An apparatus for improving transient and periodic temperature measurement dynamic response and a design method thereof

Abstract

This application belongs to the field of temperature measurement technology, and discloses a device and its design method for improving the dynamic response of transient and periodic temperature measurements. The method includes: performing spectral analysis on the transient or periodic temperature signal of the heat source under test based on Fourier transform, and determining the cutoff frequency according to a preset measurement accuracy level; determining the dynamic time constant and thermal junction thickness of the thin-film thermocouple accordingly; determining the geometric dimensions of the heat pipe based on the measurement conditions, the structure under test, and the thermal junction area, wherein the relationship between the cross-sectional area and the thermal junction area is set to be greater than, equal to, or less than the temperature measurement requirements; calculating the total heat transfer based on the change in internal energy and conduction energy of the thin-film thermocouple, and determining the required equivalent thermal conductivity in conjunction with the heat pipe dimensions to select a suitable heat pipe. The device includes a thin-film thermocouple and a heat pipe thermally coupled to it. This invention significantly improves the dynamic response speed and accuracy by directing heat flow and removing heat stagnation through the heat pipe.

Description

Technical Field

[0001] This application belongs to the field of temperature measurement technology, specifically relating to a device and its design method for improving the dynamic response of transient and periodic temperature measurements. Background Technology

[0002] In fields such as automobile manufacturing, aerospace, and shipbuilding, temperature is a crucial parameter reflecting the operating status of critical components. Accurate monitoring of temperature changes during operation, especially rapid temperature changes, is a prerequisite for ensuring safe operation. In general temperature measurement applications, thermocouples, resistance temperature detectors (RTDs), and thermal radiation thermometers are relatively mature and well-established technologies. However, in applications requiring transient temperature measurements, these traditional methods, due to their inherent dynamic response characteristics, cannot quickly and accurately capture instantaneous temperature changes. Taking thermocouples as an example, due to the thermal inertia and limited thermal conductivity of the temperature sensor's sensing element, the sensor needs a certain amount of time to reach equilibrium with the measured temperature. In periodic temperature signal measurements, repeated periodic rapid equilibrium between the measured temperature and the ambient temperature is also required. However, due to the thermal inertia and other delays in the sensing element, the measured value cannot follow and accurately reflect the actual temperature changes in real time. There is a lag in amplitude and phase between the measured temperature and the actual temperature, and even thermal hysteresis can prevent the timely reproduction of the temperature periodic signal, resulting in so-called dynamic response error. Therefore, to obtain real-time, online, fast, and accurate measurement results, dynamic design and calibration of temperature sensors are becoming increasingly important.

[0003] Current technologies primarily address the dynamic response problem in transient temperature measurement through various technical improvements. For example, optimizing sensor structure design aims to reduce sensor thermal inertia and improve response speed. While these measures have some positive effects on improving the dynamic response of thermocouples, existing technologies still have many shortcomings.

[0004] For example, patents CN202210588653.0, "A Fast-Response Thin-Film Thermocouple on Alloy Surface and Its Preparation Method", and CN202411250833.3, "A Fast-Response Thermal Flow Ceramic Thin-Film Temperature Sensor and Its Preparation Method", both of which improve the dynamic response of temperature sensors to some extent, have relatively complex processes. Moreover, vapor deposition technology requires the use of high-vacuum and high-precision equipment, resulting in high process costs and stringent requirements for the production environment. Their production efficiency is low, significantly increasing the difficulty and cost of large-scale production, limiting their large-scale application, and resulting in poor versatility. Most importantly, they do not provide a quantitative method for designing thin-film thermocouples that improve the dynamic response of transient and periodic temperature signal measurements, nor do they consider the thermal retention problem formed after the thin-film thermocouple is attached to the substrate to be measured.

[0005] For example, in the patent application CN202223002744.6, "A fast-response nickel-chromium-nickel-silicon K-type thermocouple sensor", the fast-response design usually sacrifices part of the temperature measurement range. For example, the small hot junction may not be able to withstand extreme high temperatures, or in low-temperature scenarios, the low heat capacity may cause the heat dissipation to be too fast, affecting the accuracy of low-temperature measurement. Therefore, its temperature measurement range is limited.

[0006] For example, the patent application number CN202210588653.0, "A Fast-Response Thin Film Thermocouple on Alloy Surface and Its Preparation Method", although it improves the dynamic response speed of the thermocouple to a certain extent, the internal sensing thin film and insulating film are easily damaged in extremely harsh service environments, causing the temperature measurement error to gradually increase. Therefore, it cannot achieve transient temperature measurement in harsh environments, nor can it meet the comprehensive improvement requirements of the thickness, strength and durability of the temperature measurement hot junction.

[0007] For example, the patent application CN202410648485.9, entitled "A High Dynamic Response, High Precision Fiber Optic Temperature Sensor", uses heat insulation material to insulate the temperature sensor's measuring end in order to eliminate the influence of the measuring substrate or support. However, it is often difficult to achieve a good heat insulation effect. Even if the heat insulation effect is good, it also reduces the rapid heat dissipation of the measuring end, resulting in a large thermal inertia at the measuring end, which seriously affects the continuous measurement of transient temperature changes.

[0008] Therefore, existing technologies cannot effectively isolate thermal interference from the support substrate while rapidly removing thermal stagnation at the measurement end, making it difficult to balance the dynamic response speed and measurement accuracy of the sensor in transient and periodic temperature measurements. Summary of the Invention

[0009] To address the problem of thermal inertia accumulation and limited dynamic response speed caused by the inability to quickly remove heat retention in existing temperature measurement technologies, this application provides a device and its design method for improving the dynamic response of transient and periodic temperature measurements. This device thermally couples a thin-film thermocouple to a heat pipe radiator, utilizing the directional and efficient heat transfer along the film thickness direction of the heat pipe. This achieves both support and insulation while rapidly eliminating heat retention at the measuring end, thereby realizing rapid and accurate thermal equilibrium between the measuring end and the heat source being measured.

[0010] To achieve the above technical objectives, this application specifically adopts the following technical solution: In one aspect of this application, an apparatus for improving the dynamic response of transient and periodic temperature measurements is provided, comprising: a thin-film thermocouple and a heat pipe radiator; the heat pipe radiator is divided into an evaporation section, an adiabatic section and a condensation section along the axial direction, and the evaporation section of the heat pipe radiator is filled with a phase change working fluid; The thin-film thermocouple is used to be attached to the surface of the transient heat source to be measured, and the thin-film thermocouple is provided with a thermal contact. The heat pipe radiator is connected to the thin-film thermocouple. The heat pipe radiator forms a directional heat flow from the evaporation section to the condensation section along the thickness direction of the thin-film thermocouple through the phase change working fluid, thereby removing the heat retention generated at the thermal junction during temperature measurement.

[0011] In one embodiment, the thin-film thermocouple has a multilayer structure, comprising, in sequence, an insulating substrate layer for attaching a heat source, a thermocouple material layer, and a protective encapsulation layer.

[0012] In one embodiment, the evaporation section of the heat pipe radiator is connected to the protective encapsulation layer.

[0013] In one embodiment, the heat pipe radiator includes a sleeve, a core, and a phase change working fluid filled in the core. The core is sleeved inside the sleeve and is an axially penetrating hollow pipe. The wall of the core has a leaf vein capillary structure. The cavity of the core and the wall of the core form a condensation channel for condensing the gaseous phase change working fluid. The inner cavity of the core communicates with the condensation channel to form a closed loop for the circulation of the phase change working fluid.

[0014] In another aspect of this application, a design method for the device for improving the dynamic response of transient and periodic temperature measurements is provided, comprising the following steps: S1. Perform spectral analysis on the transient or periodic temperature signal of the heat source under test based on Fourier transform. Based on the spectral analysis results, determine the cutoff frequency of the temperature signal of the heat source under test according to the preset measurement accuracy levels. ; S2, according to the cutoff frequency The bandwidth of the temperature signal from the heat source to be measured and the required operating bandwidth of the thin-film thermocouple are determined, thereby determining the cutoff frequency of the thin-film thermocouple output signal. ; S3. Based on the preset dynamic test error threshold and the cutoff frequency The dynamic time constant of the temperature-sensing thin-film thermocouple was calculated. Furthermore, considering the dynamic time constant of the thin-film thermocouple... convective heat transfer coefficient Material equivalent density Equivalent specific heat capacity Calculate the thickness of the thin-film thermocouple thermal junction. ; S4. Based on the target measurement conditions, the physical parameters of the structure under test, and the area of ​​the thin-film thermocouple hot junction, determine the geometric dimensions of the matching heat pipe radiator. Then, select the phase change working fluid of the heat pipe radiator according to the range of temperature variation and the ambient temperature, and determine the temperature difference between the condenser and evaporator ends of the heat pipe radiator. The geometric dimensions include length. and cross-sectional area ; S5. Calculate the change in internal energy of the thin-film thermocouple during the temperature measurement process. and the heat energy of continuous heat conduction The total heat transfer is obtained. : Based on the total heat transfer Length of heat pipe radiator Cross-sectional area Temperature difference The equivalent thermal conductivity of the required heat pipe radiator is calculated. Select or design a suitable heat pipe radiator.

