JP2008107091A - Gas concentration measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas concentration measuring device capable of accurately measuring gas concentration without being influenced by ambient temperature even in a cold district and a hot district. <P>SOLUTION: An ozone gas concentration measuring device 1 for the cold district is constituted by a gas detection object 2 which has an exposure part 7 discolored in response to ozone gas, a phase change substance 3 which keeps constant the temperature of the gas detection object 2, a metal container 10 which stores the phase change substance 3, and a heat insulation container B storing the metal container 10 and the gas detection object 2. As for the phase change substance 3, a phase change substance which changes in phase from liquid to solid is used. The heat insulation container B is constituted by a plastic container 11 which has a window 17 and stores the gas detection object 2 and the metal container 10, and a container 12 made of insulation material which has an opening 19 and stores the plastic container 11. The gas detection object 2 is stuck closely onto the surface of the metal container 10 and stored in the plastic container 11 together with the metal container 10, and the exposure part of the gas detection object 2 is exposed outside the heat insulation container B out of the window 17 and the opening 19. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is influenced by the temperature of the measurement environment even in a hot or cold region, particularly a gas concentration measuring device that measures the concentration of a specific type of gas such as ozone gas or nitrogen dioxide gas contained in the air. The present invention relates to a gas concentration measuring device that can measure with high accuracy without any problems.

In recent years, the environmental impact of gaseous air pollutants with high environmental risks, especially ozone gas (O ₃ ) that constitutes the main component of photochemical oxidants and nitrogen dioxide gas (NO ₂ ) generated by the combustion of substances has been greatly affected. It has become a problem. In particular, ozone gas has a strong oxidizing ability, so if the concentration in the air exceeds a certain level (0.1 ppm) due to its toxicity, it stimulates the respiratory system and inhales even a minute amount for a long time. It is considered harmful. Nitrogen oxide (NOx) gas is a causative substance of air pollution, and its relation to respiratory diseases has been pointed out. For this reason, various gas concentration measuring devices for measuring the concentration of specific gases such as harmful ozone gas and nitrogen dioxide gas have been developed and proposed.

  As such a gas concentration measuring device, a small porous body such as filter paper or porous glass (outside dimension of about 1 cm square, thickness of 8 mm or less) selectively reacts with a detection target gas such as ozone and changes its color. For example, by using a gas detector that is impregnated with an organic dye containing an indigo ring and the exposed portion exposed to ozone gas, which is the gas to be detected, is impregnated with this dye. Have been developed (see, for example, Patent Documents 1 and 2).

  In addition, a gas detector is obtained by impregnating a small porous body such as porous glass with a detection agent containing a dye that changes color (coloring) by selectively reacting with a detection target gas such as nitrogen dioxide gas. Also, a storage sensor for detecting an ultra-small nitrogen dioxide gas that is inexpensive and can be carried by an individual has been developed (see, for example, Patent Documents 3 and 4).

  Among the accumulation-type sensors used to measure these gas concentrations, the sheet-shaped gas detector using filter paper, etc., mainly detects the amount of personal gas exposure for one day. Assume the evaluation of the exposure of special workers who use. This sheet-like gas detector is designed to discolor (discolor), for example, so as to be visually observable at an accumulated concentration amount (concentration standard × time) determined in the labor standard with an average working time of 8 hours.

  When measuring ozone gas (as well as nitrogen dioxide gas), if a gas concentration meter equipped with a gas detector is exposed to the measurement environment for a certain period of time, the exposed part of the gas detector is exposed to ozone gas contained in the air. As a result, the color changes (discolors). The degree of this color change is determined by the concentration of the specific gas and the measurement time. That is, when the concentration of ozone gas is high, the color changes remarkably even in a short time, and when the concentration is low, it takes a long time to change color. Then, the concentration of ozone gas is measured by comparing the discolored color with a color sample corresponding to the ozone concentration shown in the color chart and reading the scale of the gas concentration.

  However, the risk to the human body due to exposure to ozone gas is that the stratospheric ozone is destroyed or the ozone layer is thinned by ozone layer depleting substances such as chlorofluorocarbon gas, so that the ultraviolet rays that reach the ground surface are strong and the outside temperature can reach even below freezing point. It is considered high in the region. In addition, since NOx and hydrocarbons (HC) emitted from automobiles, factories, etc. cause photochemical reaction due to strong sunlight and high temperature, photochemical oxidants (Ox; ozone is the main component) are generated, so the outside air temperature is 40 It is considered that the risk to the human body is high even in low-latitude areas that reach ℃. For this reason, in high latitude regions and low latitude regions, it has been requested to provide an ozone gas concentration measuring device that can detect the ozone concentration in the environment at an individual or household level.

JP 2004-144729 A WO 2006/016623 (PCT / JP2005 / 014689) JP 09-274032 A Japanese Patent Laid-Open No. 2000-081426

  By the way, the fading speed (or coloring speed) of an organic dye that fades or develops color by a selective chemical reaction with a specific gas depends on the temperature of the measurement environment.

FIG. 14 shows the temperature dependence of the reaction rate of fading (or color development) of organic dyes.
FIG. 14 shows an Arrhenius plot with the reciprocal of temperature on the horizontal axis, and the reaction rate of fading (or color development) on the vertical axis. As can be seen from this figure, the reaction rate of fading increases as the temperature increases, and the reaction rate decreases as the temperature decreases.

  In general, the rate of chemical reaction depends on the activation energy, and when the temperature differs by 10 ° C., the reaction rate differs by a factor of 2-3. For this reason, a gas concentration measuring device equipped with a gas detector designed to fade (or develop color) in 8 hours at room temperature (assuming about 20 ° C.) is operated in a cold region (for example, assuming 0 ° C.). When used, the chemical reaction that takes place inside the porous body is very slow. On the other hand, when used in a hot place (for example, assuming 40 ° C.), the chemical reaction becomes very fast. For this reason, even if the gas concentration is measured using the same gas concentration measuring instrument, the measured value of the gas concentration differs depending on the ambient temperature of the measurement area, and the reliability as the gas concentration measuring instrument is low, and the area where it is used. However, there was a problem that it was constrained by warm regions.

  The present invention has been made to solve the above-described conventional problems, and the object of the present invention is to measure the gas concentration with high accuracy without being affected by the ambient temperature even in cold or hot areas. An object of the present invention is to provide a gas concentration measuring device capable of performing the above.

  To achieve the above object, the present invention provides a gas detector having an exposed portion that changes color in response to a specific gas, a heat storage body that keeps the temperature of the gas detector constant, the heat storage body, and the gas detection body. A heat insulating container for storing the body, and the heat storage body is composed of a phase change material that changes its phase due to latent heat within a certain temperature range under atmospheric pressure, and a metal container that stores the phase change material. The gas detector is housed in the heat insulating container in close contact with the surface of the metal container, and the heat insulating container is provided with an opening for exposing the exposed portion of the gas detector to the outside. It is.

  The present invention also provides a gas detector having an exposed portion that changes color in response to a specific gas, a heat storage body that keeps the temperature of the gas detector constant, and heat insulation that houses the heat storage body and the gas detector. The heat storage body is constituted by a phase change material that changes phase due to latent heat in a certain temperature range under atmospheric pressure, and a metal container that stores the phase change material, and the heat insulating container. A plastic container that has a window and houses the metal container and the gas detector, and a heat insulating material container that has an opening corresponding to the window and houses the plastic container; The gas detector is disposed in a gap between the metal container and the plastic container in a state of being in close contact with the metal container, and the exposed portion is disposed from the window and the opening. Exposed outside the insulated container .

  According to the present invention, the phase change substance is any one of a substance that changes phase from solid to liquid, liquid to solid, liquid to gas, gas to liquid, solid to gas, and gas to solid.

  According to the present invention, the metal container has a sealed structure, and the phase change material is made of solid or powder, and the temperature of the gas detector is kept constant by the heat of fusion.

  In the present invention, the metal container has a sealed structure, and the phase change material is made of a liquid, and the temperature of the gas detector is kept constant by heat of solidification.

  Further, the present invention provides a transpiration unit in which the phase change material is a liquid, the temperature of the gas detector is kept constant by the heat of vaporization, and the phase change material is sucked into the metal container and evaporated to the outside of the container. It is provided.

