Method for measuring amount of heat release and heat flow sensor

Abstract

To easily and accurately measure the amount of heat release from a heat source by a heat flow sensor, and a heat flow sensor used for the measurement.SOLUTION: The present invention relates to a method for measuring the amount of heat release from a heat source by a heat flow sensor, and a heat flow sensor used for the measurement. The thermal sensor is in the shape of a sheet, and has a first main surface tightly attached to the heat release surface and covering a part of the heat release surface, and an emissivity adjusting thin film for correcting the emissivity for a heat release surface on a second main surface opposed to the first main surface. The emissivity adjusting thin film includes a non-metal thin film on the second main surface and a metal thin film on the non-metal thin film, the metal thin film exposing at least a part of the non-metal thin film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for measuring the amount of heat radiated from a heat source and a heat flux sensor used therefor.

Background Art

[0002] A heat flux sensor can be provided near a heat source to measure the amount of heat radiated from the heat source. Here, since the gap between the heat flux sensor and the heat source becomes a thermal resistance, in order to make a more accurate measurement, the heat flux sensor is arranged along the surface of the heat source.

[0003] For example, Patent Document 1 discloses a heat flux sensor using a thermoelectric conversion element and a method for measuring the amount of radiant heat using the same. A first thermoelectric member and a second thermoelectric member made of thermoelectric materials (thermoelectric conversion materials) having different characteristics are juxtaposed on a heat source (object to be measured) so as to generate an electromotive force due to the Seebeck effect, and the amount of heat of radiant heat is measured from such an electromotive force.

[0004] Further, Patent Document 2 discloses a heat flux sensor that measures the respective amounts of heat of radiant heat and convective heat using a thermoelectric conversion element in the same manner, and a method for measuring the amount of heat radiation using the same. From the output values of the thermoelectric conversion units in two regions of sensor members having different emissivities, the relationship between the total amount of convective heat and radiant heat and the emissivity is obtained. Here, since the convective heat amount is constant regardless of the magnitude of the emissivity, while the radiant heat amount varies depending on the magnitude of the emissivity, it is said that the convective heat amount and the radiant heat amount from the heat source (object to be measured) can be obtained.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in the measurement of the heat dissipation amount from a heat source by a heat flux sensor, for more accurate measurement, it is important to closely arrange the heat flux sensor along the surface of the heat source. In recent years, flexible film-like heat flux sensors have also been proposed, enabling easy close arrangement of the heat flux sensor along the surface of heat sources having various shaped surfaces as well as flat surfaces.

[0007] Here, when the heat flux sensor is arranged on the heat source without a gap, in the air, heat dissipation from the surface of the heat source occurs by convection and radiation. First, if the thermal resistance of the heat flux sensor is sufficiently smaller than the thermal resistance between the heat flux sensor surface and air (ambient air) estimated from convective heat transfer, the influence on the convective component of the heat dissipation amount from the surface of the heat source due to the arrangement of the heat flux sensor becomes small. On the other hand, in order to reduce the influence on the radiation component due to the arrangement of the heat flux sensor, it is necessary to make the emissivities of the surface of the heat source and the surface of the heat flux sensor uniform. To control the emissivity of the surface of the heat flux sensor, for example, a metal thin film can be considered to give a lower emissivity, and a blackbody coating film can be considered to give a higher emissivity to the surface. However, these surface thin films give an emissivity inherent to the material and cannot continuously control the emissivity. Therefore, a method that can measure the heat dissipation amount more simply and accurately using an emissivity adjustment thin film capable of continuously controlling the emissivity has been demanded.

[0008] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method capable of more simply and accurately measuring the heat dissipation amount from a heat source using a heat flux sensor and a heat flux sensor used for this measurement.

Means for Solving the Problem

[0009] The measurement method according to the present invention is a method for measuring the heat dissipation amount from a heat source using a heat flux sensor. The heat flux sensor is sheet-shaped and has its first main surface closely arranged so as to cover a part of the heat dissipation surface of the heat source. The heat flux sensor includes a emissivity adjustment thin film for correcting the emissivity between the heat dissipation surface and the second main surface opposite to the first main surface. The emissivity adjustment thin film is composed of a non-metal thin film provided on the second main surface and a metal thin film provided on the non-metal thin film so as to expose at least a part of the non-metal thin film.

[0010] According to such a feature, by simply providing a metal thin film that intermittently covers the surface of the non-metal thin film in an island shape, the emissivity can be continuously controlled, and the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flux sensor.

[0011] In the above invention, the emissivity adjustment thin film may be characterized in that it corrects the emissivity with the heat dissipation surface by changing the covering area of the non-metal thin film by the metal thin film. According to such a feature, the emissivity can be continuously controlled, and the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flux sensor.

[0012] In the above invention, the non-metal thin film may be made of an organic substance. According to such a feature, the emissivity can be easily controlled, and the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flux sensor.

