JP2006208257A - Method and device for measuring heat transfer characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating and cooling method having spatial uniformity and time controllability easily and inexpensively, and also to provide a heat transfer characteristic measuring method using this method. <P>SOLUTION: In the heat transfer characteristic measuring method, pressure fluctuation is applied to fluid to vary the fluid temperature, and an object is heated or cooled using the temperature variation. Temperature variation occurring in the fluid or an object in contact with the fluid is detected by a temperature sensor 1, and the heat transfer characteristic of the fluid or the object is measured based on the detected temperature variation. The pressure fluctuation in the fluid propagates at an acoustic velocity, so that uniform heating and cooling in a large region is allowed. It is also easy to acquire a signal of temperature variation in the fluid, and the time control in heating and cooling is made with an extremely high precision. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for measuring heat transfer characteristics of solids, liquids and gases. Further, it is applied to a thermal conductivity detector for chromatography that detects a contained component by measuring thermal conductivity characteristics, a non-destructive inspection that measures a temperature change of an object when a thermal load is applied, and the like.

  When measuring thermal properties such as thermal diffusivity and thermal conductivity from temperature changes when the target is heated or cooled, or when non-destructively inspecting the target state from the temperature response when a thermal load is applied, etc. In addition, as a method of heating or cooling an object, conventionally, a method of generating Joule heat by supplying an electric current to a heater (including an AC calorimeter method), a method of using the Peltier effect, and a method of irradiating a laser ( Laser flash method), irradiation with a halogen lamp, method using microwaves or induction, method of contacting with a heat source of different temperature (including hot and cold air), method of using latent heat of vaporization of liquid, etc. ing.

In order to carry out the above measurement and nondestructive inspection with high accuracy, the spatial distribution of heating or cooling and the accuracy of time control are required. However, there are few heating / cooling methods that can satisfy the two requirements at the same time, and if two requirements are to be pursued at the same time, an extremely high cost apparatus is required. An object of the present invention is to provide a simple and inexpensive heating / cooling method having both spatial uniformity and time controllability, and further to provide a heat transfer characteristic measurement method using this method.

  In the present invention, in order to achieve the above object, pressure fluctuation is applied to the fluid to change the fluid temperature, and the temperature is used to heat or cool the object. Then, a temperature change occurring in the fluid or an object in contact with the fluid is detected, and a heat transfer characteristic of the fluid or the object is measured based on the detected temperature change (claims 1 and 2).

  In the heat transfer characteristic measuring apparatus according to the third aspect, the temperature change in the temperature boundary layer near the object is detected. The heat transfer characteristic measuring apparatus according to the fourth aspect utilizes the pressure change in the fluid not only for heating and cooling but also for detecting the temperature. In the heat transfer characteristic measuring apparatus according to the fifth aspect, a differential structure is used to detect a difference in heat transfer characteristics between the substance to be measured and the reference substance.

  An equation of state is established between the pressure, volume, and temperature of the fluid. For example, if the pressure of the fluid rises due to compression, the fluid temperature rises accordingly. If this is utilized, the object in contact with the fluid or the fluid itself can be heated and cooled. Since the pressure fluctuation in the fluid propagates at the speed of sound, uniform heating and cooling over a wide area is possible. In particular, the fluid itself can be directly heated and cooled for the purpose of measuring the heat transfer characteristics of the fluid. Furthermore, it is also easy to obtain a temperature fluctuation signal in the fluid by using a synchronization signal from the compression means, a pressure detection means in the fluid, or a temperature detection means in the fluid, and the heating and cooling time control can be performed. It can be performed with extremely high accuracy.

  In the present invention, the object is heated and cooled using pressure fluctuation, and the temperature change is detected and the heat transfer characteristic is measured based on the fact that the temperature change generated at this time depends on the heat transfer characteristic of the object. By using the pressure fluctuation, as described above, it is possible not only to apply a uniform thermal load over a very wide spatial range, but also to precisely control the phase of the thermal load. For this reason, it is possible to measure heat transfer characteristics with high accuracy and at low cost.

