Pulsating airflow enhanced heat exchange system and method in confined space

Abstract

The application provides a pulsating air flow reinforced heat exchange system and method in a confined space. According to the Fourier series expansion principle, a pulsating air flow generating device capable of realizing any waveform pulsating air flow is designed. The pulsating air flow is combined with the turbulent flow rib channel and the micro-scale porous structure to realize the coordinated regulation of the flow field near the wall area in the confined space and the flow field in the micro-scale porous structure, improve the heat exchange limitation near the turbulent flow rib area, effectively strengthen the convective heat exchange performance in the confined space, and improve the cooling and heat dissipation capacity of the heated wall surface, and improve the wall surface temperature uniformity.

Description

Technical Field

[0001] This application relates to a pulsed airflow enhanced heat transfer system and method in confined spaces, belonging to the field of confined space enhanced heat transfer technology. Background Technology

[0002] Enhanced heat transfer in confined spaces has wide applications in energy, aerospace, electronics, and nuclear reactors. With the increasing integration and performance of equipment, the operating temperature of these devices is constantly rising. To ensure the service life and safe operation of equipment at high temperatures, the heat transfer problem of high-temperature equipment must be solved.

[0003] To enhance convective heat transfer in confined spaces, existing research typically optimizes the shape and arrangement of fins to improve wall-to-wall convective heat transfer. However, due to limitations in the size of the cooling space, using fins to enhance channel convective heat transfer has limitations: fin spacing is required to enhance heat transfer, but the heat transfer area is not expanded; furthermore, the trailing edge of the fins near the wall exhibits a low-velocity region and stagnant vortices, resulting in poor heat transfer performance in localized areas, leading to problems such as high local wall temperatures and poor wall temperature uniformity. Summary of the Invention

[0004] This application provides a pulsed airflow-enhanced heat transfer system and method for confined spaces, which solves the problem that existing solutions using turbulence ribs to enhance channel convective heat transfer have limitations.

[0005] To achieve the above objectives, this application provides the following technical solution: In a first aspect, embodiments of this application provide a pulsed airflow enhanced heat exchange system for confined spaces, including a pulsed airflow generator, a confined space enhanced heat exchange channel, and a pulsed airflow controller; The pulsating airflow generator includes a gas source storage tank, a main airflow pipeline, and multiple pulsating airflow branches. A main flow regulating valve is installed on the main airflow pipeline, and it is normally open during system operation. Each pulsating airflow branch is equipped with a branch flow regulating valve and a high-frequency switching valve. During system operation, the branch flow regulating valve maintains a set opening, and the high-frequency switching valve operates in a periodic opening and closing state at different frequencies. The inlet of the gas source storage tank is connected to a high-pressure gas supply device. The inlet of the main airflow pipeline and the inlets of the multiple pulsating airflow branches are connected in parallel and respectively connected to multiple outlets of the gas source storage tank. The outlets of the multiple pulsating airflow branches are connected in parallel to form a pulsating airflow pipeline. The confined space enhanced heat exchange channel has a heat source on the outer side of its heating surface and multiple turbulence ribs arranged on the inner side of the heating surface. The inner side of the heating surface of the confined space enhanced heat exchange channel also has a microscale porous structure. The confined space enhanced heat exchange channel has a main airflow inlet, multiple distributed pulsating airflow inlets, and a main airflow outlet. The main airflow inlet is connected to the outlet of the main airflow pipeline, and the multiple distributed pulsating airflow inlets are all connected to the pulsating airflow pipeline. The main airflow outlet is used to discharge the airflow inside the confined space enhanced heat exchange channel. The multiple distributed pulsating airflow inlets are distributed at the rear edge of each of the turbulence ribs and are used for periodically allowing cooling airflow to flow in laterally. The pulsed airflow controller includes a signal input terminal, a signal output terminal, and a pulsed airflow control program. The signal input terminal is used to input the operating parameters of the pulsed airflow enhanced confined space heat exchange system. The pulsed airflow control program is used to process the operating parameters to obtain valve control signals. The signal output terminal is used to output the valve control signals to the corresponding valve actuators to control the opening degree of the valves in the main airflow pipeline and the pulsed airflow branch.

[0006] Based on the above system, optionally, the operating parameters of the pulsed airflow enhanced confined space heat exchange system include: the temperature and pressure signals of the gas source storage tank, the inlet and outlet temperature signals of the confined space enhanced heat exchange channel, and the wall temperature signal; the valve control signals include the opening control signal of the main flow regulating valve and the opening and closing frequency control signals of each of the high-frequency switching valves.