[0013] In the above invention, the metal thin film may be a vapor deposition film with a maximum thickness of 100 nm or less. Further, the vapor deposition film may contain aluminum. According to such a feature, the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flux sensor.

[0014] In the above invention, it may also be characterized in that the heat flow between the first main surface and the second main surface is thermoelectrically converted to provide a signal output corresponding to the heat dissipation amount. According to such a feature, the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flux sensor.

[0015] Also, the sensor according to the present invention is a heat flux sensor that measures the amount of heat radiated from a heat source, and the heat flux sensor is in a sheet shape and is closely arranged so as to cover a part of the heat radiating surface of the heat source. It includes a sensor body portion composed of a first main surface and a second main surface opposite to the first main surface, and an emissivity adjustment thin film that corrects the emissivity between the second main surface and the heat radiating surface. The emissivity adjustment thin film is characterized by comprising a non-metallic thin film provided on the second main surface and a metallic thin film provided on the non-metallic thin film so as to expose at least a part of the non-metallic thin film.

[0016] According to such a feature, by providing a metallic thin film that intermittently covers the surface of the heat flux sensor in an island shape, the amount of heat radiated from the heat source can be measured more simply and accurately using the heat flux sensor.

[0017] In the above-described invention, the emissivity adjustment thin film may be characterized by changing the covering area of the non-metallic thin film by the metallic thin film to provide correction of the emissivity with the heat radiating surface. According to such a feature, the emissivity can be continuously controlled, and the amount of heat radiated from the heat source can be measured more simply and accurately using the heat flux sensor.

[0018] In the above-described invention, the non-metallic thin film may be characterized by being made of an organic substance. According to such a feature, the emissivity can be easily controlled, and the amount of heat radiated from the heat source can be measured more simply and accurately using the heat flux sensor.

[0019] In the above-described invention, the metallic thin film may be characterized by being a vapor deposition film with a maximum thickness of 100 nm or less. Further, the vapor deposition film may be characterized by containing aluminum. According to such a feature, the amount of heat radiated from the heat source can be measured more simply and accurately using the heat flux sensor.

[0020] In the above-described invention, it is also good that the sensor main body portion thermoelectrically converts the heat flow between the first main surface and the second main surface and gives a signal output corresponding to the heat dissipation amount. According to such a feature, the heat dissipation amount from the heat source can be measured more accurately and simply using the heat flow sensor.

Brief Description of Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0022] A heat flow sensor according to one embodiment of the present invention and a method for measuring the heat dissipation amount using the heat flow sensor will be described.

[0023] The heat flux sensor 10 is a flexible sheet-like body and includes a sensor main body 1 and an emissivity adjustment thin film 2. The sensor main body 1 is made to have flexibility such that its shape can change along the bent heat dissipation surface 21 of the heat source 20. One main surface 1a of the sensor main body 1 is closely arranged in contact with the heat dissipation surface 21, and the other main surface 1b paired with this is the surface on the heat dissipation side. Then, the emissivity adjustment thin film 2 is arranged on the main surface 1b on the heat dissipation side.

[0024] The emissivity adjustment thin film 2 is composed of a non-metal thin film 2a and a metal thin film 2b thereon, and has flexibility to follow the bending of the sensor main body 1. And the metal thin film 2b is provided so as to expose at least a part of the non-metal thin film 2a. For example, the metal thin film 2b is arranged so as to cover the surface of the non-metal thin film 2a in an intermittent island shape. Here, the non-metal thin film 2a is made of a material having a significantly different emissivity from that of the metal, and is, for example, an organic substance or an inorganic substance. Considering having flexibility, an organic substance such as a resin film is particularly suitable. Since the emissivities are different, the emissivity of the emissivity adjustment thin film 2 is adjusted according to the exposed area of the non-metal thin film 2a. In other words, the emissivity of the emissivity adjustment thin film 2 can be corrected by changing the covering area by the metal thin film 2b. Thereby, the emissivity of the emissivity adjustment thin film 2 can be continuously adjusted to be a value between the emissivity of the non-metal thin film 2a and the emissivity of the metal thin film 2b. Such a covering area of the non-metal thin film 2a can be controlled, for example, by the thickness of the metal thin film 2b to be formed.

[0025] For example, the metal thin film 2b is a vapor deposition film with a maximum thickness of 100 nm or less. Also, it is preferable that such a vapor deposition film is formed of a metal material containing aluminum because the emissivity adjustment thin film 2 can be easily manufactured.

