JP2866925B2 - How to measure thermal properties of objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment of an object as a plate-like or block-like material used for various uses such as a glass plate, a ceramic plate, an alloy plate, a plastic plate, a firebrick, etc. The present invention relates to a measuring method for simultaneously obtaining specific heat capacity and heat diffusivity, or specific heat capacity, heat conductivity and heat diffusivity, which are physical property values. The method according to the present invention is useful as a method for a physicochemical test or an experiment for measuring the thermal properties of the object.

[0002]

2. Description of the Related Art In the above-mentioned conventional method or apparatus, it is not possible to measure the respective thermal physical properties using different apparatuses, or even to measure them simultaneously using the same apparatus. could not. Note that a method for simultaneously obtaining the thermal conductivity and the thermal diffusivity is known.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of simultaneously measuring a plurality of the above-mentioned thermal properties with the same apparatus.

[0004]

According to a first aspect of the present invention, an object to be measured is provided in a vacuum tank facing a heat supply source provided in the vacuum chamber, and the object to be measured faces the heat supply source of the object to be measured. Measure the temperature of the heating or cooling surface and the back surface which is the opposite surface, the measurement result, the temperature of the heat supply source, the temperature of the vacuum chamber wall and the thickness and density of the measured object in advance, the The present invention relates to a method for measuring a thermal property value of an object for simultaneously measuring a specific heat capacity and a thermal conductivity.

According to a second aspect of the present invention, an object to be measured is provided in a vacuum chamber facing a heat supply source provided in the vacuum chamber, and a heating or cooling surface of the object to be measured facing the heat supply source and a heating or cooling surface thereof. Measure the temperature of the reverse side, which is the opposite side, and determine the specific heat capacity and thermal conductivity of the measured object from the measured result, the temperature of the heat supply source, the temperature of the vacuum chamber wall surface and the thickness and density of the measured object. And a method for measuring the thermal physical property value of an object for simultaneously measuring the thermal diffusivity.

The method for measuring the thermal properties of an object according to the first and second aspects of the present invention comprises a vacuum chamber, a heat source provided in the vacuum chamber, and a heat source provided in the vacuum chamber facing the heat source. A setting section of the measured object provided in the, and a temperature measuring means for separately measuring the temperature of the heating or cooling surface facing the heat supply source of the measured object set in the setting section and the temperature of the back surface which is the opposite surface, respectively. Is achieved by a measuring device comprising:

[0007]

In each of the above-mentioned inventions, the above measurement results, the temperature of the heat supply source, the temperature of the vacuum chamber wall surface, and the previously measured values of the thickness and density of the object to be measured are represented by the following (Equation 15) and (Equation 15). (Equation 16) (Claim 1 or 3) or (Equation 15),
The specific heat capacity and the thermal conductivity of the object to be measured (Claim 1 or 3), or the specific heat capacity and heat are calculated by using the mathematical formulas of (Equation 16) and (Equation 12) (Claim 2 or 3). The measurement results of the conductivity and the thermal diffusivity (claim 2 or 3) can be obtained simultaneously. A microcomputer can be used as the calculation means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the method for measuring the thermal properties of an object according to the present invention will be described. As an example, consider a system in which a thin plate-like object is continuously heated or cooled by a suitable heat source (see FIG. 1). When the temperature of the object rises and falls at a constant speed, the specific heat capacity Cp and the thermal conductivity λ to be determined are related to the following equations (Equation 1), (Equation 2), and (Equation 3). Holds. L and ρ are the thickness and density of the object. T _L and T _O are the temperature of the heated surface of the object and its back surface. δT / δt is a temperature change per unit time of the object, that is, a temperature rate. W _h and W _o are the heat energy per unit time and unit area that the heating surface transmits and receives from the heat source, and the heat energy emitted from the back surface. If the temperature gradient in an arbitrary thickness direction X of the object is expressed by the following expression (4), the expression (1) is expressed by the following expression (5). In the method for measuring the thermal properties of an object according to the present invention, the temperature of the front and back surfaces of the object, the thermal energy of supply and discharge, and the temperature rate are simultaneously measured when the object is in a heated and cooled state. The method for simultaneously obtaining the specific heat capacity and the thermal conductivity, or the specific heat capacity, the thermal conductivity and the thermal diffusivity from the measured physical quantities will be described below.