[0007] Based on the above system, optionally, the microscale porous structure is a porous skeleton with an uneven surface, and its thermal conductivity is higher than that of the substrate material of the confined space enhanced heat exchange channel.

[0008] Based on the above system, optionally, the protruding porous skeleton has open micro-gaps inside, and there are open micro-pits between the protruding porous skeleton, and both the open micro-gaps and the open micro-pits allow cooling airflow to flow in and out.

[0009] Secondly, embodiments of this application also provide a method for enhancing heat transfer in a confined space using pulsating airflow, applicable to the pulsating airflow-enhanced confined space heat transfer system described in any one of the first aspects, the method comprising: Step S1: Based on the Fourier series principle, construct the pulsating airflow model of the pulsating airflow generator; wherein, in the pulsating airflow model, the total air supply flow rate of the pulsating airflow generator is... Q The flow rate of the main airflow pipeline Q 0 and the flow rate and Δ of each of the aforementioned pulsating airflow branches Q The sum of the values; and the time-averaged flow rate of the pulsating airflow pipeline is equal to the pulsation amplitude.A The wave characteristics of pulsating airflow include square waves or triangular waves. Step S2: Verify and measure the flow characteristics of each pipeline valve sequentially to obtain the functional relationship between the flow rate of each pipeline and the valve opening of the corresponding flow control valve, and construct a flow characteristic model, denoted as: In the formula, p This refers to the gauge pressure inside the gas source storage tank. T Δ represents the internal temperature of the gas source storage tank. Q 1. Δ Q 2. Δ Q 3. Δ Q 4 represents the flow rates of each pulsating airflow branch, in order. V 0、 V 1. V 2. V 3. V 4. The valve opening of the main flow regulating valve and the valve opening of each branch flow regulating valve are set in sequence. Step S3: Based on the fundamental principles of heat transfer, and combined with experimental and operational data, establish a heat transfer model for enhanced heat transfer channels in a confined space, denoted as: In the formula, q To enhance the average heat flux density of the heat exchange channel surface in a confined space, T W To enhance the average wall temperature of the heat exchange channel surface in a confined space, T f To enhance the qualitative temperature of the airflow within a confined space in the heat exchange channel, h To enhance the convective heat transfer coefficient within a confined space, X To enhance the geometric dimensional parameters of heat exchange channels in confined spaces, f The pulsation frequency of the pulsating airflow; Step S4: Integrate the established confined space enhanced heat exchange channel heat transfer model, the flow characteristic model, and the pulsating airflow model into the pulsating airflow control program of the pulsating airflow controller; Step S5: Obtain the actual wall temperature of the heating surface of the confined space enhanced heat exchange channel. T W and the wall temperature setpoint T W,set Calculate the temperature deviation; if the temperature deviation exceeds the upper threshold Δ of the wall temperature of the heat-receiving surface of the confined space enhanced heat exchange channel... T w,up Or lower limit threshold Δ T w,down Then the main airflow rate Q0. Flow rate Δ of the pulsating airflow branch Q At least one of the pulsation frequencies is adjusted to change the heat exchange capacity of the cooling airflow.

[0010] Based on the above method, optionally, in step S1, the number of pulsating airflow branches is 4, and the flow characteristics of each pulsating airflow branch are trigonometric functions, with the pulsation amplitude and pulsation frequency related to the pulsating airflow flow rate Δ. Q The flow satisfies a Fourier series expansion, and retaining the first four terms, the established pulsating airflow model is as follows: in, t It is a time series of pulsation occurrences, Δ Q 1. Δ Q 2. Δ Q 3. Δ Q 4 represents the flow rates of the four pulsating airflow branches. A 1. A 2. A 3. A 4 are Δ Q 1. Δ Q 2. Δ Q 3. Δ Q The pulsation amplitude is 4.

[0011] Based on the above method, optionally, in step S5, the main airflow rate is... Q The adjustment method for adjusting 0 is as follows: When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W > T W,set +Δ T w,up At the same time, based on experimental data, the valve opening of the main flow regulating valve is gradually increased. V 0; when T W = T W,set At the same time, maintain the valve opening of the main flow regulating valve. V 0 remains unchanged; When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W < T W,set +Δ T w,down At the same time, gradually reduce the valve opening of the main flow regulating valve. V 0; when T W = T W,setAt the same time, maintain the valve opening of the main flow regulating valve. V 0 remains unchanged.