  The apparatus for installing a temperature sensor in a fluid in the vicinity of an object according to claim 3 is a system in which the fluid is directly heated and the temperature change is directly measured. It becomes possible to measure the transfer characteristic simply, inexpensively and with high accuracy. In the apparatus according to the fourth aspect, the heat transfer characteristic measuring apparatus can be configured by using only the acoustic device, and it is possible to realize an inexpensive and simple apparatus.

  In the apparatus according to the fifth aspect, since the apparatus has a differential structure and measurement is performed by comparison with a reference material, a change in heat transfer characteristics can be detected extremely sensitively. This apparatus can be applied as an inexpensive and highly sensitive gas chromatographic heat transfer characteristic detector.

  When the present invention is applied to non-destructive inspection, the effect of spatial uniformity of heat load is great. Conventional heating means such as laser irradiation, infrared irradiation, heating by a halogen lamp, heating by hot air or cooling by cold air have a problem that it is difficult to apply a uniform heat load over a wide range. Since a uniform heat load can be realized, highly accurate and reliable nondestructive inspection is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Example)
FIG. 1 is a first embodiment of the present invention configured to measure the thermal diffusivity of a gas. In the figure, reference numeral 1 denotes a temperature sensor, the structure of which will be described later. Reference numeral 2 denotes a speaker, which functions to apply a pressure fluctuation in the measurement cell 3. 4 is a pipe | tube which guide | induces the gas 10 which is a measuring object. An electromagnetic valve 5 controls the inflow / outflow of the gas 10 into the measurement cell 3. An oscillator 11 outputs a cosine wave signal having an angular frequency ω to the speaker 2 and the phase comparator 13 based on a control signal from the calculation unit 14. An electric resistance detection circuit 12 converts the electric resistance of the thin line of the temperature sensor 1 into a voltage output. The phase comparator 13 detects a phase difference φ between the pressure fluctuation in the measurement cell 3 and the electric resistance fluctuation of the temperature sensor 1. The calculation unit 14 outputs the control signal of the angular frequency to the oscillator as described above, calculates the thermal diffusivity of the gas based on the phase difference signal φ and the angular frequency ω from the phase comparator 13, and displays the display unit 15. Is output. Reference numeral 16 denotes a valve controller which controls the electromagnetic valve and samples the gas 10 in the measurement cell 3 at an appropriate timing.

  FIG. 2 is a diagram illustrating the structure of the temperature sensor 1. 101 in the figure is a fine metal wire having a diameter d, and is suspended in parallel to the base at a distance h from the sensor base 102. Reference numerals 103 and 103 ′ denote connector portions at both ends of the thin wire 101, and lead wires extending from the connector portions are connected to the electric resistance detection circuit 12. In this embodiment, the temperature sensor 1 has a circular metal cross-section 101 having a diameter of about 5 μm attached to a base 102. If you want to make the measuring device smaller, you can use micromachine technology, pattern the beam-like structure, and then remove the lower layer by etching to produce a structure similar to that shown in Fig. 2 and use it as a temperature sensor. is there.

