JP4547551B2 - Thermal sensing remote sensing method and apparatus for thermal insulation properties - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a heat sensing property remote sensing method and apparatus for a heat insulating material, and more particularly to a heat insulation property measuring method and device for a heat insulating material capable of remote sensing using a photothermal infrared detection method.

  Freon, a substance that causes ozone layer destruction and global warming, has been banned in recent years and is moving toward recovery. In Japan, it is obliged to collect and dispose of refrigerant chlorofluorocarbons, but chlorofluorocarbons contained in heat insulating materials have not yet reached specific regulations and measures for collection and treatment. However, the amount of chlorofluorocarbon remaining in the heat insulating material is estimated to be about 1.5 to 2 times that of refrigerant chlorofluorocarbon, and it is expected that movement to collect and treat the chlorofluorocarbon remaining in the heat insulating material will become active in the future. Is done.

  In particular, the amount of remaining chlorofluorocarbons in the heat insulating material for buildings varies greatly depending on the construction method and use environment, and when collecting and processing the chlorofluorocarbon in the foamed heat insulating material, an appropriate treatment process according to the chlorofluorocarbon remaining amount is required. For this reason, it is very important to measure the residual amount of CFCs at the determination stage, and an inspection method that can easily measure the CFC residual amount in the heat insulating material on site is desired.

  There is no standardized analysis method for chlorofluorocarbon in insulation materials in JIS, ISO and major countries. What is required for the on-site simple measurement method for the remaining amount of CFCs is that (1) the apparatus is small, (2) high precision, (3) short-time measurement, and (4) low cost.

  Gas chromatography has attracted attention as a method for measuring the amount of residual chlorofluorocarbon. Since gas chromatography is generally prevalent, it can be obtained at a relatively low cost. However, if high accuracy is to be obtained, the apparatus becomes large and is not suitable for in-situ measurement. Moreover, it is necessary to cut out and measure the sample. However, when the sample is cut out, chlorofluorocarbon is diffused from the cut surface, and it is difficult to measure with high accuracy.

By the way, although it is not directly related to the analysis method of the chlorofluorocarbon in the heat insulating material, in the patent document 1, the present applicant presses a metal foil against the surface of the heat insulating material of the sample and irradiates the heating light through the metal foil. We have proposed a photothermal infrared detection method that detects thermal radiation and remotely senses the thermal insulation properties of thermal insulation.
Japanese Patent Laid-Open No. 2002-340828 J. Appl. Phys., 47-1, (1976), 649.

  It is considered that air flows into the air bubbles of the heat insulating material with the decrease of the chlorofluorocarbon gas. There is a big difference in the thermal properties between chlorofluorocarbon and air (the thermal conductivity of air is about three times that of CFC11, which is a kind of chlorofluorocarbon, and the temperature conductivity is about nine times). Considering it, it is considered that the thermophysical property value of the heat insulating material greatly changes with the decrease of the chlorofluorocarbon concentration inside the heat insulating material.

  The present invention has been made in view of such a situation in the prior art, and an object of the present invention is to provide a thermal insulation characteristic measuring method and apparatus for a thermal insulation capable of remote sensing using a photothermal infrared detection method. It is to make it possible to accurately measure the heat insulation characteristics and to apply it to, for example, the measurement of the remaining amount of CFC in the heat insulating material.

The thermal insulation property remote sensing method of the thermal insulation material of the present invention that achieves the above object irradiates a sample with periodically modulated heating light, detects thermal radiation emitted from the sample, and detects the frequency of the detection signal for the heating light -In the thermal insulation remote sensing method for thermal insulation, the thermal conductivity and temperature conductivity (thermal diffusivity) of the sample are determined by measuring the phase difference characteristics and analyzing the frequency-phase difference characteristics.
A photoselective film that transmits all or part of the heating light to the surface of the heat insulating material of the sample and that does not transmit heat radiation light is adhered, and the heating light is irradiated through the photoselective film, and the heat radiation light is irradiated. It is a method characterized by detecting.

  In this case, it is desirable to obtain the thermal conductivity and temperature conductivity of the heat insulating material of the sample by curve fitting a theoretical formula with respect to the measured frequency-phase difference characteristics.

  For example, borosilicate glass can be used as the photoselective film.

  Further, the above method can be applied to, for example, measuring the residual amount of CFC in the foamed heat insulating material containing CFC of the sample by determining the thermal conductivity and the temperature conductivity.