  In addition, the present invention provides a pressure reducing valve that keeps the temperature of the gas detector constant by the sublimation heat of the phase change material and releases it to the outside when the internal pressure becomes higher than a certain value. It is a thing.

  In the present invention, the phase change material may be an n-paraffin hydrocarbon, an organic compound, an organic solvent in which a fragrance is dissolved, a hydrate or a supercooling inhibitor added with a phase separation inhibitor. Any one of the hydrates added.

  In the present invention, the heat storage body is configured such that the phase change material is housed in a microcapsule and the microcapsule as a powder is filled in a metal container.

  In the present invention, a heat storage plate is formed by coating the microcapsules with a resin, and a metal film is formed on the surface thereof.

  In the present invention, the phase change substance is selected from the group consisting of n-eicosane, n-nonadecane, n-octadecane, n-heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, and n-tridecane. And at least one paraffinic hydrocarbon.

  In the present invention, the hydrate or hydrate to which the phase separation inhibitor is added or the hydrate to which the supercooling inhibitor is added is hydrated calcium chloride, hydrated lithium nitrate, sodium sulfate / dehydrated water. Japanese (Glauber salt), hydrated sodium carbonate, disodium hydrogen phosphate dodecahydrate, zinc nitrate hexahydrate, calcium bromide hexahydrate, zinc sulfate heptahydrate, odor Any one of iron and hexahydrate.

  In the present invention, the organic solvent in which the organic compound or fragrance is dissolved is trimyristin, methyl palmitate, capric acid (decanoic acid), d-form-lactic acid, glycerin (glycerol), acetic acid, caprylic acid (octanoic acid). ), Ethylenediamine, formic acid, n-pentane, isopentane, neopentane, n-butane, 1-pentene, acetaldehyde, ethyl methyl ether, diethyl ether, ethylene oxide, R11, R21, dichloromethane, carbonyl chloride, R114, lauric acid, p-nitro One of phenol, o-nitroaniline, and ε-caprolactam is used.

  In the present invention, the metal container is made of any one of copper, aluminum, silver, tungsten, and zinc, and an inner surface is coated with a corrosion-resistant protective film, and further, a metal having good thermal conductivity. The container is filled with small pieces or substantially spherical fine particles or fibrous fine particles.

  In the present invention, the fine particles to be filled are any one of alumina fine particles and silica fine particles.

  In the present invention, the corrosion-resistant protective film is a surface coat film of plastic, glass, or fluororesin.

  Moreover, this invention sticks the sheet | seat on which the color chart which shows the color corresponding to the density | concentration of specific gas was displayed on the surface in which the opening part of the container made from the said heat insulating material is formed.

  Further, according to the present invention, the transpiration portion is constituted by a transpiration hole provided in a metal container, and a liquid-absorbing transpiration member inserted into the transpiration hole and protruding at one end to the outside of the container.

  In the present invention, a phase change material consisting of solid (powder), liquid or gas is used as a heat storage and heat retaining material, and latent heat (melting heat, solidification heat, sublimation heat, evaporation (vaporization) during the phase change (during state change). ) Heat or condensation heat) is used to keep the temperature inside the metal container constant, and this temperature is kept in the gap between the metal container and the plastic container. Since the temperature of the gas detector is kept constant by conducting heat from the heat source, the pigment contained in the exposed area of the gas detector is identified even in hot and cold areas where the ambient temperature is high. It is possible to measure accurately without increasing or decreasing the reaction rate with respect to the gas.

  A substance that changes in phase from a solid to a liquid absorbs heat of fusion and keeps the temperature of the gas detector constant, so that it is suitable for use in hot areas. A substance that changes in phase from a liquid to a solid releases heat of solidification to keep the temperature of the gas detector constant, and is therefore suitable for use in cold regions. Since the volume change of the substance that changes phase from solid to liquid and the substance that changes phase from liquid to solid are small, the consumption of the phase change substance can be reduced if the metal container has a sealed structure.

  A substance that changes phase from liquid to gas absorbs heat of vaporization (heat of vaporization) to keep the gas detector at a constant temperature, and is therefore suitable for use in hot areas. The transpiration unit evaporates the liquid and releases it to the outside of the container, thereby preventing the container from being damaged due to an increase in pressure inside the container.

  A substance that changes in phase from a solid to a gas is suitable for use in a hot area because it absorbs sublimation heat and keeps the temperature of the gas detector constant. The pressure reducing valve allows the vaporized gas to escape to the outside of the container and prevents the container from being damaged due to an increase in pressure inside the container.

First, the operation principle of the present invention will be described with reference to FIG.
In general, when a phase change material (hereinafter abbreviated as PCM) changes to a solid (or powder), liquid, or gas phase, the bonding state of the substance called latent heat (more commonly, transition heat) is changed. In order to change, thermal energy that is absorbed (or released) without changing (increasing or decreasing) the temperature is required. When PCM changes from a solid phase (or liquid phase) to a liquid phase (or solid phase), a latent heat of melting (or solidification) is required. Is fixed at a constant temperature called a melting point (or freezing point). While the latent heat of melting (or solidification) is exchanged, a solid-liquid coexisting phase is realized. When all of the solid phase PCM is liquefied, the temperature of the PCM rises in proportion to the amount of heat applied, and when reaching the boiling point, the PCM changes from the liquid phase state to the gas phase state. At this time, latent heat (vaporization heat or evaporation heat) for vaporization (evaporation) is required, and the temperature therebetween is also fixed at the boiling point. Conversely, when PCM changes from a gas phase state to a liquid phase state, latent heat (condensation heat) of condensation (liquefaction) is released, and the temperature at that time is also fixed at the boiling point.

  In addition, in the sublimation process in which PCM changes directly from the solid phase to the gas phase (or vice versa), sublimation latent heat (sublimation heat) is required (or released), while PCM (in this case, solid phase) The temperature of the part) is fixed at the sublimation point. Since there is no liquid phase at a pressure below the intrinsic triple point of the substance, evaporation, condensation, melting and solidification do not occur. This causes a sublimation process. At pressures above the critical point, there is no difference between the gas phase and the liquid phase, and there is only a single phase.

  In general, a change in state between three states of a substance is a first-type phase transition, and transition temperatures such as a melting point and a boiling point change with pressure. In any case, a very large amount of heat energy, called transition heat, is associated with this phase change (i.e. change from solid phase to liquid phase, change from liquid phase to gas phase, or from solid phase to gas phase). Change) is absorbed by PCM. A large amount of heat of transition is required for the phase change, and the temperature of the PCM remains unchanged during this phase transition, even though a large amount of heat energy is absorbed during the phase transition process. .

  The present invention relates to a gas detector that is in thermal contact with PCM by utilizing the absorption or release of transition heat when the PCM changes its phase state within a certain temperature range under atmospheric pressure. The basic principle is that the temperature is fixed or held at a constant value collectively referred to as a PCM transition point. Here, “within a certain temperature range” means the temperature of the environment in which the present gas concentration measuring apparatus is used, specifically, a range of about −20 ° C. to 5 ° C. in a cold region, and 35 ° C. to 50 ° C. in a hot region. The range of about ℃ is assumed.

In that case, the following three types of phase changes (state changes) used in the present invention can be considered.
(1) When the PCM changes from the solid phase (or liquid phase) to the liquid phase (or solid phase), the temperature of the PCM is the melting point (freezing point) in order to absorb (or release) the heat of fusion (or heat of solidification). Method that uses fixed to

(2) When the PCM changes from the liquid phase (or gas phase) to the gas phase (or liquid phase), the PCM temperature absorbs (or releases) heat of evaporation or heat of vaporization (or heat of condensation). Method that uses fixed to

(3) The temperature of the PCM is fixed at the sublimation point in order to absorb (or release) sublimation heat (or solidification heat) when the PCM changes from the solid phase (or gas phase) to the gas phase (or solid phase). Method to be used

  The PCM (1) that changes from a solid phase to a liquid phase absorbs heat of fusion. On the other hand, PCM that changes phase from a liquid phase to a solid phase releases heat of solidification. Since these PCMs have a small volume change, they are not subject to strong restrictions on the containers that contain the PCMs. Therefore, the container can have a sealed structure. In addition, since the amount of PCM does not change if a sealed structure is used, it can be used for a long time in the sense that the PCM is not consumed, and is most practical.

