A thermal switching device based on time-cooled heating medium and its control method

Abstract

This invention discloses a thermal switching device based on a time-controlled heating medium and its control method. The thermal conductivity and volumetric heat capacity of the heating medium exhibit traveling wave modulation, and the phase difference between them is adjustable. This invention achieves active control of the directionality of heat flow transmission by switching the boundary conditions at both ends of the heating medium and continuously adjusting the phase difference: when both ends are constant temperature boundaries, heat flow is bidirectionally symmetrically transmitted regardless of their values, and the device is in an "off" state; when at least one end is a periodic temperature boundary, heat flow exhibits unidirectional asymmetrical transmission, the device is in an "on" state, generating a diode effect, and the rectification intensity is continuously controlled by the equivalent convection term coefficient. This invention, through the coordinated control of boundary conditions and phase difference, achieves a thermal switching function with continuously adjustable diode effect intensity from "off" to "on," and has significant application prospects in microelectronic heat dissipation, intelligent thermal management, and thermal logic devices.

Description

Technical Field

[0001] This invention relates to the field of thermal metamaterials and thermal management technology, specifically to a thermal switching device based on a time-cooled heating medium and its control method. Background Technology

[0002] With the increasing integration of microelectronic devices, efficient thermal management has become a key bottleneck restricting device performance. Traditional heat dissipation solutions provide passive bidirectional heat conduction paths, which cannot achieve active control over the direction of heat flow. However, in cutting-edge applications such as thermal logic computing and thermal diode bridge power generation, what is needed is an intelligent thermal control mechanism—that is, to open the heat conduction channel when heat dissipation is needed and to block heat flow when heat preservation is needed.

[0003] Devices that achieve this unidirectional heat conduction function are called "thermal switches" or "thermal diodes." An ideal thermal switch should have extremely low forward conduction thermal resistance, extremely high reverse blocking thermal resistance, and the ability to switch quickly and reliably. Currently, existing solutions mainly fall into two categories: one is based on the temperature dependence of material thermal conductivity to achieve thermal rectification; the other is based on phase change materials or mechanical motion to change the thermal path on / off state.

[0004] However, existing solutions generally have drawbacks. Thermal diodes based on intrinsic material properties have low rectification ratios and limited operating temperature ranges. While thermal switches based on phase change or mechanical motion can achieve higher on / off ratios, they suffer from slow response speeds, complex structures, poor reliability, and are difficult to miniaturize and integrate. For example, shape memory alloy-driven mechanical thermal switches, although highly responsive, have multi-layered structures and moving parts that limit their application at the micro- and nano-scale. Summary of the Invention

[0005] To address the technical problems of complex structure, slow response speed, difficulty in integration, and inability to actively control the direction of heat flow in existing thermal switching devices, this invention provides a thermal switching device based on a time-controlled heating medium and its control method. This method achieves mode switching from "bidirectional heat conduction" to "unidirectional heat conduction" on the same device, as well as continuous control of the diode effect intensity, by switching the boundary conditions at both ends of the device and continuously adjusting the phase difference of the modulation wave. This invention is applicable to scenarios requiring active control of the direction of heat flow, such as microelectronic heat dissipation, intelligent thermal management, and thermal logic devices.

[0006] The technical solution of the present invention is described in detail below.

[0007] This invention provides a thermal switch device based on a time-controlled heating medium, comprising: The thermal conductivity of the heating medium in an air conditioner and volumetric heat capacity It exhibits traveling wave modulation and has a volumetric heat capacity The modulation wave relative to thermal conductivity The modulated wave has an adjustable phase difference. ,in For density, Specific heat capacity; The first hot port and the second hot port are respectively located at both ends of the air conditioning heating medium and are used to connect to an external heat source or heat sink. A boundary condition control unit, connected to the first hot port and the second hot port, is used to independently control the thermal excitation mode at both ends; The boundary condition control unit is configured to: In the first operating mode, both the first and second hot ports are kept at constant temperature boundaries. At this time, the heat flow is bidirectionally symmetrically transferred in the air conditioning heating medium, the device is in the off state, and there is no diode effect. In the second operating mode, at least one of the first and second hot ports is positioned at a periodic temperature boundary. At this time, heat flow in the air conditioning heating medium exhibits unidirectional asymmetric transmission, the device is in the on state, and a diode effect is generated. The intensity of the diode effect is determined by the equivalent convection term coefficient. Continuous regulation, Phase difference The function, and as Continuous change.