[0026] As shown in FIG. 2, the sensor main body 1 measures the temperature difference between the main surfaces 1a and 1b using, for example, the Seebeck effect, and obtains the heat dissipation amount from the dimensions and thermal conductivity of the sensor main body 1. That is, it is a sensor that thermoelectrically converts the heat flow between the main surface 1a and the main surface 1b and outputs a signal corresponding to the heat dissipation amount. The sensor main body 1 includes a substrate 11, a thermoelectric material thin film 12, and an electrode thin film 13. The thermoelectric material thin film 12 and the electrode thin film 13 are inserted into a through hole 11a provided through the substrate 11 and are alternately connected at the main surfaces 1a and 1b. For example, if the substrate 11 is a polymer film and the thicknesses of the thermoelectric material thin film 12 and the electrode thin film 13 are set to several μm or less, it is preferable because relatively high flexibility can be imparted to the sensor main body 1.

[0027] As described above, the heat flux sensor 10 has flexibility and can be closely arranged on the heat dissipation surface 21 of the heat source 20. As a result, it is possible to prevent the formation of a gap that causes a thermal resistance between the heat flux sensor 10 and the heat dissipation surface 21. And the thermal resistance of the heat flux sensor 10 can be made sufficiently smaller than the thermal resistance between the surface of the heat flux sensor and the outside air, for example, by making the film thickness of the substrate 11 thinner, and the influence on the convective component of the heat dissipation amount from the heat dissipation surface 21 due to the installation of the heat flux sensor can be suppressed to a small level.

[0028] Here, according to the heat flux sensor 10, since the emissivity adjustment thin film 2 is provided, the emissivity can be adjusted. Therefore, the heat flux sensor 10 is obtained by the emissivity adjustment thin film 2 whose emissivity is adjusted so as to match the emissivity of the heat dissipation surface 21 of the heat source 20 and the heat flux sensor 10. When the heat dissipation amount is measured by such a heat flux sensor 10, the influence on the radiation component of the heat dissipation amount from the heat dissipation surface 21 due to the installation of the heat flux sensor 10 can be reduced. Therefore, more accurate measurement of the heat dissipation amount is enabled.

[0029] As described above, the emissivity of the heat flux sensor 10 can be adjusted by a simple method of adjusting the thickness of the metal thin film 2b. Therefore, according to the heat flux sensor 10, the heat dissipation amount from the heat source can be measured more accurately in a simple manner.

[0030] [Demonstration test] The above-described heat flux sensor 10 was fabricated, and the results of measuring the heat flux will be described. First, the emissivity adjustment thin film was verified.

[0031] First, as shown in FIG. 3, the emissivity of the emissivity adjustment thin film 2 according to the thickness of the metal thin film 2b was investigated. Here, a polyethylene naphthalate film with a thickness of 25 μm was used as the non-metal thin film 2a, and aluminum was deposited as the metal thin film 2b. As a result, it was found that an adjustment region where the emissivity continuously changes exists in the range where the film thickness of aluminum is 0 to 20 nm. In order to accurately control the film thickness in this adjustment region, for example, vapor deposition of aluminum by sputtering or vacuum evaporation is preferable. The film thickness can be measured using, for example, a crystal oscillator type film thickness meter.

[0032] Next, as shown in FIGS. 4 to 6, the surface state of the polyethylene naphthalate film was observed with an atomic force microscope. When aluminum was not deposited (FIG. 4), the surface was flat. On the other hand, when aluminum was deposited with a thickness of 5 nm (FIG. 5), aluminum formed particles and partially exposed the surface of the polyethylene naphthalate film. When aluminum was deposited with a thickness of 100 nm (FIG. 6), aluminum similarly formed particles, but no exposure of the surface of the polyethylene naphthalate film was observed. At this time, the emissivity showed a value equivalent to that of pure aluminum.

[0033] Here, since aluminum is a metal, it has a low emissivity, and its value is about 0.05. On the other hand, since the polyethylene naphthalate film is an organic substance, the emissivity is close to 1. That is, in the above-described adjustment region, it is considered that the emissivity was reduced by reducing the exposed area of the polyethylene naphthalate film. In other words, the emissivity can be freely controlled by controlling the film thickness of aluminum.

[0034] Next, a heat flux sensor 10 (see FIG. 2) was fabricated. A polyethylene naphthalate was used for the substrate 11, a composite material of single-walled carbon nanotubes and polyvinyl alcohol was used for the thermoelectric material thin film 12, and a silver paste was used for the electrode thin film 13. Here, two types of heat flux sensors with surface emissivities of 0.97 and 0.05 were fabricated. The former was fabricated by applying a paint with an emissivity of 0.97 instead of the emissivity adjustment thin film 2. For the latter, in the emissivity adjustment thin film 2, a polyethylene naphthalate film was used as the non-metal thin film 2a, and aluminum was deposited as the metal thin film 2b with a thickness of 672 Å.

[0035] The above two types of heat flux sensors were respectively installed on a heated copper plate, and the surface temperature of the heat flux sensor and the heat dissipation amount released into the atmosphere passing through the heat flux sensor were measured.