  When the latent heat of fusion is absorbed while the PCM changes from the solid phase to the liquid phase, heat is taken from the gas detector that is in thermal contact with the PCM, so that the gas detector is cooled. That is, when PCM that changes phase from a solid to a liquid is used, the gas detector is cooled by the latent heat of fusion and kept at a constant temperature, and thus is suitable for use in a hot area.

  Conversely, when the solidification heat is released while the PCM changes from the liquid phase to the solid phase, the gas detector in thermal contact with the PCM is heated by the solidification heat. That is, when PCM that changes phase from a liquid to a solid is used, the PCM releases heat of condensation to warm the gas detector and keep it at a constant temperature, which is suitable for use in cold regions. The first and second embodiments to be described later of the present invention relate to a gas concentration measuring device using PCM that changes phase from a liquid to a solid.

  In the case of the PCM that absorbs the heat of vaporization when the phase is changed from the liquid phase to the gas phase in (2), it is necessary to evaporate or evaporate the PCM to the outside of the container by the evaporating part including the evaporating member. In this case, since the amount of PCM is consumed as it is used, it cannot be used for a long period of time, but the temperature can be fixed at the boiling point during evaporation within a limited period. In this case, since the PCM absorbs the heat of vaporization, it takes heat from the gas detector in thermal contact with the PCM and keeps the temperature of the gas detector at a constant temperature. It is. The third embodiment to be described later of the present invention relates to a gas concentration measuring device using PCM that changes phase from this liquid to a gas.

  On the other hand, when using PCM that changes phase from the gas phase to the liquid phase, the heat of condensation is released when changing from the gas phase to the liquid phase, and the temperature of the gas detector is kept constant by this condensation heat. Suitable for use in cold regions. However, in this case, since it is necessary to pressurize and inject PCM into the container in advance, a pressure resistant container is required.

  When the PCM that changes phase from the solid phase to the gas phase is used, the phenomenon of absorbing sublimation heat when changing from the solid phase to the gas phase is used. Since the volume expansion of PCM is large during sublimation, the container for storing PCM cannot have a sealed structure, and it is necessary to release the internal pressure using a pressure reducing valve or the like. Furthermore, in this case, since the PCM absorbs sublimation heat, it takes heat away from the gas detector that is in thermal contact, and keeps the temperature of the gas detector at a constant temperature. . Also, this PCM is not used for a long period of time because the amount of PCM is consumed with use in the same manner as PCM that changes phase from liquid to gas. However, the temperature can be fixed at the transition point (sublimation point) during sublimation within a limited period. The fourth embodiment of the present invention relates to a gas concentration measuring device using PCM that changes phase from a solid to a gas.

  On the other hand, when PCM that changes phase from gas phase to solid phase is used, the temperature of the gas detector is kept constant by the heat of solidification released when changing from gas phase to solid phase. It is preferable. However, in this case, since it is necessary to fill the container with PCM in a gaseous state that can be solidified by compression in advance, a compression device and a pressure vessel are required.

Hereinafter, the present invention will be described in detail with reference to the drawings.
2 is an exploded perspective view showing a first embodiment in which the present invention is applied to an ozone gas concentration measuring device, and FIG. 3 is a sectional view taken along the line III-III in FIG. This embodiment shows an example in which the present invention is applied to an ozone gas concentration measuring device that is suitable for use in a cold district that uses heat of solidification when a phase change material in a liquid state is solidified. An ozone gas concentration measuring device generally indicated by reference numeral 1 includes a gas detector 2, a heat storage body A used to keep the temperature of the gas detector 2 constant, and the heat storage body A and the gas detector 2. And a heat insulating container B for storing. In addition, the thermal storage body A and the heat insulation container B comprise the thermal storage thermal insulation body.

  The gas detector 2 is a sheet-like porous carrier 6 containing an organic dye that selectively reacts with ozone gas, which is a specific gas, and discolors (discolors or develops color), such as porous glass or filter paper. The exposed portion 7 is formed by impregnating a desired portion of the material, and the portion impregnated with the organic dye is discolored when exposed to ozone gas. The exposed portion 7 can be formed, for example, by supporting a dye containing an organic indigo ring, a humectant, and a buffer solution having a buffering action in an acid or acidic region. In the present embodiment, an example in which a dye containing an indigo ring is used as an organic dye and the exposed portion 7 is formed at the center of the porous carrier 6 is shown. Also good.

  According to such a gas detector 2, a low concentration (ppb order) ozone gas contained in the atmosphere is converted into ozone gas from a fading reaction corresponding to decomposition of the pigment having an indigo ring by ozone gas or a pigment having an indigo ring. It can be detected as a color reaction caused by a decomposition product generated as a result of decomposition by the above.

  As the pigment having an indigo ring, for example, indigo, indigo carmine sodium salt, indigo carmine potassium salt, indigo red and the like are preferably used. As the humectant, glycerin, ethylene glycol or the like is preferably used. As the acid, it is preferable to use acetic acid, phosphoric acid, tartaric acid and the like. As the buffer solution, a buffer solution having a buffering action in the range of pH 1-4, preferably 2-3, more preferably 3-4, such as acetic acid and sodium acetate, or phosphoric acid and sodium dihydrogen phosphate, or A buffer solution consisting of tartaric acid and sodium tartrate is used.

  In the specific production of the gas detector 2, for example, 0.06 g of indigo carmine, 3.0 g of citric acid as an acid, and 15 g of glycerin as a moisturizer are placed in a container, and water is added to these. Is added to dissolve indigo carmine to prepare 50 g of detection solution.

  Next, cellulose filter paper (for example, filter paper No. 2 manufactured by Advantic Co., Ltd.) is dipped in this detection solution and taken out for a predetermined time, and then water contained in the cellulose filter paper is evaporated by air drying. Thereby, the exposure part 7 completes the indigo blue gas detector 2. The size of the gas detector 2 is about 30 × 30 mm, and the thickness is about 1 to 2 mm.

  The gas detector 2 thus produced was exposed to a test gas containing ozone gas from an ozone gas generator for a certain time (for example, 8 hours), and the degree of discoloration was observed with the naked eye. The ozone gas in the test gas is taken into the water held by the glycerin of the gas detector 2 and then causes a reaction to decompose the C = C double bond of the dye having an indigo ring. The structure and electronic state of the dye molecule change, and the absorption near 600 nm in the visible region changes. For this reason, the color (blue) of the exposed part 7 of the gas detector 2 fades faintly.

  On the other hand, the decomposition product generated by the decomposition of the indigo dye has light absorption in the vicinity of a wavelength of 400 nm in the visible light region, so that the exposed portion 7 starts to turn yellow (coloring reaction). As described above, when the exposed portion 7 of the gas detector 2 is exposed to ozone gas, the fading reaction and coloring reaction of the dye occur simultaneously, so that even if the ozone concentration is in the ppb order, the color changes and can be detected reliably.

  The heat storage body A includes a heat storage and heat insulating material 3 and a container 10 having good thermal conductivity for storing the heat storage and heat insulating material 3. As the heat storage and heat insulating material 3, PCM (hereinafter referred to as PCM3) that undergoes a phase change due to latent heat within a certain temperature range under atmospheric pressure is used. As the container 10 having good thermal conductivity, a metal container having high thermal conductivity (hereinafter referred to as a metal container or a metal container) is used.

  The PCM 3 is held in a liquid state by being held at a temperature slightly higher than the transition point in the state where it is housed in the heat insulating container B together with the metal container 10, and releases heat of solidification when solidified. By doing so, the gas detector 2 and the metal container 10 described later are heated to keep these temperatures constant.