  The heat insulating property remote sensing device of the heat insulating material of the present invention has a photoselective film that transmits all or part of the heating light and does not transmit heat radiation light on the surface of the heat insulating material of the sample, and through the photoselective film Irradiate the sample with periodically modulated heating light, detect the thermal radiation emitted from the thermal insulation of the sample through the photoselective film, measure the frequency-phase difference characteristics of the detection signal for the heating light, A heat insulation characteristic remote sensing device for a heat insulating material for obtaining a thermal conductivity and a temperature conductivity of a sample by analyzing the frequency-phase difference characteristic, wherein the sample is irradiated with the periodically modulated heating light. Measuring a frequency-phase difference characteristic of a detection signal of the thermal radiation light with respect to the heating light; a light irradiation means; a thermal radiation light detection means for detecting the thermal radiation light; Based on the frequency-phase difference characteristic measuring means, the physical property value input means for inputting the physical property value of the photoselective film and the absorption coefficient of the heat insulating material, and the physical property value of the photoselective film and the absorption coefficient of the heat insulating material. It is characterized by comprising a theoretical formula determining means for determining the formula and a curve fitting means for curve fitting the theoretical formula to the measured frequency-phase difference characteristic.

  In this case, the physical property value input by the physical property value input means requires the temperature conductivity, the thermal conductivity, the thickness, the absorption coefficient, and the absorption coefficient of the heat insulating material of the photoselective film.

  As is apparent from the above description, according to the heat sensing property remote sensing method and apparatus of the heat insulating material of the present invention, the photoselective light that transmits all or part of the heating light to the surface of the heat insulating material of the sample and does not transmit the heat radiation light. The film is brought into close contact and irradiated with heating light through the photoselective film, and the heat radiation is detected, so the heat conductivity and temperature conductivity of the heat insulating material can be determined at the same time with high accuracy. There is no limitation on the thickness of the heat insulating material of the sample, and it becomes possible to measure the heat insulating characteristics of the heat insulating material in a non-destructive manner on site. This method and apparatus can be used to measure the amount of remaining chlorofluorocarbon in a foam insulation including, for example, chlorofluorocarbon.

  The conventional heat insulation characteristic measurement method using the photothermal infrared detection method proposed in Patent Document 1 is performed by attaching a metal foil to the surface of a heat insulating material, and does not depend on the thickness of the sample. Although measurement in a high-frequency region that is not easily affected by dimensional heat conduction or convection is possible, it is not necessarily sufficient for accurate measurement of temperature conductivity and heat conductivity that are sensitive to changes in CFC concentration.

  Therefore, in the present invention, instead of the metal foil, it is considered to use, for example, a thin plate of borosilicate glass (hereinafter referred to as a photoselective film) that transmits all or part of the heating light and does not transmit the heat radiation. It was. When a photoselective film with such characteristics is in close contact with the surface of the heat insulating material and irradiated with heating light, light absorption and heat generation inside the sample occur, and the measured phase difference is caused by the thermophysical property value of the sample. This increases the simultaneous measurement of thermal conductivity and thermal conductivity.

Hereinafter, the theory of the photothermal infrared detection method of the present invention, which is a modification of the photoacoustic method (RG theory: Non-Patent Document 1) that is fundamentally the same as the photothermal infrared detection method, will be described. This theory assumes the following assumptions:
1) The light intensity of the heating light changes in a sine wave shape.
2) Other than the sample (gas) does not absorb light.
3) All the light absorbed by the sample is converted into heat.
4) The movement of heat is only in the one-dimensional direction parallel to the optical axis.
5) There is no thermal resistance at the interface between the sample and the gas.
6) Convection does not occur in the gas.

  FIG. 1 shows a one-dimensional model of the theory of the present invention. FIG. 1A shows how the AC temperature amplitude is attenuated, and FIG. 1B shows how the light is absorbed. As shown in FIG. 1, a photoselective film 2 is brought into close contact with the surface of a heat insulating material 1 to be measured, and the photoselective film 2 is irradiated with laser light 4 that is sine-wave modulated from the gas 3 side. In the following discussion, see the symbol table in Table 1 below for the meaning of each symbol.