(1) Derivation of specific heat capacity From the following equations (Equation 1), (Equation 2) and (Equation 3), (Equation 6)
Expression is found. From Equation (6), Equation (7) holds for the same heating surface temperature when the temperature of the object rises and falls. Here, (') indicates the time of temperature drop. This equation shows that the specific heat capacity can be derived by obtaining the right side of the equation. The temperature of the object at this time is the average temperature of the heating surface and the emission surface.

(2) Derivation of thermal conductivity From equation (5), when the temperature of an object rises and falls, it has the same temperature rate and the same emission surface temperature, the sum of both equations is obtained. (Equation 8) is obtained. On the other hand, when Expression (4) is integrated with respect to X, Expression (9) representing the temperature difference between both surfaces is obtained. Using Equations (8) and (9), Equation (10) is obtained from the equations relating to temperature rise and fall at the same emission surface temperature of the object. When the value on the right side of this equation is obtained, the thermal conductivity is obtained. Expression (Equation 10) is an expression obtained at the same emission surface temperature. However, Expression (Equation 11) is obtained when the same heating surface temperature is obtained.

(3) Derivation of thermal diffusivity From equations (5) and (9), when the temperature of the object rises and falls, and the same emission surface temperature, the difference between the two equations is obtained. Equation 12) is obtained, and the left side of this equation is the thermal diffusivity a
Which gives

FIG. 1 is a schematic configuration diagram of an apparatus for measuring a thermal property value of an object according to the present invention. As shown in FIG. 1, this device is a device in which a plate-shaped measured object 2 and a heater 3 as a heat supply source are opposed to each other in a water-cooled vacuum chamber 1. The measured object 2 is set in a setting unit in the vacuum chamber 1. The vacuum chamber 1 is provided with temperature measuring means for continuously measuring the temperature of the heating surface of the object 2 to be measured facing the heater 3 and the temperature of the back surface opposite thereto, respectively. The vacuum chamber 1 is always kept at a constant temperature by water cooling or the like. A temperature signal from the temperature measuring means, a set temperature signal of the heater 3,
The temperature of the vacuum chamber wall surface and the thickness and density of the measured object measured in advance are calculated by the following formula, and the specific heat capacity and the thermal conductivity, or the specific heat capacity, the thermal conductivity and the thermal diffusivity over time are calculated. A computer operation means for continuously or intermittently measuring and displaying is provided.

When the object to be measured 2 is heated by the heat radiation of the heater 3, the radiant energy per unit area and per unit time transmitted and received by the heated surface of the object to be measured 2 is given by the following equation (13). The energy radiated by the emission surface of the measurement object is given by equation (14). Here, Th is the temperature of the heater, and _Tr is the temperature of the wall surface of the vacuum chamber, which is always kept constant by water cooling or the like. σ is Stefan's constant, and E _h is the effective emissivity established between the heater and the object heating surface. ε is the emissivity of both surfaces of the object. b is a coefficient of energy dissipated from the heating surface to the vacuum chamber wall, and is 1
Has a smaller value than In this measuring device, the specific heat capacity is given by Expression (15) from Expression (7),
Similarly, the thermal diffusivity can be obtained from equation (12). The thermal conductivity is given by Expression (16) from Expression (10).

Next, a procedure for measuring a thermal physical property value of an object measured by the above-described measuring device will be described. What is measured and recorded are the temperature of the heater (T _h ), the temperature of the sample surface (T _L ), and the temperature of the sample back surface (T _O ) when the temperature rises and falls. As a recording method, the data of the above three temperatures is recorded as a set continuously, at regular intervals (for example, every 10 seconds), or at regular temperatures (for example, every 1 degree). The rise and fall of the temperature can be performed by controlling the current flowing through the heater to increase or decrease. The temperature speed can be obtained by dividing the temperature difference between data by the time between data. This can be easily obtained by computer processing.