Here, as the PCM 3, a substance having a phase transition point in the temperature range assumed as the operating temperature of the gas detector 2 is selected. Table 1 below shows the physical property values of some PCMs that can be used at about 40 ° C. or less and near room temperature. Broadly classified, PCM3 includes n-paraffinic hydrocarbons represented by the formula C _n H _{2n + 2} (ie, linear hydrocarbons), hydrated salts and organic substances. Preferred paraffinic hydrocarbons are those in which n is in the range of 13 to 20 in the above formula. Hydrated salts suitable for PCM3 include hydrated calcium chloride, hydrous lithium nitrate, sodium sulfate, decahydrate (Glauber salt), hydrated sodium carbonate, disodium hydrogen phosphate twelve hydrate, nitric acid Examples include zinc hexahydrate, calcium bromide hexahydrate, zinc sulfate heptahydrate, and iron bromide hexahydrate. Other organic substances suitable for PCM3 include trimyristin, methyl palmitate, capric acid (ie, decanoic acid), d-form-lactic acid, glycerin (glycerol), acetic acid, caprylic acid (ie, octanoic acid), Examples include ethylenediamine and formic acid.

The temperature T _{1 at} which the gas detector 2 operates effectively requires a value near room temperature, that is, a temperature in the range of 7 ° C. to 30 ° C. PCM3 having a phase transition temperature within the above range includes RT6 (paraffinic material) having a phase transition temperature of 7 ° C, RT10 (paraffinic material) having a phase transition temperature of 7 ° C, Contempemp (registered trademark) having a temperature of 28 ° C, and Outlast. It is assumed that (registered trademark) (paraffin wax) or the like is used.

  The metal container 10 is formed in a horizontally long rectangular thin box shape, and the inlet 14 for injecting the PCM 3 formed in the upper lid 13 is closed with a metal cap 15 so as to be airtight. Thus, a sealed container is formed. Further, since the metal container 10 may corrode depending on the material of the PCM 3 to be stored, the entire inner surface (preferably also the surface) is coated with a corrosion-resistant protective film made of plastic, glass, or fluororesin.

Regarding such a metal container 10, it is desirable to consider the following two points.
(1) Since heat is taken in and out of the PCM 3 through the wall of the container, it is necessary to sufficiently improve heat transfer characteristics between the wall and the PCM 3. For example, the transmission area is increased by creating a honeycomb structure in the container that is thermally and securely bonded to the container wall. Moreover, since it uses in a gravitational field, in order to promote the natural convection of PCM3 and to improve heat transfer, the core of a honeycomb structure is arranged in a perpendicular direction. Furthermore, in order to improve the low thermal conductivity of the PCM material itself, the metal container 10 is filled by filling a small piece of metal having a good thermal conductivity, or substantially spherical fine particles or fibrous fine particles, and filling this with PCM3. And heat transfer to the gas detector 2 can be promoted by increasing the effective thermal conductivity of the heat storage body A constituted by the PCM 3. As the filler, alumina fine particles (diameter 1 mm, density 3880 [kg / m ³ ], specific heat 0.3 [kJ / kg · K], thermal conductivity 17 [W / mK]), or silica fine particles (diameter 1 mm, A density of 2590 [kg / m ³ ], a specific heat of 0.75 [kJ / kg · K], a thermal conductivity of 0.745 [W / m · K], and the like are desirable.
(2) In order to cope with some volume change due to thermal expansion and phase change, it is necessary to give the container appropriate flexibility or to make the container wall strong to withstand pressure rise. For this purpose, it is desirable that the PCM 3 is not completely filled in the container, but is filled while leaving some space in the container.

  As described in (1) above, the metal container 10 that accommodates the PCM 3 is a gas detector that is in thermal contact with the PCM 3 through the wall of the container for the solidification heat released when the PCM 3 undergoes a phase change. 2 needs to be transmitted well. That is, in order to perform heat transfer satisfactorily, it is necessary to manufacture the container 10 with a material having a large thermal conductivity. On the other hand, in order to store the selected PCM 3 for a long period of time, it is necessary to configure the container 10 with a material that is insoluble and corrosion resistant to the PCM 3. Furthermore, as described in the above (2), it is desirable that the material has a strength capable of withstanding a volume change when the PCM 3 undergoes a phase change. Table 2 shows metals having a relatively large thermal conductivity as such materials.

  According to Table 2, for example, copper having a large thermal conductivity κ [W / m · K] near room temperature (κ = 386 [W / m · K], 20 ° C.), silver (418 [W / m · K). K], 20 ° C.) (or gold (295 [W / m · K], 20 ° C.)) or aluminum (204 [W / m · K], 20 ° C.) as a constituent material of the container 10. It is possible to do.

  As the heat insulating container B, a container 11 made of a heat insulating plastic material for storing the metal container 10 (hereinafter referred to as a plastic container or a plastic container) and a heat insulating material for storing the plastic container 11 are used. 1 (hereinafter also referred to as a heat-insulating material container) 12. For this reason, the ozone gas concentration measuring device 1 includes a three-layered container including a metal container 10, a plastic container 11, and a heat insulating material container 12.

  The plastic container 11 can be matched to the shape of the metal container 10 in order to achieve good thermal contact by sandwiching the gas detector 2 between the metal container 10 and mounting. It is manufactured in a horizontally-long rectangular thin box shape using a moldable plastic material. The plastic container 11 has an open portion 16 that opens upward, and a rectangular window 17 is formed near one surface of the front plate 11A. The window 17 has substantially the same size as the exposed portion 7 of the gas detector 2. In the central portion of the bottom plate 11B of the plastic container 11, a finger hole 18 used when the metal container 10 is pushed out is formed.

  The container 12 made of heat insulating material is a container opened upward, and an opening 19 for exposure is formed on the front surface corresponding to the window 17 of the plastic container 11 and corresponds to the concentration of ozone gas. A sheet 20 displaying a color chart 21 indicating colors is attached. The window 17 and the opening 19 have substantially the same size. In such a heat insulating material container 12, a plastic container 11 that houses a metal container 10 is stored at the time of measurement, and then an opening 22 that opens upward is closed by a lid 23. The lid body 23 is also formed of the same heat insulating material as the heat insulating material container 12.

  In such a three-layered container including the metal container 10, the plastic container 11, and the heat insulating material container 12, the gas detector 2 has a gap formed between the metal container 10 and the plastic container 11. The exposed portion 7 faces the outside of the heat insulating container B through the window 17 of the plastic container 11 and the opening 19 of the heat insulating container 12. In addition, the gas detector 2 is inserted into the gap 30 in a state of being in close contact with the surface of the metal container 10 so that the heat of the heat storage body A can be satisfactorily transmitted. Note that portions other than the exposed portion 7 of the gas detector 2 are covered with a plastic container 11.

  The sheet 20 is made of the same material as the sheet-like carrier 6 of the gas detector 2, and has a color chart 21 on its surface, a scale 24 of 0 ppb, 400 ppb and 800 ppb for indicating the concentration of ozone gas, and an ozone gas concentration measuring device. 1 usage warning 25 is printed, and the entire front and back surfaces are plastic-coated.

  The color chart 21 is divided into three colors, and is composed of color samples 21a to 21c with ozone concentrations of 0 ppb, 400 ppb, and 800 ppb, respectively. The color sample 21a having an ozone concentration of 0 ppb exhibits the same indigo color as the color of the exposed portion 7 of the gas detector 2 before measurement, and the color of the color sample 21b having an ozone concentration of 400 ppb is faded from the color sample 21a. The color sample 21c having an ozone concentration of 800 ppb is a color that indicates a further faded state from the color sample 21b. The color chart 21 is not limited to the one that indicates the ozone concentration step by step, and may be one that continuously displays the ozone concentration in the form of a gradation.

  The points to be considered when selecting PCM3 are that the liquid has a freezing point within the given operating temperature range, and secondly, among such liquids, the latent heat is large and stable against thermal cycles. Third, it fits well with the container material. Table 3 shows the corrosion resistance data of the material of the metal container 10 with respect to the assumed PCM material.

  For example, when n-octadecane of n-paraffin type is selected as PCM3, the melting point and heat of fusion are 28.2 ° C. and 243 [kJ / kg] from Table 1 above, respectively. And as a material of the metal container 10 which accommodates PCM3, copper with a larger thermal conductivity than Table 2 can be selected.