[0012] Based on the above method, optionally, according to claim 6, the method is characterized in that, when the pulsating airflow has a pulsating amplitude of A The pulse frequency is f When the square wave is used, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsation airflow in each of the pulsation airflow branches are related to the pulsation amplitude of the square waveform pulsation airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3. f 4 represents the pulsation frequency of each of the pulsating airflow branches.

[0013] Based on the above method, optionally, when the pulsating airflow has a pulsation amplitude of A The pulse frequency is f When the triangular wave is generated, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsating airflow in each of the pulsating airflow branches are related to the pulsation amplitude of the triangular waveform pulsating airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3. f 4 represents the pulsation frequency of each of the pulsating airflow branches.

[0014] The pulsed airflow enhanced confined space heat transfer system and method provided in this application are designed based on the Fourier series expansion principle to generate a pulsed airflow with arbitrary waveform. The pulsed airflow is combined with the turbulence rib channel and the microscale porous structure to achieve coordinated control of the flow field in the near-wall region of the confined space and the flow field in the microscale porous structure. This improves the heat transfer limitation near the turbulence rib region, effectively enhances the convective heat transfer performance in the confined space, thereby improving the cooling and heat dissipation capacity of the heated wall surface and improving the uniformity of the wall surface temperature. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Furthermore, these drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art by reference to specific embodiments.

[0016] Figure 1 This is a schematic diagram of the structure of a pulsed airflow enhanced confined space heat exchange system according to one embodiment of this application; Figure 2 This is a schematic diagram of the flow field near the wall of a confined space channel with non-pulsating airflow, provided in one embodiment of this application. Figure 3 This is a schematic diagram of the flow field near the wall of a confined space channel with pulsating airflow, provided in one embodiment of this application. Figure 4 A schematic diagram of the flow field inside and near-wall region of a microscale porous structure under pulsationless airflow, provided in one embodiment of this application; Figure 5 A schematic diagram of the flow field inside and near-wall region of a microscale porous structure with pulsating airflow, provided for an embodiment of this application; Figure 6 A schematic flowchart of a method for enhancing heat transfer in a confined space using pulsating airflow, provided in one embodiment of this application; Figure 7 This is a schematic diagram illustrating the decomposition principle of a square wave-type pulsating airflow according to an embodiment of this application; Figure 8 This is a schematic diagram illustrating the decomposition principle of triangular wave-shaped pulsating airflow according to one embodiment of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0018] Some embodiments of this application provide a pulsed airflow-enhanced confined space heat exchange system, see reference... Figure 1 , Figure 1 This is a schematic diagram of a pulsed airflow-enhanced confined space heat exchange system according to one embodiment of this application. Figure 1As shown, the pulsed airflow enhanced confined space heat exchange system of this embodiment includes a pulsed airflow generator U1, a confined space enhanced heat exchange channel U2, and a pulsed airflow controller U3; wherein, The pulsating airflow generator includes an air source storage tank E1, a main airflow pipeline C0, and multiple pulsating airflow branches C1, C2, C3, and C4. A main flow regulating valve Vq0 is installed on the main airflow pipeline C0, which is normally open when the system is working. Each pulsating airflow branch C1, C2, C3, and C4 is equipped with a branch flow regulating valve Vq1, Vq2, Vq3, and Vq4, and a high-frequency switching valve Vf1, Vf2, Vf3, and Vf4. When the system is working, the branch flow regulating valves Vq1, Vq2, Vq3, and Vq4 maintain a set opening degree, while the high-frequency switching valves Vf1, Vf2, Vf3, and Vf4 are in a periodic opening and closing state at different frequencies.

[0019] The inlet E11 of the gas source storage tank E1 is connected to the high-pressure gas supply device, such as a compressor or a gas compressor; the inlet of the main gas flow pipeline C0 and the inlets of multiple pulsating gas flow branches C1, C2, C3, and C4 are connected in parallel and respectively connected to multiple outlets of the gas source storage tank E1; the outlets of multiple pulsating gas flow branches C1, C2, C3, and C4 are connected in parallel to form the pulsating gas flow pipeline C5.

