Heat pipe heat transfer performance test method and control system using laser heat source

Abstract

Disclosed in the present invention are a heat pipe heat transfer performance test method and control system using a laser heat source. The test method comprises the following steps: clamping a heat pipe to be tested; arranging a temperature measurement point, and starting temperature data acquisition; performing laser beam positioning; enabling a laser to emit light and heating the heat pipe; processing test data and generating a report; and unloading the tested heat pipe. The control system comprises an upper computer, a motion controller module, a laser module, a temperature acquisition module, a motion execution module and a cooling module. The present invention focuses on the heat transfer performance testing process of heat pipes, and uses a laser as a heat source, thus significantly increasing the temperature rise rate of heat pipes; the developed control system promotes the automated process of testing, and solves the problem of high requirements of devices on professional knowledge of operators, thus reducing production costs and improving production efficiency.

Description

A heat pipe heat transfer performance testing method and control system using laser heat source Technical Field

[0001] The present invention belongs to the field of heat pipe power testing and laser application equipment automation control, and in particular relates to a heat pipe heat transfer performance testing method and control system using a laser heat source. Background Art

[0002] The heat pipe is a two-phase heat exchange element with excellent thermal conductivity, and its thermal conductivity can reach 1×10 4 W / (m·K) or above. With its outstanding heat exchange performance, diversified structure, light and thin design and no need for additional energy drive, heat pipes and their assemblies have become the preferred heat dissipation devices for 3C products represented by laptop computers. With the advancement of computer chip technology, chips are developing towards high computing power and high integration, resulting in an increasingly large heat flux density of chips, which puts higher requirements on the heat dissipation performance of heat pipes. In order to control the factory performance of heat pipe products, heat pipes need to be tested for heat transfer performance before leaving the factory. The heat source for the common heat transfer performance test of heat pipes is a copper block with an embedded electric heating rod. The temperature rise rate provided by this method is low, the time it takes for the heat pipe to reach a thermally stable state is long, the thermal response speed is slow, and it is impossible to accurately simulate the actual working conditions of the heat pipe, so it is impossible to obtain an accurate evaluation result of the heat pipe performance.

[0003] The present invention overcomes the shortcomings of the traditional copper block contact heating with an embedded electric heating rod in the above-mentioned heat pipe heat transfer performance test process, and provides a heat pipe heat transfer performance test method using a laser heat source. The laser light emitted by the laser and processed is irradiated on the area to be heated on the surface of the heated body. The laser irradiates the heated body, thereby directly or indirectly generating a faster temperature rise rate on the heat pipe, which can enable the heat pipe to reach a thermally stable state in a shorter time, thereby improving the detection efficiency. The heating method of the laser-heated heat pipe can more realistically simulate the power step of the chip, thereby simulating the actual thermal effect on the heat pipe during the operation of the chip, meeting the needs of experimental verification in the existing research and development of heat exchangers for high heat flux density chips. The method is practical and effective with good economic efficiency. In addition, the manual operation of the laser equipment is complicated, the interoperability of the modules is poor, the degree of automation is low, the maintenance cost is high, and the professional knowledge of the operator is required. In response to such problems, a heat pipe heat transfer performance test control system using a laser heat source is also proposed.

[0004] Summary of the Invention

[0005] In order to solve the technical problems existing in the background technology, the present invention aims to provide a heat pipe heat transfer performance testing method and control system using a laser heat source.

[0006] In order to solve the technical problem, the technical solution of the present invention is:

[0007] A method for testing heat transfer performance of a heat pipe using a laser heat source, the method comprising:

[0008] S1: Clamp the heat pipe to be tested: Use a special fixture to clamp and position the heat pipe to be tested;

[0009] S2: Arrange temperature measurement points and start temperature data collection: Use thermocouples as temperature sensors installed on the heat pipe wall to collect temperature data of the heat pipe;

[0010] S3: Laser beam positioning: According to the set spatial position information, move the three-axis linear module equipped with the laser output head until the laser beam output by the laser output head can be focused on the heating surface and can accurately irradiate the area to be heated;

[0011] S4: The laser emits light and heats the heat pipe: After the relevant heating parameters are set, the timing is started, the laser is enabled to emit light, and the laser output is the set power. After the timing is over, the laser is disabled and stops outputting laser light. During the whole process, the temperature acquisition module works, dynamically collecting and outputting temperature data in real time.

[0012] S5: Process test data and generate report: The system determines whether the heat transfer performance of the heat pipe is qualified based on the collected test temperature data and automatically generates a test report;

[0013] S6: Uninstall the tested heat pipe.

[0014] Furthermore, the laser beam positioning step S3 specifically includes:

[0015] S31: Input the relative position information between the fixture and the laser output head;

[0016] S32: Turn on the red light indication;

[0017] S33: Move the z-axis linear module;

[0018] S34: Determine whether the distance between the focal plane of the light beam and the heated plane is less than 0.2 mm. If so, proceed to step S35; if not, return to step S33.