When the sample is irradiated with the heating light 4 having the wavelength λ and the light intensity I ₀ which is modulated into a sine wave at the angular frequency ω, the time change of the heating light intensity I is a function of the light intensity time incident on the sample and the expression (1). It can be expressed as

I = 1/2 × I ₀ (1 + cos ωt) (1)
The heating light 4 enters the sample and attenuates. The parameters representing the degree of attenuation are the absorption coefficients β _p and β _s , and the heating light 4 is attenuated as follows using β _p and β _s .

I (x) = Iexp (β _p x) [−L _p ≦ x ≦ 0] (2)
I (x) = Iexp (−β _p L _p ) exp {β _s (x + L _p )} [x ≦ −L _p ]
... (3)
As a result, the resulting heat flux q can be expressed as in equations (4) and (5).

q = 1/2 × β _p I ₀ exp (β _p x) (1 + cos ωt) [−L _p ≦ x ≦ 0]
... (4)
_{q = 1/2 × β s} I 0 exp {β s (x + L p) -β p L p}
× (1 + cosωt) [x ≦ −L _p ] (5)
Assuming that all absorbed light is converted into heat and this heat is transmitted only in the one-dimensional direction of the x-axis 3), 4), the one-dimensional heat conduction equation for photoselective film, sample, and gas (gas) is a complex number. The complex temperature Φ taken into account can be expressed as:

_{^{∂ 2 Φ g / ∂x 2 =}} 1 / a g × ∂Φ g / ∂t [0 ≦ x] (6)
∂ ² Φ _p / ∂ x ² = 1 / _ap × ∂Φ _p / ∂t
−β _p I ₀ / (2λ _p ) × exp (β _p x) {1 + exp (jωt)}
[−L _p ≦ x ≦ 0] (7)
_{^{∂ 2 Φ s / ∂x 2 =}} 1 / a s × ∂Φ s / ∂t
−β _s I ₀ / (2λ _s ) × exp {β _s (x + L _p ) −β _p L _p }
X {1 + exp (jωt)} [x ≦ −L _p ] (8)
The boundary condition is as follows from the condition of continuous temperature and heat flux.

Φ _g (0, t) = Φ _p (0, t) (9)
Φ _p (−L _p , t) = Φ _s (−L _p , t) (10)
−λ _g × ∂Φ _g (0, t) / ∂x = −λ _p × ∂Φ _p (0, t) / ∂x
(11)
−λ _p × ∂Φ _p (−L _p , t) / ∂x = −λ _s × ∂Φ _s (−L _p , t) / ∂x
(12)
Φ _g (∞, t) = 0 (13)
Φ _s (−∞, t) = 0 (14)
Solving the above equation, the complex temperature amplitude θ ₁ at the sample-gas interface is obtained as follows.

θ ₁ = β _p I ₀ / {2λ _p (β _p ² −σ _p ² )}
× {(b + 1) (γ _p −1) exp (σ _p L _p ) − (b−1) (γ _p +1)
_{× exp (-σ p L p)} +2 (b-γ p) exp (-β p L p)}
÷ {(b + 1) (g + 1) exp (σ _p L _p )
- (b-1) (g -1) exp (-σ p L p)}
+ Β _s I ₀ / {2λ _s (β _s ² −σ _s ² )}
× {2b (γ _s −1) exp (−β _p L _p )}
÷ {(b + 1) (g + 1) exp (σ _p L _p ) − (b−1) (g−1)
× exp (−σ _p L _p )} (15)
Here, the AC temperature change on the sample surface is
Φ _AC (0, t) = θ ₁ exp (jωt) (16)
It becomes. Since the actually measured temperature is the real part of equation (16), when θ ₁ is set as in equation (17), the actual temperature change δT is expressed as in equation (18).

θ ₁ = θ _R + jθ _I = Aexp (−jφ) (17)
δT = Acos (ωt−Δφ) (18)
Here, Δφ and A are set as follows.

Δφ = tan ⁻¹ (Imθ ₁ / Reθ ₁ ) = tan ⁻¹ (−θ _I / θ _R ) (19)
A = √ (θ _R ² + θ _I ² ) (20)
Further, the equation (19) is written in detail as follows.