[0008] In this invention, the thermal conductivity of the air conditioning heating medium is... and volumetric heat capacity Both are modulated by traveling waves, and the amplitude and phase difference between the two modulated waves are... The thermal conductivity can be adjusted independently. and volumetric heat capacity The traveling wave modulation and the phase difference between them The adjustment is achieved through external physical field control or dynamic modulation of material parameters.

[0009] In this invention, the thermal conductivity of the air conditioning heating medium is... and volumetric heat capacity The modulation format is as follows: ; (1) in: and These represent the spatial average values ​​(background values) of thermal conductivity and volumetric heat capacity, respectively. and These represent the modulation amplitude (fluctuation amplitude) of thermal conductivity and volumetric heat capacity, respectively. Spatial location coordinates, Using time as the coordinate, For the modulation wavenumber, For modulation speed, Volumetric heat capacity Modulated wave relative to thermal conductivity The phase difference of the modulated wave.

[0010] In this invention, the intensity of the diode effect in the second operating mode is determined by the equivalent convection term coefficient. With continuous regulation, the equivalent convection term coefficient satisfies: (2) in These are dimensionless modulation parameters. The modulation wavelength; when hour, Taking the maximum value, the diode effect is significant, manifested as a clear separation between the forward and reverse temperature distributions; when hour, As the voltage approaches zero, the diode effect disappears, and the forward and reverse temperature distributions overlap.

[0011] In this invention, the constant temperature boundary is a boundary condition in which the temperature at both ends remains constant, and the periodic temperature boundary is a boundary condition in which the temperature fluctuates periodically over time, including but not limited to sine wave, square wave or triangular wave forms.

[0012] In this invention, the boundary condition control unit includes a constant temperature controller and a periodic temperature generator. The constant temperature controller is used to achieve a constant temperature boundary, and the periodic temperature generator is used to achieve a periodic temperature boundary.

[0013] In this invention, under a constant temperature boundary, regardless of the phase difference Regardless of the value, the forward and reverse temperature distributions satisfy a symmetrical complementary relationship: (3) in The initial temperature was used to verify the thermal flow symmetry of the device in the off state.

[0014] The present invention also provides a control method based on the above-mentioned thermal switching device based on the time-cooled heating medium, comprising the following steps: Step (1): Set the thermal excitation mode of the first hot port and the second hot port through the boundary condition control unit; Step (2): When the device needs to be in the off state, set both ends to constant temperature boundaries; Step (3): When the device needs to be in the on state, set at least one end as a periodic temperature boundary; Step (4): Adjust the phase difference The intensity of the diode effect in the on state is continuously adjusted.

[0015] Furthermore, in step (4), the phase difference is adjusted. This causes the diode effect intensity to change continuously from zero to its maximum; when When the diode effect disappears, the forward and reverse temperature distributions coincide; when At this time, the diode effect is strongest, and the forward and reverse temperature distributions are clearly separated.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Switchable mode: This invention proposes for the first time to achieve active control of heat flow direction by switching boundary conditions (constant / periodic), and realizes the mode switching from "bidirectional heat conduction" (off state) to "unidirectional heat conduction" (on state) on the same device, which solves the problem of the single function of traditional thermal switches.