[0015] In one implementation, the spectral analysis based on Fourier transform in step S1 includes: For transient temperature signals, the following Fourier integral transform is used for spectral analysis:

[0016] in, Temperature signal Fourier transform, Angular frequency, For time, The imaginary unit; For periodic temperature signals, the following Fourier integral transform is used for spectral analysis:

[0017] in, For the first Fourth Fourier coefficient ω is the fundamental angular frequency.

[0018] In one implementation, in step S1, the frequency corresponding to when the amplitude drops to a preset threshold of the maximum amplitude is determined as the cutoff frequency through amplitude-frequency characteristic analysis. ; The preset threshold is one-tenth, one-hundredth, one-thousandth, or one-ten-thousandth of the maximum amplitude, which respectively correspond to 1 / 10, 1 / 100, 1 / 1000, or 1 / 10000 accuracy in the accuracy classification of measuring instruments.

[0019] In one embodiment, in step S2, the cutoff frequency of the thin-film thermocouple output signal is... Values .

[0020] In one implementation, in step S3, the dynamic time constant Calculated using the following method: Based on the preset dynamic test error threshold, and using the temperature measurement amplitude-frequency characteristic formula of the first-order step system... Determine the time constant The ratio of the characteristic time of the heat source signal to that of the measured heat source. The angular frequency is used; the characteristic time is: for periodic temperature signals, the period of the heat source signal is taken; for transient temperature signals, the duration of the transient temperature signal is taken.

[0021] In one implementation, in step S3, the dynamic test error threshold and ratio The correspondence is as follows: When the dynamic test error is one-tenth ; When the dynamic test error is one percent ; When the dynamic test error is one-thousandth ; When the dynamic test error is one ten-thousandth ; in, This refers to the period of the heat source signal or the duration of a transient temperature signal.

[0022] In one embodiment, in step S3, the thickness of the thin-film thermocouple thermal junction... for: .

[0023] In one implementation, step S4, determining the geometry of the heat pipe includes: Determine the cross-sectional area of ​​the heat pipe thermal junction area with thin-film thermocouple The relationship, based on the temperature distribution gradient or measurement accuracy requirements, includes... Greater than ,equal or less ; According to the cross-sectional area Calculate the heat pipe diameter ,Right now And set the heat pipe length ; Based on the measured temperature amplitude and ambient temperature, the phase change working fluid inside the heat pipe is selected, and the temperature difference between the condenser and evaporator ends is determined by the difference between the boiling point and dew point of the selected phase change working fluid. .

[0024] In one implementation, the cross-sectional area The value of satisfies .

[0025] The beneficial effects of this application are as follows: By directly thermally coupling a thin-film thermocouple to a heat pipe radiator, an efficient directional heat conduction path is constructed along the film thickness direction. This structure, while providing thermal isolation to the supporting substrate, actively and rapidly dissipates heat accumulated at the temperature sensing end, significantly reducing its thermal inertia and effectively shortening its dynamic time constant. This allows the sensor to more accurately track rapid changes in transient temperature signals and maintain stable response performance in periodic temperature measurements, overcoming the technical challenge of the conflict between thermal insulation and heat dissipation in traditional methods. The device is compact, reliable, and expands the applicability of high-dynamic-precision temperature measurement technology under complex operating conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device for improving the dynamic response of transient and periodic temperature measurements according to this application. Figure 2 This is a schematic diagram of the structure of the thin-film thermocouple of this application; Figure 3 This is a schematic diagram of the thermocouple material layer structure of the thin-film thermocouple of this application; Figure 4 The waveform of the sinusoidal temperature signal is shown in the embodiment of this application; where a is the transient temperature signal and b is the periodic temperature signal; Figure 5 This is a diagram showing the amplitude-frequency response of a sinusoidal temperature signal according to an embodiment of this application. Figure 6 The waveform of the sawtooth wave temperature signal is shown in the embodiment of this application; where a is the transient temperature signal and b is the periodic temperature signal; Figure 7 This is a diagram showing the amplitude-frequency response of a sawtooth wave temperature signal according to an embodiment of this application. Figure 8 The waveform of the triangular wave temperature signal is shown in the embodiment of this application; where a is the transient temperature signal and b is the periodic temperature signal; Figure 9 This is a diagram showing the amplitude-frequency response of a triangular wave temperature signal according to an embodiment of this application. Figure 10 The image shows a trapezoidal temperature signal waveform according to an embodiment of this application; where a is a transient temperature signal and b is a periodic temperature signal. Figure 11This is a diagram showing the amplitude-frequency response of a trapezoidal wave temperature signal according to an embodiment of this application. Figure 12 The above describes a rectangular wave temperature signal waveform according to an embodiment of this application; where a is a transient temperature signal and b is a periodic temperature signal. Figure 13 This is a diagram showing the amplitude-frequency response of a rectangular wave temperature signal according to an embodiment of this application. In the diagram: 1-Heat pipe radiator, 11-Tube sleeve, 12-Tube core; 2-Thin film thermocouple, 21-Insulating base layer, 22-Thermocouple material layer, 23-Protective encapsulation layer, 24-Thermal junction; 3-Cylinder. Detailed Implementation

[0027] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this application, not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] The fundamental principle of temperature measurement is based on thermal equilibrium, requiring the sensitive element (sensing end) of the temperature sensor to reach the same temperature as the object being measured (measured end). In thin-film thermocouple applications, this manifests as thermal equilibrium between the thin-film thermal junction and the surface being measured. However, during transient temperature measurements, due to the extremely rapid rate of temperature change, the temperature response of the thermal junction lags behind that of the measured surface, resulting in a longer time required to reach equilibrium (i.e., the dynamic time constant). Consequently, the residual heat in the thermal junction after measurement (thermal retention) is difficult to dissipate quickly. In continuous measurements of periodic temperature signals, the accumulation of thermal retention further exacerbates thermal inertia, severely degrading the sensor's dynamic response and signal tracking performance.

[0029] To improve response speed, traditional methods focus on reducing the thickness of thermocouple hot contacts, thereby shortening the thermal equilibrium time by reducing their heat capacity. However, in the actual structure of thin-film thermocouples, excessively thin hot contacts must be fabricated on an insulating substrate or a specific mechanical support. To minimize thermal interference from the support, a thermal insulation layer is often introduced between the hot contact and the support. While this partially blocks heat flow from the support, it also severely hinders the dissipation of heat generated by the hot contact itself to the external environment, creating a technical contradiction: while the insulation measures isolate external interference, they also lead to internal heat accumulation, ultimately compromising the accuracy of periodic rapid temperature measurements.

[0030] To overcome the aforementioned technical contradictions, this application introduces a heat pipe radiator as a high-efficiency heat transfer element along the thickness direction of the thin-film thermocouple's measuring end. The heat pipe radiator is filled with a phase change working fluid, achieving rapid heat transfer through the cyclic phase change of the working fluid between the evaporation and condensation sections. The heat pipe radiator is thermally coupled to the measuring hot end of the thin-film thermocouple, ensuring that the evaporation section of the heat pipe radiator is in close contact with the non-measuring side of the thin-film thermocouple. This provides reliable mechanical support for the thin-film thermocouple and establishes a significant heat transfer gradient and directional heat flow along its thickness direction, rapidly dissipating the heat retention generated during measurement and effectively reducing the thermal inertia of the measuring end.

[0031] This application relates to a device for improving the dynamic response of transient and periodic temperature measurements. (See reference...) Figures 1-3 As shown, it includes a thin-film thermocouple 2 and a heat pipe radiator 1 connected to the thin-film thermocouple 2.

[0032] The thin-film thermocouple 2 is used to directly adhere to the surface of the transient heat source to be measured, such as the wall of the cylinder 3 shown in the attached figure. The thin-film thermocouple 2 has a multi-layered film structure, consisting of an insulating base layer 21, a thermocouple material layer 22, and a protective encapsulation layer 23, stacked sequentially from the side closest to the heat source. The insulating base layer 21 directly contacts the object being measured, providing electrical insulation and mechanical adhesion. The thermocouple material layer 22 is composed of two different thermocouple materials, whose junction forms a thermal junction 24 for sensing temperature. The protective encapsulation layer 23 covers the thermocouple material layer 22, providing physical and environmental protection. The positive and negative leads of the thin-film thermocouple 2 are led out from its side or at an appropriate location for connecting to an external measuring circuit.