FIG. 2 shows the relationship between temperature rise and fall and time.
Referring to the graph, for example, when the temperature rises,
The temperature difference between the heaters is 1 ° C and the time between them is 10 seconds
Then the temperature rate would be 1/10 (° C / sec),
When descending, the temperature difference is negative, so the temperature speed is also -1/1.
0 (° C / sec). The data of each temperature when the temperature rises
Data set (T_h, T_L, T_O) And when the temperature drops
Data set of each temperature in (T_h’, T_L’,
T_O′), The sample surface temperature at a certain rise is T
_L(For example, 100 ° C.)
T_L’(E.g., 100 ° C.)
T_hAnd T_h’Is not the same,_OAnd T_O’Is not the same
No. In this case, the specific heat capacity is obtained from Expression (15).
be able to. Similarly, the back surface temperature of the sample when the temperature rises
Is T_OAnd the back surface temperature of the sample when the temperature falls is T_O’
At the same time, the thermal diffusivity is calculated from the equations (12) and (16).
The thermal conductivity is determined.

FIG. 3 shows experimental results of simultaneous measurement of the specific heat capacity Cp (upper part) and the thermal conductivity λ (lower part) using Pyrex glass (thickness 3 mm, diameter 25 mm) as a sample. These experimental results have confirmed that the method using the device according to the present invention is valid.

[0017]

(Equation 1)

[0018]

(Equation 2)

[0019]

(Equation 3)

[0020]

(Equation 4)

[0021]

(Equation 5)

[0022]

(Equation 6)

[0023]

(Equation 7)

[0024]

(Equation 8)

[0025]

(Equation 9)

[0026]

(Equation 10)

[0027]

[Equation 11]

[0028]

(Equation 12)

[0029]

(Equation 13)

[0030]

[Equation 14]

[0031]

(Equation 15)

[0032]

(Equation 16)

[0033]

According to the present invention, there is an effect that the specific heat capacity and the thermal conductivity, or the specific heat capacity, the thermal conductivity and the thermal diffusivity, which are the thermal properties of the object, can be measured simultaneously. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus according to the present invention.

FIG. 2 is a graph showing the relationship between temperature rise and fall and time.

FIG. 3 is a diagram showing temperature changes of specific heat capacity and thermal conductivity of Pyrex glass measured simultaneously using the apparatus according to the present invention.

[Explanation of symbols]

 1 vacuum chamber, 2 object to be measured, 3 heaters

Claims (2)

(57) [Claims] An object to be measured is provided in a vacuum chamber facing a heat supply source provided in the vacuum chamber, and a heating or cooling surface of the object to be measured facing the heat supply source and a back surface opposite to the heating or cooling surface. Is measured, and the measurement result, the temperature of the heat supply source, the temperature of the wall surface of the vacuum chamber, and the thickness and density of the object to be measured which have been measured in advance are calculated using the following formulas (15) and (16). A method of measuring thermal physical properties of an object by calculating the specific heat capacity and thermal conductivity of the object to be measured simultaneously. (Equation 15) (Equation 16) In the above formula, C _p : specific heat capacity, λ: thermal conductivity,
L, ρ: object thickness, same density, ε: emissivity of object surface,
δT / δt: temperature rate, σ: Stefan constant, _Th , T
_l, T _o: the heater temperature at the time of temperature rise, the temperature of the heating surface of the object, the rear surface thereof in the _{temperature, T h ', T l'} , T
_o ': The temperature of the heater when the temperature drops, the temperature of the heating surface of the object, and the temperature of the back surface thereof. 2. An object to be measured is provided in a vacuum chamber facing a heat supply source provided in the vacuum chamber, and a heating or cooling surface facing the heat supply source of the object to be measured and a back surface opposite to the heating or cooling surface. And the measured result, the temperature of the heat supply source, the temperature of the vacuum chamber wall surface and the thickness and density of the object to be measured, which were measured in advance, are represented by the following (Equation 15), (Equation 16) and (Equation 12). A method for measuring thermal physical properties of an object by simultaneously calculating the specific heat capacity, the thermal conductivity, and the thermal diffusivity of the object to be measured by calculating using the mathematical formula: (Equation 15) (Equation 16) (Equation 12) In the above formula, C _p : specific heat capacity, λ: thermal conductivity,
a: thermal diffusivity, L, [rho: the thickness of the object, the density, epsilon: emissivity of the object surface,? T / .DELTA.t: raising rate, sigma: Stefan _{constant, T h, T l, T} o: Temperature rise The temperature of the heater, the temperature of the heating surface of the object,
T _h ′, T _l ′, T _o ′: the temperature of the heater when the temperature drops, the temperature of the heating surface of the object, and the temperature of the back surface thereof.