JP2009281910A - Measuring instrument of thermophysical properties - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring instrument of thermophysical properties capable of measuring the heat conductivity of a heat insulating material with high precision. <P>SOLUTION: The heat transmitted to a heat flow density detecting means 109 from a heat source 102 through a measuring target 101 during the measurement of thermophysical properties of the measuring target 101 is stored in a heat accumulation material 113 having large specific heat or latent heat in a fixing means 108 to reduce the temperature rise of the heat flow density detecting means 109. As a result, since the temperature rise of a heat flow density sensor 107 can be suppressed, the density of a heat flow passing through the measuring target 101 can be stabilized and the thermophysical properties of the measuring target 101 can be measured with high precision by a simple constitution. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermophysical property measuring apparatus for evaluating the heat insulating performance of polyurethane foam and vacuum heat insulating material.

  In recent years, interest in global environmental issues has increased, and there has been an increasing social demand for energy-saving designs for refrigeration equipment such as refrigerators and vending machines and thermal equipment such as jar pots. In response, equipment manufacturers are competing to develop insulation technology.

  As a typical heat insulation technique, there is a polyurethane foam used for a box wall surface of a refrigerator-freezer such as a refrigerator. Recently, glass wool or silica powder is used as a core material, and this core material is covered with a film excellent in gas barrier properties such as a laminate film of resin and metal foil. The vacuum heat insulating material produced by making the inside into a vacuum state is used as a high performance heat insulating material.

  Generally, the heat insulating performance of these heat insulating materials is evaluated by the thermal conductivity obtained by dividing the heat flow density per unit area from one surface of the heat insulating material to the opposite surface by the thickness. A smaller thermal conductivity means higher thermal insulation performance. The heat conductivity is measured by sandwiching the heat insulating material between parallel flat plates whose temperature can be adjusted, and measuring the heat flow density per unit area when a predetermined temperature difference is provided in the thickness direction of the heat insulating material. At the same time, the thickness between parallel flat plates is measured, and the thermal conductivity is calculated.

  This measurement method measures the heat flow density when the temperature difference between both surfaces of the heat insulating material is constant, that is, in a steady state. For this reason, time from the start of measurement to the steady state is required. In order to shorten this time, a heat resistance material such as silica, which hardly changes the material due to temperature, is placed on the heat insulation material to be measured, and the heat insulation material is insulated from the temperature difference between two or more points inside the heat resistance material. There is a method for estimating the thermal conductivity of a material (see, for example, Patent Document 1).

  FIG. 2 is an explanatory diagram of a conventional thermal conductivity measuring device. As shown in FIG. 2, the thermal conductivity measuring device 1 includes a heat generating device 2 and a heat resistance material 3. The thermal resistance material 3 measures an internal temperature difference.

The heat generation device 2 generates heat between the object to be measured 4 and the heat resistance material 3, and heat is passed through the object to be measured 4 and the heat resistance material 3, and a temperature difference caused by the heat flow inside the heat resistance material 3 is calculated. It can measure with the temperature difference measuring apparatus 5, and can obtain | require the thermal conductivity of the to-be-measured object 4 from this temperature difference. In addition, an adhesion imparting material 6 is provided above the heat resistance material 3 to bring the heat generating device 2, the heat resistance material 3, and the measurement object 4 into close contact with each other by applying a load from above.
JP 2002-131257 A

  However, in the above conventional configuration, the amount of heat supplied from the heat generating part to the heat resistance material side is determined depending on the thermal conductivity of the object to be measured, and the amount of heat supplied to the heat resistance material is large. The temperature difference between the heat resistance surface and the inside becomes small, and when the amount of heat is small, the temperature difference becomes large. From this correlation, the thermal conductivity of the object to be measured is calculated. In this method, the temperature of the heat resistance material is substantially the same as the outside air temperature before the start of measurement, and the temperature rises due to the heat from the heat generating part after the measurement. If the direction of the heat flow that travels through the heat resistance material is uniform from the heat generating part to the adhesion imparting material direction, there is no problem, but in reality there is a temperature difference between the heat resistance material and the outside air. Heat is released to the outside air. For this reason, even for the same object to be measured, the temperature difference between the surface and the inside of the heat resistance material also changes due to the temperature change of the outside air, and there is a problem that the measured value varies.

  The present invention relates to a method for detecting the heat flow density passing through the object to be measured by a heat flow density sensor on the opposite side of the heat source across the object to be measured. Stabilize the heat transferred from the temperature controlled heat source to the heat flow density sensor via the measured object by maintaining the temperature of the heat flow density sensor during measurement by storing it in a heat storage material with large latent heat. Accordingly, an object of the present invention is to provide a thermophysical property measuring apparatus capable of measuring thermophysical properties with high accuracy while having a small and simple configuration.