[0019] S35: Move the x and y axis linear module;

[0020] S36: Determine whether the margin between the focused spot area and the area to be heated is less than 0.1 mm. If so, execute step S37; if not, return to step S35;

[0021] S37: Turn off the red light indication;

[0022] In step S32, the purpose of turning on the red light indicator is that the laser outputs a low-power red laser visible to the human eye, which facilitates manual observation of the output laser beam position and judgment of the irradiation range of the laser beam;

[0023] In step S33, the z-axis direction is determined to be the normal direction of the heated surface, the central axis of the output laser beam is parallel to the z-axis, and the laser beam irradiates the heated surface perpendicularly along the negative direction of the z-axis;

[0024] In step S34, if the distance between the focal plane of the light beam and the heated surface is less than 0.2 mm, it is determined that the laser beam is accurately focused on the heated surface, and the next step can be performed. If the distance between the focal plane of the light spot and the heated surface is greater than 0.2 mm, it is determined that the laser beam is not accurately focused on the heated surface, and step S33 needs to be continued until the determination of step S34 is yes.

[0025] In step S35, the x-axis direction is determined to be the radial direction of the heat pipe, the y-axis direction is determined to be the axial direction of the heat pipe, the x, y, and z axes form a Cartesian coordinate system, and the xOy plane coincides with the heated plane;

[0026] In step S36, if the margin between the focused spot area and the area to be heated is less than 0.1 mm, it is determined that the laser beam is accurately irradiated on the position to be heated of the heat pipe, and the next step can be performed at this time; if the margin between the focused spot area and the area to be heated is greater than 0.1 mm, it is determined that the laser beam is not accurately irradiated on the position to be heated of the heat pipe, and it is necessary to continue step S35 until the judgment of step S36 is yes.

[0027] Furthermore, the heated surface in the laser beam positioning step S3 refers to the heat pipe surface or the heat sink surface;

[0028] If the heat pipe to be tested is a flattened heat pipe (2-1) and the heated surface is the surface of the flattened heat pipe, the laser beam directly irradiates the surface of the flattened heat pipe and directly heats the flattened heat pipe (2-1) by radiation heat transfer;

[0029] If the heat pipe to be tested is a flattened heat pipe (2-1) and the heated surface is the surface of the flattened heat pipe heat sink (3-1), the flattened heat pipe heat sink (3-1) and the flattened heat pipe (2-1) are tightly fitted, the laser beam irradiates the flattened heat pipe heat sink (3-1), and the flattened heat pipe heat sink (3-1) is heated by radiation heat transfer. After the temperature of the flattened heat pipe heat sink (3-1) is increased, the flattened heat pipe (2-1) is indirectly heated by heat conduction.

[0030] If the heat pipe to be tested is a circular pipe (4-1), a circular pipe heat sink (4-2) is designed and tightly fitted with the circular pipe (4-1). In this case, the heated surface is the circular pipe heat sink (4-2). The laser beam irradiates the circular pipe heat sink (4-2) and heats the circular pipe heat sink (4-2) by radiation heat transfer. After the circular pipe heat sink (4-2) is heated, it indirectly heats the circular pipe (4-1) by heat conduction.

[0031] The heated plane refers to the surface plane of the heated surface; the area to be heated refers to the range area on the heated surface that needs to be heated.

[0032] Furthermore, in step S4, the laser emits light and heats the heat pipe, and the specific steps include:

[0033] S41: Input heating power and heating time;

[0034] S42: The timing starts and the laser is enabled to emit light;

[0035] S43: output real-time temperature test data;

[0036] S44: The timing ends and the laser is disabled;

[0037] Among them, in step S41, after the heating power, heating time and heating information are set in the system, the system converts the set setting information into relevant electrical signals to configure the relevant functions of the laser;

[0038] In step S42, an enable signal is input to the laser and program timing is used.

[0039] Furthermore, the step S5 processes the test data and generates a report. The specific process is as follows:

[0040] If the temperature difference ΔT between the evaporation and condensation ends of the heat pipe is less than 3°C, it means that the heat pipe to be tested meets the performance test requirements and a heat pipe heat transfer performance test qualification report is generated; if the temperature difference ΔT between the evaporation and condensation ends is greater than 3°C, the heat pipe does not meet the performance test requirements and a heat pipe heat transfer performance test failure report is generated.

[0041] A heat pipe heat transfer performance test control system using a laser heat source, the system being used to execute any of the above methods, the system comprising:

[0042] Host computer: used to interact with users, process user-issued control commands and send them to subordinate modules, and receive operation data fed back by each module;

[0043] Motion controller module: used to receive motion control instructions from the host computer, process them into corresponding control signals, and then send them to the motion execution module and laser module to control their working status; receive the operating data of the motion execution module and laser module and feed it back to the host computer;

[0044] Laser module: generates laser light and processes it into an output laser beam, which serves as a heat source to heat the heat pipe to be tested;

[0045] Motion execution module: includes a pneumatic actuator consisting of a three-axis linear module, a solenoid valve, and a cylinder. It executes the motion instructions issued by the motion controller module, completes the movement of the three-axis linear module and the clamping and release of the cylinder, thereby realizing the focusing and positioning of the output laser beam and the clamping function of the fixture;

[0046] Temperature acquisition module: includes thermocouples and temperature acquisition cards, used to collect temperature data during the heat pipe test and transmit it to the host computer after processing.