[0017] (2) Continuously adjustable intensity: This invention introduces a phase difference As an adjustable parameter, it enables continuous control of the diode effect intensity in the on-state. When The diode effect is strongest when the forward and reverse heat flows differ the most; when When the diode effect disappears, the heat flow returns to symmetry. This characteristic provides new degrees of freedom for the fine-grained control of thermal management systems.

[0018] (3) Simple structure and fast response: This invention does not require complex mechanical moving parts or phase change materials. It can achieve thermal switching function by simply controlling the external boundary conditions. It has a fast response speed and is easy to miniaturize and integrate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the thermal switching device of the present invention.

[0020] Figure 2 This is a schematic diagram of the working mode switching of the thermal switching device of the present invention.

[0021] Figure 3 Phase difference Comparison of forward / reverse temperature distributions under different boundary conditions. (a) represents constant boundary conditions; (b) represents periodic boundary conditions.

[0022] Figure 4 Phase difference Comparison of forward / reverse temperature distributions under different boundary conditions. (a) represents constant boundary conditions; (b) represents periodic boundary conditions.

[0023] Figure 5This is a comparison of the thermal response amplitudes under periodic boundary conditions with different phase differences. The solid line represents the forward temperature distribution, and the dashed line represents the reverse temperature distribution. (a) shows... (b) is .

[0024] Figure 6 This is a comparison of the thermal response amplitudes under constant boundary conditions with different phase differences. The solid line represents the forward temperature distribution, and the dashed line represents the reverse temperature distribution. (a) shows... (b) is . Detailed Implementation

[0025] The present invention will now be described clearly and completely with reference to the accompanying drawings and embodiments.

[0026] This invention achieves active control of heat flow directionality and adjustable diode effect intensity by modulating the thermal conductivity and volumetric heat capacity of the air conditioning heating medium during design, introducing an adjustable phase difference parameter, and combining this with the switching of boundary conditions. The main scientific principles and specific implementation methods of this method will be detailed below:

[0027] 1. Structure of thermal switching devices

[0028] See Figure 1 This invention provides a thermal switch device based on a time-controlled heating medium, comprising a time-controlled heating medium 100, a first hot port 110, a second hot port 120, and a boundary condition control unit 130; wherein: The heating medium of the air conditioner is 100, and its thermal conductivity is... and volumetric heat capacity It exhibits traveling wave modulation and has a volumetric heat capacity The modulation wave relative to thermal conductivity The modulated wave has an adjustable phase difference. ,in For density, Specific heat capacity; The first hot port 110 and the second hot port 120 are respectively disposed at both ends of the air conditioning heating medium 100 and are used to connect to an external heat source or heat sink. Boundary condition control unit 130 is connected to the first hot port 110 and the second hot port 120 and is used to independently control the thermal excitation mode at both ends.

[0029] See Figure 2 The boundary condition control unit 130 is configured to operate in two modes: First operating mode (off state): Both the first hot port 110 and the second hot port 120 are at a constant temperature boundary. At this time, the heat flow is bidirectionally and symmetrically transmitted in the air conditioning heating medium 100, without diode effect. Second operating mode (on state): at least one of the first hot port 110 and the second hot port 120 is at a periodic temperature boundary. At this time, the heat flow in the air conditioning heating medium 100 exhibits unidirectional asymmetric transmission, generating a diode effect.

[0030] 2. Parameter design of heating medium for hourly air conditioning

[0031] Thermal conductivity of the heating medium in an air conditioner (100%) and volumetric heat capacity The modulation format is as follows: ; (1) in: and These represent the spatial average values ​​(background values) of thermal conductivity and volumetric heat capacity, respectively. and These represent the modulation amplitude (fluctuation amplitude) of thermal conductivity and volumetric heat capacity, respectively. Spatial location coordinates, Using time as the coordinate, For the modulation wavenumber, For modulation speed, Volumetric heat capacity Modulated wave relative to thermal conductivity The phase difference of the modulated wave.