[0033] The heat pipe radiator 1 is a component that utilizes a phase change working fluid circulation for efficient heat transfer. Its exterior is a sealed sleeve 11, and inside the sleeve 11 is a core 12 extending axially. The core 12 itself is an axially continuous hollow pipe structure, and the tube wall of the core 12 has a leaf vein capillary structure; the core 12 is filled with an appropriate amount of phase change working fluid, such as pure water, ammonia, or methanol.

[0034] The heat pipe radiator 1 can be divided into three functionally distinct sections along its axial direction: an evaporation section, an insulation section, and a condensation section. The evaporation section is located at one end of the heat pipe radiator 1. The tube sleeve 11 of this section is firmly thermally connected to the protective encapsulation layer 23 of the thin-film thermocouple 2, ensuring a good thermal interface between them. The insulation section is located between the evaporation and condensation sections. This section is typically covered with insulation material to minimize radial heat loss. The condensation section is located at the other end of the heat pipe radiator. Its outer wall may be equipped with heat dissipation fins or contact other cooling media to enhance heat dissipation.

[0035] During operation, the hot junction of the thin-film thermocouple 2 senses the temperature change of the measured object. Simultaneously, both the hot junction 24 and the thin-film thermocouple 2 generate heat retention during temperature measurement. This heat is rapidly transferred to the evaporation section of the heat pipe radiator 1 through the thermal interface. The evaporation section absorbs heat, causing the liquid phase change working fluid in the core 12 of this section to evaporate and transform into steam. Driven by the pressure difference, the steam rapidly flows through the hollow pipe of the core 12 to the condensation section. The steam releases latent heat in the condensation section and condenses back into liquid. The condensed liquid working fluid flows back to the evaporation section along the capillary wall of the leaf vein structure (i.e., the condensation channel), thus completing a closed phase change cycle.

[0036] The cyclic process establishes a continuous and efficient directional heat flow along the thickness direction of the thin-film thermocouple 2 (i.e., from the hot junction towards the heat pipe). This directional heat flow continuously and rapidly conducts the heat stagnation generated at the measuring hot junction of the thin-film thermocouple 2 to the distant condensation section for dissipation, thereby significantly reducing the thermal inertia of the measuring junction. This allows the thin-film thermocouple 2 to respond more quickly to transient temperature changes of the measured object, and in periodic temperature measurements, the thermal state of the measuring junction can be effectively reset before the start of each cycle, thus ensuring continuous dynamic response speed and measurement accuracy.

[0037] By quantitatively designing the geometry, phase change working fluid type, and equivalent thermal conductivity of the heat pipe radiator 1, it is ensured to match the thermal characteristics, measured temperature range, and environmental conditions of the thin-film thermocouple 2, thus guaranteeing timely dissipation of heat retention at the measuring end. This enables the thin-film thermocouple 2 to rapidly respond to transient temperature signal changes and maintain good signal tracking in periodic temperature measurements, ultimately achieving rapid dynamic thermal equilibrium between the measuring end and the measured object, significantly improving the accuracy, response speed, and stability of the measurement results.

[0038] Specifically, the design method of the device includes the following steps: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal The temperature change of the heat source under test over time is divided into transient temperature signal or periodic temperature signal, and Fourier transform is performed on them respectively to obtain the corresponding amplitude-frequency characteristic spectrum.

[0039] For non-repetitive transient temperature signals, their frequency domain characteristics are obtained through continuous Fourier transform, and the transform formula is as follows:

[0040] in, It is a time-domain signal The Fourier transform (spectral function) represents the angular frequency in the spectral domain. The corresponding component amplitude and phase, For time, Angular frequency that varies continuously ), It is the imaginary unit.

[0041] For recurring periodic temperature signals, which consist of the superposition of the fundamental frequency and its integer multiples of harmonics, Fourier series expansion is suitable for analysis, as follows:

[0042] in, The fundamental angular frequency; n For harmonic order; For the first The values ​​of the next Fourier coefficients are determined by the following formula:

[0043] in, For the heat source signal period, coefficient sequence The discrete spectrum characterizes the periodic signal.

[0044] By analyzing the amplitude-frequency characteristics, the frequency range in which energy is significantly concentrated in the heat source temperature signal is determined.

[0045] To meet specific measurement accuracy requirements, a cutoff frequency is defined. Cutoff frequency The measurement accuracy is determined by a certain percentage of the spectral amplitude decreasing to its maximum value. The percentage corresponds to the required measurement accuracy level, such as one-tenth (1 / 10), one-hundredth (1 / 100), one-thousandth (1 / 1000), or one-ten-thousandth (1 / 10000).

[0046] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal. Based on the obtained cutoff frequency This further clarifies the bandwidth requirements of the measurement system. The effective frequency components of the heat source temperature signal are distributed from DC (0 Hz) to the cutoff frequency. Within this range, the range constitutes the passband of the signal under test.

[0047] To ensure the measurement system can respond without distortion to all temperature changes within the passband, the thin-film thermocouple used for temperature sensing has a sufficiently wide operating bandwidth. The lower limit of the operating bandwidth is also 0 Hz, and the upper limit... That is, the cutoff frequency of the thin-film thermocouple output signal. The accuracy is determined by calculation based on the required measurement precision. The accuracy level corresponds to step one and is divided into one-tenth (1 / 10), one-hundredth (1 / 100), one-thousandth (1 / 1000), and one-ten-thousandth (1 / 10000).

[0048] To meet specific accuracy requirements while also considering engineering feasibility, the cutoff frequency of the thin-film thermocouple output signal is... Based on the complexity of the heat source temperature signal waveform, in The selection should be made within the specified range. For applications with relatively gradual changes or requiring standard precision, a value can usually be directly selected. = .

[0049] Step 3: Determine the dynamic response error of the thin-film thermocouple and the geometric parameters of the thermal junction. The response characteristics of thin-film thermocouples under rapid temperature changes can be simplified and modeled as a first-order dynamic system. For an angular frequency of... Given a sinusoidal input signal, the amplitude-frequency response of this system is described by the following equation:

[0050] in, The dynamic time constant of the thin-film thermocouple is... ω Angular frequency ( ω =2π f ).

[0051] To achieve the preset dynamic testing accuracy, the system needs to be set at the cutoff frequency. The amplitude attenuation at a given point is controlled within the allowable error range. Accuracy levels are divided into 1 / 10, 1 / 100, 1 / 1000, and 1 / 10000. This is achieved by combining the amplitude-frequency response characteristics with those at a specific accuracy. Values, taking into account the period T of a periodic signal or the duration of a transient signal. The relationship with angular frequency is used to derive the dynamic time constant. The constraints that must be satisfied between the test and the period T. Specifically, if the dynamic test error is to be controlled to be within one-tenth (1 / 10), then... If the dynamic test error is controlled to be within one percent (1 / 100), then If the dynamic test error is controlled to be within one-thousandth (1 / 1000), then If the dynamic test error is controlled to be within one ten-thousandth (1 / 10000), then .

[0052] The obtained time constant Converted to thin-film thermocouple thermal junction thickness :

[0053] in, The convective heat transfer coefficient between the temperature-sensing thin film and the temperature-sensing medium. This is the equivalent density of the thermal junction material of a thin-film thermocouple.c Specific heat capacity.

[0054] Step 4: Determine the basic relevant parameters of the heat pipe structure. Based on the target measurement conditions, the physical parameters of the structure under test, and the area of ​​the thin-film thermocouple hot junction, the geometric dimensions of the matching heat pipe radiator are determined. Specifically, the geometric dimensions include the length of the heat pipe. and cross-sectional area .

[0055] Determine the cross-sectional area of ​​the heat pipe At that time, establish its thermal junction area with the thin-film thermocouple. The corresponding relationship. This relationship is selected based on the temperature distribution gradient or measurement accuracy requirements, and is specifically divided into three cases: Greater than , equal or Less than Cross-sectional area The value of can be further limited to .

[0056] Determining the cross-sectional area Based on this, calculate the heat pipe diameter. The calculation formula is: Heat pipe length The settings satisfy conditions.

[0057] The phase change refrigerant (PCR) for heat pipe radiators is selected based on the range of temperature variation to be measured and the ambient temperature. After selecting the PCR, the temperature difference between the condenser and evaporator ends is determined by the difference between the boiling point and dew point of the selected PCR. This temperature difference corresponds to the phase change characteristic parameters of the working fluid within the range of the measured temperature and the ambient temperature.

[0058] Step 5: Quantify heat pipe thermal conductivity requirements and select heat pipe model. To determine the heat transfer performance of a heat pipe radiator, the total heat load that needs to be derived during temperature measurement is quantitatively calculated, and the key performance indicator—equivalent thermal conductivity—is derived accordingly.

[0059] Total heat transfer Originating from the internal energy change of the thin-film thermocouple measuring end itself The thermal energy conducted by its supporting structure , represented as .