[0020] The confined space enhanced heat transfer channel U2 is a small-scale rectangular or non-circular channel. The channel flow area is divided into a mainstream region E21 and a near-wall region E22. The average flow velocity in the mainstream region E21 is denoted as... The near-wall velocity is very small; a heat source is provided on the outer side of the channel heating surface E3, and multiple turbulence ribs E32 and E33 are arranged on the inner side of the heating surface E3. The inner side of the heating surface E3 of the confined space enhanced heat exchange channel U2 is combined with a micro-scale porous structure E31; the airflow channel E2 of the confined space enhanced heat exchange channel U2 has a main airflow inlet, multiple distributed pulsating airflow inlets C51 and a main airflow outlet; the main airflow inlet is connected to the outlet of the main airflow pipe C0, and the multiple distributed pulsating airflow inlets are all connected to the pulsating airflow pipe C5. The main airflow outlet is used to discharge the airflow inside the confined space enhanced heat exchange channel U2; the multiple distributed pulsating airflow inlets C51 are distributed at the rear edge of each turbulence rib E32 and E33, and are used for periodic lateral inflow of cooling airflow.

[0021] Furthermore, such as Figure 2 As shown, the heated surface inside the channel is composited with a microscale porous structure E31, which is a porous skeleton with an uneven surface and a higher thermal conductivity than the substrate material of the confined space reinforced heat exchange channel. Thus, the microscale porous structure E31 increases the heat exchange area inside the heat exchange channel, improving heat dissipation efficiency.

[0022] Furthermore, the raised porous skeleton has open micro-gaps E311 inside, and open micro-recesses E312 between the raised porous skeleton, and both the open micro-gaps E311 and the open micro-recesses E312 allow cooling airflow to flow in and out. In this way, heat dissipation efficiency can be further improved.

[0023] like Figure 3 and Figure 4 As shown, the multiple distributed pulsating airflow inlets are located at the trailing edges of each of the turbulence ribs E32 and E33, and the cooling airflow periodically flows in laterally. ΔQ This enhances heat transfer at the trailing edge of the turbulence ribs, addressing the issues of localized heat transfer deterioration and excessively high channel wall temperature caused by the presence of stagnant vortices E23 at the trailing edge of the turbulence ribs. Specifically, on a macroscopic scale, the transverse pulsating airflow causes the downstream vortex E24 between the ribs to detach from the near-wall region E22, strengthening the mixing of the higher-temperature airflow in the near-wall region E22 with the lower-temperature airflow in the mainstream region E21. On a microscopic scale, the transverse pulsating airflow promotes airflow within the microscale porous structure E31, which is a composite of the heated surfaces inside the channel. When there is no transverse pulsating airflow, such as... Figure 2 As shown, the open micro-pits E312 between the protruding porous skeleton of the composite micro-scale porous structure of the heated surface contain tiny stagnant vortices E25 and E26, which are not conducive to convective heat transfer; when there is transverse pulsating airflow, such as Figure 5 As shown, when the transversely pulsating airflow is injected into the open micro-dimples E312, it breaks the original stagnant vortices E26 and induces new small vortices E27 and E28. At the same time, it drives the airflow in the open micro-dimples E312 into the open micro-voids E311 in the porous skeleton, enhancing the heat transfer in the micro-scale porous structure E31 of the heat-receiving surface composite. Furthermore, it can also promote the flow of the stagnant vortices E25 in the surrounding open micro-dimples to the mainstream area, thereby enhancing the heat exchange between the micro-scale porous structure E31 of the heat-receiving surface composite and the airflow in the near-wall region E22.

[0024] In addition, such as Figure 1 As shown, the pulsed airflow controller U3 includes a signal input terminal E4, a signal output terminal E6, and a pulsed airflow control program E5. The signal input terminal E4 is used to input the operating parameters of the pulsed airflow enhanced confined space heat exchange system. The pulsed airflow control program E5 is used to process the operating parameters to obtain valve control signals. The signal output terminal E6 is used to output valve control signals to the corresponding valve actuators to control the opening degree of the valves on the main airflow pipeline C0 and the pulsed airflow branches C1, C2, C3, and C4.

[0025] Furthermore, the operating parameters of the pulsed airflow enhanced confined space heat exchange system include: the temperature and pressure signals of the gas source storage tank E1, the inlet and outlet temperature signals of the confined space enhanced heat exchange channel U2, and the temperature signal of the wall; the valve control signals include the opening control signal of the main flow regulating valve Vq0, and the opening and closing frequency control signals of each high-frequency switching valve Vf1, Vf2, Vf3, and Vf4.

[0026] The pulsed airflow control program E5 mainly includes a heat transfer mathematical model and an empirical model based on experience or historical data. Furthermore, the pulsed airflow control program E5 is a control model established with the signal input end as feedback and the signal output end as execution.