  As the plastic container 11, it is necessary to make the heat storage body A and the gas detection body 2 housed in the plastic container 11 less susceptible to the temperature of the outside air. Is desirable. Table 4 shows plastics having a relatively low thermal conductivity as such materials.

  For example, as a heat-insulating plastic, polystyrene (0.125 [W / m · K], 300K) or acrylic (0.189 [W / m · K) having a thermal conductivity κ of around 0.1 near room temperature. ], 300K), vinyl chloride (0.161 [W / m · K], 300K) and the like. Finally, Table 5 shows the thermophysical values of the heat insulating materials used to insulate all of them from the outside air.

  The foamed plastic heat insulating material (extruded polystyrene foam, beaded polystyrene foam, rigid polyurethane foam) can be used as the heat insulating material container 12 because it can be molded using a mold. On the other hand, in the case of an inorganic fiber-based heat insulating material (typically glass wool, rock wool), it is necessary to prepare a container for holding the fibrous material separately, which is suitable for the gas concentration measuring device of the present invention. Absent.

  From Table 5, as a heat insulating material of the container 12 made of heat insulating material, a material having a thermal conductivity of 0.04 [W / m · K] or less, an extruded polystyrene foam (κ = 0.028) of a foamed plastic heat insulating material. To 0.040 [W / m · K]), bead method polystyrene foam (κ = 0.034 to 0.043 [W / m · K]), rigid polyurethane foam (κ = 0.023 to 0.026 [K]). W / m · K]), or aerogel, particularly silica aerogel (κ = 0.17 [W / m · K]) or the like may be used.

  When measuring ozone gas with such an ozone gas concentration measuring device 1, the liquid phase PCM 3 is filled into the metal container 10 from the inlet 14, and the inlet 14 is hermetically closed with the cap 15.

  Next, the metal container 10 is housed in a plastic container 11 in a state in which the gas detector 2 is brought into close contact with a predetermined position on the front surface of the metal container 10, and the exposed portion 7 of the gas detector 2 is connected to a window. 17 to the outside of the container. On the inner edge of the upper open portion 16 of the plastic container 11, a drop prevention portion 31 made of a projecting body having a triangular cross section for preventing the gas detector 2 and the metal container 10 from coming off is integrally projected. Yes.

  Next, the plastic container 11 is loaded into the heat insulating material container 12, and the opening 22 is closed with the lid 23. Thereby, the assembly of the ozone gas concentration measuring device 1 is completed.

  Such an ozone gas concentration measuring device 1 is installed and used for a certain period of time (for example, 8 hours) in an environment where ozone gas exists, or is used while being carried by a measurer. When the measurer is to be carried around, for example, the clip 33 with the pin 34 is fixed to the back side of the container 12 made of heat insulating material by the double-sided adhesive tape 35 and the pin 34 is fixed to the measurer's clothes or used. The ozone gas concentration measuring device 1 is used by suspending it from the neck or waist by a hanging means such as a string or a chain.

  When ozone gas is present in the atmosphere of the measurement environment, the exposed portion 7 of the gas detector 2 is exposed to ozone gas and changes color. By comparing this discolored color with the color samples 21a to 21c of the color chart 21, the exposure amount of ozone gas can be measured. That is, if the color of the exposed portion 7 is substantially equal to the color of the color sample 21b, the ozone concentration is determined to be 400 ppb, and if it is approximately equal to the color of the color sample 21c, the ozone concentration is determined to be 800 ppb.

  In the measurement in a cold region, the liquid PCM 3 filled in the metal container 10 releases all solidification heat to freeze. Until the solidification heat is released, the PCM 3 in the metal container 10 is not frozen, and the temperature of the metal container 10 is fixed at the freezing point. For this reason, the metal container 10 is heated by the heat of solidification and maintained at a constant temperature. Further, since the temperature of the metal container 10 is also transmitted to the gas detector 2 by heat conduction, the gas detector 2 is also maintained at a constant temperature. This constant temperature is maintained until the PCM 3 is completely solidified. Therefore, even in a cold region, the chemical change of the organic dye contained in the exposed portion 7 of the gas detector 2 is not delayed by the outside air temperature, and the ozone concentration can be accurately measured. Since the heat of solidification is generally given per unit mass, the operable time is determined by the mass of the PCM 3 stored in the metal container 10. That is, when it is desired to extend the measurement time, a large amount of PCM3 is used. When a short time is required, a small amount of PCM3 may be used.

  Since it is sufficient for the metal container 10 to withstand a certain pressure of the solid-liquid coexisting phase, the weight of the ozone gas concentration measuring device 1 is reduced by reducing the thickness of the metal plate constituting the metal container 10. Is possible. When the measurement of the ozone concentration is completed, the metal container 10 and the heat insulating container B itself can be reused by taking out the gas detecting body 2 from the heat insulating container B and replacing it with a new gas detecting body 2. Further, PCM3 is hardly consumed and can be used as it is by returning from the solid phase to the liquid phase.

FIGS. 4A to 4C are diagrams illustrating one-dimensional heat conduction that passes through each part of the ozone gas concentration measuring device 1.
The figure (a) is the figure which simulates and shows the heat conduction in the cross section which does not include the window 17 and the opening part 19 for atmospheric exposure, (b) is the figure which simulates and shows the heat conduction in the cross section including the cover body 23, (C) is the figure which simulates and shows the heat conduction in the cross section containing the window 17 and opening part 19 for atmospheric exposure. For the most part, as shown in FIG. 4A, the PCM 3 having a temperature T ₁ is stored in a metal container 10 having a thermal conductivity κ ₁ and a thickness δ ₁ . The metal container 10 is housed in a plastic container 11 (thermal conductivity κ ₂ , thickness δ ₂ ) having heat insulation properties. Furthermore, the whole is exposed to the atmosphere of the temperature T _{outside air} through a container 12 (thermal conductivity κ ₃ , thickness δ ₃ ) made of a heat insulating material.

Hereinafter, n-octadecane is used as PCM3, copper is used as the material of the metallic container 10, and filter paper is used as the material of the sheet-like gas detector 2 (thermal conductivity κ ₄ = 0.13 [W / m · K]. , Thickness δ ₄ = 100 [μm] = 0.1 [mm]), polyethylene is assumed as the material of the plastic container 11, and extruded polystyrene foam is assumed as the material of the container 12 made of the heat insulating material. Then, it is estimated how much heat energy escapes to the outside air by exposure to the atmosphere, and the required mass of PCM 3 is calculated. In the following estimation, the heat transfer coefficient h by natural convection with the outside air is h = 10 [W / m ² · K].

  Since the heat transfer rate per unit area (q / A) is the same at any boundary surface, the following equation is established using Fourier's law of heat conduction.

  Here, A is a heat transfer area, and q is a heat transfer amount per unit time.

From the above equation (1), when T ₂ , T ₃ and T ₄ are eliminated and the overall heat transfer coefficient U _a is obtained, the following equation (2) is given.

When the overall heat transfer coefficient U _a is used, the heat transfer amount q is given by the following equation (3).

Here, △ T _entire ≡ (T ₁ -T _{outside air)} represents the total temperature difference between the temperature T _l and the outside air temperature T _{outside air} PCM. Copper of thickness δ ₁ = 1 [mm], κ ₁ = 384 [W / m · K], thickness δ ₂ = 1.5 [mm], κ ₂ = 0.34 [W / m · K] For a multilayer structure comprising a polyethylene container 11 and a resin container 12 of extruded polystyrene foam having a thickness δ ₃ = 1 [cm] and κ ₃ = 0.028 [W / m · K], The overall heat transfer coefficient U _a is 2.17 [W / m ² · K] (when the heat insulating material thickness is 1 [cm]) or 1.22 [W / m · K] (the heat insulating material thickness is 2 [cm]). In the case of

In the upper part of the container, as shown in FIG. 4B, the PCM 3 held at the temperature T ₁ is stored in a metal container 10 having a thermal conductivity κ ₁ and a thickness δ _1. It is exposed to the atmosphere of the temperature T _{outside air} through a container 12 made of a heat insulating material having a thermal conductivity κ ₃ and a thickness δ ₃ . Considering in the same manner as the above equation (1), the overall heat transfer coefficient U _b in this portion is given by the following equation (4).