  In order to achieve the above object, the thermophysical property measuring apparatus of the present invention is composed of a heat source having a flat upper portion on which the object to be measured is installed, and a heat flow density detecting means which is provided above the object to be measured and is movable up and down. The heat flow density detecting means includes a heat flow density sensor that contacts the object to be measured when descending, and a fixing means that fixes the heat flow density sensor by arranging the heat flow density sensor to form a space with the bottom surface, and stores heat in the space. A material is provided.

  In the above configuration, an object to be measured such as a heat insulating material placed on the heat source is heated by the heat from the heat source, and the temperature rises. Then, heat is transferred from the surface opposite to the heat source to the heat flow density sensor, and the heat is stored in the heat storage material in the fixing means, but the heat storage material has a large specific heat or latent heat, and the temperature change due to heat intrusion from the heat flow density sensor There is almost no. That is, the heat flow density detecting means can maintain a substantially constant temperature with almost no increase in temperature. Therefore, the temperature of the heat flow density detecting means (low temperature side) can be stabilized without using a special temperature control device, so that the thermophysical property of the object to be measured can be measured with high accuracy while having a small and simple configuration. It becomes possible.

  According to the present invention, the heat transmitted from the heat source to the heat flow density detection means via the object to be measured is stored in the heat storage material, so that the temperature rise of the heat flow density detection means can be suppressed while having a simple configuration, A compact thermophysical property measuring apparatus capable of measuring thermophysical property values with high accuracy can be provided.

  The thermophysical property measuring apparatus according to claim 1 is composed of a heat source having a flat upper portion on which the object to be measured is installed and a heat flow density detecting means which is provided above the object to be measured and is movable up and down. The detection means includes a heat flow density sensor that comes into contact with the object to be measured when descending, and a fixing means that fixes the heat flow density sensor by arranging the heat flow density sensor as a bottom surface to form a space, and includes a heat storage material in the space. Because the heat transmitted from the heat source to the heat flow density detection means through the measured object during the measurement of the thermophysical properties of the measured object is stored by the heat storage material having a large specific heat or latent heat, there is almost no temperature change of the heat storage material. Since the temperature rise of the heat flow density sensor can be suppressed, the heat flow density passing through the object to be measured can be stabilized, so that the thermophysical properties of the object to be measured can be measured with high accuracy while having a small and simple configuration. To become.

  A thermophysical property measuring apparatus according to a second aspect is the invention according to the first aspect, wherein the fixing means is made of resin.

  Resins have a lower thermal conductivity than metals. From this, it is possible to reduce heat transmitted from the heat source to the heat storage material via the object to be measured and the heat flow density sensor, and heat entering from the outside of the fixing means. From this, there is almost no temperature change of the heat storage material, and since the temperature rise of the heat flow density detection sensor can be further suppressed, the heat flow density passing through the object to be measured can be further stabilized, so that it is a small and simple configuration, The thermophysical property of the object to be measured can be measured with higher accuracy.

  The invention of the thermophysical property measuring apparatus according to claim 3 is the invention according to claim 1 or 2, wherein the fixing means is composed of a foamed resin having a large number of bubbles in the resin layer, and heat insulation of the fixing means. The performance is high, the heat entering the heat storage material from the outside of the fixing means can be further reduced, and the temperature change of the heat storage material can be suppressed. As a result, the temperature rise of the heat flow density detection sensor can be further suppressed, and the heat flow density passing through the object to be measured can be further stabilized, so that the thermophysical properties of the object to be measured can be further enhanced while having a small and simple configuration. It becomes possible to measure with accuracy.

  The invention of the thermophysical property measuring apparatus according to claim 4 is the invention according to any one of claims 1 to 3, wherein the heat storage material is water, and the specific heat of the heat storage material is Compared with other materials, it is very large, can store a lot of heat despite its small volume, and has a small temperature change. As a result, the temperature rise of the heat flow density detection sensor can be further suppressed, and the heat flow density passing through the object to be measured can be further stabilized, so that the thermophysical properties of the object to be measured can be further enhanced while having a small and simple configuration. It becomes possible to measure with accuracy.

  The invention of a thermophysical property measuring apparatus according to claim 5 is the invention according to any one of claims 1 to 4, further comprising a thickness measuring means for measuring the thickness of the object to be measured, which is measured by a heat flow density sensor. And a calculation means for calculating the thermal conductivity of the measurement object by dividing the heat flow density by the thickness of the measurement object measured by the thickness measurement means and the temperature difference of the heat flow density sensor and the temperature of the heat source. The thermal conductivity can be used as the thermophysical value. The thermal conductivity can be compared with the ease of heat transfer regardless of the thickness of the object to be measured, so in addition to being able to measure the thermal properties of the object to be measured with high accuracy, it is possible to measure differently. The thermophysical properties of objects can be evaluated with the same index.

