JP2002156345A - Specific heat measuring instrument and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the specific heat of a sample to be measured, using the temperature of a heat source. SOLUTION: A first sample cell 7 having the sample S to be measured sealed therein and an empty second sample cell 8 formed substantially similar to the first sample cell 7, are heated from the outside by the heat source 3. Temperature Ts of the heated first sample cell 7, temperature Tso of the second sample cell 8, and temperature T of the heat source 3 are detected. Time variations in respective temperatures T, Ts, and Tso are integrated. The respective times t1 and t2, when the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 are the same, are extracted so as to extract temperatures of Th and Tho of the heat source 3 at respective times t1 and t2. Specific heat CM of the sample S to be measured are calculated, based on the extracted temperatures of Th and Tho of the heat source 3 at respective times t1 and t2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specific heat measuring apparatus and method for performing a thermal analysis on a sample to be measured such as a solid, a liquid, and a powder while changing the temperature and thermal radiation energy of the sample according to a predetermined program. In particular, the present invention relates to a specific heat measuring apparatus and method for performing thermal analysis based on the temperature of a heat source and thermal radiation energy to measure the specific heat of a sample to be measured.

[0002]

2. Description of the Related Art Conventionally, differential thermal analysis (DTA) and differential scanning calorimetry (DSC) have been known as thermal analysis methods using twin cells.

[0003] Differential thermal analysis (DTA) is a technique that records the temperature difference between two substances with respect to temperature (or time) when heating or cooling with a certain program. That is, as shown in FIG. 10, a sample S and a thermally inactive standard substance R are packed in cells 31 and 32, and in contrast, placed in a furnace 33. When the temperature of the furnace 33 is raised (falled), the reference material T
The temperature rises (falls) slightly later than the temperature of 3. Sample S is
During transition, melting, reaction, etc., the temperature changes differently from the steady rising (falling) temperature. Therefore, if the temperature difference between the two is determined by the thermocouples 34 and 35, the thermal change of the sample S can be observed.

[0004] Differential scanning calorimetry (DSC) is a method in which the thermal energy required for the temperature difference between a standard substance R and a sample S is measured as electric energy of an auxiliary heater, and a specific heat value is derived from the result. .

In both methods, one cell 31 is filled with a standard substance R having a known thermal property, the other cell 32 is filled with an unknown substance (sample S), and the unknown substance is subjected to thermal analysis. It is supposed to be. In both methods, thermal analysis is performed in the state where the same heat energy is transferred from the heat sources of both cells 31 and 32.

However, in the differential thermal analysis (DTA), only the thermal change of the sample S is calculated, and the specific heat of the sample S cannot be measured as a measurement result. In the differential scanning calorimetry (DSC), it is necessary to attach another auxiliary heat source (auxiliary electric heater) for canceling the temperature difference between the two cells in the apparatus. Therefore, the apparatus becomes large-scale, and a measurement error occurs due to heat radiation from the auxiliary electric heater and energy dissipated through the copper wire.
Furthermore, in both of the above methods, since the standard substance R is used in addition to the sample S, the measurement is troublesome and costly.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to make it easy to measure the specific heat of a sample to be measured by using the temperature of a heat source. It is an object of the present invention to provide an apparatus and a method for measuring specific heat. In particular, it is to enable low-cost and high-precision measurement without using a reference sample or an auxiliary heat source.

Another object is to easily measure the specific heat of a solute contained in a measured sample by using a standard sample and a measured sample (solution) using the standard sample as a solvent. is there.

[0009]

The specific heat measuring apparatus according to claim 1 comprises a first sample cell 7 in which a sample S to be measured is enclosed;
An empty second sample cell 8 substantially identical to the first sample cell 7
A heat source 3 for heating the first sample cell 7 and the second sample cell 8, a temperature control means 13 for heating and controlling the heat source 3, and a temperature Ts (T ') of the heated first sample cell 7
s), a sample cell temperature detecting means 9 for detecting the temperature Tso (T'so) of the second sample cell 8, and a heat source data detecting means 10 for detecting a heating state of the heat source 3 as heat source data.
And the detected temperatures Ts (T's) and Tso (T'so)
And data accumulating means 14 for accumulating the heat source data;
From the data accumulating means 14, the temperature Ts (T's) of the first sample cell 7 and the temperature Tso (T'so) of the second sample cell 8 are obtained.
There each time t ₁ when the same (t _1), 'extracts _(2, respective time t ₁ (t _1), t ₂ (t t ₂ t)' heat source data of the heat source 3 in ₂₎ Heat source data extracting means 15 for extracting heat
And the extracted heat source data of the heat source 3 at the respective times t ₁ (t ′ ₁ ) and t ₂ (t ′ ₂ ), and the temporal change rate dT _s / dt (dT ′ _s ) of the temperature of both sample cells 7 and 8. / dt) and dT _so / dt (dT ′ _so / dt), and specific heat calculating means 16 for calculating the specific heat CM of the sample S to be measured.