[0032] The following are typical materials that can be used as the heating medium for air conditioning, but are not limited to them: Electrothermal sensitive materials, such as barium titanate (BaTiO3) based ceramics, bismuth telluride (Bi2Te3) thermoelectric materials, vanadium dioxide (VO2) phase change materials, etc., are suitable for electric field driven traveling wave modulation; Photothermal sensitive materials, such as chalcogenides (GST) and doped silicon (Si), are suitable for optically driven traveling wave modulation. Conventional high / low thermal conductivity material combinations, such as copper (Cu) and stainless steel, or aluminum (Al) and ceramics, are suitable for equivalent modulation of mechanical motion (rotating fan blades / slider).

[0033] thermal conductivity and volumetric heat capacity The traveling wave modulation and the phase difference between them The adjustment is achieved through external physical field control or dynamic modulation of material parameters. The specific implementation methods fall into three categories, with phase difference being a key factor in each category. The regulatory logic is consistent, as follows: 1. Electric / Magnetic Field Control Method: Electrothermal and magnetocaloric sensitive materials (such as VO2 phase change materials, BaTiO3-based ceramics, and Bi2Te3 thermoelectric materials) are selected. Two independent electric / magnetic fields with a spatially distributed traveling wave pattern are applied to the thermal medium to drive the material's thermal conductivity. and volumetric heat capacity Traveling wave modulation is achieved; by adjusting the phase difference between the two electric / magnetic field driving signals, the phase difference between the thermal conductivity and volumetric heat capacity modulated waves can be realized. Continuous adjustment.

[0034] 2. Light field modulation method: Select a photothermal sensitive material (such as GST chalcogenide compounds or silicon-based doped materials), and irradiate the thermal medium with two independent traveling wave-moving grating / interference fringe light fields to excite the material's thermal conductivity. and volumetric heat capacity It generates periodic traveling wave changes; by adjusting the phase difference between the two light beams, the phase difference between the thermal conductivity and volumetric heat capacity modulated wave is achieved. Precise control.

[0035] 3. Mechanical Motion Equivalent Modulation Method: An array of fan blades / translation sliders is fabricated using a combination of materials with high / low thermal conductivity and high / low heat storage properties (such as copper-stainless steel, aluminum-alumina ceramic). Two independent mechanical motion mechanisms drive the corresponding material arrays to perform traveling wave motion, effectively achieving high thermal conductivity. and volumetric heat capacity Traveling wave modulation; by adjusting the phase difference of the motion of two sets of mechanical motion mechanisms, the phase difference between their modulated waves is achieved. Continuously adjustable.

[0036] According to the homogenization theory of the thermal diffusion equation, the equivalent convection term coefficient satisfy: (2) in These are dimensionless modulation parameters. This is the modulation wavelength. This coefficient determines the intensity of the asymmetric heat transfer.

[0037] In this embodiment, the following parameters are selected for numerical simulation: , Modulation wavelength Modulation speed Dimensionless modulation parameters Length of heat medium initial temperature .

[0038] Under constant temperature boundary conditions, the temperatures at both ends are set as follows: and Under periodic temperature boundaries, the temperature expression is: ,in ,cycle .

[0039] 3. The mechanism by which phase difference modulates the amplitude of thermal response

[0040] Under constant boundary conditions, the heat flow is always symmetrical, and the forward and reverse temperature distributions satisfy a symmetrical complementary relationship: =596 K; (3) This means that the two curves are about Symmetrical. However, phase difference. The magnitude of the temperature fluctuation is significantly affected by the difference in modulation efficiency.

[0041] when hour, Equivalent convection term coefficient When a large positive value is reached, the modulation efficiency is high. At this point, the thermal conductivity wave and the volumetric thermal capacity wave work together to generate a strong heat pump effect, transferring heat from the cold end to the hot end. Therefore, the overall positive temperature distribution is higher than the initial temperature, reaching 310 K near the hot end, with a fluctuation range of approximately... ,like Figure 3 As shown in (a).