Now, the wavelength λ = 2πc / ω at the angular frequency ω is selected to be sufficiently larger than the dimension of the measurement cell 3 (c is the speed of sound). At this time, the pressure fluctuation generated in the measurement cell due to the vibration of the speaker may be uniform in the measurement cell. The pressure fluctuation is defined as P cos (ωt). On the other hand, the dimensions of the measurement cell 3 are designed to be sufficiently larger than the temperature boundary layer thickness δ = (2κ / ρc _p ω) ^1/2 = (2α / ω) ^1/2 at the angular frequency ω. and that (kappa is the thermal conductivity of the gas, [rho is the density of the gas, c _p is equal ratio heat of gas, alpha is the thermal diffusivity of the gas). In this case, the amplitude of the temperature fluctuations is equal to the value P / rho] c _p in the case of adiabatic compression in most in the measuring cell. However, since the temperature of the wall surface and the sensor base is almost constant, a temperature boundary layer is generated in the vicinity thereof. The magnitude of the temperature fluctuation in a place vertically separated from the flat wall by the distance y is
θ (y) = (P / ρc p) (1-exp (- (1 + i) y / δ)) ···· (1)
It becomes. However, i represents an imaginary unit, and θ is the amplitude when temperature variation is complexly displayed (Toroshikoshi and Ishii: Measurement of surface area using sound, Proceedings of Society of Instrument and Control Engineers, Vol. 34, No. 3, 182) Page, 1998). θ and amplitude (normalized by _P / ρc _p) a plot of phase with respect to y / [delta] of the (y) shown in FIG.

  In this embodiment, the vibration frequency of the speaker is set to about several tens of Hz. At this time, the temperature distribution inside the fine metal wire having a diameter of about 5 μm is almost uniform, and the temperature is almost the same as the temperature of the surrounding gas. For example, under the condition of a tungsten wire with a diameter of 5 μm, in air, and a frequency of 40 Hz, the difference between the internal average temperature of the tungsten wire and the far air temperature is about 1% in amplitude and about 0.04 rad in phase difference. This difference becomes smaller as the diameter of the thin wire is thinner and the frequency is lower. By utilizing the fact that the internal temperature of the fine metal wire is almost equal to the temperature of the surrounding gas, the fine wire can be used as a gas temperature sensor. In this embodiment, the electrical resistance detection circuit 12 measures the electrical resistance change accompanying the temperature change of the fine metal wire, and detects the temperature change of the gas near the fine wire.

From equation (1), the temperature fluctuation amplitude at the location of the thin wire 101 at a distance h from the sensor base is θ (h) = (P / ρc _p ) (1-exp (− (1 + i) h / δ)). ... (2)
It is. The phase of this temperature fluctuation is determined only by h / δ, and is a constant value with h being fixed, and therefore becomes a function of temperature boundary layer thickness δ = (2α / ω) ^1/2 . Furthermore, since the angular frequency ω is known, the thermal diffusivity α of the gas can be known by measuring the phase of temperature fluctuation at the distance h. In this embodiment, a difference φ between the phase of temperature fluctuation at a distance, that is, the phase of pressure fluctuation, and the phase of electric resistance fluctuation of the thin wire is detected, and the thermal diffusivity α is calculated from this phase difference. As can be seen from FIG. 3, when the height h of the thin metal wire is larger than 3δ, not only the phase difference becomes almost zero, but also the relationship between the phase difference and the thermal diffusivity α is not unique. Therefore, it is necessary to set the height h to 3δ or less, and it is advantageous that the height h is a region where the rate of change in phase due to the change in the thermal diffusivity α is large, that is, a value less than or equal to δ. It is. For example, when the gas is air, δ = 0.4 mm at 40 Hz.

  The above is description of operation | movement of the 1st Example which is a typical structure for measuring the thermal diffusivity of gas. However, the configuration of the thermal diffusivity measurement according to the present invention is not limited to the configuration of the first embodiment, and many variations are conceivable. For example, since the heat conduction equation on which the formula (1) is based is linear, the superposition theory holds. Therefore, even when pressure fluctuation having an arbitrary waveform is applied instead of sinusoidal pressure fluctuation, the equation (1) is established for each Fourier component. If this is utilized, the complex amplitude of the temperature fluctuation | variation can also be measured about several frequency simultaneously. In this case, the thermal diffusivity can be calculated not only by applying the above method to a certain Fourier component, but also by using information on changes in phase difference due to frequency and information on changes in amplitude due to frequency. Is possible. By the way, when the pressure difference between the upstream side and the downstream side of the measurement cell 3 is large, the upstream and downstream solenoid valves are alternately opened and closed to sample the gas 10 and at the same time, form a rectangular wave in the cell. Pressure fluctuations can be generated. If the superposition theory is used, it is possible to measure the thermal diffusivity from this pressure fluctuation, and in this case, the speaker 2 can be omitted.