[0047] Cooling module: controlled by the host computer and feedback of operation data.

[0048] Furthermore, the host computer is pre-set with human-computer interaction software, which can realize laser light control, three-axis linear module motion control, pneumatic actuator motion control, temperature measurement, cooling system control and heat pipe qualification judgment and display of working status information of each part. The software is developed based on the C++ / Qt environment and tools.

[0049] Furthermore, the motion controller module includes two parts: the motion controller, i.e., the master station, and the IO expansion module, i.e., the slave station. The master station and the slave station are connected via a CAN bus to achieve data exchange and information flow.

[0050] The motion controller, i.e., the master station, can output direction signals and pulse signals for controlling the motor, controlling the independent motion of each axis of the three-axis linear module; it can output high and low level signals to control the on and off of the solenoid valve, thereby realizing the clamping and releasing motion of the cylinder;

[0051] The motion controller is the master station, which has the function of outputting PWM modulation signals;

[0052] The IO expansion is a slave station with a DA analog signal output function, capable of outputting a voltage in the range of 0-10V, with an output voltage accuracy of ±0.1V and a 12-bit resolution.

[0053] Furthermore, the laser module includes a laser and a laser output head;

[0054] The laser receives high and low level signals from the motion controller to realize the functions of turning on the red indicator light, laser enabling and emergency stop; receives the PWM modulation signal from the motion controller to adjust the pulse part parameters of the output laser beam; receives the DA analog signal from the IO expansion to adjust the continuous part parameters of the output laser beam; the laser module simultaneously feeds back the alarm signal, laser ready signal and laser light output signal to the motion controller module for processing.

[0055] Furthermore, the laser generates laser light, which is transmitted to the laser output head, processed into an output laser beam and irradiated vertically on the heated surface, directly heating the heat pipe by radiation heat transfer or indirectly heating the heat pipe by heat conduction heat transfer. The heat power received by the heated body is Q i,t The output laser beam power is calculated as shown in formula (1):

[0056] In formula (4), i represents the power stage of the i-th laser heating during a test of the heat pipe to be tested; t represents the current moment; P i,t represents the power output of the laser at time t in the power stage of the i-th laser heating; D represents the enable signal received by the laser. When the enable signal is high, D = 1, and when the enable signal is low, D = 0; β i Indicates the voltage ratio of the DA analog signal received by the laser module in the power stage of the i-th laser heating; V i,t V represents the PWM modulation signal function received by the laser module with time t as the independent variable in the power stage of the i-th laser heating; max Indicates the peak voltage of the PWM modulation signal; P max Indicates the maximum output power of the laser;

[0057] In formula (4): β i The calculation method of is shown in formula (5) and formula (6):

[0058] In formula (5): U i It represents the voltage value of the DA analog signal received by the laser at the power stage of the i-th laser heating during a test of the heat pipe to be tested; U max Indicates the voltage value of the DA analog signal that the laser needs to receive to output the maximum power laser;

[0059] The calculation formula of the heat power received by the heating surface is as follows: Q i,t =αP i,t (6)

[0060] In formula (6): Q i,t It represents the laser thermal power received by the heat pipe under test at time t in the power stage of the i-th laser heating; α is the absorption rate of the laser beam on the heated surface.

[0061] Compared with the prior art, the advantages of the present invention are:

[0062] The present invention uses laser as a heat source in the heat transfer performance testing process of heat pipes, greatly improving the temperature rise rate of the heat pipes and simulating the actual working conditions of the chip during operation, making the test results of the heat pipes and the heat dissipation systems they comprise more accurate. The developed control system promotes the automation process of testing, solves the problem of high professional knowledge requirements of operators on the equipment, reduces production costs, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG1 is a schematic flow diagram of a method for testing heat transfer performance of a heat pipe using a laser heat source;

[0064] FIG2 is a schematic diagram showing the structure of a flattened heat pipe tested using a laser heat source and wherein the heated object is a flattened heat pipe;

[0065] FIG3 is a schematic diagram showing the structure of a flattened heat pipe tested using a laser heat source and a heated object being a flattened heat pipe heat sink;

[0066] FIG4 is a schematic diagram of the structure of a circular tube using a laser heat source for testing a circular tube and a heat sink as the heated object;

[0067] FIG5 is a schematic diagram of the architecture of a heat pipe heat transfer performance test control system using a laser heat source. DETAILED DESCRIPTION

[0068] The specific implementation of the present invention is described below in conjunction with examples:

[0069] It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0070] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0071] Example 1:

[0072] Figure 1 shows the specific process of the heat transfer performance test method of the heat pipe using a laser heat source, which includes the following steps:

[0073] 1) Clamp the heat pipe to be tested: Use a special fixture to clamp and position the heat pipe to be tested;

[0074] 2) Arrange temperature measurement points and start temperature data collection: Use thermocouples as temperature sensors and place them on the wall of the heat pipe to collect temperature data of the heat pipe;

[0075] 3) Laser beam positioning: Based on the set spatial position information, move the three-axis linear module carrying the laser output head until the laser beam output by the laser output head can be focused on the heated surface and can accurately irradiate the area to be heated; specifically, the following steps are included:

[0076] i. Input the relative position information of the fixture and the laser output head;

[0077] ii. Turn on the red light indicator;

[0078] iii. Move the z-axis linear module;

[0079] iv. Determine whether the distance between the focal plane of the beam and the heated plane is less than 0.2mm. If so, proceed to step v., if not, return to step iii.;

[0080] v. Move the x, y axis linear module;

[0081] vi. Determine whether the margin between the focused spot area and the heated area is less than 0.1 mm. If so, proceed to step vii. If not, return to step v.;

[0082] vii. Turn off the red light indication.