[0036] As shown in FIG. 7(a), in the measurement by the heat flux sensor with an emissivity of 0.97, the surface temperature of the heat flux sensor showed almost the same value as the temperature of the copper plate, and the heat dissipation amount (heat flux) increased in proportion to the temperature of the copper plate. On the other hand, as shown in FIG. 7(b), in the measurement by the heat flux sensor with an emissivity of 0.05 equivalent to that of the copper plate, the surface temperature of the heat flux sensor also showed almost the same value as the temperature of the copper plate, but the heat dissipation amount (heat flux) was less than half that of the heat flux sensor with an emissivity of 0.97.

[0037] From these facts, when comparing the two heat flux sensors, the following considerations can be made. First, since both sensors showed almost the same surface temperature as the copper plate temperature, it is considered that the convective component of the heat dissipation amount from the heat flux sensor is almost the same. Therefore, the difference in the heat dissipation amount between the two heat flux sensors is due to the radiative component, and it is considered that the radiative component decreased due to the heat flux sensor with an emissivity of 0.05 having the same emissivity as the copper plate. From this result, it can be concluded that in the measurement of the heat dissipation amount, accurate measurement can be achieved by using a heat flux sensor having an emissivity similar to that of the heat dissipation surface of the heat source.

[0038] As described above, according to the above-described heat flux sensor, the emissivity of the sensor surface can be corrected to be equivalent to that of the heat dissipation surface, and the heat dissipation amount from the heat source can be measured simply and more accurately.

[0039] The embodiments of the present invention and the modified examples based thereon have been described above. However, the present invention is not necessarily limited thereto, and those skilled in the art will be able to find various alternative embodiments and modified examples without departing from the gist of the present invention or the scope of the appended claims.

Description of Reference Numerals

[0040] 1 Sensor main body 2 Emissivity adjustment thin film 2a Non-metal thin film 2b Metal thin film 10 Heat flux sensor 20 Heat source 21 Heat dissipation surface

Claims

1. A method for measuring the heat dissipation amount from a heat source using a heat flux sensor, wherein the heat flux sensor is sheet-shaped and has its first main surface closely arranged so as to cover a part of the heat dissipation surface of the heat source, and includes a emissivity adjustment thin film for correcting the emissivity between the first main surface and the heat dissipation surface above the second main surface opposite to the first main surface, the emissivity adjustment thin film is composed of a non-metallic thin film provided on the second main surface and a metallic thin film provided on the non-metallic thin film so as to expose at least a part of the non-metallic thin film, and is characterized in that it is a method for measuring the heat dissipation amount from a heat source.

2. The method for measuring the heat dissipation amount according to claim 1, wherein the emissivity adjustment thin film corrects the emissivity with the heat dissipation surface by changing the covering area of the non-metallic thin film by the metallic thin film.

3. The method for measuring the heat dissipation amount according to claim 2, wherein the non-metallic thin film is made of an organic substance.

4. The method for measuring the heat dissipation amount according to claim 3, wherein the metallic thin film is a vapor deposition film with a maximum thickness of 100 nm or less.

5. The method for measuring the heat dissipation amount according to claim 4, wherein the vapor deposition film contains aluminum.

6. The method for measuring the heat dissipation amount according to any one of claims 1 to 5, wherein the heat flow between the first main surface and the second main surface is subjected to thermoelectric conversion to provide a signal output corresponding to the heat dissipation amount.

7. A heat flux sensor for measuring the heat dissipation amount from a heat source, wherein the heat flux sensor is sheet-shaped, a sensor body portion composed of a first main surface closely arranged so as to cover a part of the heat dissipation surface of the heat source and a second main surface opposite to the first main surface, an emissivity adjustment thin film for correcting the emissivity between the second main surface and the heat dissipation surface above the second main surface, is included, the emissivity adjustment thin film is composed of a non-metallic thin film provided on the second main surface and a metallic thin film provided on the non-metallic thin film so as to expose at least a part of the non-metallic thin film, and is characterized in that it is a heat flux sensor for measuring the heat dissipation amount from a heat source.

8. The heat flux sensor according to claim 7, wherein the emissivity adjustment thin film corrects the emissivity with the heat dissipation surface by changing the covering area of the non-metallic thin film by the metallic thin film.

9. The heat flux sensor according to claim 8, wherein the non-metallic thin film is made of an organic substance.

10. The heat flux sensor according to claim 9, wherein the metallic thin film is a vapor deposition film with a maximum thickness of 100 nm or less.

11. The heat flux sensor according to claim 10, wherein the vapor deposition film contains aluminum. **Claim 12** The heat flux sensor according to any one of claims 7 to 11, wherein the sensor main body thermoelectrically converts a heat flux between the first main surface and the second main surface and provides a signal output corresponding to the heat dissipation amount.

Images