In the above embodiment, the gas heat transfer coefficient α is measured using the phase change information of the resistance change of the thin metal wire 101, that is, the temperature change of the gas. However, since the amplitude P of the pressure variation applied by the loudspeaker 2 is constant, the temperature fluctuation amplitude at that time, as can be seen from equation (1) or (2), changes depending rho] c _p of the gas. That is, not only the phase information of the temperature change of the gas, if we also use information of amplitude can also be known rho] c _p well heat transfer coefficient alpha. It can be seen that if the relationship of κ / ρc _p = α is used, the thermal conductivity κ of the gas can be measured simultaneously. Also, if otherwise known density [rho, the specific heat c _p is also determined.

Using a signal synchronized with the pressure fluctuation, rather than the first embodiment of a method of calculating the phase difference between the temperature variation, by measuring the temperature variation of the gas at the far the (P / ρc _p) directly, the near-wall It is also possible to obtain the phase difference from the temperature fluctuation. FIG. 4 shows a configuration of a temperature sensor suitable for this method. 104, which is stretched at a distance of h ₂ from the sensor base 102, is a thin metal wire for detecting the temperature fluctuation of the gas at a distance. As can be seen from FIG. 3, if h ₂ is sufficiently large, the phase of the temperature fluctuation amplitude at that location is constant, and the temperature fluctuation detected by the remote temperature detection thin wire 104 is used as a phase reference signal. Can do. Needless to say, this signal can also be used as a signal for measuring the thermal conductivity κ and the specific heat c _p.

  In this embodiment, heat transfer occurs between a wall having a constant temperature and a gas whose temperature fluctuates, and the temperature fluctuation in the temperature boundary layer formed along with this is detected to measure the thermal diffusivity. Yes. From this basic principle, it is clear that the structure of the sensor is not limited to a thin line suspended on a flat base. FIG. 5 shows another configuration example of the temperature sensor. In the example of FIG. 5, a structure is adopted in which a thin wire is suspended at the center of two parallel flat plates. In this case, the complex amplitude of the temperature variation at the position of the thin line has a function form different from the expression (1). However, if the interval between the parallel plates and the fluctuation frequency are constant, the phase of the complex amplitude is the same as the function of only the thermal diffusivity. In addition to this, a thin wire suspended inside the cylinder can be used, and in principle, any shape and combination can be used as a sensor as long as the relative positional relationship between the wall surface and the temperature detection unit is constant. Can be used.

  In addition to the method of detecting the phase difference with a constant angular frequency as in this embodiment, a phase-locked loop is configured so that the phase difference is constant, and thermal diffusion is performed based on the angular frequency at this time. The rate may be calculated. This is the same when any of the above structures is used as the temperature sensor unit. In addition, a method of measuring a temperature change with respect to a pressure fluctuation including a DC component, such as a stepped input, instead of an AC pressure fluctuation is also possible.

(Second embodiment)
FIG. 6 shows a second embodiment of the present invention having a differential configuration. In the figure, the configuration of the lower measurement cell is the same as in the first embodiment. 3 ′ on the upper side is a reference cell for detecting the thermal diffusivity of the reference gas 20, 1 ′ is a temperature sensor for the reference gas, and has the same shape as the temperature sensor 1 in the measurement cell 3 on the lower side. have. 4 ′ is a pipe for introducing a reference gas, and 5 ′ is an electromagnetic valve for sampling the reference gas at an appropriate timing. The measurement cell 3 and the reference cell 3 ′ are subjected to differential pressure fluctuations with the same amplitude and opposite phase by the speaker 2. The electrical resistance change of the temperature sensors 1 and 1 ′ has a phase difference of 180 degrees if the gas to be measured 10 and the reference gas 20 are the same component. On the other hand, if the gas to be measured contains a component having a composition different from that of the reference gas, the thermal diffusivity changes, so that the phase difference takes a value deviated from 180 degrees. In this embodiment, an electrical resistance detection circuit and a phase difference meter (not shown) are used to measure this phase shift and detect a component in the gas to be measured.