[0042] when hour, , Equivalent convection term coefficient Approaching zero, the modulation efficiency is suppressed. The thermal conductivity wave and the volumetric heat capacity wave cancel each other out, the heat pump effect disappears, and the temperature distribution approaches a pure diffusion state. At this point, the overall forward temperature distribution is slightly lower than the initial temperature, reaching a minimum of 297.65 K, with a fluctuation amplitude of only... ,like Figure 4 As shown in (a).

[0043] Although their fluctuation ranges differ significantly, they both satisfy the complementary relationship. This verifies that the thermal flux symmetry of the system under constant boundary conditions is unaffected by the modulation intensity. This is precisely... Figure 6 The content displayed; The modulation efficiency is low, the temperature fluctuation amplitude is extremely small, and the forward and reverse temperature distributions are related. symmetry; High modulation efficiency, large temperature fluctuation range, and similar temperature distribution in both the forward and reverse directions. Symmetry. Under constant boundary conditions, the forward and reverse temperature distributions always satisfy a symmetrical complementary relationship. ,in The initial temperature is given; neither graph shows a diode effect. Under constant boundary conditions, the temperature distribution for different phase differences is related to... symmetry.

[0044] 4. The modulation mechanism of phase difference on diode effect

[0045] Under periodic boundary conditions, the intensity of asymmetric heat transfer is determined by the equivalent convection term coefficient. Decide.

[0046] when hour, Taking a larger value results in a significant diode effect. For example... Figure 3 As shown in (b), the forward and reverse temperature distributions are clearly separated, with the forward temperature generally higher and the reverse temperature generally lower, indicating that the heat flow exhibits strong unidirectional asymmetric transmission.

[0047] when hour, As the diode approaches zero, the diode effect disappears. For example... Figure 4 As shown in (b), the forward and reverse temperature distributions basically overlap, and the heat flow resumes symmetrical transmission, similar to the case under constant boundary conditions.

[0048] This result indicates that by adjusting the phase difference... It is possible to continuously control the intensity of the diode effect under periodic boundary conditions, and even completely "turn off" the diode effect. This is precisely... Figure 5 The content shown—under periodic boundaries, The forward and reverse temperature distributions are asymmetrical and clearly separated, resulting in a significant diode effect; while Forward and reverse temperature distributions about the midpoint Symmetrical, no diode effect.

[0049] 5. Numerical simulation verification

[0050] Finite element simulation was performed using COMSOL Multiphysics with a time step of 0.1 s and a total computation time of 1500 s to ensure the system reached a time-periodic steady state. Temperature distribution data at t=1400 s were extracted for analysis.

[0051] To further verify the heat flow symmetry under constant boundary conditions, we extracted The data of the forward and reverse temperature distributions along the path were obtained, and the forward temperature at each location was calculated. Reverse temperature sum and deviation The results show that the deviation The absolute values ​​are all less than 0.03 K across the entire spatial range, with a maximum negative deviation of approximately -0.025 K and a maximum positive deviation of approximately 0.008 K. Considering the grid discretization error and solver tolerance in the numerical simulation, this small deviation is within an acceptable range, verifying that the system strictly satisfies the symmetric complementary relationship under constant boundary conditions and exhibits no diode effect.

[0052] Based on the transformation theory of the heat diffusion equation, this invention proposes a thermal switching device and its control method based on a time-controlled heating medium, realizing mode switching from "bidirectional heat conduction" to "unidirectional heat conduction" on the same device and continuous control of the diode effect intensity. This is achieved by designing the thermal conductivity... and volumetric heat capacity Traveling wave modulation, and the introduction of an adjustable phase difference. By switching boundary conditions (constant temperature / periodic temperature), active control of the directionality of heat flow is achieved. Under constant boundary conditions, the system maintains heat flow symmetry, and the forward and reverse temperature distributions satisfy a point-to-point complementary relationship. Under periodic boundaries, the diode effect intensity is determined by the equivalent convection term coefficient. Continuous regulation, when The diode effect is strongest when... The diode effect disappears. Based on this, the feasibility of the method was verified through finite element simulation. Numerical results show that under constant boundary conditions, the sum of the forward and reverse temperatures is equal to... The deviation is less than 0.03 K, verifying the thermal symmetry of the system. This invention has a simple structure, flexible control, and rapid response. It does not require complex mechanical moving parts or phase change materials, and the thermal switching function can be achieved simply by adjusting the external boundary conditions. It is also easy to miniaturize and integrate.