[0027] Through the heat exchange system described above, a pulsed airflow generator was designed and implemented. The pulsed airflow is combined with the turbulence rib channel and the microscale porous structure to achieve coordinated control of the flow field in the near-wall region of the confined space and the flow field in the microscale porous structure. This improves the heat exchange limitations near the turbulence rib region, effectively enhances the convective heat transfer performance in the confined space, thereby improving the cooling and heat dissipation capacity of the heated wall surface and improving the uniformity of the wall surface temperature.

[0028] Furthermore, this application also provides a method for enhancing heat transfer in confined spaces with pulsating airflow, which is applicable to the pulsating airflow enhanced heat transfer system in any of the above embodiments.

[0029] like Figure 6 As shown, the method includes the following steps: Step S1: Based on the Fourier series principle, construct a pulsating airflow model for the pulsating airflow generator.

[0030] The flow rate of the main airflow duct C0 is set as follows: Q 0, the flow rate of the pulsating airflow pipe C5 is Δ Q The pulsation amplitude of the flow rate in pulsating gas flow pipe C5 is denoted as... A And the time-average flow rate of the pulsating airflow is .

[0031] In the pulsating airflow model, the total air supply flow of the pulsating airflow generator is the sum of two parts, denoted as: (1) In addition, depending on the heat transfer control requirements, the pulsating airflow characteristics include square waves or triangular waves.

[0032] If the number of pulsating airflow branches is 4 (C1, C2, C3, C4), then the flow rate Δ of pulsating airflow branch C5 is... Q Let Δ be the sum of the flow rates of the four pulsating airflow branches C1, C2, C3, and C4, where the flow rate of the first-stage pulsating airflow branch C1 is denoted as Δ. Q1. The flow rate of the second-stage pulsating airflow branch C2 is denoted as Δ. Q 2. The flow rate of the third-stage pulsating airflow branch C3 is denoted as Δ. Q 3. The flow rate of the fourth-stage pulsating airflow branch C4 is denoted as Δ. Q 4. The following relationship must be satisfied: (2) Furthermore, in step S1, if the number of pulsating airflow branches is 4, and the flow characteristics of each pulsating airflow branch are trigonometric functions, the pulsation amplitude and pulsation frequency are related to the pulsating airflow flow rate Δ. Q The flow satisfies a Fourier series expansion, and retaining the first four terms, the established pulsating airflow model is as follows: in, f The pulsation frequency of the pulsating airflow. t It is a time series of pulsation occurrences, Δ Q 1. Δ Q 2. Δ Q 3. Δ Q 4 represents the flow rates of the four pulsating airflow branches. A 1. A 2. A 3. A 4 are Δ Q 1. Δ Q 2. Δ Q 3. Δ Q The pulsation amplitude is 4.

[0033] Step S2: Verify and measure the flow characteristics of each pipeline valve sequentially to obtain the functional relationship between the flow rate of each pipeline and the valve opening of the corresponding flow regulating valve (Vq0, Vq1, Vq2, Vq3, Vq4). Construct a flow characteristic model, denoted as: In the formula, p This refers to the gauge pressure inside the gas source storage tank. T This refers to the internal temperature of the gas source storage tank. V 0、 V 1. V 2. V 3. V 4. The valve opening of the main flow control valve and the valve opening of each branch flow control valve are adjusted sequentially. That is, V 0、 V 2. V 3. V 4. V5. The valve opening of the main flow regulating valve Vq0, the valve opening of the branch flow regulating valve Vq1 of the first-stage pulsating airflow branch, the valve opening of the branch flow regulating valve Vq2 of the second-stage pulsating airflow branch, the valve opening of the branch flow regulating valve Vq3 of the third-stage pulsating airflow branch, and the valve opening of the branch flow regulating valve Vq4 of the fourth-stage pulsating airflow branch are sequentially set.

[0034] Step S3: Based on the fundamental principles of heat transfer, and combined with experimental and operational data, establish a heat transfer model for enhanced heat transfer channels in a confined space, denoted as: In the formula, q To enhance the average heat flux density of the heat exchange channel surface in a confined space, T W To enhance the average wall temperature of the heat exchange channel surface in a confined space, T f To enhance the qualitative temperature of the airflow within a confined space in the heat exchange channel, h To enhance the convective heat transfer coefficient within a confined space, X Geometric dimensional parameters for enhancing heat exchange channels in confined spaces.

[0035] The specific implementation process of this step is existing technology, so it will not be described in detail here.

[0036] Step S4: Integrate the established confined space enhanced heat transfer channel heat transfer model, flow characteristic model and pulsating airflow model into the pulsating airflow controller's pulsating airflow control program.

[0037] Specifically, the model established in the previous steps is essentially an algorithm, which can be written into a program and integrated into the pulsed airflow control program.