  Instead of using the temperature sensors 1 and 1 ', a change in the thermal diffusivity can be detected by detecting pressure fluctuations in the measurement cells 3 and 3' and measuring the phase difference. In the second embodiment, the temperature change of the gas is generated by the pressure change, and the temperature change caused by the heat transfer from the gas to the sensor base is detected. The thermophysical property of the target gas can be measured by this because the magnitude and phase of the heat transfer depend on the target thermophysical property. This means that the heat transfer from the gas to each cell wall surface also depends on the thermophysical properties of the gas, and the average temperature of the gas in each cell depends on the thermophysical properties of the gas. If the shapes of the measurement cells 3 and 3 'are designed so that the inner surface area is large and the heat transfer distance is small, the average temperature in the cell greatly depends on the thermophysical properties of the gas in the cell. Even if the same volume fluctuation is applied, if the average temperature fluctuation in the container is different, the generated pressure fluctuation is different. Therefore, when there is a difference in the thermophysical value of the gas in the measurement cells 3 and 3 ′, the phase difference of the pressure fluctuation in the cell deviates from 180 degrees. If this is utilized, a pressure detector such as a microphone that detects pressure fluctuations in the measurement cells 3 and 3 'can be used instead of the temperature sensor.

  In addition to the temperature sensor configuration of the second embodiment, any of the various temperature detection methods described in relation to the first embodiment can be applied to the differential configuration as in the second embodiment. . Further, instead of detecting the change in thermophysical properties from the phase of the temperature sensor signals of the two cells, it is also possible to detect the change in thermophysical properties using the change in the amplitude of the temperature fluctuation.

(Third embodiment)
FIG. 7 shows a third embodiment of the present invention configured to measure heat transfer characteristics of a conductive thin plate. In FIG. 7, 2, 11, and 12 are the same as those in the first embodiment, and are a speaker, an oscillator, and an electric resistance measurement circuit, respectively. Reference numeral 32 denotes a thin plate to be measured, and the thickness 2h is a value at which the fluctuation of the average temperature in the thin plate cannot be ignored when the temperature of the surrounding gas fluctuates. Reference numeral 301 denotes a metal electrode formed on the thin plate 32 by vapor deposition or sputtering. Reference numeral 33 denotes a measurement cell, which can open and close the lid and allow the measurement object 32 to be taken in and out. The measurement cell 33 is filled with a measurement gas 30 whose density and thermophysical properties are known. Reference numeral 34 denotes a synchronous detection circuit, which separates the signal of the electrical resistance change of the thin plate 32 into a component orthogonal to the component in phase with the pressure fluctuation and outputs the magnitude thereof. An arithmetic circuit 35 controls the oscillation angular frequency of the oscillator 11, calculates heat transfer characteristics of the thin plate 32 to be measured based on the signal from the synchronous detection circuit 34, and outputs it to the display unit 36. Reference numeral 37 denotes a valve, which is opened during the process of filling the inside of the cell with the gas 30 after opening and closing the lid of the measurement cell 33, but is closed during the measurement process.