[0083] In step ii., the purpose of turning on the red light indicator is to enable the laser to output a low-power red laser visible to the human eye, making it easier for humans to observe the position of the output laser beam and determine the irradiation range of the laser beam;

[0084] In step iii., the z-axis direction is defined as the normal direction of the heated surface, the central axis of the output laser beam is parallel to the z-axis, and the laser beam irradiates the heated surface perpendicularly along the negative direction of the z-axis;

[0085] In step iv., if the distance between the focal plane of the beam and the heated surface is less than 0.2 mm, the laser beam is considered to be accurately focused on the heated surface, and the next step can be performed. If the distance between the focal plane of the spot and the heated surface is greater than 0.2 mm, the laser beam is considered to be not accurately focused on the heated surface, and step iii. needs to be continued until the judgment in step iv. is yes.

[0086] In step v., define the x-axis direction as the radial direction of the heat pipe, the y-axis direction as the axial direction of the heat pipe, and the x, y, and z axes form a Cartesian coordinate system, with the xOy plane coinciding with the heated plane;

[0087] In step vi., if the margin between the focused spot area and the area to be heated is less than 0.1 mm, the laser beam is considered to have accurately irradiated the area to be heated on the heat pipe, and the next step can be performed. If the margin between the focused spot area and the area to be heated is greater than 0.1 mm, the laser beam is considered to have not accurately irradiated the area to be heated on the heat pipe, and step v. needs to be continued until the determination in step vi. is yes.

[0088] Wherein, the heated surface refers to the surface of the heat pipe or the surface of the heat sink;

[0089] As shown in FIG2 , if the heat pipe to be tested is a flattened heat pipe (2-1) and the heated plane is the surface of the flattened heat pipe, the heated area is as shown in FIG2-2 , and the laser beam directly irradiates the surface of the flattened heat pipe, heating the flattened heat pipe (2-1) by radiation heat transfer;

[0090] As shown in FIG3 , if the heat pipe to be tested is a flattened heat pipe (2-1) and the heated surface is the surface of the flattened heat pipe heat sink (3-1), the flattened heat pipe heat sink (3-1) is tightly fitted with the flattened heat pipe (2-1). At this time, the heated area is as shown in FIG3-2 . ​​The laser beam irradiates the flattened heat pipe heat sink (3-1) and heats the flattened heat pipe heat sink (3-1) by radiation heat transfer. After the flattened heat pipe heat sink (3-1) is heated, it heats the flattened heat pipe (2-1) by heat conduction.

[0091] As shown in FIG4 , if the heat pipe to be tested is a circular tube ( 4 - 1 ), a circular tube heat sink ( 4 - 2 ) needs to be designed and fit tightly with the circular tube ( 4 - 1 ). At this time, the heated area is as shown in FIG4 - 3 ; the laser beam irradiates the circular tube heat sink ( 4 - 2 ) and heats the circular tube heat sink ( 4 - 2 ) by radiation heat transfer. After the circular tube heat sink ( 4 - 2 ) is heated, it heats the circular tube ( 4 - 1 ) by heat conduction.

[0092] The heated plane refers to the surface plane of the heated surface; the area to be heated refers to the range area on the heated surface that needs to be heated, as shown by the dotted lines 2-2, 3-2 and 4-3 in the figure;

[0093] 4) The laser emits light and heats the heat pipe: After the relevant heating parameters are set, the timing is started, the laser is enabled to emit light, and the laser output is the set power. After the timing is over, the laser is disabled and stops outputting laser light. During the whole process, the temperature acquisition module works, dynamically collects and outputs temperature data in real time, which specifically includes the following steps:

[0094] i. Input heating power and heating time;

[0095] ii. The timing starts and the laser is enabled to emit light;

[0096] iii. Output real-time temperature test data;

[0097] iv. When the timer ends, the laser will stop emitting light;

[0098] In step i., after setting the heating information such as heating power and heating time in the system, the system converts the set setting information into relevant electrical signals to configure the relevant functions of the laser;

[0099] In step ii., an enable signal is input to the laser and programmed timing is used;

[0100] 5) Process test data and generate reports: The system determines whether the heat transfer performance of the heat pipe is qualified based on the collected test temperature data and automatically generates a test report. The specific process is as follows:

[0101] If the temperature difference ΔT between the evaporation and condensation ends of the heat pipe is less than 3°C, it means that the heat pipe to be tested meets the performance test requirements and a heat pipe heat transfer performance test qualification report is generated; if the temperature difference ΔT between the evaporation and condensation ends is greater than 3°C, it means that the heat pipe does not meet the performance test requirements and a heat pipe heat transfer performance test failure report is generated.

