oscillating Heat Pipe (OHP) and traditional heat pipes, and it is also the most important reason for the thermal reaction. In order to reveal the high thermal conductivity of the Oscillating Heat Pipe (OHP), it is necessary to study the influence of its oscillation behavior on the maximum effective thermal conductivity (ETC).

[0062] Therefore, this application discloses a method for obtaining the optimal heating power of an oscillating heat pipe OHP, comprising:

[0063] Multiple fluctuation information of pressure change over time inside the oscillating heat pipe OHP under multiple heating powers is obtained; each fluctuation information includes first data to characterize the degree of pressure disorder and second data to characterize the oscillation intensity;

[0064] The target fluctuation information is determined from multiple fluctuation information, and the disorder level and oscillation intensity corresponding to the target fluctuation information conform to the preset rules. The heating power corresponding to the target fluctuation information is the optimal heating power.

[0065] Since the measured fluctuation information is an oscillating waveform that changes over time, quantification is required. This application quantifies the pressure oscillation period by introducing the degree of oscillation disorder and quantifies the pressure oscillation amplitude by introducing oscillation intensity. Then, by comparing and analyzing the degree of pressure disorder and oscillation intensity, the optimal heating power can be quickly determined.

[0066] In one embodiment, the preset rule is:

[0067] Among the multiple fluctuation information, multiple first data corresponding to the multiple fluctuation information are compared. When the maximum value and the second largest value of the first data exceed the set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information.

[0068] When the maximum and second largest values ​​of the first data are within a set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the target fluctuation information.

[0069] The degree of disorder conforms to the formula:

[0070]

[0071] Where ΔT i Indicates the pressure fluctuation cycle. The value represents the average value of the pressure fluctuation period, and n represents the total number of periods. A baseline is drawn on the pressure fluctuation graph to represent the pressure fluctuation period.

[0072] The oscillation intensity satisfies the following formula:

[0073]

[0074] In the formula: E is the oscillation intensity, W; T sample ρ is the sampling time of the dynamic pressure signal, in seconds; ρ is the density of liquid helium, in kg / m³. 3 c is the speed of sound, m / s; S is the cross-sectional area of ​​the pipe, m. 2 ;P i For pressure fluctuation amplitude, Pa; Δt i The pressure fluctuation period is s.

[0075] In one embodiment, to get closer to the optimal heating power, the method for determining the target fluctuation information from multiple fluctuation information includes:

[0076] Identify suboptimal volatility information from multiple volatility data points;

[0077] Expanding from both sides of the heating power corresponding to the suboptimal fluctuation information, multiple updated heating powers are selected respectively;

[0078] Obtain multiple updated fluctuation information of the pressure change over time inside the oscillating heat pipe OHP corresponding to the multiple updated heating powers;

[0079] The target fluctuation information is determined from the plurality of updated fluctuation information.

[0080] In this scheme, by expanding the heating power corresponding to the suboptimal fluctuation information on both sides, and then obtaining the fluctuation information corresponding to the expanded heating power, the optimal heating power corresponding to the optimal fluctuation information among the multiple expanded fluctuation information is obtained.

[0081] In one embodiment, the method for determining the target fluctuation information from multiple fluctuation information includes:

[0082] First fluctuation information is determined from multiple fluctuation information; multiple first data corresponding to multiple fluctuation information are compared; when the maximum value and the second largest value of the first data exceed a set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information; when the maximum value and the second largest value of the first data are within the set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the first fluctuation information.

[0083] Expanding from both sides of the heating power corresponding to the first fluctuation information, select multiple heating powers respectively, and obtain multiple updated fluctuation information corresponding to the multiple updated heating powers;

[0084] The first fluctuation information is determined from the plurality of updated fluctuation information;

[0085] When the first fluctuation information conforms to the preset rule, the heating power corresponding to the first fluctuation information is determined to be the optimal heating power;

[0086] If the first fluctuation information does not conform to the preset rule, then return to the execution: determine the first fluctuation information from multiple fluctuation information;

[0087] Expanding from both sides of the heating power corresponding to the first fluctuation information, select multiple updated heating powers respectively, and obtain multiple updated fluctuation information corresponding to the multiple updated heating powers.

[0088] In this scheme, the optimal heating power is finally determined by updating the first fluctuation information multiple times, after a set number of times or to a required level of accuracy.

[0089] In one embodiment, before obtaining multiple fluctuation information of the pressure change over time inside the oscillating heat pipe OHP under multiple heating powers, the method further includes: constructing the oscillating heat pipe OHP and establishing the oscillating heat pipe OHP experimental device, including constructing the oscillating heat pipe OHP and establishing the oscillating heat pipe OHP experimental device by building a physical platform, and / or constructing the oscillating heat pipe OHP and establishing the oscillating heat pipe OHP experimental device in simulation software.