When the speaker 2 is vibrated and a sinusoidal pressure fluctuation is generated in the measurement cell, the temperature of the gas 30 fluctuates sinusoidally. Since the thin plate 32 is in contact with the gas, heat transfer occurs and a temperature distribution is generated in the thin plate. The electrical resistance between the electrodes 301 is determined by the average temperature in the thin plate 32 and varies with the temperature variation of the gas. The complex amplitude of the average temperature fluctuation of the thin plate 32 is β · (P / ρc _p ) · (δ _w / (1 + i) h) · sinh ((1 + i) h / δ _w ) / (β · cosh ((1 + i) h / δ _w ) + sinh ((1 + i) h / δ _w )) (3)
Given in. Here, the density of the thin plate is ρ _w , the specific heat is c _w , the thermal conductivity is κ _w , the thermal diffusivity is α _w , and the thermal boundary layer thickness in the thin plate is δ _w = (2α _w / ω) ^1/2. And β = ((ρc _p κ) / (ρ _w c _w κ _w )) ^1/2 . Density measurement gas 30 [rho, the thermal conductivity kappa, since the equal ratio heat c _p is known, if the amplitude and phase or real part of the complex amplitude and the imaginary part is known, thermal diffusivity and thermal conductivity of the sheet Can be calculated.

  In this embodiment, since the thin plate 32 to be measured is conductive, an electrode is formed and the electrical resistance in the thin plate 32 is measured to detect the average temperature and measure the heat transfer characteristics of the thin plate. If the thin plate is not conductive, a metal thin film is formed on the surface of the thin plate by sputtering or vapor deposition, and the electrical resistance is measured to detect the temperature of the thin plate surface, thereby knowing the heat transfer characteristics of the thin plate. it can. In this case, the means for detecting the surface temperature is not limited to the measurement of the electrical resistance of the metal thin film, but a thermocouple, thermistor, or the like brought into contact with the surface can be used, or a radiation thermometer, a thermoreflectance method, or the like can be used. It is also possible to adopt a configuration using a contact-type temperature detection method. In addition, a thin plate is placed in contact with a base made of a material with known thermophysical properties with the metal thin film side down, and the upper surface without the metal thin film is exposed to temperature fluctuations of the gas. You may make it detect a temperature fluctuation. This configuration is the same as that of the conventional AC calorimeter method, and the present invention is applied as a heating means in the AC calorimeter method.

  In the third embodiment, the object to be measured is heated to measure the heat transfer characteristics in a known gas atmosphere. However, as is apparent from the above description, the thermal properties of the object are known. If so, the heat transfer characteristics of the gas can be measured. That is, if a known object or a known thin plate is installed and its surface temperature or average temperature is detected, it is possible to configure a gas heat transfer characteristic measuring device. In this case, as in gas chromatography, not the absolute value of the heat transfer characteristic of the gas, but the purpose of detecting that the heat transfer characteristic of the gas to be measured is different from the reference gas, not the complex amplitude of the temperature change, It is sufficient to detect only the phase or only the amplitude.

(Fourth embodiment)
FIG. 8 shows the configuration of a fourth embodiment in which the present invention is applied to nondestructive inspection. Reference numeral 43 denotes a base to be inspected, and a thin film 41 is bonded to the top thereof. Reference numeral 42 denotes a gap between the substrate 43 and the thin film 41 generated due to poor adhesion. 44 is an inspection tank which puts a test object inside. 45 is a pump for pressurizing the inside of the inspection tank 44. 46 is an infrared thermo camera, which measures the temperature distribution on the surface of the thin film 41. In this embodiment, an observation window is opened in the inspection tank 44, and measurement with an infrared thermocamera is possible while maintaining an airtight state. However, an infrared sensor is installed inside the inspection tank. Thus, the measurement can be performed without using the observation window. In some cases, the inspection tank is not provided and the sound wave is emitted toward the object in the open space.