Δφ = tan ⁻¹ {(E × Q + F × P + G × N + H × M)
÷ (E × PF × Q + G × M−H × N)} (21)
P = (b + 1) ² (g + 1) (Bp −1) exp (2k _p L _p )
+ (B ² −1) (g + 1) {B _p sin (2k _p L _p )
- (Bp +1) cos (2k p L p)}
+2 (b + 1) (g + 1) exp (k _p L _p ) exp (−β _p L _p )
_{× {Bp sin (k p L} p) + (b-Bp) cos (k p L p)}
^{+ (B-1) 2 (} g-1) (Bp +1) exp (-2k p L p)
-(B ² -1) (g-1) {B _p sin (2k _p L _p )
+ (Bp −1) cos (2k _p L _p )}
+2 (b-1) (g -1) exp (-k p L p) exp (-β p L p)
_{× {Bp sin (k p L} p) - (b-Bp) cos (k p L p)}
···(twenty two)
Q = -Bp (b + 1) 2 (g + 1) exp (2k p L p)
+ (B ² −1) (g + 1) {(Bp + 1) sin (2k _p L _p )
+ Bp cos (2k _p L _p )}
+2 (b + 1) (g + 1) exp (k _p L _p ) exp (−β _p L _p )
× {- (b-Bp) sin (k p L p) + Bp cos (k p L p)}
^{-Bp (b-1) 2 (} g-1) exp (-2k p L p)
-(B ² -1) (g-1) {(Bp -1) sin (2k _p L _p )
_{-Bp cos (2k p L p)} }
-2 (b-1) (g -1) exp (-k p L p) exp (-β p L p)
× {(b-Bp) sin (k p L p) + Bp cos (k p L p)}
···(twenty three)
M = 2b (b + 1) (g + 1) exp (k _p L _p ) exp (−β _p L _p )
_{× {-Bs sin (k p L} p) + (Bs -1) cos (k p L p)}
-2b (b-1) (g -1) exp (-k p L p) exp (-β p L p)
_{× {Bs sin (k p L} p) + (Bs -1) cos (k p L p)}
···(twenty four)
N = -2b (b + 1) (g + 1) exp (k p L p) exp (-β p L p)
× {(Bs -1) sin ( k p L p) + Bs cos (k p L p)}
+ 2b (b-1) ( g-1) exp (-k p L p) exp (-β p L p)
× {- (Bs -1) sin (k p L p) + Bs cos (k p L p)}
···(twenty five)
E = (Zp β _p ² ) / (β _p ⁴ +4 k _p ⁴ ) (26)
F = (2Zp k _p ² ) / (β _p ⁴ +4 k _p ⁴ ) (27)
^{_{G = (Zs β s 2)}} / (β s 4 + 4k s 4) ··· (28)
H = (2Z _s k _s ² ) / (β _s ⁴ +4 k _s ⁴ ) (29)
However, Bp, Bs, Zp, Zs are set as follows.

_{Bp = β p / (2k p} ) ··· (30)
Bs = β _s / (2 k _s ) (31)
Zp = β _p I ₀ / (2λ _p ) (32)
Zs = β _s I ₀ / (2λ _s ) (33)
The measured amplitude A and phase difference Δφ contain information on the thermophysical value, absorption coefficient, and thickness of the sample. By measuring in a certain frequency region and performing appropriate analysis, the heat in the thickness direction of the sample can be measured. Information on physical property values can be obtained.

Table 1 (Symbol table)
────────────────────────────────────
Symbol Expression Meaning [Unit]
────────────────────────────────────
a _i λ _i / ρ _i c _i Temperature conductivity of material i [m ² / s]
b e _s / e _p samples and specific heat at constant pressure ratio c _i substance i the thermal effusivity of the photo Selective Film [J / (kg · K)]
e _i √ (λ _i ρ _i c _i ) Thermal permeability of substance i [Ws ^0.5 / (m ² · K)]
f Modulation frequency [Hz]
_g e g / e _p air ratio h convective heat transfer coefficient of the thermal effusivity of the photo Selective film [W / (m ² · K)]
I ₀ irradiation light intensity [W / m ² ]
j Imaginary unit k _i √ (πf / a _i ) Wave number [m ⁻¹ ] of temperature wave of substance i
_Li material i thickness [m]
q _i Heat flux flowing into material i [W / m ² ]
T temperature [K]
β _i absorption coefficient of substance i [m ^-1 ]
Φ Complex temperature
Δφ Phase difference between modulated light and thermal radiation signal [°]
γ _i β _i / σ _i
λ _i Thermal conductivity of substance i [W / (m · K)]
θ Complex temperature coefficient
The density of [rho _i substance i [kg / m ^3]
σ _i (1 + j) k _i Wave number of complex temperature wave of material i [m ^-1 ]
ω 2πf Modular angular frequency [rad / s]
────────────────────────────────────
I in the subscript means g: gas, p: photoselective film, s: sample.