  The invention of the thermophysical property measuring apparatus according to claim 6 is the invention according to claim 5, wherein the computing means compares the value stored in advance with the value calculated by the computing means, It is characterized in that it is connected to a determination means for determining whether or not it has a desired thermophysical property, and it is possible to mechanically determine whether the thermophysical property value of the object to be measured is good or bad. From this fact, in addition to being able to measure the thermophysical property of the object to be measured with high accuracy, it is possible to evaluate the thermophysical property without erroneous recognition.

  According to a seventh aspect of the present invention, there is provided the thermophysical property measuring apparatus according to the sixth aspect, further comprising display means for displaying a result determined by the determining means. It is possible to mechanically judge whether the physical property value is good or bad and to visually recognize it. From this, in addition to being able to measure the thermophysical property of the object to be measured with high accuracy, it is possible to evaluate the thermophysical property without further misrecognition.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a thermophysical property measuring apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the DUT 101 is a heat insulating material having a thermal conductivity of 0.045 W / mK or less, for example. There is a polyurethane foam generally used as a heat insulating material for refrigerators and houses. In addition, the core material made by baking powder or glass wool into a plate shape is inserted into a jacket material made into a bag shape with a laminate film of resin and aluminum foil, the inside is evacuated, and the opening is thermally welded There are sealed vacuum insulation materials. The heat source 102 includes a metal plate 103 made of stainless steel or iron on the upper surface, and the object to be measured 101 can be placed on the upper portion. An electric heater 104 is provided in contact with the lower part of the metal plate 103 to heat the metal plate 103. The temperature of the metal plate 103 is detected by the thermocouple 105, and the output of the electric heater 104 can be adjusted via the temperature regulator 106 so that the metal plate 103 reaches a predetermined temperature.

  Above the object to be measured 101, a heat flow density detecting means 109 comprising a heat flow density sensor 107 and a fixing means 108 made of resin or foamed resin is provided. The heat flow density sensor 107 has a thermocouple embedded therein, and measures the heat flow passed per unit area from the electromotive force generated in the thermocouple due to the temperature difference between the upper and lower surfaces. The fixing means 108 is coupled via an air cylinder 111 fixed below the beam 110 and a spring 112, and a heat flow density sensor 107 is provided on the lower surface thereof. Furthermore, the fixing means 108 forms a space between the heat flow density sensor 107 and is filled with water as the heat storage material 113. The beam 110 has a reinforcing structure such as a rib on the upper surface because a concentrated load is applied to the substantially central portion. The air cylinder 111 is connected to a compressor 115 via a tube 114.

  A plurality of thickness measuring means 116 are provided above the DUT 101. The thickness measuring means 116 is an optical non-contact type. Each component except the compressor 114 is housed in a casing 117.

  The heat flow density sensor 107 and the thickness measuring means 116 are connected to a calculating means 119 outside the casing 117 through a signal line 118. The calculation means 119 calculates the thermal conductivity from the heat flow density and thickness of the object to be measured 101 detected by the heat flow density sensor 107 and the thickness measurement means 116 and the temperature difference between the upper and lower surfaces, and further stores the value in advance. A determination unit 120 is provided for comparing the calculation panels and determining whether the DUT 101 has desired thermophysical properties. Moreover, the display part 121 which displays the determination result of the determination means 120 is provided.

  The operation of the thermophysical property measuring apparatus configured as described above will be described below.

  First, in order to measure the thermal conductivity of the DUT 101, the temperature of the heat source 102 (high temperature side) is adjusted. For example, the output of the electric heater 104 may be adjusted by the temperature regulator 106 so that the metal plate 103 on the upper surface becomes 40 ° C. to 70 ° C. The heat released from the metal plate 103 slightly raises the temperature in the casing 117. At this time, the fixing means 108 and the casing 117 are brought to substantially the same temperature by exchanging heat with each other via the heat exchanging means 113. As a result, the temperature of the heat flow density sensor 107 is also substantially the same as that of the fixing means 108.