[0102] 6) Uninstall the tested heat pipe.

[0103] Figure 5 shows the specific framework of the heat pipe heat transfer performance test control system using a laser heat source, which includes the following modules:

[0104] 1) Host computer: used to interact with the user, process the control instructions issued by the user and send them to the subordinate modules, and receive the operation data fed back by each module;

[0105] Among them, the upper computer is installed with human-computer interaction software, which can specifically realize functions such as laser light control, three-axis linear module motion control, pneumatic actuator motion control, temperature measurement, cooling system control and heat pipe qualification judgment and display of working status information of each part. The software is developed based on the C++ / Qt environment and tools.

[0106] 2) Motion controller module: Receives motion control instructions from the host computer, processes them into corresponding control signals, and then sends them to the motion execution module and laser module to control their working status. It also receives the operating data of the motion execution module and laser module and feeds it back to the host computer.

[0107] The motion controller module consists of two parts: the motion controller (master) and the IO expansion module (slave). The master and slave are connected via the CAN bus to achieve data exchange and information flow.

[0108] Among them, the motion controller (master station) can output direction signals and pulse signals to control the motor, control the independent movement of each axis of the three-axis linear module; it can output high and low level signals to control the on and off of the solenoid valve, thereby realizing the clamping and releasing movement of the cylinder;

[0109] In addition, the motion controller (master station) has a PWM modulation signal output function;

[0110] Among them, the IO expansion (slave) is characterized by having a DA analog signal output function, capable of outputting a voltage in the range of 0-10V, with an output voltage accuracy of ±0.1V and 12-bit resolution;

[0111] 3) Laser module: generates laser and processes it into an output laser beam, which serves as a heat source to heat the heat pipe to be tested;

[0112] Among them, the laser module consists of two parts: the laser and the laser output head;

[0113] The laser receives high and low level signals from the motion controller (master station) to realize the functions of turning on the red light indicator, laser enabling and emergency stop; receives the PWM modulation signal from the motion controller (master station) to adjust the parameters of the pulse part of the output laser beam; receives the DA analog signal from the IO expansion (slave station) to adjust the parameters of the continuous part of the output laser beam; the laser module simultaneously feeds back the alarm signal, laser ready signal and laser light output signal to the motion controller module for processing;

[0114] The laser can generate a certain power of laser, which is transmitted to the laser output head, processed into an output laser beam and irradiated vertically on the heated surface, directly heating the heat pipe through radiation heat transfer or indirectly heating the heat pipe through heat conduction heat transfer. The heat power received by the heated body is Q i,t The output laser beam power is calculated as shown in formula (7):

[0115] In formula (7), i represents the power stage of the i-th laser heating during a test of the heat pipe to be tested; t represents the current moment; P i,t represents the power output of the laser at time t in the power stage of the i-th laser heating; D represents the enable signal received by the laser. When the enable signal is high, D = 1, and when the enable signal is low, D = 0; β i Indicates the voltage ratio of the DA analog signal received by the laser module in the power stage of the i-th laser heating; V i,t V represents the PWM modulation signal function received by the laser module with time t as the independent variable in the power stage of the i-th laser heating; max Indicates the peak voltage of the PWM modulation signal; P max Indicates the maximum output power of the laser;

[0116] In formula (7): β i The calculation method of is shown in formula (8) and formula (9):

[0117] In formula (8): U i It represents the voltage value of the DA analog signal received by the laser at the power stage of the i-th laser heating during a test of the heat pipe to be tested; U max Indicates the voltage value of the DA analog signal that the laser needs to receive to output the maximum power laser;

[0118] The calculation formula of the heat power received by the heating surface is as follows: Q i,t =αP i,t (9)

[0119] In formula (9): Q i,t It represents the laser thermal power received by the heat pipe under test at time t in the power stage of the i-th laser heating; α is the absorption rate of the laser beam on the heated surface.

[0120] 4) Motion execution module: This module includes a pneumatic actuator consisting of a three-axis linear module, a solenoid valve, and a cylinder. It executes the motion instructions issued by the motion controller module, completes the movement of the three-axis linear module, and clamps and releases the cylinder, thereby achieving the focusing and positioning of the output laser beam and the clamping function of the heat pipe.

[0121] 5) Temperature acquisition module: including thermocouples and temperature acquisition cards, used to collect temperature data during the heat pipe test and transmit it to the host computer after processing.

[0122] 6) Cooling module: controlled by the host computer and feedback of operation data.

[0123] The following is an operational example of the present invention, employing a heat pipe heat transfer performance testing method and control system utilizing a laser heat source, to test a flattened heat pipe process. The heated surface is the flattened surface of the flattened heat pipe, and the heat receiving body is the heat pipe. To simulate the thermal impact of thermal steps during chip operation on the heat pipe, four different power levels were set during a single test, and the heat pipe was heated sequentially at the four different heating powers.