In a specific heat measuring apparatus according to a second aspect of the present invention, a first sample cell in which a sample to be measured S ′ in which a standard sample R and a substance to be measured B are mixed is sealed, and the standard sample R is sealed. A second sample cell 8 substantially the same as the first sample cell 7, a heat source 3 for heating the first sample cell 7 and the second sample cell 8, and a temperature control means for heating and controlling the heat source 3 13 and the temperature Ts of the heated first sample cell 7
(T's) and a sample cell temperature detecting means 9 for detecting the temperature Tso (T'so) of the second sample cell 8, and a heat source data detecting means 1 for detecting a heating state of the heat source 3 as heat source data.
0 and the detected temperatures Ts (T's) and Tso (T'so
) And data accumulating means 14 for accumulating the heat source data
From the data accumulating means 14, the temperature Ts (T's) of the first sample cell 7 and the temperature Tso (T's) of the second sample cell 8 are obtained.
o) at the same time t ₁ (t ₁ ), t ₂ (t ′ ₂ )
And a heat source data extracting means 1 for extracting heat source data of the heat source 3 at the respective times t ₁ (t ₁ ) and t ₂ (t ′ ₂ ).
5 and the heat sources 3 at the respective times t ₁ (t ′ ₁ ) and t ₂ (t ′ ₂ ).
And the time-dependent change rates dT _s / dt (dT ′ _s / dt) and dT _so / dt (dT ′ _so / dt) of the temperature of the sample cells 7 and 8 based on the extracted heat source data '' B specific heat C of the substance to be measured in
a specific heat calculating means 16 for calculating b.

[0011] The specific heat measuring apparatus according to the third aspect is the first aspect of the invention.
Or the specific heat measuring device according to 2, wherein the heat source data is the temperature T (T ') of the heat source 3 and the heat source data detecting means 10 is a temperature detecting element for detecting the temperature T of the heat source 3. I do. Therefore, the heat source data extracting means 15, the respective times t ₁ (t temperature Th of the heat source 3 at _{'1), t 2 (t} ' 2) (T'h), Tho (T'ho) is extracted.

[0012] The specific heat measuring apparatus according to the fourth aspect is the first aspect.
Or the specific heat measurement device according to 2, wherein the heat source data is heat radiation energy W from the heat source 3, and the heat source data detection means 10 is a heat radiation detector that detects the heat radiation energy W. . Therefore, the heat source data extracting means 15 outputs the time t ₁ (t ′ ₁ ), t
₂ (t ' ₂ ), the thermal radiation energy Wh (W'h) of the heat source 3
Who (W'ho) is extracted.

[0013] The specific heat measuring apparatus according to the fifth aspect is the first aspect.
5. The specific heat measurement device according to any one of items 1 to 4, wherein a plurality of the first sample cells are provided.

In the method for measuring specific heat according to claim 6, the first sample cell 7 in which the sample S to be measured is enclosed, and the first sample cell 7
And the empty second sample cell 8 which is substantially the same as above, is heated by the heat source 3 and the heated temperature Ts (T's) of the first sample cell 7 is increased.
And the temperature Tso (T'so) of the second sample cell 8 and heat source data indicating the heating state of the heat source 3 are detected, and the detected temperatures Ts (T's), Tso (T'so) and the heat source are detected. Data is accumulated and each time t when the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 are the same.
₁ (t ' ₁ ) and t ₂ (t' ₂ ) are extracted, and the respective times t ₁ (t ' ₁ ), t
₂ (t ′ ₂ ), the heat source data of the heat source 3 is extracted, and the extracted heat source data of the heat source 3 at each of the times t ₁ (t ′ ₁ ) and t ₂ (t ′ ₂ ) and the sample cells 7 and 8 are extracted. Temperature change rate dT
_s / dt (dT based on _{'s / dt), dT so} / dt (dT' so / dt), and calculates the specific heat CM of the measured sample S.