Claims

1. A thermal switching device based on a time-controlled heating medium, characterized in that, include: The thermal conductivity of the heating medium in an air conditioner and volumetric heat capacity It exhibits traveling wave modulation and has a volumetric heat capacity The modulation wave relative to thermal conductivity The modulated wave has an adjustable phase difference. ,in For density, Specific heat capacity; The first hot port and the second hot port are respectively located at both ends of the air conditioning heating medium and are used to connect to an external heat source or heat sink. A boundary condition control unit, connected to the first and second hot ports, is used to independently control the thermal excitation modes at both ends. The boundary condition control unit is configured as follows: In a first operating mode, both the first and second hot ports are at constant temperature boundaries, where heat flow is bidirectionally symmetrically transmitted in the refrigeration medium, the device is in a closed state, and there is no diode effect; In a second operating mode, at least one of the first and second hot ports is at a periodic temperature boundary, where heat flow exhibits unidirectional asymmetric transmission in the refrigeration medium, the device is in an open state, and a diode effect is generated. The intensity of the diode effect is determined by the equivalent convection term coefficient. Continuous regulation, Phase difference The function, and as Continuous change.

2. The thermal switch device based on time-controlled heating medium according to claim 1, characterized in that, In the heating medium of an air conditioner, its thermal conductivity and volumetric heat capacity Traveling wave modulation, that is, the spatial distribution changes in a traveling wave manner over time, which is achieved through external physical field control or dynamic modulation of material parameters.

3. The thermal switch device based on time-controlled heating medium according to claim 1, characterized in that, The thermal conductivity of the air conditioning heating medium and volumetric heat capacity The modulation format is as follows: in: and These represent the spatial average values ​​of thermal conductivity and volumetric heat capacity, respectively. and These represent the modulation amplitudes of thermal conductivity and volumetric heat capacity, respectively. The spatial coordinates of the heat medium Using time as the coordinate, For the modulation wavenumber, For modulation speed, Volumetric heat capacity Modulated wave relative to thermal conductivity The phase difference of the modulated wave.

4. The thermal switch device based on time-controlled heating medium according to claim 3, characterized in that, Equivalent convection term coefficient satisfy: in These are dimensionless modulation parameters. , For modulation wavelength, when hour, Taking the maximum value, the diode effect is significant, manifested as a clear separation between the forward and reverse temperature distributions; when hour, As the voltage approaches zero, the diode effect disappears, and the forward and reverse temperature distributions overlap.

5. A method for controlling heat transfer based on the thermal switching device according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step (1): Set the thermal excitation mode of the first hot port and the second hot port through the boundary condition control unit; Step (2): When the device needs to be in the off state, set both ends to constant temperature boundary, that is, the boundary condition where the temperature at both ends remains constant; Step (3): When the device needs to be in the on state, at least one end is set as a periodic temperature boundary, that is, a boundary condition in which the temperature fluctuates periodically over time. Step (4): Adjust the phase difference The intensity of the diode effect in the on state is continuously adjusted.

6. The control method based on time-controlled air conditioning heating medium according to claim 5, characterized in that, In step (4), the phase difference is adjusted. This causes the diode effect intensity to change continuously from zero to its maximum; when When the diode effect disappears, the forward and reverse temperature distributions coincide; when At this time, the diode effect is strongest, and the forward and reverse temperature distributions are clearly separated.

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