[0124] The inherent parameters of the relevant equipment of the heat pipe heat transfer performance test method and its control system for implementing the laser heat source are set as follows: 1) When the enable signal received by the laser is high, D = 1, and when the enable signal received by the laser is low, D = 0; 2) The maximum voltage value of the DA analog signal U max =10V; 3) In the power stage of the i-th laser heating, the PWM modulation signal function V received by the laser module i,t ≡24V; 4) Peak voltage of PWM modulation signal V max =24V, 5) the maximum output power of the laser Pmax =1500W, 6) The absorption rate of the flattened heat pipe surface to the laser beam α=6.1%.

[0125] Table 1 Examples of parameters in one laser test cycle of flattened heat pipe

[0126] In the table, i represents the power stage of the i-th laser heating in a test cycle of the heat pipe to be tested; Q i,t T represents the thermal power received by the heat pipe at time t in the power stage of the i-th laser heating; i represents the power stage heating time of the i-th laser heating; U i It represents the voltage value of the DA analog signal received by the laser in the i-th laser heating power stage during a test of the heat pipe to be tested; P i,t It represents the power of the laser output at time t in the power stage of the i-th laser heating.

[0127] The operation example process according to the above parameter settings is as follows:

[0128] 1) Test starts;

[0129] 2) The heat pipe to be tested is placed on a special fixture by a mechanical device. The pneumatic actuator composed of the solenoid valve and cylinder in the motion execution module starts working and clamps the heat pipe to be tested after receiving a high level opening and closing signal;

[0130] 3) Arrange temperature measurement points and start the temperature acquisition function in the industrial computer. The industrial computer sends a working signal, the temperature acquisition module starts working, starts collecting temperature data, and feeds the temperature data back to the industrial computer for processing;

[0131] 4) Input the relative position information of the fixture and the laser output head into the industrial computer;

[0132] 5) The laser turns on the red light indication after receiving the high level red light signal;

[0133] 6) After receiving the motion signal, the three-axis linear module moves the z-axis linear module until the laser beam is accurately focused on the surface of the flattened heat pipe;

[0134] 7) After receiving the motion signal, the three-axis linear module moves the x-axis and y-axis linear modules until the laser beam accurately irradiates the area to be heated of the flattened heat pipe;

[0135] 8) The laser turns off the red light indication after receiving the red light signal of low level;

[0136] 9) Input the heating power and heating time parameters into the industrial computer, which converts the input parameters into corresponding signal data, as shown in Table 1; the laser receives the enable signal high level D=1 and the PWM modulation signal V i,t ≡24V;

[0137] At this time, the first laser heating power stage begins. The industrial computer starts at t1=0, and the laser receives the DA analog signal voltage U1=1.640V until t1=50s. During the 50s timing, the laser output laser power is 245.9W, and the heat power received by the flattened heat pipe is 15W.

[0138] Entering the second laser heating power stage, the timer returns to zero t2 = 0, and the laser receives the DA analog signal voltage U2 = 2.185V until the timing ends at t2 = 20s. During the 20s timing process, the laser output laser power is 327.9W, and the heat power received by the flattened heat pipe is 20W;

[0139] Entering the third laser heating power stage, the timer returns to zero t3 = 0, and the laser receives the DA analog signal voltage U2 = 3.825V until the timing ends at t3 = 10s. During the 10s timing process, the laser output laser power is 573.8W, and the heat power received by the flattened heat pipe is 35W;

[0140] Entering the fourth laser heating power stage, the timer returns to zero t4 = 0, and the laser receives the DA analog signal voltage U4 = 1.640V until the timing ends at t4 = 50s. During the 40s timing process, the laser output laser power is 245.9W, and the heat power received by the flattened heat pipe is 15W;

[0141] The laser receives the low level enable signal, D=0;

[0142] During the whole process, the temperature acquisition module collects temperature data and feeds the temperature data back to the host computer for processing and display;

[0143] 10) The host computer processes the feedback temperature data. If the data shows that the temperature difference ΔT between the evaporation and condensation ends of the heat pipe is less than 3°C, it means that the heat pipe under test meets the performance test requirements, and a heat pipe heat transfer performance test qualification report is generated; if the data shows that the temperature difference ΔT between the evaporation and condensation ends of the heat pipe is greater than 3°C, it means that the heat pipe under test does not meet the performance test requirements, and a heat pipe heat transfer performance test failure report is generated;

[0144] 11) The pneumatic execution module composed of the solenoid valve and the cylinder in the motion execution module starts working and releases the tested heat pipe after receiving the low level opening and closing signal. The tested heat pipe is removed from the special fixture by the mechanical device;

[0145] 12) The test is completed.

[0146] The criterion for determining whether the laser beam is accurately focused on the surface of the flattened heat pipe in step 6) is that the distance between the focal plane of the light spot and the heated surface of the heat pipe is less than 0.2 mm;

[0147] In step 7), the criterion for determining whether the laser beam is accurately irradiated on the position to be heated of the heat pipe is that the margin between the focused spot area and the area to be heated is less than 0.1 mm.

[0148] The timing in step 9) is the program timing of the industrial computer.

[0149] The expressions "laser heat source", "laser heating" and "laser heated heat pipe" mentioned in this embodiment all refer to the use of a laser to generate a laser of a certain power. The laser is capable of generating laser light, which is transmitted to a laser output head, processed into an output laser beam and vertically irradiated on the heated surface, directly heating the heat pipe through radiation heat transfer or indirectly heating the heat pipe through heat conduction heat transfer.