According to a seventh aspect of the present invention, in the specific heat measuring method, the first sample cell 7 in which the sample to be measured S 'in which the standard sample R and the substance to be measured B are mixed is sealed, and the standard sample R is sealed. The second sample cell 8 substantially the same as the first sample cell 7 is heated by the heat source 3, and the temperature Ts (T's) of the heated first sample cell 7 and the temperature of the second sample cell 8 are measured. Temperature Tso
(T'so) and the heating state of the heat source 3 are detected as heat source data, and the detected temperatures Ts (T's) and Tso (T'so
) And the heat source data, and the first sample cell 7
At each time t ₁ when the temperature Tso is the same of the temperature Ts second sample cell _{8 (t '1), t} 2 (t' 2) is extracted, respective time t ₁ (t _'1) , t ₂ (t ′ ₂ ), the heat source data of the heat source 3 at each time t ₁ (t ′ ₁ ), t ₂ (t ′ ₂ ), and the sample cell 7 temporal rate of change of temperature of _{8 dT s / dt (dT '} s / dt), dT so / dt (dT' so / dt)
The specific heat Cb of the measured substance B in the measured sample S 'is calculated based on

[0016] The specific heat measuring method according to claim 8 is the same as in claim 6.
Or the specific heat measurement method according to 7, wherein the heat source data is a temperature T (T ') of the heat source 3.
Therefore, at each of the times t ₁ (t ′ ₁ ) and t ₂ (t ′ ₂ ), the temperatures Th (T′h) and Tho (T′ho) of the heat source 3 are extracted.

According to a ninth aspect of the present invention, there is provided the specific heat measuring method according to the sixth aspect.
Or the specific heat measurement method according to 7, wherein the heat source data is heat radiation energy W from the heat source 3. Therefore, at each of the times t ₁ (t ′ ₁ ) and t ₂ (t ′ ₂ ), the thermal radiation energies Wh (W′h) and Who (W′h) of the heat source 3 are obtained.
o) is extracted.

According to a tenth aspect of the present invention, there is provided a specific heat measuring method according to any one of the sixth to ninth aspects, wherein a plurality of the first sample cells are provided.

[0019]

FIG. 1 is a schematic block diagram showing an embodiment of a specific heat measuring apparatus 1 according to the present invention. In the vacuum chamber 2, a heater 3 serving as a heat source is provided. The heater 3 includes a pair of parallel ceramic heat sinks 4,
It comprises a heating wire 5 and a drive circuit 6. As the heating wire 5, for example, a sheath nichrome wire is used.
It is laid inside. The heating wire 5 is connected to the heat sink 4
It may be formed on the surface of (4a, 4b). The drive circuit 6 is connected to the heating wire 5 and supplies a current to the heating wire 5 in accordance with a command from the control unit 11 described later.

In the vacuum chamber 2, twin cells 7, 8 are housed. The twin cells 7 and 8 are both Pyrex (registered trademark) glass tubes (diameter 8 mm, inner diameter 6 mm, length 30 mm)
Are sealed with thin silicon rubber stoppers at both ends. In one of the twin cells 7, 8 (first sample cell 7), a sample S to be measured for specific heat is sealed. The other cell (second sample cell 8) is left empty.

The sample cell temperature detecting means 9 comprises a temperature detecting element such as a thermocouple, for example, and continuously measures the temperatures Ts (T's) and Tso (T'so) of the twin cells 7, 8 heated by the heater 3 for a predetermined time. Detection. Further, the heat source data detecting means 10 is also constituted by a temperature detecting element such as a thermocouple, for example, and continuously detects the temperature T (T ') of the heater 3 for a predetermined time.

Next, the control section 11 will be described. The control unit 11 includes an arithmetic processing unit such as a CPU (not shown), a ROM,
It comprises a storage unit such as an AM and a specific heat measurement program stored in a ROM. In FIG. 1, the block configuration in the control unit 11 is functionally expressed.
The functions corresponding to the respective units 13 to 16 in the control unit 11 are executed by software processing by the execution program stored therein.

The input means 12 is composed of, for example, a push button switch, and the measurement is started by pressing this button.