────────────────────────────────────
.

In the present invention, as shown in FIG. 1, the photoselective film 2 is brought into close contact with the surface of the heat insulating material 1 to be measured, and the photoselective film 2 is irradiated with the laser light 4 that is sinusoidally modulated from the gas 3 side. By measuring the phase difference Δφ characteristic of the modulated light 4 and the thermal radiation light 5 from the surface of the photoselective film 2 with respect to the frequency f, and determining a _s and λ _s so that the theoretical equation fits the measured value. The temperature conductivity (thermal diffusivity) a _s and the thermal conductivity λ _s of the heat insulating material 1 are obtained.

  In applying the above-described theory of the present invention, the photoselective film 2 that irradiates the laser beam 4 that has been sinusoidally modulated from the gas 3 side in close contact with the surface of the heat insulating material 1 to be measured has a small bio number and is based on convection. Use one that suppresses the effect.

Here, the bio number Bi is
Bi = hL / λ (34)
Where h is the convective heat transfer coefficient [W / (m ² · K)], λ is the thermal conductivity of the solid [W / (m · K)], and L [m] is the representative length ( In general, L = volume / surface area).

  That is, the bio number is the ratio of the thermal resistance (1 / h) due to heat transfer on the surface of the object to the thermal resistance (L / λ) due to heat conduction inside the object, and represents the contribution of heat loss. When the number of bioses is infinite, the heat transfer coefficient h is large. In this case, heat escapes to the fluid (here, air) and moves constant, so that it is greatly affected by convection. And the surface temperature of a sample and the fluid temperature of a medium become equal. Conversely, when the bio number is close to 0, the effect of convection hardly affects the internal heat transfer phenomenon.

  Samples with low thermal conductivity, such as thermal insulation, have a large bionumber and are susceptible to convection.

  On the other hand, as shown in FIG. 1, when a photoselective film 2 such as borosilicate glass is brought into close contact with the surface of the heat insulating material 1 and the bio number of solids (that is, measurement objects) is reduced, it is affected by convection. This makes it difficult to apply the equations (1) to (33) of the theory of the present invention, which is a modification of the RG theory as described above.

  Now, the phase difference Δφ between the modulated light 4 and the thermal radiation light 5 in the equation (21) is expressed as the following equation. Where f is the modulation frequency.

Δφ = F (f: g, b, k _p , k _s , L _p , β _p , β _s ) (35)
here,
_{b = √ (λ s ρ s} c s) / √ (λ p ρ p c p): Photo Selective film and the ratio of the thermal effusivity of the sample,
g = √ (λ _g ρ _g c _g ) / √ (λ _p ρ _p c _p ): ratio of thermal permeation rate between photoselective film and air,
k _i = √ (πf / a _i ): temperature wave number,
L _p : the thickness of the photoselective film,
a _i = λ _i / ρ _i c _i : temperature conductivity,
ρ _i : density,
c _i : constant pressure specific heat,
λ _i : thermal conductivity,
β _i : absorption coefficient,
It is. However, i of the subscript means g: gas, p: photoselective film, and p: sample.

  Equation (35) can be rewritten as follows.

Δφ = F (f: g, b, k _p , k _s , L _p , β _p , β _s )
= F (f: √ (λ _g ρ _g c _g ) / √ (λ _p ρ _p c _p ),
√ (λ _s ρ _s c _s ) / √ (λ _p ρ _p c _p ),
√ (πf / a _p ), √ (πf / a _s ), L _p , β _p , β _s )
= F (f: √ (λ _g ρ _g c _g ) / √ (λ _p ρ _p c _p ),
(Λ _s / √a _s ) / (λ _p / √a _p ),
√ (πf / a _p ), √ (πf / a _s ), L _p , β _p , β _s )
... (36)
It becomes. The physical property values a _p , λ _p , L _p , β _p of the photoselective film 2 are known, and the absorption coefficient β _s of the heat insulating material 1 of the sample is known by other methods, g = √ (λ _g ρ _g c _g ) / √ (λ _s ρ _s c _s ) ≈0,
Δφ = F (f: λ _s , a _s ) (37)
The phase difference Δφ between the modulated light 4 and the thermal radiation light 5 is in the form of a function of the modulation frequency f of the heating light 4 and the temperature conductivity a _s and thermal conductivity λ _{s of the} heat insulating material 1 to be measured. . This equation (37) gives a frequency-phase difference curve of the heat insulating material 1 to be theoretically measured.