  When the pressure in the inspection tank 44 is increased by flowing gas from the pump 45, the temperature of the gas in the inspection tank rises above the room temperature. At this time, a heat flux from the surface of the thin film 41 to the inside of the thin film and further to the base 43 is generated. However, since the thermal resistance of the upper part of the gap 42 is significantly different from that of the appropriately bonded part, the temperature distribution on the surface of the thin film is not uniform and has a distribution corresponding to the shape of the gap. By measuring the non-uniformity of the temperature distribution with the infrared thermo camera 46, it is possible to detect a defective portion of adhesion. In addition, in order to perform nondestructive inspection based on the above principle, not only pressurization but also the pressure in the inspection tank may be reduced to lower the temperature. In addition, when the temperature distribution on the surface of the thin film changes slightly and is affected by noise, the AC pressure is repeatedly increased and reduced, and the signal-to-noise ratio is calculated by correlating the pressure increase / decrease signal with the infrared thermocamera signal. May improve. In addition, if the thermal resistance distribution of the target is not uniform from the beginning even if it is a normal target, the inspection should be performed using the difference between the observed temperature distribution and the normal temperature distribution. That's fine.

  Since the present invention relates to a method and an apparatus for measuring heat transfer characteristics, which are basic characteristic quantities of substances, it is used in the field of scientific research and a wide range of industrial fields dealing with substances. Moreover, it is not used for the purpose of measuring the heat transfer characteristic itself, but as an indirect application field, it is also used for a thermal conductivity detection part of a chromatograph for detecting components using the heat transfer characteristic. In addition, it can be applied to non-destructive inspection that measures the temperature change of the target when a thermal load is applied, so it is also used as equipment diagnosis and maintenance, and diagnostic and inspection technologies in many industrial fields. .

It is a figure which shows the structure of the 1st Example of this invention. 1 is a diagram illustrating a structure of a temperature sensor 1. FIG. It is a graph which shows the relationship between the distance from a wall surface, and the complex amplitude of a temperature fluctuation. FIG. 6 is a structural diagram of a sensor that simultaneously detects a temperature change in a distant place. It is a structural diagram of a temperature sensor using a parallel plate. It is a figure which shows the 2nd Example of this invention which took the differential structure. It is a figure which shows the 3rd Example of this invention. It is a figure which shows the 4th Example which applied this invention to the nondestructive inspection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Temperature sensor 1 'Temperature sensor 101 Metal thin wire 102 Sensor base 103 Connector part 103' Connector part 104 Metal thin wire for far-field temperature detection 2 Speaker 3 Measurement cell 3 'Reference cell 4 Tube 4' Tube 5 Electromagnetic valve 5 'Electromagnetic valve DESCRIPTION OF SYMBOLS 10 Gas to be measured 11 Oscillator 12 Electric resistance detection circuit 13 Phase comparator 14 Operation part 15 Display part 16 Valve controller 20 Reference gas 30 Gas for measurement 301 Metal thin film 302 Electrode 32 Object to be measured 33 Measurement cell 34 Synchronous detection circuit 35 Operation part 36 Display unit 37 Valve 41 Thin film 42 Air gap 43 Base 44 Inspection tank 45 Pump 46 Infrared thermo camera

Claims (5)

Apply pressure fluctuation to the fluid to change the fluid temperature,
Detecting a temperature change of the fluid or an object in contact with the fluid;
A heat transfer characteristic measuring method, comprising: measuring a heat transfer characteristic of the fluid or the object based on the detected temperature change. Means for applying a pressure fluctuation to the fluid to vary the fluid temperature;
Means for detecting a temperature change of the fluid or an object in contact with the fluid;
A heat transfer characteristic measuring apparatus comprising: means for calculating a heat transfer characteristic of the fluid or the object based on a temperature change detected by the detection means.   The heat transfer characteristic measuring apparatus according to claim 2, wherein a temperature sensor is installed in a fluid in the vicinity of the object to detect a temperature change in the temperature boundary layer generated in the vicinity of the object.   3. The heat transfer characteristic measuring apparatus according to claim 2, wherein the temperature change is detected in the form of a pressure change of the fluid. The heat transfer characteristic measuring apparatus according to claim 2, wherein the heat transfer characteristic of the measurement object is measured by comparing with the heat transfer characteristic of the reference material.

Images