The temperature control means 13 controls the heating and cooling of the heater 3 based on a command from the CPU. Specifically, C
Upon receiving a temperature rise command from the PU, the drive circuit 6 of the heater 3
Drive. The drive circuit 6 supplies a predetermined amount of current to the heating wire 5 based on the command. Due to the heat conduction of the heating wire 5, the temperature T of the heat radiating plate 4 continuously increases by a predetermined temperature, for example, about 1.5 ° C. per unit time. When cooling, the amount of current is gradually reduced, and similarly, the temperature is lowered by 1.5 ° C. per unit time.

The data accumulating means 14 accumulates the detected temperatures T, Ts, Tso (T ', T's, T'so). Specifically, the temperature of the first sample cell 7 and the temperature of the second sample cell 8 are plotted against the temperature of the heater 3 plotted at a predetermined temperature (for example, 1.5 ° C.) per unit time, and stored in the storage unit. To be stored. FIG. 2 shows the temperatures T, Ts, Tso (T ', T's, Ts, Ts) of the first sample cell 7, the second sample cell 8, and the heater 3.
4 is a graph showing a temporal change of T′so). (') Is data at the time of temperature drop.

When the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 when the temperature of the heater 3 rises are the same (Ts = Tso), the heat source data extracting means 15 It extracts each time t _1, t _2, and the temperature Th of the heater 3 at the respective times t _1, t _2, Tho
Is extracted. Specifically, the extraction of the times t ₁ and t ₂ and the temperatures Th and T are performed with reference to the respective temperature data stored in the storage unit.
Extract ho. Similarly, the temperature T ′s of the first sample cell 7 when the temperature of the heater 3 falls
And the temperature T'so of the second sample cell 8 is the same (T's
= T'so), the respective times t ' ₁ and t' ₂ are extracted, and the respective times t '
_1, t 'temperature of the heater 3 in ₂ T'h, extracts the T'ho. Specifically, extraction of the times t ′ ₁ and t ′ ₂ and extraction of the temperatures T′h and T′ho are performed with reference to the respective temperature data stored in the storage unit.

The specific heat calculating means 16 includes a data accumulating means 14
Based on the temperature data collected at
Temporal rate of change of temperature dT_s/ dt, dT_so/ dt (dT '_s/ dt,
dT ' _so/ dt). Then, the temperature of the heater 3 rises
Extraction temperature Th, Th, time rate of change dT_s/ dt, dT_so
/ dt and the extraction temperatures T'h, T'ho when the temperature of the heater 3 drops.
 , Temporal change rate dT '_s/ dt, dT '_so/ dt, based on
Then, the specific heat CM of the sample S to be measured is calculated. Calculation method is later
Will be described.

The display means 17 is composed of, for example, a CRT or a liquid crystal display, and various output results from the data accumulating means 14, the heat source data extracting means 15 and the specific heat calculating means 16 are displayed in a visible form. Things.

Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. First, the sample S to be measured is put in the first sample cell 7 and a rubber stopper is placed. The two sample cells 7 and 8 are stored in the vacuum chamber 2. Then, the inside of the vacuum chamber 2 is evacuated (ST1).

The press measurement start button of the input unit 12 to start the measurement of specific heat C _M of the measured sample S. First, heating control of the heater 3 is performed (ST2). A current is supplied to the heater 3 to increase the temperature by 1.5 ° C. per unit time. At this time, the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 are detected and stored in the storage unit. When the temperature of the heater 3 reaches the upper limit temperature, the amount of current is decreased, and the temperature is decreased by 1.5 ° C. per unit time. At this time, the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 are detected and stored in the storage unit (ST3).

The times t ₁ and t ₂ when the temperature Ts of the first sample cell 7 and the temperature Tso of the second sample cell 8 are the same are extracted from the storage unit (ST4). The temperatures Th and Tho of the heater 3 at the respective times t ₁ and t ₂ are extracted (ST5). The temperatures Th and Th of the heater 3 at these times t ₁ and t ₂ are different. This is because the heat capacities of the first sample cell 7 and the second sample cell 8 are not the same.

On the other hand, based on the temperature data accumulated by the data accumulating means 14, the temporal change rates dT _s / dt and dT _so / dt of the temperatures of the sample cells 7 and 8 are calculated (ST6). Then, the extracted temperatures Th and Tho of the heater 3, the rate of change over time dT _s / dt, dT _so / dt, the mass M of the sample S to be measured, the mass m of the second sample cell 8, and the temperature of the second sample cell 8 from the specific heat C _m,
Calculating the specific heat C _M of the measured sample S (ST7).