Extrusion method with thickness δ ₁ = 1 [mm], κ ₁ = 384 [W / m · K], thickness δ ₃ = 1 [cm], κ ₃ = 0.028 [W / m · K] For a multilayer structure composed of polystyrene foam, the overall heat transfer coefficient U _b is 2.19 [W / m ² · K] (when the heat insulating material thickness is 1 [cm]), or 1.23 [W / M · K] (in the case of a heat insulating material thickness of 2 [cm]), which is substantially the same as the value in the configuration of FIG. That is, U _b ≈U _a . Therefore, it can be said that the heat insulation effect of the container 11 using a heat insulating plastic material is insignificant.

4C, the PCM 3 is stored in a metal container 10 having a thermal conductivity κ ₁ and a thickness δ ₁ , and the metal container 10 has a thermal conductivity κ ₄ . It is exposed to the atmosphere of temperature T _outside through a gas detector 2 (mainly composed of paper) having a thickness δ ₄ . Considering in the same manner as the above equation (1), the overall heat transfer coefficient U _c in this portion is given by the following equation (5). Copper of thickness δ ₁ = 1 [mm], κ ₁ = 384 [W / m · K], thickness δ ₄ = 0.1 [mm], κ ₄ = 0.13 [W / m · K] The overall heat transfer coefficient U _c is 9.92 [W / m ² · K] with respect to the multilayer structure formed of the gas detector 2. The heat transfer in this part is almost determined by heat convection by air.

  Here, when the amount of PCM 3 to be mounted is M [kg] and the latent heat per unit mass of PCM 3 is Hm [kJ / kg], the amount of heat Q [J] released to the external environment while the PCM 3 undergoes phase change. Is given by Q = M · Hm.

Now, a metal container 10 having a business card size, that is, 9 cm long × 6 cm wide × 2 cm thick is assumed. From Table 1, since the heat of fusion Hm of octadecane, which is PCM, is 243 [kJ / kg] and the density ρ is 850 [kg / m ³ ] in the case of a solid, the mass M of the solid octadecane is given by the following formula (6). Given.

  The heat of fusion Q is given by the following equation (7).

The total surface area S of the metal container 10 filled with the PCM 3 is given by the following equation (8).

Of these, the surface area S ₁ of the portion exposed to the atmosphere is given by the following equation (9).

In the ozone gas concentration measuring device 1 having the structure shown in the first embodiment, when octadecane which is PCM3 is kept at a temperature T ₁ = 30 ° C., it is exposed to an environment having an outside temperature of 0 ° C. The total temperature difference ΔT _overall = 30 ° C., and the thermal resistance of the part exposed to the atmosphere and the other part are: R _{atmospheric exposure} = (A _opening / Uc) ⁻¹ = (2.25 × 10 ⁻⁴⁾ × 9.92) ⁻¹ = 448 [° C./W], R _otherwise = (A _{exposed part} / Ua) ⁻¹ = (1.6575 × 10 ⁻² × 2.19) ⁻¹ = 27.55 [° C. / W] (when the heat insulating material thickness is 1 cm) or 49.1 [° C./W] (when the heat insulating material thickness is 2 cm). Since these are connected in parallel, the total thermal resistance is given by 1 / R _overall = 1 / R _{atmospheric exposure} + 1 / R, _otherwise R _overall = 25.95 [° C / W] (when the insulation thickness is 1 cm) ) Or 44.25 [° C./W] (when the heat insulating material thickness is 2 cm).

Therefore, the amount of heat transfer q escaping from the multilayer structure shown in FIG. 4 to the outside air is q = ΔT _overall / R _overall = 1.16 [W] (when the heat insulation thickness is 1 cm) or 0.68 [W]. (When the thickness of the heat insulating material is 2 cm).

Therefore, the time τ held at the temperature T ₁ by dividing the total amount of heat Q that can be supplied during the phase change of the PCM 3 by the heat transfer amount q per unit time is given by the following equation (10).

Therefore, when the area of the opening 19 is 1.5 [cm ² ], by using the heat insulating material container 12 having a heat insulating material thickness of 2 cm, the transition temperature of 28.2 ° C. is about 9.1 [ h] It can be seen that it can be held to the extent.

  In addition, when PCM3 which the whole melt | dissolves completely is cooled, according to the relationship between the heat capacity of PCM3 and a heat flow, temperature will fall gradually, and solidification will begin when it reaches freezing point temperature soon. While solidification is in progress, the temperature is kept constant, and once everything has solidified, the temperature begins to drop again. Conversely, when the temperature is raised, the opposite phase change (phase change from solid to liquid) occurs due to absorption of heat of fusion.

  The above is the ideal temperature behavior of PCM3. However, in reality, a considerable degree of supercooling appears for solidification, and the temperature inside PCM is uneven, which is slightly different from the ideal case. There is also concern about showing changes.

  In particular, when a high-purity medium is used as PCM3, since the degree of supercooling tends to increase, PCM3 in which impurities are slightly mixed may be used. In that case, decomposition of the PCM 3 due to contamination of impurities or corrosion of the structural material may be promoted. Therefore, it is desirable that the material of the metal container 10 is selected in consideration of the selection of impurities. .

  Therefore, as PCM3 used in the present invention, in addition to PCM3 (for example, n-octadecane), a known heat storage and heat-retaining material, n-paraffin (having a melting point different from n-octadecane), and low molecules such as glycerin. Compound, polyethylene glycol, polyvinyl alcohol, polyethylene, cross-linked polyethylene, polymer such as fluororesin, water-insoluble water-absorbent resin, carboxymethylcellulose, sodium alginate, potassium alginate, fine silica, synthetic mica, thickener, phenolic, amine-based , Hydroxylamine-based, sulfur-based, phosphorus-based and other antioxidants, chromate, polyphosphate, metal corrosion inhibitors such as sodium nitrite, and fatty acid metal salts such as stearate and behenate. You may add additives, such as a cooling inhibitor, suitably.

  In this embodiment, paraffin, particularly octadecane, is described as an example of PCM3, but other than that, a hydrated salt having a heat of fusion Hm [kJ / kg] of around 200, for example, hydrated chloride Calcium, hydrous lithium nitrate, sodium sulfate decahydrate (Glauber salt), hydrated sodium carbonate, disodium hydrogen phosphate dodecahydrate, zinc nitrate hexahydrate, and the like can also be used. Other organic substances suitable for PCM3 include trimyristin, methyl palmitate, capric acid (decanoic acid), d-form-lactic acid, glycerin (glycerol), acetic acid, caprylic acid (octanoic acid), ethylenediamine, formic acid, etc. Can also be used.

  As an example of solid PCM3, a heat storage microcapsule filled with PCM3 in a microcapsule having a diameter of 2 to 3 μm may be used. As described in detail in the first embodiment, Needless to say, it is not limited to liquid pure substances.

  For example, the comforter shown in Table 1 is one in which heat storage microcapsules (Thermasorb (registered trademark)) coated with a metal oxide gel having a diameter of 2 to 3 μm are dispersed in urethane foam. This thermal storage microcapsule is filled with PCM such as n-paraffinic straight chain hydrocarbons, and the microcapsule functions to absorb and release heat by changing the state between liquid and solid depending on temperature. It has itself.

  Similarly, the PMCD (Miki Riken Kogyo Co., Ltd.) shown in Table 1 is a powder-like heat storage regenerator microcapsule coated with a core material paraffin with a shell material melamine resin and is provided in a powder form.

  Therefore, a microcapsule filled with PCM3 may be used as in the second embodiment shown in FIG. That is, in this embodiment, the thermal storage microcapsule 36 (36A, 36B) is filled with PCM3 made of powder having a diameter of 2 to 3 μm having a transition point corresponding to the operating temperature of the gas detector 2 constituting the present invention. Then, the microcapsule 36 is filled in the metal container 10 in a close-packed manner to constitute the heat storage body as described in the first embodiment of the present invention. In this case, since the PCM 3 is only filled in the metal container 10 in a state of being accommodated in the microcapsule 36, a process of coating a corrosion-resistant protective film on the inner surface of the metal container 10 in order to prevent corrosion due to the PCM 3 is omitted. Is possible. The shell portion constituting the microcapsule 36 itself is a coating that improves the oxidation resistance, solvent resistance, mechanical stress resistance and flame resistance of the built-in PCM 3.