[0090] like Figure 4 As shown, in one embodiment, the construction of an oscillating heat pipe OHP and the establishment of an oscillating heat pipe OHP experimental apparatus by building a physical platform include:

[0091] An oscillating heat pipe (OHP) is prepared, comprising alternating condensation, adiabatic, and evaporation sections.

[0092] An experimental setup for an oscillating heat pipe (OHP) is established. A refrigeration unit, a cooling unit, a heating unit, a gas supply unit, a vacuum pump unit, and a measuring unit are prepared. The oscillating heat pipe (OHP) is placed in the refrigeration unit. The condensing section is fixed to the cooling unit, and the evaporating section is fixed to the heating unit. A vacuum is created inside and outside the oscillating heat pipe (OHP) using the vacuum pump unit. Experimental gas is filled into the oscillating heat pipe (OHP) using the gas supply unit. A first pressure sensor for measuring the pressure inside the oscillating heat pipe (OHP) is installed at its port.

[0093] Specifically, the refrigerator includes a GM multi-stage cold head and multiple cold shields disposed within a vacuum chamber. The GM multi-stage cold head maintains corresponding temperature environments within different cold shields. The multiple cold shields are stacked and nested, with the coldest cold shield located in the innermost layer. In a specific example, there are two cold shields: the outer cold shield has a temperature of 40K, and the inner cold shield has a temperature of 4K.

[0094] The cooling unit includes a first copper plate that fixes the condensation section of the oscillating heat pipe OHP.

[0095] The heating unit is set in a 4K environment and includes a second copper plate that fixes the 0HP evaporation section, which is used to provide heating power to the oscillating heat pipe OHP, so that the evaporation section of the heat pipe is heated.

[0096] The gas supply unit includes a gas storage tank, a pressure valve, and a buffer chamber arranged sequentially on a pipeline. The end of the pipeline is connected to the input end of the oscillating heat pipe OHP. The pressure valve includes pressure valve HV1 at the output end of the gas storage tank, pressure valve HV3 at the input end of the buffer chamber, pressure valve HV5 on the pipeline between the buffer chamber and the oscillating heat pipe OHP, and pressure valve HV4 on the pressure regulating pipeline of the buffer chamber. The gas supply unit is used to provide the gas required for the experiment and can control the flow rate and pressure of the gas. The buffer chamber prevents excessive gas flow from damaging the structure of the oscillating heat pipe OHP. After evacuating the gas, pressure valves HV1 and HV3 are opened to fill the buffer chamber. Then, pressure valves HV1 and HV3 are closed, and pressure valve HV5 is opened for refueling. This process is repeated several times to ensure that the helium concentration in the oscillating heat pipe OHP reaches 99.999%.

[0097] The vacuum pump unit is used to evacuate the system, removing internal air and impurities to ensure the heat pipe is filled with pure input gas. Helium is commonly used. The vacuum pump unit includes a vacuum pump for evacuating the buffer chamber, vacuum chamber, oscillating heat pipe OHP, and cold shield, as well as pressure valves HV2 and HV6. Before adding the oscillating heat pipe OHP, pressure valves HV2, HV3, HV5, and HV6 are opened, pressure valve HV1 is closed, and the vacuum pump is turned on to expel any remaining gas from the oscillating heat pipe OHP and the buffer chamber.

[0098] The measuring unit includes multiple pressure sensors and multiple temperature sensors. The multiple pressure sensors include a first pressure sensor installed on the gas supply unit input to the oscillating heat pipe OHP and located on the external pipeline of the refrigerator, and a second pressure sensor installed on the pipeline at the input end of the buffer chamber.

[0099] In one embodiment, when the first pressure sensor for measuring the pressure inside the oscillating heat pipe OHP is installed at the port, the method further includes: installing a third pressure sensor in the vacuum pump unit, wherein the third pressure sensor is located on the pipeline between the vacuum pump and the vacuum chamber of the vacuum pump unit; installing a first temperature sensor on the cooling unit at the condensation section; and installing a second temperature sensor on the heating unit at the evaporation section.

[0100] Specifically, a third pressure sensor is installed on the pipeline connecting the vacuum pump and the vacuum chamber, and the plurality of temperature sensors include a first temperature sensor for monitoring the temperature of the first copper plate and a second temperature sensor for monitoring the temperature of the second copper plate.