[0150] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

[0151] Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for testing heat transfer performance of a heat pipe using a laser heat source, characterized in that: The method comprises: S1: Clamp the heat pipe to be tested: Use a special fixture to clamp and position the heat pipe to be tested; S2: Arrange temperature measurement points and start temperature data collection: Use thermocouples as temperature sensors installed on the heat pipe wall to collect temperature data of the heat pipe; S3: Laser beam positioning: According to the set spatial position information, move the three-axis linear module equipped with the laser output head until the laser beam output by the laser output head can be focused on the heating surface and can accurately irradiate the area to be heated; S4: The laser emits light and heats the heat pipe: After the relevant heating parameters are set, the timing is started, the laser is enabled to emit light, and the laser output is the set power. After the timing is over, the laser is disabled and stops outputting laser light. During the whole process, the temperature acquisition module works, dynamically collecting and outputting temperature data in real time. S5: Process test data and generate report: The system determines whether the heat transfer performance of the heat pipe is qualified based on the collected test temperature data and automatically generates a test report; S6: Uninstall the tested heat pipe.

2. A heat pipe heat transfer performance testing method using a laser heat source according to claim 1, characterized in that: The step S3 of laser beam positioning specifically includes: S31: Input the relative position information between the fixture and the laser output head; S32: Turn on the red light indication; S33: Move the z-axis linear module; S34: Determine whether the distance between the focal plane of the light beam and the heated plane is less than 0.2 mm. If so, proceed to step S35; if not, return to step S33. S35: Move the x and y axis linear module; S36: Determine whether the margin between the focused spot area and the area to be heated is less than 0.1 mm. If so, execute step S37; if not, return to step S35; S37: Turn off the red light indication; In step S32, the purpose of turning on the red light indicator is that the laser outputs a low-power red laser visible to the human eye, which facilitates manual observation of the output laser beam position and judgment of the irradiation range of the laser beam; In step S33, the z-axis direction is determined to be the normal direction of the heated surface, the central axis of the output laser beam is parallel to the z-axis, and the laser beam irradiates the heated surface perpendicularly along the negative direction of the z-axis; In step S34, if the distance between the focal plane of the light beam and the heated surface is less than 0.2 mm, it is determined that the laser beam is accurately focused on the heated surface, and the next step can be performed. If the distance between the focal plane of the light spot and the heated surface is greater than 0.2 mm, it is determined that the laser beam is not accurately focused on the heated surface, and step S33 needs to be continued until the determination of step S34 is yes. In step S35, the x-axis direction is determined to be the radial direction of the heat pipe, the y-axis direction is determined to be the axial direction of the heat pipe, the x, y, and z axes form a Cartesian coordinate system, and the xOy plane coincides with the heated plane; In step S36, if the margin between the focused spot area and the area to be heated is less than 0.1 mm, it is determined that the laser beam is accurately irradiated on the position to be heated of the heat pipe, and the next step can be performed at this time; if the margin between the focused spot area and the area to be heated is greater than 0.1 mm, it is determined that the laser beam is not accurately irradiated on the position to be heated of the heat pipe, and it is necessary to continue step S35 until the judgment of step S36 is yes.

3. A heat pipe heat transfer performance testing method using a laser heat source according to claim 2, characterized in that: The heated surface in the laser beam positioning step S3 refers to the heat pipe surface or the heat sink surface; If the heat pipe to be tested is a flattened heat pipe (2-1) and the heated surface is the surface of the flattened heat pipe, the laser beam directly irradiates the surface of the flattened heat pipe and directly heats the flattened heat pipe (2-1) by radiation heat transfer; If the heat pipe to be tested is a flattened heat pipe (2-1) and the heated surface is the surface of the flattened heat pipe heat sink (3-1), the flattened heat pipe heat sink (3-1) and the flattened heat pipe (2-1) are tightly fitted, the laser beam irradiates the flattened heat pipe heat sink (3-1), and the flattened heat pipe heat sink (3-1) is heated by radiation heat transfer. After the temperature of the flattened heat pipe heat sink (3-1) is increased, the flattened heat pipe (2-1) is indirectly heated by heat conduction. If the heat pipe to be tested is a circular pipe (4-1), a circular pipe heat sink (4-2) is designed and tightly fitted with the circular pipe (4-1). In this case, the heated surface is the circular pipe heat sink (4-2). The laser beam irradiates the circular pipe heat sink (4-2) and heats the circular pipe heat sink (4-2) by radiation heat transfer. After the circular pipe heat sink (4-2) is heated, it indirectly heats the circular pipe (4-1) by heat conduction. The heated plane refers to the surface plane of the heated surface; the area to be heated refers to the range area on the heated surface that needs to be heated.

4. A heat pipe heat transfer performance testing method using a laser heat source according to claim 1, characterized in that: The step S4 wherein the laser emits light and heats the heat pipe comprises: S41: Input heating power and heating time; S42: The timing starts and the laser is enabled to emit light; S43: output real-time temperature test data; S44: The timing ends and the laser is disabled; Among them, in step S41, after the heating power, heating time and heating information are set in the system, the system converts the set setting information into relevant electrical signals to configure the relevant functions of the laser; In step S42, an enable signal is input to the laser and program timing is used.