  If the temperatures of the metal plate 103 and the heat flow density sensor 107 are stabilized, the DUT 101 is placed on the metal plate 103. Thereafter, compressed air is supplied from the compressor 115 through the tube 114 to the air cylinder 111, and the heat flow density sensor 107 is lowered so as to be in contact with the surface of the object 101 to be measured. At this time, even if the surface of the object to be measured 101 is inclined, the heat flow density sensor 107 and the object to be measured 101 can be in close contact with each other by the plurality of springs 112. In this close contact state, heat is transferred from the heat source 102 to the heat flow density sensor 107 via the object to be measured 101, so the heat flow density sensor 107 tries to raise the temperature, but there is a temperature difference between the heat flow density sensor 107 and the heat storage material 113. When generated, the heat moves to the heat storage material 113 and is stored. The heat storage material 113 sufficiently stores heat transmitted from the heat source 102 via the object to be measured 101 and the heat flow density sensor 107 and heat transmitted from the outside of the fixing means 108 via the fixing means 108, and there is almost no temperature change. Thereby, the temperature rise of the heat flow density sensor 107 is suppressed. Note that if the compressive force applied to the device under test 101 is too strong, the device under test 101 may be deformed, so the air pressure from the compressor 115 is adjusted in advance according to the compression deformation behavior of the device under test 101. .

  The thickness of the DUT 101 is measured by the thickness measuring means 116 provided above.

  The measured heat flow density and thickness of the object to be measured 101 and the temperature difference between the two surfaces of the object to be measured are transmitted to the computing means 119 via the signal line 118 as an electric signal. In the calculation means 119, the thermal conductivity of the device under test 101 is calculated from the transmitted data by the discriminating device 120 and compared with a desired value recorded in advance, so that the heat insulation performance of the device under test 101 is good or bad. Judging. The determination result is displayed by the display means 121 so that it can be easily understood visually.

  As described above, the heat source 102 having a flat upper portion on which the object to be measured 101 is installed and the heat flow density detecting means 109 provided above the object to be measured 101 and movable up and down are configured. A heat flow density sensor 107 that contacts the object to be measured 101 when descending, and a fixing means 108 that fixes the heat flow density sensor 107 by arranging the heat flow density sensor 107 as a bottom surface to form a space, and a heat storage material 113 in the space. The heat transferred from the heat source 102 to the heat flow density detecting means 109 via the measured object 101 during the measurement of the thermophysical property of the measured object 101 is stored in a sufficient amount of the heat storage material 113. . For this reason, since the temperature rise of the heat flow density sensor 107 can be suppressed, the heat flow density passing through the object to be measured 101 can be stabilized, so that the thermophysical properties of the object to be measured 101 can be highly accurate while having a small and simple configuration. It becomes possible to measure.

  As described above, the thermophysical property measuring apparatus according to the present invention can measure the thermal conductivity of a heat insulating material or the like with high accuracy. For this reason, quality inspection can be performed with high accuracy in a mass production factory for heat insulating materials, which can contribute to improving the quality of the heat insulating materials, and further improve the quality of refrigerators and houses using the heat insulating materials.

Configuration diagram of thermophysical property measuring apparatus according to Embodiment 1 of the present invention Illustration of a conventional thermal conductivity measurement device

Explanation of symbols

101 Object to be measured 102 Heat source 107 Heat flow density sensor 108 Fixing means (resin or foamed resin)
109 Heat flow density detection means 113 Heat storage material (water)
116 Thickness measurement means 119 Calculation means 120 Determination means 121 Display means

Claims (7)

A heat source having a flat upper portion on which the object to be measured is installed, and a heat flow density detecting means provided above the object to be measured and movable up and down, the heat flow density detecting means being in contact with the object to be measured when lowered. A heat flow density sensor, a fixing means for fixing the heat flow density sensor by arranging the heat flow density sensor as a bottom surface to form a space, and a heat storage material in the space. . The thermophysical property measuring apparatus according to claim 1, wherein the fixing means is a resin. The thermophysical property measuring apparatus according to claim 1 or 2, wherein the fixing means is a foamed resin having a large number of bubbles in the resin layer. The thermophysical property measuring apparatus according to any one of claims 1 to 3, wherein the heat storage material is water. A thickness measuring means for measuring the thickness of the object to be measured is provided, and the heat flow density that is measured by the heat flow density sensor is determined by the difference between the thickness of the object to be measured and the temperature of the heat source measured by the thickness measuring means, The thermophysical property measuring apparatus according to any one of claims 1 to 4, further comprising an arithmetic unit that calculates the thermal conductivity of the object to be measured by dividing the measured value. The calculation means is connected to a determination means for comparing the value stored in advance with the value calculated by the calculation means to determine whether the object to be measured has a desired thermophysical property. The thermophysical property measuring apparatus according to claim 5. The thermophysical property measuring apparatus according to claim 6, further comprising display means for displaying a result determined by the determining means.