The processing of ST3 to ST7 is performed even when the temperature of the heater 3 drops due to the cooling of the heater 3.

Here, a method of calculating the specific heat CM of the sample S to be measured will be described. First, assuming that the temperature T of the heater 3, the temperature Ts of the first sample cell 7, the temperature Tso of the second sample cell 8, and the temperature Tr in the vacuum chamber 2, the first sample cell 7 is heated when the temperature of the heater 3 rises. The relationship between the energy transferred from the heater 3 per unit time and the energy released to the inner surface of the vacuum chamber 2 is expressed by the following equation (1).

[0035]

(Equation 1)

When descending, it is expressed by the following equation (1 ').

[0037]

(Equation 2)

When the temperature of the heater 3 drops, the relationship between the energy transferred from the heater 3 by the second sample cell 8 per unit time and the energy released to the inner surface of the vacuum chamber is expressed by the following equation (2). You.

[0039]

(Equation 3)

At the time of descent, it is expressed by the following equation (2 ').

[0041]

(Equation 4)

Here, all temperatures indicate absolute temperatures. σ
Is the Stefan-Boltzmann constant. dQs / dt is the thermal energy dissipated through the wire supporting the first sample cell 7 in which the sample S to be measured is enclosed. dQso
/ dt is the thermal energy dissipated through the wire supporting the empty second sample cell 8. M is the mass of the sample S to be measured, and m is the mass of the second sample cell 8.

C _M is the specific heat of the sample S when the temperature of the heater 3 rises, C ′ _M is the specific heat of the sample S when the temperature of the heater 3 drops, and Cm is the first sample cell 7 and the second sample C 2. This is the specific heat of the sample cell 8 itself. A is the surface area of the sample cells 7, 8.

Eh is the effective emissivity of the first sample cell 7 involved in the transfer of thermal energy, and Es is the effective emissivity of the second sample cell 8 involved in the transfer of thermal energy. Eh and Es have the same and constant values in both the sample cells as long as the emissivity of the heater 3 and the sample cells 7 and 8 is constant and their geometrical arrangement does not change.

The equation (3) obtained from the difference between the equations (1) and (2) is shown below.

[0046]

(Equation 5)

When the temperature is lowered by cooling the heater 3, the equation (3 ') is obtained from the difference between the equations (1') and (2 ').

[0048]

(Equation 6)

Th and Th are the extraction temperatures of the heater 3 respectively extracted by the heat source data extraction means 15 when the temperature of the heater 3 rises. T'h and T'ho are
These are the extraction temperatures of the heater 3 extracted by the heat source data extraction means 15 when the temperature of the heater 3 decreases. In the equations (3) and (3 ′), the energy dissipated from the wire is very small and is ignored.

The storage section stores the equation (3), and the right side of the equation (3) is calculated according to the specific heat measurement program. And specific heat C based on the data at the time of temperature rise
_M (left side) is calculated.

The storage unit stores the equation (3 '), and the right side of the equation (3') is calculated according to the specific heat measurement program. Then, the specific heat C _M ′ (left side) based on the data at the time of temperature decrease is calculated.

[0052] and, finally calculate the specific heat CM by averaging the specific heat C _M and the specific heat C _M '. Specific heat CM is CRT1
7 is displayed on the screen.

The coefficient Eh is calculated in advance. The calculation method uses only the empty second sample cell 8. After the temperature is increased by the heater 3, the temperature is decreased. And FIG.
As shown in the figure, the temperature Tso of the second sample cell 8 when the temperature rises
And times t ₃ and t ₄ when the temperature T′so of the second sample cell 8 at the time of the temperature drop are the same (Tso = T′so). The temperature Tho of the heater 3 when the temperature rises at the times t ₃ and t ₄ and the temperature T′ho of the heater 3 when the temperature falls are extracted. By substituting the temperature Tho into the equation (2), and substituting the temperature T'ho into the equation (2 '), and calculating the difference between the equations (2) and (2'), the following equation (4) is obtained. Become. Since all the expressions (4) are measurable quantities, the coefficient Eh can be measured in advance. (') Indicates data at the time of descending.

[0054]

(Equation 7)

From the above, the mass M of the sample S to be measured is
If the mass m of the second sample cell 8 and the specific heat Cm of the second sample cell 8 are known, when the temperature of the heater 3 rises and falls, the equations (3) and (3 ') The right side can be calculated from the measurement result, and the specific heat CM of the sample S to be measured can be derived.