[0101] In this embodiment, the process involves obtaining multiple fluctuations in the pressure inside the oscillating heat pipe OHP under multiple heating powers over time. To obtain more accurate heating powers, those skilled in the art obtain a large heating power range based on experience, divide the heating power range equally, and obtain multiple heating powers.

[0102] In one embodiment, the steps for obtaining the optimal heating power in the range of 1-9W are as follows:

[0103] Divide the power range: First, divide 1-9W into 5 equal parts (1W-3W-5W-7W-9W);

[0104] Finding the relative optimal power: By experimentally measuring the internal pressure fluctuation, compare the pressure fluctuation under these 5 heating powers. If the disorder is more severe, then the heating power is optimal.

[0105] Expanding beyond the relative optimal power: If 5W is the relative optimal power, then expand beyond 5W (4.6W-4.8W-5W-5.2W-5.4W-5.6W).

[0106] Comparing the pressure fluctuations under these 5 heating powers, the more severe the disorder, the better the heating power. If there are maximum and second maximum values ​​of disorder that do not exceed the set error range, the fluctuation information with the largest oscillation intensity is determined from the two fluctuation information corresponding to the maximum and second maximum values ​​of disorder, and is used as the target fluctuation information. The heating power corresponding to the target fluctuation information is the optimal heating power.

[0107] Based on this embodiment, the specific heating power can be measured in practice, thus more accurately reflecting the real situation.

[0108] In one embodiment, constructing an oscillating heat pipe OHP and establishing an oscillating heat pipe OHP experimental setup in simulation software includes:

[0109] Draw a 3D model of the oscillating heat pipe OHP and mesh it;

[0110] Set boundary conditions and set monitoring points on the oscillating heat pipe OHP, wherein the boundary conditions include; the monitoring points include a first pressure sensor set at the input end of the oscillating heat pipe OHP;

[0111] Different heating powers are obtained within the defined heating power range, and the internal pressure fluctuation of the oscillating heat pipe OHP is measured by the first pressure sensor.

[0112] Specifically, the process of drawing a three-dimensional model of the oscillating heat pipe OHP and drawing a mesh on it involves the number of meshes falling within a range of a second and a third set value. This range ensures that the error is small while avoiding excessive demands on computer performance.

[0113] Specifically, setting monitoring points on the oscillating heat pipe OHP includes: the monitoring points further include temperature monitoring points set in the evaporation section and the condensation section. In one embodiment, six monitoring points are evenly distributed in the evaporation section and six in the condensation section. Since pressure propagates at the speed of sound (the speed of sound in saturated liquid hydrogen at 20K is 1129.1 m / s, and the speed of sound in saturated hydrogen gas is 354.31 m / s), and the distance between the two ends of the oscillating heat pipe OHP is 0.2 m, the time required for pressure to travel from one end to the other is less than 1 ms. Therefore, the pressure at each location changes almost synchronously, so setting monitoring points inside the pipe, selecting only one temperature monitoring point is sufficient.

[0114] Based on this embodiment, by constructing the relevant boundary conditions of the oscillating heat pipe OHP and obtaining the values ​​of the monitoring points in the software, the cost of the physical installation process can be reduced. Since it is necessary to evacuate and repeatedly fill the oscillating heat pipe OHP with nitrogen when it reaches the experimental conditions, this process consumes a lot of costs. However, by constructing the oscillating heat pipe OHP and the experimental device in the software, the cost of the experiment can be effectively avoided.

[0115] In one embodiment, the construction of the oscillating heat pipe OHP and the establishment of the oscillating heat pipe OHP experimental apparatus include:

[0116] A physical platform was built to construct the oscillating heat pipe OHP and an experimental device for the oscillating heat pipe OHP was established. The oscillating heat pipe OHP and the experimental device for the oscillating heat pipe OHP were also constructed in simulation software.

[0117] Within the defined heating power range, different heating powers are obtained on the physical platform and in the simulation software, and the internal pressure fluctuation of the oscillating heat pipe OHP is measured by the first pressure sensor.

[0118] This embodiment combines a physical platform and simulation software. The physical platform can verify the correctness of the simulation software data. After verifying the data's correctness, repeated experiments are avoided when obtaining a more accurate optimal heating power. By comparing pressure fluctuations, it was found that the peaks and troughs are almost identical, and the period is also similar. Therefore, both the experimental and simulation data are valid values.