  Similarly, the outlast shown in Table 1 is a fibrous heat storage and heat insulating material in which heat storage microcapsules filled with paraffin wax and having a diameter of 2 to 3 μm are dispersed in acrylic fibers. It is also possible to configure the heat storage body described in the first embodiment of the present invention by filling the fibrous heat storage heat retaining material into the metal container 10.

  In general, when a solid sphere having a diameter of d μm is filled into a cube having a side length d, when the solid sphere is filled in a simple cubic lattice, the occupation ratio of the hard sphere is only π / 6 = 0.524, and 0.476 Voids remain. Since the amount of heat storage is determined by the amount of PCM in the microcapsule, it is necessary to further improve the occupation ratio of the hard sphere. Therefore, when filling a face-centered cubic lattice shape (or hexagonal close-packed structure), which is called a close-packed structure, the occupancy of the hard sphere is improved to √2π / 6 = 0.740, but still 0.26. Voids remain. Therefore, if the gap formed by the steel ball of radius √2d / 4 at the position of the face center and the four lattice points surrounding it is filled with the second hard ball having a different diameter, the second rigid body The diameter of the sphere may be (2-√2) /2=0.293 times the diameter of the first hard sphere. By filling the second hard sphere in the gap, the filling rate increases by 3π (20−14√2) /128=0.148. Therefore, the heat storage microcapsule 36A having a diameter of 2 μm and the heat storage microcapsule 36B having a diameter of 0.586 μm are filled in the metal container 10 to physically vibrate, thereby forming a heat storage body having a filling rate of about 0.755. Is possible.

  Needless to say, after the metal container 10 is filled with the powder heat storage microcapsules 36 by the above-described method, the injection port 14 (FIG. 2) in the upper lid 13 is made airtight by the metal cap 15. By closing so as to form a sealed container. Alternatively, a mold having approximately the same volume as that of the metal container 10 is prepared, and heat storage microcapsules each having a peak particle diameter of 2 μm and 0.586 μm are filled therein, and the same as above. In addition, the filling rate is improved by applying vibration to the liquid, and methyl methacrylate liquid is press-fitted and penetrated into the remaining gap 0.245, and radicals are generated by ultraviolet irradiation or the like to perform addition polymerization. Finally, polymethyl methacrylate (or acrylic resin) filled with heat storage microcapsules is obtained. Here, the methyl methacrylate liquid to be press-fitted and permeated is obtained by subjecting a liquid previously dissolved in an organic solvent to addition polymerization to such an extent that the viscosity penetrates into a container filled with microcapsules by ultraviolet irradiation or the like. .

  In this case, the acrylic resin acts as a skeleton member for maintaining the shape of a heat storage plate or the like, and the heat storage action itself is carried by the heat storage microcapsules. Incidentally, since the thermal conductivity of pure acrylic resin (PMMA = polymethyl methacrylate) is 0.21 [W / m · K], it is a thermal conductivity characteristic close to that of a heat insulating material. However, 75% of the total volume of the heat storage plate is constituted by PCM, and the composition ratio of PMMA as a skeleton material is only about 24%.

  When a heat storage cold storage microcapsule coated with melamine resin is used as the powdery PCM to be filled, melamine resin is suitable as the skeleton resin for constituting the heat storage plate. Also in this case, an intermediate solution in which melamine and formalin are reacted in advance to produce methylol melamine, dimethylol melamine, and trimethylol melamine is prepared. The viscosity of the solution is kept at such a level that the solution penetrates into the heat storage cold storage microcapsule filling body. After allowing the intermediate solution to penetrate into the filler, the melamine resin finally became a skeleton by heating to a temperature that does not destroy the melamine coating of the microcapsules and causing the methyleneation reaction to cure. A heat storage plate filled with heat storage cold storage microcapsules is obtained. Incidentally, the thermal conductivity of pure melamine resin is about 0.32 to 0.421 [W / m · K], which is 1.5 to 2 times that of PMMA. As in the discussion at PMMA, melamine resin is only a skeleton material, and it goes without saying that the heat storage action itself is carried by heat storage cold storage microcapsules that occupy 75% of the total volume of this heat storage plate. It is not. These heat storage plates bring about the same action as the metal container 10 filled with PCM3. However, it is desirable to form a metal film such as aluminum on the entire surface of the heat storage plate by vapor deposition or the like as a measure against degasification while increasing the thermal conductivity. If such a metal film is formed, the metal container 10 is not necessarily required, and the gas concentration measuring device itself can be reduced in weight.

  Here, in the said 1st Embodiment, although the ozone gas concentration measuring device 1 used in a cold region was demonstrated, according to the average temperature of the place where this ozone gas concentration measuring device 1 is used, it is set to the metal container 10. By changing the phase state of the PCM 3 to be stored, it can be used even in hot areas. In that case, an ozone gas concentration measuring device using heat of fusion at the time of phase change from solid to liquid may be used in a hot region. That is, when the solid changes to a liquid, the heat of fusion is absorbed from the outside, so the temperature of the PCM 3 is fixed at the melting point. For this reason, the heat | fever of the metal container 10 is deprived and it fixes to this melting point. Further, when the metal container 10 is cooled, the temperature of the gas detector 2 is lowered and held at the melting point. Therefore, the temperature of the gas detector 2 can be kept constant until the PCM 3 completely changes from solid to liquid, and ozone gas can be measured.

  6 is an exploded perspective view showing a third embodiment in which the present invention is applied to an ozone gas concentration measuring device, and FIG. 7 is a sectional view taken along line VII-VII in FIG. This embodiment is applied to an ozone gas concentration measuring device 40 suitable for use in a hot area using the heat of vaporization (heat of vaporization) when the PCM 3 in a liquid state is vaporized. Note that the same constituent members and portions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The upper lid 13 of the metallic container 10 that stores the PCM 3 in a liquid state is provided with an inlet 14 for the PCM 3 and a plurality of transpiration units 41 that evaporate the PCM 3 to the outside of the container. The inlet 14 is hermetically sealed by the cap 15 after injecting the PCM 3. The transpiration unit 41 includes a plurality of transpiration holes 42 formed in the upper lid 13 and a transpiration member 43 that sucks up the PCM 3 inside the container and evaporates it outside the container. In particular, as the evaporating member 43 for evaporating the liquid PCM 3 into the atmosphere at a constant rate, a material having a good liquid absorbing property, such as twisted yarn or felt, is used, and the inner end of the evaporating member 43 is the PCM 3 in the metal container 10. It is immersed and the outer end is led out of the container through the transpiration hole 42. For this reason, a plurality of insertion holes 46 are also formed in the lid 23 corresponding to the transpiration portions 41 in order to evaporate the PCM 3 to the outside of the container. Other configurations are the same as those in the first embodiment.

FIG. 8 is a pressure-volume diagram of PCM when the temperature is below the critical temperature of liquid PCM.
When the volume is variable in the isothermal state, the pressure rapidly decreases as the volume increases slightly when the PCM 3 is in the liquid phase state, and the pressure decreases as the volume increases in the gas phase state. In the gas-liquid coexistence state, the pressure is maintained at a constant value even if the volume changes. This is because in the gas-liquid coexistence state, gas phase liquefaction or liquid phase vaporization occurs so as to adjust the volume change, and the pressure is adjusted to be constant.

  As will be described in detail below, in the third embodiment of the present invention, the temperature of the gas detector 2 is maintained at a constant temperature using the heat of vaporization of the liquid PCM 3. For this purpose, liquid PCM 3 is infiltrated into a transpiration member 43 such as a twisted yarn and transpiration into the atmosphere, thereby fixing the boiling point temperature and preventing an increase in pressure due to vaporization in the metal container 10. In this case, since it is sufficient for the metal container 10 to withstand a certain pressure of the gas-liquid coexisting phase, the weight of the metal container 10 is reduced by reducing the thickness of the metal plate constituting the metal container 10. Is possible.