Next, a second embodiment will be described.
In this embodiment, the second sample cell 8 is filled with a standard sample R (for example, water (solvent)), and the first sample cell 7 is a mixture of the standard sample R and the substance to be measured B (for example, lysozyme). The measurement sample S ′ (solute) is packed. The description of the same parts as those of the first embodiment is omitted.

The heat capacity of the sample S ′ (solution) to be measured is C_MM
And the heat capacity of the solvent (water) is C_am _aAnd the substance to be measured
The heat capacity of B (solute) is C_bM_bAnd These include:
There is the following relationship. C_MM = C_am_a+ C_bM_b… (5) equation (temperature of heater 3
C ')_MM = C_a'm_a+ C '_bM_b... (5 ') formula (He
(When the temperature of the data 3 drops)

Here, the operation of the present embodiment will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. First, the sample to be measured S ′ is sealed in the first sample cell 7, the standard sample R is sealed in the second sample cell 8, and placed in the vacuum chamber 2 (ST 1 ′).
The processing from ST2 to ST6 is the same as in the first embodiment. After ST5 and ST6, the processing shown in ST7 'is performed.
Here, ST7 'will be described.

When the temperature rises due to the heating of the heater 3, the relation between the energy transmitted and received per unit time from the heater 3 by the first sample cell 7 in which the sample to be measured S ′ is sealed and the energy released to the inner surface of the vacuum chamber 2 is as follows. It is expressed by the above-mentioned equation (1). Similarly, when the temperature decreases, the equation (1 ′) is obtained.

When the temperature rises due to the heating of the heater 3, the relationship between the energy transferred from the heater 3 by the second sample cell 8 per unit time and the energy released to the inner surface of the vacuum chamber 2 is expressed by the following equation (6). expressed.

[0061]

(Equation 8)

Similarly, when the temperature decreases, the equation (6 ') is obtained.

[0063]

(Equation 9)

From the difference between the expressions (1) and (6), the following expression (7) is obtained as the difference in heat capacity.

[0065]

(Equation 10)

From the difference between the equations (1 ') and (6'), the following equation (7 ') is obtained as the difference in heat capacity.

[0067]

[Equation 11]

The left side of the equation (7) is the mass from the equation (5).
M_bHeat capacity C of the substance B to be measured_bM _bBecomes Similarly,
The left side of the equation (7 ') is the mass M from the equation (5')._bMeasured
Heat capacity C 'of substance B_bM_bBecomes Each of these
Quantity M_bDivided by the measured substance B when the temperature rises and falls
Specific heat C of (solute)_b, C '_bIs calculated. Average these
Then, the final specific heat Cb of the substance B to be measured is calculated.
You.

The sample to be measured S (solution) at the time of temperature rise
The specific heat C _M, the following equation (8). Further, the specific heat C ′ _M of the sample S (solution) when the temperature is lowered is expressed by the following equation (8 ′).

[0070]

(Equation 12)

[0071]

(Equation 13)

If the results are averaged, the measured sample S ′
Can be calculated.

In the above example, the temperature of the heater 3 is detected by using the temperature detecting element (thermocouple) as the heat source data detecting means 10. However, the heat radiation energy from the heater 3 is detected by contact. You may do it. In this case, a thermal radiation detector is provided instead of the thermocouple. Then, a glass infrared transmitting window is provided in the vacuum chamber 2 to detect thermal radiation energy (infrared) radiated from the heater 3. Therefore, in this modification, ST5 shown in FIG.
Becomes ST5 'shown in FIG.

Then, the equations (3), (3 ') and (4)
Equations (6), (6 '), (7), (7'),
Equations (8) and (8 ′), σT ⁴ h, σT ⁴ ho, σT ′ ⁴ h,
σT ′ ⁴ ho is represented by Wh / G, Who / G, W′h / G,
By replacing with W'ho / G, the specific heat CM of the sample to be measured and the specific heat Cb of the substance B to be measured can be derived. Here, Wh, Who, W'h, and W'ho are outputs of the thermal radiation detector, and G is the amplification of the thermal radiation detector. In this case, the coefficient Eh is replaced by (Eh / G).

In any of the above embodiments,
Although a pair of parallel heat radiating plates 4 are used for the heater 3, a cylindrical heat radiating member may be used as shown in FIG.