[0038] Additionally, the signal input terminal E4 of the pulsed airflow controller U3 is connected to the temperature of the air source storage tank E1. T ,pressure p Equal signal (E42), confined space enhances the internal wall temperature of the heat exchange channel T W Constrained space enhances heat exchange channel U2 internal airflow qualitative temperature T f Equal signal (E41); The signal output terminal E6 of the pulsed airflow controller U3 is connected to the opening actuators of the branch flow regulating valves Vq0, Vq1, Vq2, Vq3, and Vq4, outputting valve opening control commands (E61) to them; the signal output terminal E6 of the pulsed airflow controller U3 is also connected to the opening and closing state actuators of the high-frequency switching valves Vf1, Vf2, Vf3, and Vf4, outputting valve opening and closing frequency commands (E62) to them; based on experimental and historical data, for a specific operating condition, preferably, the opening signal of the main flow regulating valve Vq0 opening actuator is... V 0. The opening signal of the actuator for the branch flow regulating valve Vq1 in the first-stage pulsating airflow branch is: V 1. The opening signal of the branch flow regulating valve Vq2 in the second-stage pulsating airflow branch is: V 2. The opening signal of the branch flow regulating valve Vq3 in the third-stage pulsating airflow branch is: V 3. The opening signal of the branch flow regulating valve Vq4 in the fourth-stage pulsating airflow branch is: V 4. The opening and closing frequency signal of the high-frequency switching valve Vf1 actuator in the first-stage pulsating airflow branch is: f 1. The opening and closing frequency signal of the high-frequency switching valve Vf2 actuator in the second-stage pulsating airflow branch is: f 2. The opening and closing frequency signal of the high-frequency switching valve Vf3 actuator in the third-stage pulsating airflow branch is: f 3. The opening and closing frequency signal of the high-frequency switching valve Vf4 actuator in the fourth-stage pulsating airflow branch is: f 4.

[0039] Among them, the opening degree of the branch flow regulating valve actuator and the opening and closing frequency of the high-frequency switching valve actuator in each level of the pulsating airflow branch must meet the preferred pulsating airflow waveform, and the parameters must meet the Fourier series expansion principle of the corresponding waveform.

[0040] For example, such as Figure 7 As shown, when the pulsating airflow has a pulsating amplitude of A The pulse frequency is f When the square wave is used, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsation airflow in each of the pulsation airflow branches are related to the pulsation amplitude of the square waveform pulsation airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3.f 4 represents the pulsation frequency of each of the pulsating airflow branches.

[0041] For example, such as Figure 8 As shown, when the pulsating airflow has a pulsating amplitude of A The pulse frequency is f When the triangular wave is generated, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsating airflow in each of the pulsating airflow branches are related to the pulsation amplitude of the triangular waveform pulsating airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3. f 4 represents the pulsation frequency of each of the pulsating airflow branches.

[0042] Step S5: Obtain the actual wall temperature of the heat-receiving surface of the confined space enhanced heat exchange channel. T W and the wall temperature setpoint T W,set Calculate the temperature deviation. If the temperature deviation exceeds the upper threshold Δ of the wall temperature of the heat exchange surface in the confined space enhanced heat exchange channel, then... T w,up Or lower limit threshold Δ T w,down Then the main airflow rate Q 0. Flow rate Δ of the pulsating airflow branch Q At least one of the pulsation frequencies is adjusted to change the heat exchange capacity of the cooling airflow.

[0043] Specifically, during system operation, when the feedback signal limits the temperature of the heated wall surface E3 of the space-enhanced heat exchange channel... T W Deviation from set temperature T W,set When the upper or lower threshold of the level is reached, the main airflow rate is adjusted according to the airflow adjustment scheme selected in the pulsed airflow control program E5. Q 0 or pulsating airflow Δ Q The flow rate or pulsation frequency can be adjusted to change the heat exchange capacity of the cooling airflow in order to meet the temperature control requirements of the heat exchange channel surface in a confined space.

[0044] Furthermore, in step S5, the main airflow rate is... Q The adjustment method for adjusting 0 is as follows: When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W > T W,set +Δ T w,up At the same time, based on experimental data, the valve opening of the main flow regulating valve Vq0 is gradually increased. V 0; when T W = T W,set At the same time, maintain the valve opening of the main flow regulating valve Vq0. V 0 remains unchanged; When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W < T W,set +Δ T w,down At the same time, gradually reduce the valve opening of the main flow regulating valve Vq0. V 0; when T W = T W,set At the same time, maintain the valve opening of the main flow regulating valve Vq0. V 0 remains unchanged.