5. [Corrected 04.11.2024 according to Rule 26] A method for testing heat transfer performance of a heat pipe using a laser heat source according to claim 1, characterized in that: The step S5 processes the test data and generates a report. The specific process is as follows: If the temperature difference ΔT between the evaporation and condensation ends of the heat pipe is less than 3°C, it means that the heat pipe to be tested meets the performance test requirements and a heat pipe heat transfer performance test qualification report is generated; if the temperature difference ΔT between the evaporation and condensation ends is greater than 3°C, the heat pipe does not meet the performance test requirements and a heat pipe heat transfer performance test failure report is generated.

6. [Corrected 04.11.2024 according to Rule 26] A heat pipe heat transfer performance test control system using a laser heat source, characterized in that: The system is used to perform the method according to any one of claims 1 to 5, and the system includes: Host computer: used to interact with users, process user-issued control commands and send them to subordinate modules, and receive operation data fed back by each module; Motion controller module: used to receive motion control instructions from the host computer, process them into corresponding control signals, and then send them to the motion execution module and laser module to control their working status; receive the operating data of the motion execution module and laser module and feed it back to the host computer; Laser module: generates laser light and processes it into an output laser beam, which serves as a heat source to heat the heat pipe to be tested; Motion execution module: includes a pneumatic actuator consisting of a three-axis linear module, a solenoid valve, and a cylinder. It executes the motion instructions issued by the motion controller module, completes the movement of the three-axis linear module and the clamping and release of the cylinder, thereby realizing the focusing and positioning of the output laser beam and the clamping function of the fixture; Temperature acquisition module: including thermocouples and temperature acquisition cards, used to collect temperature data during the heat pipe test and transmit it to the host computer after processing; Cooling module: controlled by the host computer and feedback of operation data.

7. A heat pipe heat transfer performance test control system using a laser heat source according to claim 6, characterized in that: The host computer is pre-set with human-computer interaction software, which can realize laser light control, three-axis linear module motion control, pneumatic actuator motion control, temperature measurement, cooling system control and heat pipe qualification judgment and display of working status information of each part. The software is developed based on the C++ / Qt environment and tools.

8. The heat pipe heat transfer performance test control system using a laser heat source according to claim 6, characterized in that: The motion controller module includes two parts: the motion controller, i.e. the master station, and the IO expansion module, i.e. the slave station. The master station and the slave station are connected via a CAN bus to achieve data exchange and information flow. The motion controller, i.e., the master station, can output direction signals and pulse signals for controlling the motor, controlling the independent motion of each axis of the three-axis linear module; it can output high and low level signals to control the on and off of the solenoid valve, thereby realizing the clamping and releasing motion of the cylinder; The motion controller is the master station, which has the function of outputting PWM modulation signals; The IO expansion is a slave station with a DA analog signal output function, capable of outputting a voltage in the range of 0-10V, with an output voltage accuracy of ±0.1V and a 12-bit resolution.

9. The heat pipe heat transfer performance test control system using a laser heat source according to claim 6, characterized in that: The laser module includes a laser and a laser output head; The laser receives high and low level signals from the motion controller to realize the functions of turning on the red indicator light, laser enabling and emergency stop; receives the PWM modulation signal from the motion controller to adjust the pulse part parameters of the output laser beam; receives the DA analog signal from the IO expansion to adjust the continuous part parameters of the output laser beam; the laser module simultaneously feeds back the alarm signal, laser ready signal and laser light output signal to the motion controller module for processing.

10. A heat pipe heat transfer performance test control system using a laser heat source according to claim 9, characterized in that: The laser generates laser light, which is transmitted to the laser output head, processed into an output laser beam and irradiated vertically on the heated surface, directly heating the heat pipe through radiation heat transfer or indirectly heating the heat pipe through heat conduction heat transfer. The heat power received by the heated body is Q i,t The output laser beam power is calculated as shown in formula (1): In formula (1), i represents the power stage of the i-th laser heating during a test of the heat pipe to be tested; t represents the current moment; P i,t represents the power output of the laser at time t in the power stage of the i-th laser heating; D represents the enable signal received by the laser. When the enable signal is high, D = 1, and when the enable signal is low, D = 0; β i Indicates the voltage ratio of the DA analog signal received by the laser module in the power stage of the i-th laser heating; V i,t V represents the PWM modulation signal function received by the laser module with time t as the independent variable in the power stage of the i-th laser heating; max Indicates the peak voltage of the PWM modulation signal; P max Indicates the maximum output power of the laser; In formula (1): β i The calculation method is shown in formula (2) and formula (3): In formula (2): U i It represents the voltage value of the DA analog signal received by the laser at the power stage of the i-th laser heating during a test of the heat pipe to be tested; U max Indicates the voltage value of the DA analog signal that the laser needs to receive to output the maximum power laser; The calculation formula of the heat power received by the heating surface is as follows: Q i,t =αP i,t (3) In formula (3): Q i,t It represents the laser thermal power received by the heat pipe under test at time t in the power stage of the i-th laser heating; α is the absorption rate of the laser beam on the heated surface.

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