In the present invention, for example, in the arrangement as shown in FIG. 2, the phase difference Δφ characteristic with respect to the frequency f of the modulated light 4 and the thermal radiation light 5 is measured with respect to the heat insulating material 1 to be measured. The temperature conductivity a _s and the thermal conductivity λ _s of the heat insulating material 1 are determined by determining a _s and λ _s so that the equation 37) fits.

  In FIG. 2, reference numeral 10 is a personal computer, 11 is a function generator that generates a sine wave signal having an arbitrary frequency f under the control of the personal computer 10, and 12 is a semiconductor laser that oscillates near-infrared laser light having a wavelength of 810 nm, for example. The function generator 11 oscillates a laser beam modulated into a sine wave at a frequency f. Reference numeral 13 denotes an optical fiber for guiding laser light emitted from the semiconductor laser 12 to a predetermined position. Reference numeral 14 denotes an optical system provided at the tip of the optical fiber, which is a measurement point on the photoselective film 2 in close contact with the surface of the heat insulating material 1 to be measured. The heating laser beam 4 guided in the optical fiber 13 is irradiated over a wide range including The reason for irradiating the modulated light 4 over a wide range including the measurement point in this way is to mitigate the influence of errors due to three-dimensional heat conduction. A ZnSe lens 15 is arranged so that the focal point is located at the center of the irradiation range of the heating light 4. The thermal radiation light 5 emitted from the irradiation position of the heating light 4 on the photoselective film 2 is collected and emitted in parallel. Reference numeral 16 denotes another ZnSe lens whose focal point coincides with the detection surface of the infrared detector 18, and condenses the heat radiation light 5 made parallel by the ZnSe lens 15 on the detection surface of the infrared detector 18. Reference numeral 17 denotes an infrared filter disposed in front of the detection surface of the infrared detector 18, which transmits the heat radiation light 5, for example, infrared light having a wavelength of 10 μm, and reflects the heating laser light 4 and the scattered light reflected by the photoselective film 2. Stop. Reference numeral 19 denotes a preamplifier for amplifying the signal detected by the infrared detector 18, and 20 denotes a detection signal amplified by the preamplifier 19 and a modulation signal from the function generator 11, and outputs a phase difference Δφ between them and a signal intensity. It is a lock-in amplifier. The phase difference Δφ and signal strength from the lock-in amplifier 20 are input to the personal computer 10.

  Therefore, the frequency f of the sine wave signal generated by the function generator 11 by the personal computer 10 is sequentially changed within a predetermined range, and the heating laser light 4 oscillated from the semiconductor laser 12 is modulated by the frequency f, and the surface of the heat insulating material 1 The photoselective film 2 in close contact with the film is irradiated and periodically heated at a frequency f. Thermal radiation light 5 emitted from the heated heat insulating material 1 through the photoselective film 2 is condensed on the detection surface of the infrared detector 18 via the two ZnSe lenses 15 and 16 and the infrared filter 17, and is infrared rays. The detection signal of the detector 18 is converted into a voltage signal by the preamplifier 19 and input to the lock-in amplifier 20 together with the modulation signal from the function generator 11, and the phase difference Δφ and the signal intensity between the modulation light 4 and the thermal radiation light 5 are measured. Is done. The phase difference Δφ and the signal intensity are input to the personal computer 10 and analyzed as described below.