[0119] In one embodiment, as shown in Figures 2(a) and 2(b), the heating power values ​​are 0.040W, 0.078W, 0.131W, 0.160W, and 0.194W, respectively. Curves corresponding to the pressure fluctuations are obtained, showing the pressure fluctuations under different heating powers within the OHP. As the heating power increases, the amplitude of the pressure fluctuations increases significantly. However, simply averaging all pressure values ​​to limit the amplitude of dynamic fluctuations would lose a lot of information, especially information hidden in high and sharp fluctuations. This scheme effectively quantifies the amplitude by introducing oscillation intensity. It physically represents the power driving the liquid plug in the OHP and is calculated according to Equation (1). The period is identified by using custom code in MATLAB, utilizing the change in slope from positive to negative or from negative to positive.

[0120]

[0121] In the formula: E is the oscillation intensity, W; T sample ρ is the sampling time of the dynamic pressure signal, in seconds; ρ is the density of liquid helium, in kg / m³. 3 c is the speed of sound, m / s; S is the cross-sectional area of ​​the pipe, m. 2 ;P i The pressure fluctuation range is expressed in Pa; Δ ti为 The pressure fluctuation period, in seconds. The pressure fluctuation period characterizes the degree of disorder.

[0122] In one embodiment, as shown in Figure 2(a), the heating power values ​​are 0.040W, 0.078W, 0.131W, 0.160W, and 0.194W, respectively, and curves corresponding to the pressure fluctuations are obtained. It can be seen from the figure that the heating power corresponding to the greatest degree of disorder is 0.131W. Figure 2(b) is a partially enlarged view of the heating power at 0.131W.

[0123] Through experimental comparison, the relationships between oscillation intensity, disorder, effective thermal conductivity (ETC), and heating power are obtained as follows: Figure 3As shown, the inventors discovered that the oscillation intensity is caused by the heating power and is not directly related to the maximum effective thermal conductivity (ETC). The core of maximum heating efficiency is the degree of disorder in pressure fluctuations. The point with the greatest disorder is the point of highest efficiency, and its oscillation intensity is also relatively high. Generally speaking, the process of violent oscillation causes the effective thermal conductivity (ETC) to reach a relatively high value range, while the most disordered and violent oscillation process causes the effective thermal conductivity (ETC) to reach its maximum value.

[0124] Figure 5 The comparison results of constructing an oscillating heat pipe OHP in simulation software and establishing an experimental oscillating heat pipe OHP setup are shown. As can be seen from the figure, the deviation is within 5%. Therefore, the results obtained by constructing an oscillating heat pipe OHP in simulation software are reliable. Figure 6 The comparison of dynamic pressure measured by simulation software and physical platform is shown, FR=48%, Q-0.131W. The peak-to-peak deviation is within 17%, and the pressure pulsation cycle is almost the same.

[0125] In one embodiment, after obtaining the optimal heating power, the method further includes:

[0126] The temperature difference between the condensing section and the evaporating section of the oscillating heat pipe OHP is obtained, and the effective thermal conductivity corresponding to the optimal heating power is calculated based on the temperature difference.

[0127] Specifically, when constructing a physical platform to build an oscillating heat pipe OHP and establishing an experimental device for the oscillating heat pipe OHP, the temperatures of the condensation section and the evaporation section are obtained through the first temperature sensor and the second temperature sensor, respectively, and the effective thermal conductivity is calculated by obtaining the temperature difference.

[0128] Specifically, when constructing the Oscillating Heat Pipe (OHP) and establishing the Oscillating Heat Pipe (OHP) experimental device in the simulation software, it is found that there are 6 monitoring points evenly distributed in the evaporation section and 6 in the condensation section. Monitoring points are set inside the pipe to obtain the temperature difference and calculate the effective thermal conductivity.

[0129] In this application, pressure fluctuations corresponding to different heating powers are obtained, and then the oscillation intensity and oscillation disorder corresponding to different waveforms are compared. By using a stepwise approximation method, the heating power is made more precise, thereby obtaining the corresponding optimal effective thermal conductivity.

[0130] In the description of this specification, references to terms such as "some embodiments" or "example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0131] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for obtaining the optimal heating power of an oscillating heat pipe (OHP), characterized in that, include: Multiple fluctuation information of pressure change over time inside the oscillating heat pipe OHP under multiple heating powers is obtained; each fluctuation information includes first data to characterize the degree of pressure disorder and second data to characterize the oscillation intensity; the degree of disorder represents the dispersion of the absolute value of the difference between adjacent periods; The target fluctuation information is determined from multiple fluctuation information, and the disorder level and oscillation intensity corresponding to the target fluctuation information conform to the preset rules. The heating power corresponding to the target fluctuation information is the optimal heating power.