Further, in any of the above embodiments,
Although the first sample cell 7 in which the samples S and S 'to be measured are enclosed is one, a configuration in which a plurality of the first sample cells 7 are provided may be provided as shown in FIG. Thereby, the specific heats of a plurality of different measurement samples S and solutes can be measured simultaneously. Further, since all the samples 7 to be measured are based on the second sample cell 8 at the time of the same measurement, the measurement accuracy is improved as compared with the case of separately measuring.

Further, in any of the above-described embodiments, the temperature of each sample cell 7, 8 may be measured by measuring the temperature of each sample cell 7, 8 itself, or the temperature of each sample cell 7, 8 may be measured. (Sample to be measured S, S ', Standard sample R)
The temperature of the sample itself may be directly measured by bringing the thermocouple 9 into direct contact with the thermocouple 9.

In each of the above-described embodiments, the sample to be measured S, S ′, the substance to be measured B, the standard sample R
May be any substance as long as it is a solid, liquid, powder or the like or a mixture selected from these.

[0079]

Next, a specific example of the first embodiment will be described. In this embodiment, Pyrex glass tube (diameter 8 mm, an inner diameter of 6 mm, length 30 mm) by using a sample cell 7 and 8 was sealed by the thin silicon rubber stopper on both ends of, was measured the specific heat C _M of pure water S. 2
The individual sample cells 7 and 8 are installed in the vacuum chamber 2 while being surrounded by the heat sink 4. The temperatures of the heater 3 and the sample cells 7, 8 are measured using thermocouples 9, 10. By passing a current through the heater 3, the temperature of both sample cells 7, 8 is set to 1.5 / min.
Raise and lower at about ° C. Heater 3 and both sample cells 7,
8 are measured, and the rate of change of the temperature is calculated from the result.

In order to measure the effective emissivity Eh in advance, the measurement was performed using a Pyrex tube whose temperature change in the value of the specific heat was known. This value is, as shown in FIG.
Can be obtained from the data when the temperature rises and falls.
(') Shows data when descending. FIG. 8 shows the temperature change of the value of the effective emissivity Eh derived by the equation (4). The value is almost constant from 10 ° C to 100 ° C.

FIG. 9 shows the results obtained by measuring the first sample cell 7 filled with water and the empty second sample cell 8 side by side and measuring the temperature when the temperature rises according to the equation (3). These experimental results confirm that the method according to the present invention is valid.

[0082]

As described above, in the specific heat measuring apparatus and method according to the present invention, by using the temperature of the heat source,
The measurement of the specific heat of the sample to be measured becomes easy without using a reference sample or an auxiliary heat source. In particular, since no auxiliary heater is required, there is no cost, and there is no heat generated when power is supplied to the auxiliary heater or energy dissipated through the copper wire, so that a measurement error can be suppressed.

Further, by using the standard sample and the sample to be measured, the specific heat of the substance to be measured contained in the sample to be measured can be easily measured.

Further, by providing a plurality of first sample cells in which the sample to be measured is enclosed, the specific heats of a plurality of different samples to be measured and solutes can be measured simultaneously. Further, since all the samples to be measured are based on the second sample cell at the time of the same measurement, the measurement accuracy is improved as compared with the case where the measurement is performed separately.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a specific heat measuring apparatus according to the present invention.

FIG. 2 is a graph showing temporal changes in the temperatures of the heater and the twin cells when the temperature of the heater is controlled.

FIG. 3 is a flowchart of a specific heat measuring device according to the first embodiment of the present invention.

FIG. 4 is a graph showing temporal changes in the temperature of the heater and an empty second sample cell when the temperature of the heater is controlled.

FIG. 5 is a flowchart of a specific heat measuring device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the heater.

FIG. 7 is a diagram showing an example in which a plurality of first sample cells are used.

FIG. 8 is a graph showing a temperature change of the effective emissivity Eh derived by the equation (4).

FIG. 9 is a graph showing a change in specific heat with temperature obtained when the temperature rises according to the equation (3).