[0045] And for pulsating airflow Δ Q The adjustment of the flow rate or pulsation frequency can be referred to the formula principle in the aforementioned embodiments, which will not be repeated here.

[0046] In the above scheme, a pulsating airflow generator capable of generating pulsating airflow of arbitrary waveforms is designed based on the Fourier series expansion principle. The pulsating airflow is combined with the turbulence rib channel and the microscale porous structure to achieve coordinated control of the flow field in the near-wall region of the confined space and the flow field in the microscale porous structure. This improves the heat transfer limitation near the turbulence rib region, effectively enhances the convective heat transfer performance in the confined space, thereby improving the cooling and heat dissipation capacity of the heated wall surface, while also improving the uniformity of the wall surface temperature.

[0047] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0048] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0049] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0050] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0051] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0052] Furthermore, the functional units in the various embodiments of this invention can be integrated into a single processing module, or each unit can exist physically separately, or two or more units can be integrated into a single module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. The aforementioned storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0053] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., 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. In this specification, the illustrative expressions of the above terms 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 or examples.

[0054] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A pulsed airflow-enhanced confined space heat exchange system, characterized in that, Includes a pulsed airflow generator, a confined space enhanced heat exchange channel, and a pulsed airflow controller; The pulsating airflow generator includes a gas source storage tank, a main airflow pipeline, and multiple pulsating airflow branches. A main flow regulating valve is installed on the main airflow pipeline, and it is normally open during system operation. Each pulsating airflow branch is equipped with a branch flow regulating valve and a high-frequency switching valve. During system operation, the branch flow regulating valve maintains a set opening, and the high-frequency switching valve operates in a periodic opening and closing state at different frequencies. The inlet of the gas source storage tank is connected to a high-pressure gas supply device. The inlet of the main airflow pipeline and the inlets of the multiple pulsating airflow branches are connected in parallel and respectively connected to multiple outlets of the gas source storage tank. The outlets of the multiple pulsating airflow branches are connected in parallel to form a pulsating airflow pipeline. The confined space enhanced heat exchange channel has a heat source on the outer side of its heating surface and multiple turbulence ribs arranged on the inner side of the heating surface. The inner side of the heating surface of the confined space enhanced heat exchange channel also has a microscale porous structure. The confined space enhanced heat exchange channel has a main airflow inlet, multiple distributed pulsating airflow inlets, and a main airflow outlet. The main airflow inlet is connected to the outlet of the main airflow pipeline, and the multiple distributed pulsating airflow inlets are all connected to the pulsating airflow pipeline. The main airflow outlet is used to discharge the airflow inside the confined space enhanced heat exchange channel. The multiple distributed pulsating airflow inlets are distributed at the rear edge of each of the turbulence ribs and are used for periodically allowing cooling airflow to flow in laterally. The pulsed airflow controller includes a signal input terminal, a signal output terminal, and a pulsed airflow control program. The signal input terminal is used to input the operating parameters of the pulsed airflow enhanced confined space heat exchange system. The pulsed airflow control program is used to process the operating parameters to obtain valve control signals. The signal output terminal is used to output the valve control signals to the corresponding valve actuators to control the opening degree of the valves in the main airflow pipeline and the pulsed airflow branch.

2. The system according to claim 1, characterized in that, The operating parameters of the pulsed airflow enhanced confined space heat exchange system include: the temperature and pressure signals of the gas source storage tank, the inlet and outlet temperature signals of the confined space enhanced heat exchange channel, and the wall temperature signal; the valve control signals include the opening control signal of the main flow regulating valve and the opening and closing frequency control signals of each of the high-frequency switching valves.

3. The system according to claim 1, characterized in that, The microscale porous structure is a porous skeleton with an uneven surface, and its thermal conductivity is higher than that of the substrate material of the confined space enhanced heat exchange channel.

4. The system according to claim 3, characterized in that, The raised porous skeleton has open micro-gaps inside, and there are open micro-pits between the raised porous skeletons. Both the open micro-gaps and the open micro-pits allow cooling airflow to flow in and out.