[0060]

[0061] Where T is the period of the heat source signal. Or the duration of a transient temperature signal , c To measure the equivalent specific heat capacity of the thermal junction of a thin-film thermocouple, To measure the equivalent density of the thermal junction material of a thin-film thermocouple, The input temperature signal for the thermocouple. S This represents the area of ​​the hot junction of the thin-film thermocouple.

[0062]

[0063] Where T is the period of the heat source signal. Or the duration of a transient temperature signal , T 10 This is the temperature at which the thin-film thermocouple begins to conduct heat. T 20 This refers to the initial temperature of the evaporator end of the heat pipe radiator. The equivalent thermal conductivity of a thin-film thermocouple is given. Its converted thermal conductivity, A This represents the cross-sectional area of ​​the heat pipe.

[0064] To evaluate and select a heat pipe radiator that meets this heat transfer requirement, a comprehensive performance parameter is defined—equivalent thermal conductivity. Equivalent thermal conductivity The physical meaning is that the heat pipe radiator as a whole is regarded as a solid with equivalent thermal conductivity. Under the same geometric dimensions and temperature difference, the heat flow rate it conducts is the same as that of an actual heat pipe radiator.

[0065] Calculated by the following formula:

[0066] in, K eq The equivalent thermal conductivity of the heat pipe is... L This is the equivalent length of the heat pipe radiator. T The temperature difference between the hot and cold ends of a heat pipe radiator is caused by the phase change working fluid.

[0067] In another aspect of this application, given that theoretical calculation methods involve complex calculations in complex engineering field applications, this application further proposes a rapid application method based on pre-set engineering charts. The spectral analysis results of common typical temperature waveforms (such as sine waves, sawtooth waves, triangular waves, trapezoidal waves, rectangular waves, etc.) are pre-prepared into charts. During implementation, based on the waveform type of the signal to be measured, the highest harmonic frequency (i.e., the cutoff frequency) of the signal can be quickly obtained by directly consulting the chart and selecting the appropriate measurement accuracy. This allows us to determine the frequency range of the signal to be measured (0~). Subsequently, based on the selected dynamic test error accuracy, the dynamic time constant of the thin-film thermocouple is quickly obtained by directly applying the engineering calculation formulas in Table 1. Then calculate or select the thickness of the thermal junction. The design steps for heat pipe radiators are consistent with the theoretical calculation methods, calculating the total heat load. And finally based on the equivalent thermal conductivity The numerical results are used to select or design suitable heat pipes.

[0068] Table 1 Engineering Calculation of Time Constant for Thin Film Thermocouples

[0069] Example 1 like Figure 4 As shown, this embodiment illustrates the temperature change in the local heat-affected zone of high-frequency induction spot welding of thin steel plates. The eddy current power generated by the high-frequency alternating current fluctuates sinusoidally with the current, which determines the sinusoidal variation law of the temperature. In the initial heating phase, the eddy current power rapidly increases, and the temperature gradually rises from room temperature (25℃) to 412.5℃ within 0-0.025s (at this point, the curve is concave upwards, indicating a faster rate of heat accumulation, laying the foundation for subsequent weld nugget formation). Subsequently, the eddy current power maintains its peak value, and the temperature continues to rise to 800℃ within 0.025-0.05s (this temperature satisfies the requirements for weld nugget formation due to localized plastic deformation of the thin steel plate, while not exceeding the melting point to avoid weld burn-through; the curve then becomes convex upwards, and the rate of temperature increase slows down to ensure uniform heating). Next, the eddy current power decreases as the current drops, and the rate of heat dissipation exceeds the rate of heat generation; the temperature drops from 800℃ to 412.5℃ within 0.05-0.075s (the curve remains convex upwards to prevent the weld nugget from becoming too large due to sustained high temperatures). Finally, the current drops to 0, and electrode pressure assists in rapid heat dissipation; the temperature drops back to room temperature (25℃) within 0.075-0.1s (the curve returns to a concave upwards, and the rate of temperature decrease slows down, ensuring weld joint shaping without residual stress). Therefore, the temperature signal of the local heat-affected zone in high-frequency induction spot welding of thin steel plates is a sinusoidal periodic signal.

[0070] Based on the actual operating temperature of the compressor in this embodiment, a K-type thin-film thermocouple is selected, with a specific heat capacity of [missing information]. Its strength is 0.46 J / (g·K), and its density is... It is 8.6×10 6 g / m 3 thermal junction diameter The convective heat transfer coefficient is 10 mm. It is 17.5 W / (m 2 ·K); The length of the heat pipe radiator selected based on the structure under test. It is 25 mm in diameter. For a diameter of 10 mm, liquid sodium was chosen as the phase change material for the heat pipe to balance thermal conductivity and cost.

[0071] Therefore, the specific implementation steps for designing and implementing a device to improve the dynamic response of transient and periodic temperature measurements are as follows: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal The time-domain signal of the heat source temperature changing with time under this operating condition Perform a Fourier transform to obtain the corresponding frequency domain signal. ;right The amplitude-frequency characteristics are analyzed, and in this embodiment, the cutoff frequency of the heat source signal temperature change is determined with an accuracy of one-tenth (1 / 10). 17.824 Hz ( Figure 5 ).

[0072] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal: According to the cutoff frequency The bandwidth of the temperature signal from the heat source to be measured and the operating bandwidth of the thin-film thermocouple to be designed or selected are calculated. The operating bandwidth of the thin-film thermocouple should meet the bandwidth requirements of the measured temperature signal. The cutoff frequency of the thin-film thermocouple output signal is then calculated with an accuracy of one-tenth (1 / 10). Based on the complexity of the changes in the heat source temperature signal The value is usually taken as (1~5). In this embodiment, the cutoff frequency of the thin-film thermocouple output signal is calculated with an accuracy of one-tenth (1 / 10). It is 17.824 Hz.

[0073] Step 3: Determine the dynamic response error and thermal junction geometry parameters of the thin-film thermocouple: Based on the dynamic test error range of thin-film thermocouples or according to the theoretical analysis of the amplitude-frequency characteristics of first-order step temperature measurement systems, the dynamic time constant of the thin-film thermocouple for temperature measurement is determined with an accuracy of one-tenth (1 / 10). : , It is 4.348×10 -2 s. Then, based on the structure and geometric parameters of the thin-film thermocouple, the thickness of its thermal junction is calculated. 1.923×10 -7 m.

[0074] Step 4: Determine the basic relevant parameters of the heat pipe radiator structure. Based on the target measurement conditions (temperature, pressure, space constraints, etc.) and the relevant physical parameters and thermal junction area of ​​the structure under test, determine the key geometric dimensions of the matching heat pipe radiator: length. 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Based on the measured temperature amplitude and ambient temperature, liquid sodium was selected as the phase change working fluid, and the evaporation end temperature was determined to be 700 ℃, with the temperature difference between the condensation end and the evaporation end being... The temperature is 20°C.

[0075] Step 5: Quantify the heat conduction requirements of the heat pipe radiator and select the appropriate model: Calculate the internal energy change of a thin-film thermocouple during temperature measurement. It is 6.989×10 3 J and the heat energy conducted continuously through the matrix. It is 9.423 J, based on the total heat transfer. Based on the relevant parameters of the heat pipe radiator, the equivalent thermal conductivity of the heat pipe is calculated. It is 1.114 × 10 5 W / (m•K), and finally select or develop a heat pipe model that can compensate for the dynamic response error in the temperature measurement process of thin film thermocouple by forming a temperature gradient through rapid heat conduction, so that it can quickly remove the heat retention generated in the temperature measurement process of thin film thermocouple, thereby providing conditions for reducing the thermal resistance and thermal inertia of the measuring surface for transient or continuous temperature measurement.

[0076] Based on the above theoretical calculation methods and deeply integrating engineering practice experience, a design method for improving the dynamic response of transient and periodic temperature measurements in engineering applications is proposed. The specific implementation steps are as follows: Step 1: Determine the signal frequency range from the spectrum of the signal under test. : Based on the results of Fourier series transform, the transient or periodic heat source temperature signal to be measured is decomposed into a series of engineering application spectrum characteristic diagrams. Through amplitude-frequency characteristic analysis, and according to the maximum permissible error and rounded to one-tenth (1 / 10) of the accuracy according to the accuracy of the measuring instrument, the result can be directly calculated from Engineering Table 2. The frequency is set to 30 Hz, thus determining the frequency range of the periodic signal to be measured to be 0~30 Hz.

[0077] Table 2. Harmonic relationships of the highest cutoff frequency for sinusoidal temperature signals with different levels of precision (3rd harmonic).

[0078] Step 2: Determine the dynamic response characteristics and thermal junction thickness of the temperature-sensing thin-film thermocouple. Based on the dynamic test error range of the temperature-measuring thin-film thermocouple, and adhering to an engineering design accuracy of one-tenth (1 / 10), and based on the frequency range of the signal to be measured obtained in step one... According to the engineering calculations in Table 1, the dynamic time constant of the temperature-sensing thin-film thermocouple can be directly calculated. It is 2.569×10 -3 Based on this, and combined with the formula for calculating the thickness of the thermocouple thermal junction, the thickness of the thin-film thermocouple thermal junction is derived. It is 1.136×10 -8 m.