FIG. 3 is a flowchart showing the processing in the personal computer 10 and the output to the display or the like. In step ST1, the basic formula of the formula (35): Δφ = F (f: g, b, k _p , k _s , L _p , β _p , β _s ), that is, equation (21) is read out, and in step ST2, a _p , λ _p , L _p , β _p of the known photoselective film 2 and the heat insulating material 1 β _s is input, and its basic expression: Δφ = F (f: g, b, k _p , k _s , L _p , β _p , β _s ) is input to its a _p , λ _p , L _p , β _p , β Substituting _s , the theoretical formula (Δφ = F (f: λ _s , a _s )) of the formula (37) is determined in step ST3. On the other hand, the measured value Δφ measured as described with reference to FIG. 2 is input in step ST4. In step ST5, the initial values of λ _s and a _s of the heat insulating material 1 and the curve fitting convergence condition in step ST6 are input. Here, as the initial values of λ _s and a _s , it is common to use known thermal conductivity, estimated value or approximate value of thermal conductivity according to the specific type of heat insulating material 1. Note that the input of step ST4 and step ST5 may be input at any time before step ST5. After that, in step ST6, the theoretical formula obtained in step ST3: Δφ = F (f: λ _s , a _s ) is curve-fitted to the measured value Δφ input in step ST4. As the curve fitting method, any known curve fitting method such as a simplex method or a least square method may be used. The result of this curve fitting, the theoretical expression: Δφ = F (f: λ s, a s) in the lambda _s and a _s are determined. Thereafter, in step ST7, the measured value Δφ input in step ST4 and the curve fitting result in step ST6 are graphically displayed on a CRT, a printer or the like. Finally, in step ST8, λ _s and a _s of the heat insulating material 1 as an analysis result are displayed.

As described above, the thermal conductivity λ _s and the temperature conductivity a _s of the heat insulating material 1 can be accurately obtained by the remote sensing method of the present invention.

Here, the conditions required for the photoselective film 2 to which the heat insulating material 1 is adhered are as follows.
(1) The light that transmits all or part of the heating light (the wavelength is not limited as long as the sample absorbs the wavelength, but does not overlap with the detection wavelength).

In order to measure the thermophysical property value of a sample with high sensitivity, it is desirable to have an appropriate absorption coefficient for heating light.
(2) Those which do not transmit heat radiation light (detection wavelength 5.5 to 11.0 μm).

Since the temperature change on the surface of the first layer is detected as thermal radiation, only the surface temperature of the first layer cannot be detected with a material that transmits thermal radiation.
(3) Large hemispherical emissivity Since heat radiation is detected as a signal, the use of a material with a large emissivity increases the radiant energy and makes the signal easy to stabilize.
(4) Large thermal conductivity The number of bios in the measurement system is reduced, and the influence of convection can be suppressed. By the way, the number of bios in the measurement system using borosilicate glass is about 1/25 that of the heat insulating material, which is sufficiently small, and the influence of convection is not so great.
(5) Thin and easy to process When the material of the first layer is thin, measurement in a high frequency region where the thermal diffusion length is small becomes possible, and it is difficult to be affected by three-dimensional heat conduction and convection.
(6) Single layer structure.

Even if the photothermal infrared detection method is a thin coating material, the information appears sensitive to the phase difference, which causes an error.
(7) Easy to handle.

  It is a characteristic that is required when considering field measurement in the end.

  Next, as the heat insulating material 1, polystyrene foams having different amounts of remaining chlorofluorocarbon were measured. The result is shown in FIG. The remaining amount of chlorofluorocarbon is measured by gas chromatography at the Building Materials Testing Center. As the photoselective film 2, a 70 μm-thick borosilicate glass (SCHOTT GLAS, D263T) was used. Heating is performed with a laser beam having a wavelength of 810 nm, and the detection wavelength is 5.5 to 11.0 μm. Moreover, the measurement result of the temperature conductivity (thermal diffusivity) is shown in FIG.

  With respect to the physical property values of the photoselective film 2, in this measurement, a standard sample having a known thermophysical property value is measured and calculated backward. Although it is theoretically known that the method of the present invention is greatly affected by the contact thermal resistance, the influence of the contact thermal resistance can be estimated from the frequency of the maximum phase difference of the obtained frequency-phase difference curve. It is possible and the value is used in the analysis.

  FIG. 4 shows that a systematic signal corresponding to the remaining amount of chlorofluorocarbon is obtained. In addition, it can be seen from FIG. 5 that the temperature conductivity tends to increase with a decrease in the remaining amount of fluorocarbon. In the measurement of FIGS. 4 and 5, it is considered that both the measurement and the estimation formula include an error. Especially, as a measurement error factor, the contact thermal resistance is not accurately estimated, and the borosilicate glass is in the measurement wavelength region. It is considered that the infrared ray is slightly transmitted, the influence of scattering of heating light on the sample surface, and the like. However, since the systematic tendency of the temperature conductivity corresponding to the remaining amount of chlorofluorocarbon is captured, it can be seen that sensing of the chlorofluorocarbon remaining amount is possible by the measurement method of the present invention.