FIG. 10 is a diagram showing a conventional differential thermal analysis (DTA).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Specific heat measuring device, 3 ... Heat source (heater), 7 ... 1st sample cell, 8 ... 2nd sample cell, 9 ... Sample cell temperature detection means,
10: heat source data detecting means, 13: temperature control means, 14
... Data accumulation means, 15 ... Heat source data extraction means, 16 ...
Specific heat calculation unit, B ... substance to be measured, the specific heat of C _M ... the measured sample S, R ... standard sample, S (S ') ... target sample, Ts ...
Temperature of first sample cell, Tso ... Temperature of second sample cell, Th
... The temperature of the heat source at time t ₁ , Tho the temperature of the heat source at time t ₂ , t ₁ , the time of the first sample cell when the temperature of the first sample cell and the temperature of the second sample cell are the same, t ₂
... Time of the second sample cell when the temperature of the first sample cell is equal to the temperature of the second sample cell

Claims (10)

[Claims] 1. A first sample cell in which a sample to be measured is enclosed, an empty second sample cell substantially identical to the first sample cell, and heating of the first sample cell and the second sample cell A heat source, a heat source control unit that controls heating of the heat source, a sample cell temperature detection unit that detects a temperature of the heated first sample cell and a temperature of the second sample cell, and a heating state of the heat source. Heat source data detection means for detecting as heat source data; data integration means for integrating the detected temperatures and the heat source data; and, from the data integration means, a temperature of the first sample cell and a temperature of the second sample cell. Heat source data extracting means for extracting each time when the time is the same, and extracting the heat source data at each time; extracting heat source data of the heat source at each time; and temperatures of the first and second sample cells. time Rate of change and, based on a specific heat calculation means for calculating the specific heat of the sample to be measured,
A specific heat measurement device comprising: 2. A first sample cell in which a sample to be measured in which a standard sample and a substance to be measured are mixed is sealed, and a second sample cell in which the standard sample is sealed and which is substantially the same as the first sample cell. A sample cell; a heat source for heating the first sample cell and the second sample cell; a heat source control means for heating and controlling the heat source; and a temperature of the heated first sample cell and a temperature of the second sample cell. , A heat source data detecting means for detecting a heating state of the heat source as heat source data, a data accumulating means for accumulating the detected temperatures and the heat source data, and a data accumulating means. A heat source data extracting means for extracting each time when the temperature of the first sample cell and the temperature of the second sample cell are the same, and extracting the heat source data at each time; Specific heat calculating means for calculating the specific heat of the substance to be measured in the sample to be measured based on the extracted heat source data of the heat source and the temporal change rates of the temperatures of the first and second sample cells. A specific heat measuring device characterized by the above-mentioned. 3. The specific heat measuring apparatus according to claim 1, wherein said heat source data is a temperature of said heat source, and said heat source data detecting means is a temperature detecting element for detecting a temperature of said heat source. 4. The specific heat according to claim 1, wherein the heat source data is heat radiation energy from the heat source, and the heat source data detection means is a heat radiation detector for detecting the heat radiation energy. measuring device. 5. The specific heat measuring apparatus according to claim 1, wherein a plurality of said first sample cells are provided. 6. A first sample cell in which a sample to be measured is sealed and an empty second sample cell substantially identical to the first sample cell are heated by a heat source, and the heated first sample cell is heated. The temperature of the cell, the temperature of the second sample cell, and heat source data indicating the heating state of the heat source are continuously detected, and the respective temperatures and the heat source data are integrated. Extracting each time when the temperature of the two sample cells is the same, extracting the heat source data at each time, extracting the heat source data of the heat source at each time, and extracting the heat source data of the first and second sample cells. A specific heat measurement method for calculating a specific heat of the sample to be measured based on a temporal change rate of temperature. 7. A first sample cell in which a sample to be measured in which a standard sample and a substance to be measured are mixed is sealed, and an empty second cell in which the standard sample is sealed and which is substantially the same as the first sample cell. The sample cell is heated by a heat source, and the temperature of the heated first sample cell, the temperature of the second sample cell, and the heat source data indicating the heating state of the heat source are continuously detected. Integrating the heat source data, extracting each time when the temperature of the first sample cell and the temperature of the second sample cell are the same, extracting the heat source data at each time, A specific heat measurement method for calculating a specific heat of the substance to be measured in the sample to be measured based on the extracted heat source data of the heat source and a temporal change rate of the temperatures of the first and second sample cells. 8. The specific heat measuring method according to claim 6, wherein the heat source data is a temperature of the heat source. 9. The specific heat measurement method according to claim 6, wherein the heat source data is heat radiation energy from the heat source. 10. The method according to claim 6, wherein a plurality of the first sample cells are provided.