[0079] Step 3: Heat pipe heat transfer gradient and periodicity requirements and heat pipe design: Following the aforementioned method, the internal energy change of the thin-film thermocouple during the temperature measurement process was calculated. It is 7.768×10 3 J and the heat energy conducted continuously through the matrix. It is 9.423 J, based on the total heat transfer. and heat pipe related parameters (length) 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Temperature difference between condenser and evaporator ends The equivalent thermal conductivity of the heat pipe can be calculated at 20 °C. 1.238×10 5 W / (m·K). Finally, based on the calculation results, a suitable heat pipe model is selected or designed. The suitable heat pipe can effectively compensate for the dynamic response error in the thin-film thermocouple temperature measurement process, realize the rapid output of heat retention, and ensure the accuracy, tracking and stability of the thin-film thermocouple temperature measurement system.

[0080] Example 2 like Figure 6 As shown, in the working cycle of an internal combustion engine, the surface temperature of the piston crown, cylinder head combustion chamber surface, or turbine blades fluctuates drastically and periodically with each stroke. From the end of the compression stroke to the beginning of combustion, fuel is injected into high-pressure, high-temperature air and ignited, causing the gas to heat up instantaneously. The piston crown / cylinder head surface temperature rises linearly to a peak of 900°C within 5 ms. During the expansion and exhaust strokes, the high-temperature gas expands, pushing the piston to do work, and the cooling system begins to function. By the end of the exhaust stroke, the piston crown / cylinder head surface temperature drops to 300°C within 30 ms. In the subsequent intake stroke, fresh, low-temperature air enters the cylinder, further cooling the surface to 200°C, completing one cycle. Therefore, in the working cycle of an internal combustion engine, the surface temperature signal of the piston crown, cylinder head combustion chamber surface, or turbine blades is a sawtooth-like periodic signal.

[0081] Based on the actual operating temperature of the piston top / cylinder head surface during the internal combustion engine working cycle in this embodiment, a type K thin-film thermocouple is selected, with a specific heat capacity of [missing information]. Its strength is 0.46 J / (g·K), and its density is... It is 8.6×10 6 g / m 3 ,diameter The convective heat transfer coefficient is 10 mm. It is 18.2 W / (m 2 ·K); heat pipe length It is 25 mm in diameter. For a diameter of 10 mm, liquid sodium was chosen as the phase change material for the heat pipe to balance thermal conductivity and cost.

[0082] Therefore, the specific implementation steps of a method and apparatus for improving the dynamic response of transient and periodic temperature measurements are as follows: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal: The time-domain signal of the heat source temperature changing with time under this operating condition Perform a Fourier transform to obtain the corresponding amplitude-frequency characteristic spectrum; through amplitude-frequency characteristic analysis, in this implementation example, if the cutoff frequency of the heat source signal temperature change is determined with an accuracy of one-tenth (1 / 10),... 52.624 Hz ( Figure 7 ).

[0083] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal: Based on the cutoff frequency of the heat source temperature signal obtained in step one This allows us to calculate the bandwidth of the temperature signal from the heat source to be measured, as well as the operating bandwidth of the thin-film thermocouple that needs to be designed or selected. The operating bandwidth of the thin-film thermocouple should meet the bandwidth requirements of the measured temperature signal. ), based on the complexity of the changes in the heat source temperature signal The value is usually taken as (1~5). , usually taken as That is, the output signal of the thin-film thermocouple is calculated with an accuracy of one-tenth (1 / 10). It is 52.624Hz.

[0084] Step 3: Determine the dynamic response error and thermal junction geometry parameters of the thin-film thermocouple: Based on the dynamic testing error range of thin-film thermocouples, if the dynamic testing error is controlled to be within one-tenth (1 / 10), then Based on this, the dynamic time constant of the temperature-sensing thin-film thermocouple can be calculated. It is 1.739×10 -2 s; and then, based on the structure and geometric parameters of the thin-film thermocouple, the thickness of its thermal junction is calculated. 8×10 -8m; To this end, the geometric parameters of the thin-film thermocouple hot junction were determined and the dynamic response error during the temperature measurement process was controlled.

[0085] Step 4: Determine the basic relevant parameters of the heat pipe structure: Based on the target measurement conditions (temperature, pressure, space constraints, etc.) and the relevant physical parameters and thermal junction area of ​​the structure to be measured, determine the key geometric dimensions (length) of the matching heat pipe. 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Based on the measured temperature amplitude and ambient temperature, liquid sodium was selected as the phase change material for the heat pipe, and the temperature difference between the condenser and evaporator ends was determined by the difference between the boiling point and dew point of the phase change material. The temperature is 20℃.

[0086] Step 5: Quantify heat pipe thermal conductivity requirements and select heat pipe model: Calculate the internal energy change of a thin-film thermocouple during temperature measurement. It is 1.677×10 6 J and the heat energy conducted continuously through the matrix. It is 6.308 J, based on the total heat transfer. By combining the relevant parameters of the heat pipe, the equivalent thermal conductivity of the heat pipe can be calculated. 2.670×10 7 W / (m•K), and finally select or develop a heat pipe model that can compensate for the dynamic response error in the temperature measurement process of thin film thermocouple by forming a temperature gradient through rapid heat conduction, so that it can quickly remove the heat retention generated in the temperature measurement process of thin film thermocouple, thereby providing conditions for reducing the thermal resistance and thermal inertia of the measuring surface for transient or continuous temperature measurement.

[0087] Based on the aforementioned theoretical calculation methods and deeply integrating engineering practice experience, this patent proposes a design method for improving the dynamic response of transient and periodic temperature measurements for engineering applications. The specific implementation steps are as follows: Step 1: Determine the signal frequency range from the spectrum of the signal under test. : Based on the results of Fourier series transformation, the transient or periodic heat source temperature signal under test is decomposed into a series of engineering application spectrum characteristic diagrams. Through amplitude-frequency characteristic analysis, and according to the maximum permissible error and rounded to one-tenth (1 / 10) of the accuracy according to the measurement instrument, the maximum harmonic frequency of the sinusoidal periodic signal can be directly calculated from Table 3. The frequency is 175 Hz, thus determining the frequency range of the periodic signal to be measured to be 0~175 Hz.

[0088] Table 3. Frequency octave relationships of the highest cutoff frequencies for sawtooth wave temperature signals with different levels of precision (10-fold harmonics).

[0089] Step 2: Determine the dynamic response characteristics and thermal junction thickness of the temperature-sensing thin-film thermocouple. Based on the dynamic test error range of the temperature-measuring thin-film thermocouple, and adhering to an engineering design accuracy of one-tenth (1 / 10), and based on the frequency range of the signal to be measured obtained in step one... According to the engineering calculations in Table 1, the dynamic time constant of the temperature-sensing thin-film thermocouple can be directly calculated. 4.404×10 -4 Based on this, and combined with the formula for calculating the thickness of the thermocouple thermal junction, the thickness of the thin-film thermocouple thermal junction is derived. 2.026×10 -9 m.

[0090] Step 3: Heat pipe heat transfer gradient and periodicity requirements and heat pipe design: Following the aforementioned method, the internal energy change of the thin-film thermocouple during the temperature measurement process was calculated. It is 1.864×10 6 J and the heat energy conducted continuously through the matrix. It is 6.308 J, based on the total heat transfer. and heat pipe related parameters (length) 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Temperature difference between condenser and evaporator ends The equivalent thermal conductivity of the heat pipe can be calculated at 20℃. It is 2.967×10 7 W / (m·K). Finally, based on the calculation results, a suitable heat pipe model is selected or designed. The suitable heat pipe can effectively compensate for the dynamic response error in the thin-film thermocouple temperature measurement process, realize the rapid output of heat retention, and ensure the accuracy, tracking and stability of the thin-film thermocouple temperature measurement system.

[0091] Example 3 like Figure 8As shown, in a test of a certain aero-engine component, the turbine blade surface is subjected to periodic airflow impacts (alternating scouring by high-temperature combustion gases and cooling air) during acceleration and deceleration. During acceleration, the fuel supply increases, the combustion gas temperature rises, and the high-temperature airflow scours the blades, causing the temperature to linearly increase from 300°C to 1200°C in 1 second. During deceleration, the fuel supply decreases, the cooling airflow increases, and the blade temperature linearly decreases back to 300°C in the same amount of time. Therefore, the temperature signal in the aero-engine component test is a triangular wave-like periodic signal.