5. A method for enhancing heat transfer in a confined space using pulsating airflow, characterized in that, The method, applicable to the pulsed airflow enhanced confined space heat exchange system as described in any one of claims 1 to 4, comprises: Step S1: Based on the Fourier series principle, construct the pulsating airflow model of the pulsating airflow generator; wherein, in the pulsating airflow model, the total air supply flow rate of the pulsating airflow generator is... Q The flow rate of the main airflow pipeline Q 0 and the flow rate and Δ of each of the aforementioned pulsating airflow branches Q The sum of the values; and the time-averaged flow rate of the pulsating airflow pipeline is equal to the pulsation amplitude. A The wave characteristics of pulsating airflow include square waves or triangular waves. Step S2: Verify and measure the flow characteristics of each pipeline valve sequentially to obtain the functional relationship between the flow rate of each pipeline and the valve opening of the corresponding flow control valve, and construct a flow characteristic model, denoted as: In the formula, p This refers to the gauge pressure inside the gas source storage tank. T Δ represents the internal temperature of the gas source storage tank. Q 1. Δ Q 2. Δ Q 3. Δ Q 4 represents the flow rates of each pulsating airflow branch, in order. V 0、 V 1. V 2. V 3. V 4. The valve opening of the main flow regulating valve and the valve opening of each branch flow regulating valve are set in sequence. Step S3: Based on the fundamental principles of heat transfer, and combined with experimental and operational data, establish a heat transfer model for enhanced heat transfer channels in a confined space, denoted as: In the formula, q To enhance the average heat flux density of the heat exchange channel surface in a confined space, T w To enhance the average wall temperature of the heat exchange channel surface in a confined space, T f To enhance the qualitative temperature of the airflow within a confined space in the heat exchange channel, h To enhance the convective heat transfer coefficient within a confined space, X To enhance the geometric dimensional parameters of heat exchange channels in confined spaces, f The pulsation frequency of the pulsating airflow; Step S4: Integrate the established confined space enhanced heat exchange channel heat transfer model, the flow characteristic model, and the pulsating airflow model into the pulsating airflow control program of the pulsating airflow controller; Step S5: Obtain the actual wall temperature of the heating surface of the confined space enhanced heat exchange channel. T W and the wall temperature setpoint T W,set Calculate the temperature deviation; if the temperature deviation exceeds the upper threshold Δ of the wall temperature of the heat-receiving surface of the confined space enhanced heat exchange channel... T w,up Or lower limit threshold Δ T w,down Then the main airflow rate Q 0. Flow rate Δ of the pulsating airflow branch Q At least one of the pulsation frequencies is adjusted to change the heat exchange capacity of the cooling airflow.

6. The method according to claim 5, characterized in that, In step S1, there are four pulsating airflow branches, and the flow characteristics of each pulsating airflow branch are trigonometric functions, with the pulsation amplitude and pulsation frequency related to the pulsating airflow flow rate Δ. Q The flow satisfies a Fourier series expansion, and retaining the first four terms, the established pulsating airflow model is as follows: in, t It is a time series of pulsation occurrences, Δ Q 1. Δ Q 2. Δ Q 3. Δ Q 4 represents the flow rates of the four pulsating airflow branches. A 1. A 2. A 3. A 4 are Δ Q 1. Δ Q 2. Δ Q 3. Δ Q The pulsation amplitude is 4.

7. The method according to claim 5, characterized in that, In step S5, the main airflow rate is... Q The adjustment method for adjusting 0 is as follows: When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W > T W,set +Δ T w,up At the same time, based on experimental data, the valve opening of the main flow regulating valve is gradually increased. V 0; when T W = T W,set At the same time, maintain the valve opening of the main flow regulating valve. V 0 remains unchanged; When the actual wall temperature of the heat exchange channel in the confined space is enhanced T W < T W,set +Δ T w,down At the same time, gradually reduce the valve opening of the main flow regulating valve. V 0; when T W = T W,set At the same time, maintain the valve opening of the main flow regulating valve. V 0 remains unchanged.

8. The method according to claim 6, characterized in that, When the pulsating airflow has a pulsating amplitude of A The pulse frequency is f When the square wave is used, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsation airflow in each of the pulsation airflow branches are related to the pulsation amplitude of the square waveform pulsation airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3. f 4 represents the pulsation frequency of each of the pulsating airflow branches.

9. The method according to claim 6, characterized in that, When the pulsating airflow has a pulsating amplitude of A The pulse frequency is f When the triangular wave is generated, the flow rate of each of the pulsating airflow branches is set as follows: Among them, the pulsation amplitude and pulsation frequency of the pulsating airflow in each of the pulsating airflow branches are related to the pulsation amplitude of the triangular waveform pulsating airflow. A and pulsation frequency f The following relationship must be satisfied: In the formula, f 1. f 2. f 3. f 4 represents the pulsation frequency of each of the pulsating airflow branches.

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