  As described above, the embodiment of the remote sensing method for the heat insulation property of the heat insulating material according to the present invention has been described by taking the measurement of the remaining amount of fluorocarbon in the foam heat insulating material as an example, but the present invention is not limited to this example and various It is possible to accurately measure the thermal insulation characteristics of the thermal insulation material in the field, non-destructively.

It is a model figure for demonstrating the heat insulation characteristic remote sensing method of the heat insulating material of this invention. It is a figure which shows one example of arrangement | positioning for implementing the heat insulation characteristic remote sensing method of the heat insulating material of this invention. It is a figure which shows one example of the flowchart in order to obtain | require the heat insulation characteristic of the heat insulating material of this invention. It is a figure which shows the example of the measurement result and fitting curve based on this invention. It is a figure which shows the example of the measurement result and estimation formula of the temperature conductivity based on this invention.

Explanation of symbols

1 ... Insulation (sample)
2 ... Photoselective film 3 ... Gas 4 ... Laser light (heating light, modulated light)
5 ... thermal radiation 10 ... PC 11 ... function generator 12 ... semiconductor laser 13 ... optical fiber 14 ... optical system (condensing optical system)
15, 16 ... ZnSe lens 17 ... Infrared filter 18 ... Infrared detector 19 ... Preamplifier 20 ... Lock-in amplifier

Claims (6)

The sample is irradiated with periodically modulated heating light, the thermal radiation emitted from the sample is detected, the frequency-phase difference characteristic of the detection signal for the heating light is measured, and the frequency-phase difference characteristic is analyzed. In the thermal sensing remote sensing method of thermal insulation properties to obtain the thermal conductivity and temperature conductivity (thermal diffusivity) of the sample,
A photoselective film that transmits all or part of the heating light to the surface of the heat insulating material of the sample and that does not transmit heat radiation light is adhered, and the heating light is irradiated through the photoselective film, and the heat radiation light is irradiated. A method for remote sensing a thermal insulation property of a thermal insulation material, characterized by detecting. The heat insulating property of the heat insulating material according to claim 1, wherein the thermal conductivity and the temperature conductivity of the heat insulating material of the sample are obtained by curve fitting a theoretical formula with respect to the measured frequency-phase difference characteristic. Remote sensing method. The method for remote sensing thermal insulation characteristics according to claim 1 or 2, wherein the photoselective film is made of borosilicate glass. The heat insulation property of the heat insulating material according to any one of claims 1 to 3, wherein the residual amount of freon in the foamed heat insulating material containing the Freon of the sample is measured by obtaining thermal conductivity and temperature conductivity. Remote sensing method. The entire surface of the sample heat insulating material is partially or partially transmitted with heating light, and a photoselective film that does not transmit heat radiation light is adhered, and the sample is irradiated with periodically modulated heating light through the photoselective film, By detecting the thermal radiation emitted from the heat insulating material of the sample through the photoselective film, measuring the frequency-phase difference characteristic of the detection signal with respect to the heating light, and analyzing the frequency-phase difference characteristic A thermal sensing remote sensing device for a thermal insulation material for obtaining a thermal conductivity and a thermal conductivity of a heating material, a heating light irradiation means for irradiating a sample with the periodically modulated heating light, and heat for detecting the thermal radiation light Synchrotron radiation detection means, frequency-phase difference characteristic measurement means for measuring a frequency-phase difference characteristic of a detection signal of the thermal radiation light with respect to the heating light, and the photoselector A physical property value input means for inputting the physical property value of the film and the absorption coefficient of the heat insulating material, a theoretical expression determining means for determining a theoretical formula based on the physical property value of the photoselective film and the absorption coefficient of the heat insulating material, A heat insulation characteristic remote sensing device for heat insulation, comprising: curve fitting means for curve fitting a theoretical formula for the frequency-phase difference characteristic. 6. The heat insulating material according to claim 5, wherein the physical property value input in the physical property value input means includes temperature conductivity, thermal conductivity, thickness, absorption coefficient, and absorption coefficient of the heat insulating material of the photoselective film. Thermal insulation remote sensing device.

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