[0092] Based on the actual operating temperature of the aero-engine components tested in this embodiment, an R-type platinum-rhodium alloy thin-film thermocouple is selected, with a specific heat capacity... Its strength is 0.13 J / (g·K), and its density is... 2.1×10 7 g / m 3 ,diameter The convective heat transfer coefficient is 10 mm. 10 W / (m 2 ·K); heat pipe length It is 25 mm in diameter. For a diameter of 10 mm, liquid sodium was chosen as the phase change material for the heat pipe to balance thermal conductivity and cost.

[0093] Therefore, the specific implementation steps of a method and apparatus for improving the dynamic response of transient and periodic temperature measurements are as follows: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal: The time-domain signal of the heat source temperature changing with time under this operating condition Perform a Fourier transform to obtain the corresponding amplitude-frequency characteristic spectrum; through amplitude-frequency characteristic analysis, in this implementation example, if the cutoff frequency of the heat source signal temperature change is determined with an accuracy of one-tenth (1 / 10),... 0.79 Hz ( Figure 9 ).

[0094] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal: Based on the cutoff frequency of the heat source temperature signal obtained in step one This allows us to calculate the bandwidth of the temperature signal from the heat source to be measured, as well as the operating bandwidth of the thin-film thermocouple that needs to be designed or selected. The operating bandwidth of the thin-film thermocouple should meet the bandwidth requirements of the measured temperature signal. ), based on the complexity of the changes in the heat source temperature signal The value is usually taken as (1~5). , usually taken as That is, the output signal of the thin-film thermocouple is calculated with an accuracy of one-tenth (1 / 10). It is 0.79 Hz.

[0095] Step 3: Determine the dynamic response error and thermal junction geometry parameters of the thin-film thermocouple: Based on the dynamic testing error range of thin-film thermocouples, if the dynamic testing error is controlled to be within one-tenth (1 / 10), then Based on this, the dynamic time constant of the temperature-sensing thin-film thermocouple can be calculated. The time is 0.870 s; therefore, the thickness of its thermal junction is calculated based on the structure and geometric parameters of the thin-film thermocouple. 3.187×10 -6 m; To this end, the geometric parameters of the thin-film thermocouple hot junction were determined and the dynamic response error during the temperature measurement process was controlled.

[0096] Step 4: Determine the basic relevant parameters of the heat pipe structure: Based on the target measurement conditions (temperature, pressure, space constraints, etc.) and the relevant physical parameters and thermal junction area of ​​the structure to be measured, determine the key geometric dimensions (length) of the matching heat pipe. 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Based on the measured temperature amplitude and ambient temperature, liquid sodium was selected as the phase change material for the heat pipe, and the temperature difference between the condenser and evaporator ends was determined by the difference between the boiling point and dew point of liquid sodium. The temperature is 20℃.

[0097] Step 5: Quantify heat pipe thermal conductivity requirements and select heat pipe model: Calculate the internal energy change of a thin-film thermocouple during temperature measurement. It is 4.629×10 5 J and the heat energy conducted continuously through the matrix. It is 30.891 J, based on the total heat transfer. By combining the relevant parameters of the heat pipe, the equivalent thermal conductivity of the heat pipe can be calculated. It is 7.368×10 6 W / (m•K), and finally select or develop a heat pipe model that can compensate for the dynamic response error in the temperature measurement process of thin film thermocouple by forming a temperature gradient through rapid heat conduction, so that it can quickly remove the heat retention generated in the temperature measurement process of thin film thermocouple, thereby providing conditions for reducing the thermal resistance and thermal inertia of the measuring surface for transient or continuous temperature measurement.

[0098] Based on the aforementioned theoretical calculation methods and deeply integrating engineering practice experience, this patent proposes a design method for improving the dynamic response of transient and periodic temperature measurements for engineering applications. The specific implementation steps are as follows: Step 1: Determine the signal frequency range from the spectrum of the signal under test. : Based on the results of Fourier series transform, the transient or periodic heat source temperature signal to be measured is decomposed into a series of engineering application spectrum characteristic diagrams. Through amplitude-frequency characteristic analysis, and according to the maximum permissible error and rounded to one-tenth (1 / 10) of the accuracy according to the measurement instrument, the maximum harmonic frequency of the sinusoidal periodic signal can be directly calculated from Engineering Table 4. The frequency is set to 1 Hz, thus determining the frequency range of the periodic signal to be measured to be 0~1 Hz.

[0099] Table 4. Harmonic relationships of the highest cutoff frequency for triangular temperature signals with different accuracies (3rd harmonics).

[0100] Step 2: Determine the dynamic response characteristics and thermal junction thickness of the temperature-sensing thin-film thermocouple. Based on the dynamic test error range of the temperature-measuring thin-film thermocouple, and adhering to an engineering design accuracy of one-tenth (1 / 10), and based on the frequency range of the signal to be measured obtained in step one... According to the engineering calculations in Table 1, the dynamic time constant of the temperature-sensing thin-film thermocouple can be directly calculated. It is 7.708×10 -2 Based on this, and combined with the formula for calculating the thickness of the thermocouple thermal junction, the thickness of the thin-film thermocouple thermal junction is derived. 2.823×10 -7 m.

[0101] Step 3: Heat pipe heat transfer gradient and periodicity requirements and heat pipe design: Following the aforementioned method, the internal energy change of the thin-film thermocouple during the temperature measurement process was calculated. It is 5.146×10 5 J and the heat energy conducted continuously through the matrix. It is 30.891 J, based on the total heat transfer. and heat pipe related parameters (length) 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Temperature difference between condenser and evaporator ends The equivalent thermal conductivity of the heat pipe can be calculated at 20℃. 8.190×10 6 W / (m·K). Finally, based on the calculation results, a suitable heat pipe model is selected or designed. The suitable heat pipe can effectively compensate for the dynamic response error in the thin-film thermocouple temperature measurement process, realize the rapid output of heat retention, and ensure the accuracy, tracking and stability of the thin-film thermocouple temperature measurement system.

[0102] Example 4 like Figure 10 As shown, during the periodic pulse heating process of the heating wire, after the heating wire is energized, the temperature linearly rises from room temperature (20°C) to 300°C within 50 ms; subsequently, during constant power heating, the temperature stabilizes at 300°C for 100 ms; after power is cut off, the temperature linearly drops to 20°C within 50 ms before entering the next cycle. Therefore, the temperature signal during the periodic pulse heating process of the heating wire is a trapezoidal wave-like periodic signal.

[0103] Based on the actual operating temperature during the periodic pulse heating process of the heating wire in this embodiment, a T-film thermocouple with specific heat capacity is selected. Its strength is 0.4 J / (g·K), and its density is... It is 8.93×10 6 g / m 3 ,diameter The convective heat transfer coefficient is 10 mm. 9 W / (m 2 ·K); heat pipe length It is 25 mm in diameter. For a diameter of 10 mm, liquid pure water was chosen as the phase change material for the heat pipe, balancing thermal conductivity and cost.

[0104] Therefore, the specific implementation steps of a method and apparatus for improving the dynamic response of transient and periodic temperature measurements are as follows: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal: The time-domain signal of the heat source temperature changing with time under this operating condition Perform a Fourier transform to obtain the corresponding amplitude-frequency characteristic spectrum; through amplitude-frequency characteristic analysis, in this implementation example, if the cutoff frequency of the heat source signal temperature change is determined with an accuracy of one-tenth (1 / 10),... 11.202 Hz ( Figure 11 ).

[0105] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal: Based on the cutoff frequency of the heat source temperature signal obtained in step one This allows us to calculate the bandwidth of the temperature signal from the heat source to be measured, as well as the operating bandwidth of the thin-film thermocouple that needs to be designed or selected. The operating bandwidth of the thin-film thermocouple should meet the bandwidth requirements of the measured temperature signal. ), based on the complexity of the changes in the heat source temperature signal The value is usually taken as (1~5). , usually taken as That is, the output signal of the thin-film thermocouple is calculated with an accuracy of one-tenth (1 / 10). It is 11.202Hz.

[0106] Step 3: Determine the dynamic response error and thermal junction geometry parameters of the thin-film thermocouple: Based on the dynamic testing error range of thin-film thermocouples, if the dynamic testing error is controlled to be within one-tenth (1 / 10), then Based on this, the dynamic time constant of the temperature-sensing thin-film thermocouple can be calculated. It is 8.696×10 -2 s; and then, based on the structure and geometric parameters of the thin-film thermocouple, the thickness of its thermal junction is calculated. It is 2.191×10 -7 m; To this end, the geometric parameters of the thin-film thermocouple hot junction were determined and the dynamic response error during the temperature measurement process was controlled.

[0107] Step 4: Determine the basic relevant parameters of the heat pipe structure: Based on the target measurement conditions (temperature, pressure, space constraints, etc.) and the relevant physical parameters and thermal junction area of ​​the structure to be measured, determine the key geometric dimensions (length) of the matching heat pipe. 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Based on the measured temperature amplitude and ambient temperature, liquid pure water was selected as the phase change material for the heat pipe, and the temperature difference between the condenser and evaporator ends was determined by the difference between the boiling point and dew point of the liquid pure water. The temperature is 10℃.