2. The method as described in claim 1, characterized in that, The preset rule is as follows: Among the multiple fluctuation information, multiple first data corresponding to the multiple fluctuation information are compared. When the maximum value and the second largest value of the first data exceed the set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information. When the maximum and second largest values ​​of the first data are within a set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the target fluctuation information.

3. The method as described in claim 1 or 2, characterized in that, The degree of disorder conforms to the formula: Where ΔT i Indicates the pressure fluctuation cycle. This represents the average value of the pressure fluctuation cycle, where n represents the total number of cycles.

4. The method as described in claim 1 or 2, characterized in that, The oscillation intensity satisfies the following formula: In the formula: E is the oscillation intensity, W; T sample The sampling time for the dynamic pressure signal is in seconds. ρ is the density of liquid helium, kg / m³ 3 c is the speed of sound, m / s; S is the cross-sectional area of ​​the pipe, m. 2 ; P i For pressure fluctuation amplitude, Pa; Δt i The pressure fluctuation period is s.

5. The method as described in claim 1 or 2, characterized in that, The method for determining the target fluctuation information from multiple fluctuation information includes: Identify the suboptimal fluctuation information from multiple fluctuation data; Expanding from both sides of the heating power corresponding to the suboptimal fluctuation information, multiple updated heating powers are selected respectively; Obtain multiple updated fluctuation information of the pressure change over time inside the oscillating heat pipe OHP corresponding to the multiple updated heating powers; The target fluctuation information is determined from the plurality of updated fluctuation information.

6. The method as described in claim 1 or 2, characterized in that, The method for determining the target fluctuation information from multiple fluctuation information includes: First fluctuation information is determined from multiple fluctuation information; multiple first data corresponding to multiple fluctuation information are compared, and when the maximum value and the second largest value of the first data exceed a set error range, the fluctuation information corresponding to the maximum value of the first data is the target fluctuation information; when the maximum value and the second largest value of the first data are within the set error range, the second data of the two are compared, and the fluctuation information corresponding to the maximum value of the second data of the two is the first fluctuation information. Expanding from both sides of the heating power corresponding to the first fluctuation information, select multiple heating powers respectively, and obtain multiple updated fluctuation information corresponding to the multiple updated heating powers; The first fluctuation information is determined from the plurality of updated fluctuation information; When the first fluctuation information conforms to the preset rule, the heating power corresponding to the first fluctuation information is determined to be the optimal heating power; If the first fluctuation information does not conform to the preset rule, then return to the execution: determine the first fluctuation information from multiple fluctuation information.

7. The method as described in claim 1, characterized in that, Before obtaining multiple fluctuations in the pressure inside the oscillating heat pipe OHP under various heating powers over time, the following steps are also included: The oscillating heat pipe OHP is constructed by building a physical platform and establishing an experimental device for the oscillating heat pipe OHP, and / or the oscillating heat pipe OHP is constructed and established in simulation software.

8. The method as described in claim 7, characterized in that, include An oscillating heat pipe (OHP) is prepared, comprising alternating condensation, adiabatic, and evaporation sections. An experimental setup for an oscillating heat pipe (OHP) is established. A refrigeration unit, a cooling unit, a heating unit, a gas supply unit, a vacuum pump unit, and a measurement unit are prepared. The oscillating heat pipe (OHP) is placed in the refrigeration unit. The condensing section is fixed to the cooling unit, and the evaporating section is fixed to the heating unit. A vacuum is created inside and outside the oscillating heat pipe (OHP) using the vacuum pump unit. Experimental gas is filled into the oscillating heat pipe (OHP) using the gas supply unit. A first pressure sensor for measuring the pressure inside the oscillating heat pipe (OHP) is installed at its port.

9. The method as described in claim 8, characterized in that, When installing a first pressure sensor for measuring the pressure inside the OHP oscillating heat pipe at its port, the method further includes: A third pressure sensor is installed in the vacuum pump unit, wherein the third pressure sensor is located on the pipeline between the vacuum pump and the vacuum chamber of the vacuum pump unit; A first temperature sensor is installed on the cooling unit in the condensation section, and a second temperature sensor is installed on the heating unit in the evaporation section.

10. The method as described in claim 8, characterized in that, The simulation software was used to construct an oscillating heat pipe OHP and to establish an experimental setup for the oscillating heat pipe OHP, including: Draw a 3D model of the oscillating heat pipe OHP and mesh it; Set boundary conditions and set monitoring points on the oscillating heat pipe OHP, wherein the boundary conditions include; the monitoring points include a first pressure sensor set at the input end of the oscillating heat pipe OHP; Based on different heating powers, the pressure fluctuation information inside the oscillating heat pipe OHP is obtained by measuring the first pressure sensor.

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