[0108] Step 5: Quantify heat pipe thermal conductivity requirements and select heat pipe model: Calculate the internal energy change of a thin-film thermocouple during temperature measurement. 3.685×10 5 J and the heat energy conducted continuously through the matrix. It is 1044.682 J, based on the total heat transfer. By combining the relevant parameters of the heat pipe, the equivalent thermal conductivity of the heat pipe can be calculated. It is 1.176×10 7 W / (m•K), and finally select or develop a heat pipe model that can compensate for the dynamic response error in the temperature measurement process of thin film thermocouple by forming a temperature gradient through rapid heat conduction, so that it can quickly remove the heat retention generated in the temperature measurement process of thin film thermocouple, thereby providing conditions for reducing the thermal resistance and thermal inertia of the measuring surface for transient or continuous temperature measurement.

[0109] Based on the aforementioned theoretical calculation methods and deeply integrating engineering practice experience, this patent proposes a design method for improving the dynamic response of transient and periodic temperature measurements for engineering applications. The specific implementation steps are as follows: Step 1: Determine the signal frequency range from the spectrum of the signal under test. : Based on the results of Fourier series transform, the transient or periodic heat source temperature signal to be measured is decomposed into a series of engineering application spectrum characteristic diagrams. Through amplitude-frequency characteristic analysis, and according to the maximum permissible error and rounded to one-tenth (1 / 10) of the accuracy according to the measurement instrument, the maximum harmonic frequency of the sinusoidal periodic signal can be directly calculated from engineering tables 5 and 6. The value is 17.5 Hz, thus determining the frequency range of the periodic signal to be measured to be 0~17.5 Hz.

[0110] Table 5. Frequency harmonic relationships of the highest cutoff frequency for trapezoidal wave temperature signals with k=2 (triangular wave type) at different accuracies, based on the 3rd harmonic.

[0111] Table 6. Frequency octave relationships of the highest cutoff frequency for trapezoidal wave temperature signals at k=∞ (rectangular wave type) with different precision levels.

[0112] Step 2: Determine the dynamic response characteristics and thermal junction thickness of the temperature-sensing thin-film thermocouple. Based on the dynamic test error range of the temperature-measuring thin-film thermocouple, and adhering to an engineering design accuracy of one-tenth (1 / 10), and based on the frequency range of the signal to be measured obtained in step one... According to the engineering calculations in Table 1, the dynamic time constant of the temperature-sensing thin-film thermocouple can be directly calculated. 4.404×10 -3 Based on this, and combined with the formula for calculating the thickness of the thermocouple thermal junction, the thickness of the thin-film thermocouple thermal junction is derived. 1.11×10 -8 m.

[0113] Step 3: Heat pipe heat transfer gradient and periodicity requirements and heat pipe design: Following the aforementioned method, the internal energy change of the thin-film thermocouple during the temperature measurement process was calculated. 4.096×10 5 J and the heat energy conducted continuously through the matrix. It is 1044.682 J, based on the total heat transfer. and heat pipe related parameters (length) 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Temperature difference between condenser and evaporator ends The equivalent thermal conductivity of the heat pipe can be calculated at 10℃. 1.307×10 7 W / (m·K). Finally, based on the calculation results, a suitable heat pipe model is selected or designed. The suitable heat pipe can effectively compensate for the dynamic response error in the thin-film thermocouple temperature measurement process, realize the rapid output of heat retention, and ensure the accuracy, tracking and stability of the thin-film thermocouple temperature measurement system.

[0114] Example 5 like Figure 12 As shown, in periodic pulsed laser processing / heating, the laser operates in pulsed mode. The material surface is irradiated by a high-repetition-frequency pulsed laser beam. Each pulse hits the material, and the light energy is absorbed instantaneously, causing the temperature at the irradiation point to rise rapidly to a peak temperature within a very short time. After the pulse ends, due to heat conduction and radiation, the temperature rapidly drops to near ambient temperature before the next pulse arrives. The rise is determined by the laser energy density, and the fall is determined by the material's heat dissipation coefficient. The pulse width forms a flat top, and due to the delay in heat conduction, the peak is slightly rounded, resulting in an overall rectangular shape. For example, when using a Q-switched Nd:YAG laser to surface anneal a 100 mm × 100 mm × 0.5 mm silicon wafer, it emits a rectangular-wave pulsed laser with a wavelength of 1064 nm. Within each 8 μs cycle, the temperature first rises from 25°C to 550°C, then remains at a plateau of 550°C for 4 μs, before cooling back to 25°C, followed by a 4 μs interval waiting for the next pulse. Therefore, the temperature signal during periodic pulsed laser processing / heating is a rectangular-wave periodic signal.

[0115] Based on the actual operating temperature of the periodic pulsed laser annealing in this embodiment, a K-film thermocouple with specific heat capacity is selected. Its strength is 0.46 J / (g·K), and its density is... It is 8.6×10 6 g / m 3 ,diameter The convective heat transfer coefficient is 10 mm. It is 15.2 W / (m 2 ·K); heat pipe length It is 25 mm in diameter. For a diameter of 10 mm, liquid pure water was chosen as the phase change material for the heat pipe, balancing thermal conductivity and cost.

[0116] Therefore, the specific implementation steps of a method and apparatus for improving the dynamic response of transient and periodic temperature measurements are as follows: Step 1: Spectrum analysis and cutoff frequency determination of the temperature measurement signal: The time-domain signal of the heat source temperature changing with time under this operating condition Perform a Fourier transform to obtain the corresponding amplitude-frequency characteristic spectrum; through amplitude-frequency characteristic analysis, in this implementation example, if the cutoff frequency of the heat source signal temperature change is determined with an accuracy of one-tenth (1 / 10),... 230097 Hz ( Figure 13 ).

[0117] Step 2: Calculation of the passband of the input signal and the cutoff frequency of the output signal: Based on the cutoff frequency of the heat source temperature signal obtained in step one This allows us to calculate the bandwidth of the temperature signal from the heat source to be measured, as well as the operating bandwidth of the thin-film thermocouple that needs to be designed or selected. The operating bandwidth of the thin-film thermocouple should meet the bandwidth requirements of the measured temperature signal. ), based on the complexity of the changes in the heat source temperature signal The value is usually taken as (1~5). , usually taken as That is, the output signal of the thin-film thermocouple is calculated with an accuracy of one-tenth (1 / 10). It is 230097Hz.

[0118] Step 3: Determine the dynamic response error and thermal junction geometry parameters of the thin-film thermocouple: Based on the dynamic testing error range of thin-film thermocouples, if the dynamic testing error is controlled to be within one-tenth (1 / 10), then Based on this, the dynamic time constant of the temperature-sensing thin-film thermocouple can be calculated. It is 1.739×10 -6 s; and then, based on the structure and geometric parameters of the thin-film thermocouple, the thickness of its thermal junction is calculated. It is 6.670×10 -12 m; To this end, the geometric parameters of the thin-film thermocouple hot junction were determined and the dynamic response error during the temperature measurement process was controlled.

[0119] Step 4: Determine the basic relevant parameters of the heat pipe structure: Based on the target measurement conditions (temperature, pressure, space constraints, etc.) and the relevant physical parameters and thermal junction area of ​​the structure to be measured, determine the key geometric dimensions (length) of the matching heat pipe. 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Based on the measured temperature amplitude and ambient temperature, liquid pure water was selected as the phase change material for the heat pipe, and the temperature difference between the condenser and evaporator ends was determined by the difference between the boiling point and dew point of the liquid pure water. The temperature is 10℃.

[0120] Step 5: Quantify heat pipe thermal conductivity requirements and select heat pipe model: Calculate the internal energy change of a thin-film thermocouple during temperature measurement. 1.538×10 5 J and the heat energy conducted continuously through the matrix. It is 0.027 J, based on the total heat transfer. By combining the relevant parameters of the heat pipe, the equivalent thermal conductivity of the heat pipe can be calculated. It is 4.894×10 6 W / (m•K), and finally select or develop a heat pipe model that can compensate for the dynamic response error in the temperature measurement process of thin film thermocouple by forming a temperature gradient through rapid heat conduction, so that it can quickly remove the heat retention generated in the temperature measurement process of thin film thermocouple, thereby providing conditions for reducing the thermal resistance and thermal inertia of the measuring surface for transient or continuous temperature measurement.

[0121] Based on the aforementioned theoretical calculation methods and deeply integrating engineering practice experience, this patent proposes a design method for improving the dynamic response of transient and periodic temperature measurements for engineering applications. The specific implementation steps are as follows: Step 1: Determine the signal frequency range from the spectrum of the signal under test. : Based on the results of Fourier series transform, the transient or periodic heat source temperature signal to be measured is decomposed into a series of engineering application spectrum characteristic diagrams. Through amplitude-frequency characteristic analysis, and according to the maximum permissible error and rounded to one-tenth (1 / 10) of the accuracy according to the measurement instrument, the maximum harmonic frequency of the sinusoidal periodic signal can be directly calculated from Engineering Table 2. 1.25×10 6 Hz, thus determining the frequency range of the periodic signal to be measured to be 0~1.25×10 Hz. 6 Hz.

[0122] Step 2: Determine the dynamic response characteristics and thermal junction thickness of the temperature-sensing thin-film thermocouple. Based on the dynamic test error range of the temperature-measuring thin-film thermocouple, and adhering to an engineering design accuracy of one-tenth (1 / 10), and based on the frequency range of the signal to be measured obtained in step one... According to the engineering calculations in Table 1, the dynamic time constant of the temperature-sensing thin-film thermocouple can be directly calculated. It is 6.166×10 -8 Based on this, and combined with the formula for calculating the thickness of thermocouple hot junctions, the thickness of thin-film thermocouple hot junctions can be derived. 2.369×10 -13 m.

[0123] Step 3: Heat pipe heat transfer gradient and periodicity requirements and heat pipe design: Following the aforementioned method, the internal energy change of the thin-film thermocouple during the temperature measurement process was calculated. It is 1.709×10 5 J and the heat energy conducted continuously through the matrix. It is 0.027 J, based on the total heat transfer. and heat pipe related parameters (length) 25 mm in diameter 10 mm, cross-sectional area 78.54 mm 2 Temperature difference between condenser and evaporator ends The equivalent thermal conductivity of the heat pipe can be calculated at 10℃. It is 5.44 × 10 6 W / (m·K). Finally, based on the calculation results, a suitable heat pipe model is selected or designed. The suitable heat pipe can effectively compensate for the dynamic response error in the thin-film thermocouple temperature measurement process, realize the rapid output of heat retention, and ensure the accuracy, tracking and stability of the thin-film thermocouple temperature measurement system.

[0124] In the above embodiments, the output signal is calculated with an accuracy of one-tenth (1 / 10), but the scope of protection of the present invention is not limited to this. Calculations involving cutoff frequency, etc., with an accuracy of one-hundredth (1 / 100), one-thousandth (1 / 10000), or one-ten-thousandth (1 / 10000), are all within the scope of protection of the present invention.

[0125] In the above embodiments, the calculation of the harmonic relationship is based on an engineering design precision of one-tenth (1 / 10). However, the scope of protection of this invention is not limited to this. When the engineering design precision is one-hundredth (1 / 100), one-thousandth (1 / 1000), one-ten-thousandth (1 / 10000), etc., the calculation of the harmonic relationship and the frequency range of the periodic signal to be measured are all within the scope of protection of this invention.

[0126] In the above embodiments, the calculation of the time constant of the thin-film thermocouple is based on the example that the dynamic test error of the thin-film thermocouple is controlled within one-tenth (1 / 10). However, the scope of protection of the present invention is not limited to this. When the dynamic test error of the thin-film thermocouple is controlled within one-hundredth (1 / 100), one-thousandth (1 / 1000), one-ten-thousandth (1 / 10000), etc., the calculation of the time constant and dynamic response of the thin-film thermocouple is within the scope of protection of the present invention.

[0127] Although the embodiments of this application have been described above in conjunction with the accompanying drawings, this application is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of this application, and these are all within the scope of protection of this application.

Claims

1. A device for improving the dynamic response of transient and periodic temperature measurements, characterized in that, include: Thin-film thermocouples and heat pipe radiators; the heat pipe radiator is divided into an evaporation section, an insulation section and a condensation section along the axial direction, and the evaporation section of the heat pipe radiator is filled with a phase change working fluid; The thin-film thermocouple is used to be attached to the surface of the transient heat source to be measured, and the thin-film thermocouple is provided with a thermal contact. The heat pipe radiator is connected to the thin-film thermocouple. The heat pipe radiator forms a directional heat flow from the evaporation section to the condensation section along the thickness direction of the thin-film thermocouple through the phase change working fluid, thereby removing the heat retention generated at the thermal junction during temperature measurement.

2. The device for improving the dynamic response of transient and periodic temperature measurement according to claim 1, characterized in that, The heat pipe radiator includes a sleeve, a core, and a phase change working fluid filled in the core. The core is sleeved inside the sleeve and is an axially penetrating hollow pipe. The wall of the core has a leaf vein capillary structure. The cavity of the core and the wall of the core form a condensation channel for the gaseous phase change working fluid to condense. The inner cavity of the core is connected to the condensation channel to form a closed loop for the circulation of the phase change working fluid.

3. The design method of the device for improving the dynamic response of transient and periodic temperature measurement as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1. Perform spectral analysis on the transient or periodic temperature signal of the heat source under test based on Fourier transform. Based on the spectral analysis results, determine the cutoff frequency of the temperature signal of the heat source under test according to the preset measurement accuracy levels. ; S2, according to the cutoff frequency The bandwidth of the temperature signal from the heat source to be measured and the required operating bandwidth of the thin-film thermocouple are determined, thereby determining the cutoff frequency of the thin-film thermocouple output signal. ; S3. Based on the preset dynamic test error threshold and the cutoff frequency The dynamic time constant of the temperature-sensing thin-film thermocouple was calculated. Furthermore, considering the dynamic time constant of the thin-film thermocouple... convective heat transfer coefficient Material equivalent density Equivalent specific heat capacity Calculate the thickness of the thin-film thermocouple thermal junction. ; S4. Based on the target measurement conditions, the physical parameters of the structure under test, and the area of ​​the thin-film thermocouple hot junction, determine the geometric dimensions of the matching heat pipe radiator. Then, select the phase change working fluid of the heat pipe radiator according to the range of temperature variation and the ambient temperature, and determine the temperature difference between the condenser and evaporator ends of the heat pipe radiator. The geometric dimensions include length. and cross-sectional area ; S5. Calculate the change in internal energy of the thin-film thermocouple during the temperature measurement process. and the heat energy of continuous heat conduction The total heat transfer is obtained. : Based on the total heat transfer Length of heat pipe radiator Cross-sectional area Temperature difference The equivalent thermal conductivity of the required heat pipe radiator is calculated. Select or design a suitable heat pipe radiator.

4. The design method according to claim 3, characterized in that, Step S1, which involves spectral analysis based on Fourier transform, includes: For transient temperature signals, the following Fourier integral transform is used for spectral analysis: in, Temperature signal Fourier transform, Angular frequency, For time, The imaginary unit; For periodic temperature signals, the following Fourier integral transform is used for spectral analysis: in, For the first Fourth Fourier coefficient ω is the fundamental angular frequency.

5. The design method according to claim 3, characterized in that, In step S1, through amplitude-frequency characteristic analysis, the frequency corresponding to the preset threshold when the amplitude drops to the maximum amplitude is determined as the cutoff frequency. ; The preset threshold is one-tenth, one-hundredth, one-thousandth, or one-ten-thousandth of the maximum amplitude, which respectively correspond to 1 / 10, 1 / 100, 1 / 1000, or 1 / 10000 accuracy in the accuracy classification of measuring instruments.

6. The design method according to claim 3, characterized in that, In step S2, the cutoff frequency of the thin-film thermocouple output signal Values .

7. The design method according to claim 3, characterized in that, In step S3, the dynamic time constant Calculated using the following method: Based on the preset dynamic test error threshold, and using the temperature measurement amplitude-frequency characteristic formula of the first-order step system... Determine the time constant The ratio of the characteristic time of the heat source signal to that of the measured heat source. The angular frequency is used; the characteristic time is: for periodic temperature signals, the period of the heat source signal is taken; for transient temperature signals, the duration of the transient temperature signal is taken.

8. The design method according to claim 7, characterized in that, In step S3, the dynamic test error threshold and ratio The correspondence is as follows: When the dynamic test error is one-tenth ; When the dynamic test error is one percent ; When the dynamic test error is one-thousandth ; When the dynamic test error is one ten-thousandth ; in, This refers to the period of the heat source signal or the duration of a transient temperature signal.

9. The design method according to claim 7, characterized in that, In step S3, the thickness of the thin-film thermocouple thermal junction... for: 。 10. The design method according to claim 3, characterized in that, In step S4, determining the geometry of the heat pipe includes: Determine the cross-sectional area of ​​the heat pipe thermal junction area with thin-film thermocouple The relationship, based on the temperature distribution gradient or measurement accuracy requirements, includes... Greater than ,equal or less ; According to the cross-sectional area Calculate the heat pipe diameter ,Right now And set the heat pipe length ; Based on the measured temperature amplitude and ambient temperature, the phase change working fluid inside the heat pipe is selected, and the temperature difference between the condenser and evaporator ends is determined by the difference between the boiling point and dew point of the selected phase change working fluid. .

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