  The measurement time of the ozone concentration is determined by the amount of PCM3, in other words, the time until PCM3 is completely evaporated. When the measurement of the ozone concentration is completed, the metal container 10 and the heat insulation container B can be reused by taking out the gas detection body 2 from the heat insulation container B and replacing it with a new gas detection body 2.

When the liquid PCM 3 is present inside the metal container 10 and maintains the gas phase-liquid phase coexistence state, the temperature T ₁ of the metal container 10 is fixed to the boiling point temperature of the built-in liquid PCM 3. Therefore, by changing the type of PCM 3 stored in the metal container 10, the boiling point can be changed and the required operating temperature can be realized. Therefore, assuming use in a hot area, the PCM 3 to be stored in the metal container 10 may be a volatile liquid whose boiling point is several degrees below the average temperature of the local castle. The temperature of the metal container 10 is maintained at a constant value (boiling point temperature) by the vaporization heat Hb when the liquid PCM 3 evaporates.

  Here, as the PCM 3 that changes in phase from a liquid to a gas, a substance having a transition point in the temperature range that is assumed as the operating temperature of the gas detector 2 is selected. Accordingly, the physical properties of several PCMs 3 that can be used at a temperature below 40 ° C. and near room temperature are shown in Table 6 below.

The organic compound-based PCM3 suitable for the present embodiment of the present invention includes n-pentane, isopentane, neopentane, n-butane, 1-pentene, acetaldehyde, ethyl methyl ether, diethyl ether, ethylene oxide, R11 (ie, trichloro Fluoromethane, CCl ₃ F), R21 (ie, dichlorofluoromethane, CHCl ₂ F), dichloromethane, carbonyl chloride (ie, phosgene, COCl ₂ ), R114 (ie, 1,2-dichlorotetrafluoroethane, C ₂ Cl ₂ F ₄ ).

  Many liquids having a boiling point near room temperature are present in organic compounds and refrigerant liquids, but many of them are flammable and are not very good in view of their harm to the human body.

  The operating principle of the ozone gas concentration measuring device 40 in the third embodiment is different from those in the first and second embodiments in that the heat of vaporization Hb is used instead of the heat of fusion Hm. However, since the amount of liquid PCM3 decreases due to transpiration, it is necessary to replenish the amount of PCM3 periodically.

  FIG. 9 is a temperature-pressure diagram of PCM, A is a temperature-pressure diagram in the case of water, and B is a temperature-pressure diagram of a general substance other than water. As the temperature rises, the liquid PCM (A, B) sealed in a fixed volume container changes into a gas, and the internal pressure of the container increases. The container is required to be strong enough to withstand this internal pressure.

  For concrete consideration, when isopentane having a boiling point of 27.9 ° C. is selected as PCM3, the metal container 10 is assumed to be aluminum, copper or the like. However, in order to consider the operation time, not only the heat of evaporation during evaporation but also the amount of decrease in PCM3 that can be achieved by the evaporation rate becomes a problem.

Assuming that Stefan's Law is established for the process of PCM3 evaporating and diffusing from the transpiration member 43 through an air layer stationary at 25 ° C under the same temperature, the total movement of PCM3 The amount m _liquid (evaporation amount) is given by the following equation (11).

Here, A is the area of transpiration [m ² ] (= 9.8 × 10 ⁻⁷ [m ² ], the diameter of the transpiration hole 42 is about 0.5 [mmφ]), and p is atmospheric pressure. (= 1.013 × 10 ⁵ [Pa]), (z ₂ −z ₁ ) is the length of the insertion hole 46 for evaporation provided in the lid 23 (= 2 × 10 ⁻² [m], but heat insulation) In the case of a thickness of 2 [cm], therefore, z _l is the height of the upper lid 13, z ₂ is the height of the transpiration vent 46 of the lid 23, and P _{liquid 1} is for transpiration in the upper lid 13 of z ₁ . Assuming the partial pressure of PCM3 in the hole 42, here, the saturated vapor pressure of isopentane at 25 ° C. (= 9.184 × 10 ⁴ [Pa]). On the other hand, the vapor pressure p _{liquid 2} of PCM3 in the evaporating ventilation hole 46 provided in the lid 23 made of heat insulating material at the position z ₂ is 0 because it diffuses into the dry air. M _{phase change material} is the molecular weight of PCM3 (M _isopentane = 72.1), T _{outside air} is 25 ° C. at outside temperature, R ₀ (= 8.314 [J / mo1 · K]) is gas constant, 25 of isopentane. The diffusion coefficient D at 0 ° C. uses D = 8.42 × 10 ⁻⁶ [m ² ] (NHChen, DFOthmer, J. Chem. Eng. Data, 7, 37 (1962)). Accordingly, the evaporation rate m of _isopentane , m _isopentane, is given by the following equation (12).

As in the first embodiment, assuming a metal container 10 having a business card size, that is, 9 cm long × 6 cm wide × 2 cm thick, the density ρ of isopentane (liquid) is ρ = 0.62007 [g / Cm ³ ], this metal container 10 has isopentane of M = ρV = 0.62007 × 9 × 6 × 2 = 66.97 [g]. If it decreases at the above evaporation rate, it takes 2.322 × 10 ⁷ [s] = 6.45 × 10 ³ [h] to evaporate all. When all of them evaporate, the temperature of the metal container 10 is not fixed at the transition point of isopentane. Therefore, even when not all but about 1/3 evaporates, 2.18 × 10 ³ [h] = 90 During the [day] time, isopentane remains in the metal container 10 in an amount of 1/3 or more.

  FIG. 10 is an exploded perspective view showing a fourth embodiment of the present invention, and FIG. 11 is a sectional view of a pressure reducing valve. This embodiment is applied to an ozone gas concentration measuring device 60 suitable for use in a hot area using sublimation heat when the PCM 3 in a solid (or powder) state is vaporized. As long as the solid (powdered) PCM3 exists in the metal container 10 and the gas-solid phase coexistence state is maintained, the temperature of the metal container 10 is fixed to the sublimation temperature of the solid (powdered) PCM3 incorporated. Is done. Since the internal pressure of the container 10 is increased by sublimation from the solid, the metal container 10 is fixed at the boiling point temperature by letting this pressure escape to the outside of the container by the pressure reducing valve 61 provided on the upper lid 13. The pressure increase due to the vaporization of PCM3 in 10 is prevented. In this case, the metal container 10 is required to have a shape and thickness that can withstand a certain pressure of the solid-gas coexisting phase.

  For this reason, in this Embodiment, the cross-sectional shape of the metal container 10 is made elliptical. The plastic container 11 also has an elliptical cross-sectional shape that can accommodate the metal container 10, and the heat-insulating container 12 also has a cross-section that can store the plastic container 11. The shape is an ellipse.

  By changing the type of PCM 3 stored in the metal container 10, the sublimation point can be changed and the required operating temperature can be realized. For example, assuming use in a hot area, the PCM 3 to be stored in the metal container 10 may be a sublimable solid having a sublimation point that is several degrees below the average temperature in the area. The temperature of the metallic container 10 is kept at a constant value (sublimation point) by the sublimation heat Hs when the PCM 3 sublimates.

  Here, a substance having a transition point in the temperature range assumed as the operating temperature of the gas detector 2 is selected for the PCM 3 that changes phase from solid to gas. Therefore, Table 7 below shows physical property values of some PCMs that can be used at about 40 ° C. or less and near room temperature.

  Examples of the organic compound-based PCM3 suitable for this embodiment of the present invention include decanoic acid (ie, capric acid), lauric acid (ie, dodecanoic acid), p-nitrophenol, o-nitroaniline, and ε-caprolactam. Can be mentioned.

  In FIG. 11, the pressure reducing valve 61 includes a main body 63 formed of a cylindrical body open at both ends, a cap 64 which is also formed of a cylindrical body open at both ends, and is screwed into an upper end side opening of the main body 63, and the main body 63. The assembled ball 65 and the compression coil spring 67 that urges the ball 65 downward and presses the ball 65 against the seat ring 66, the cylindrical body 68 that houses the compression coil spring 67 and the ball 65, and the lower end of the main body 63 are It is composed of a combined double nut 69 or the like. The main body 63 is screwed into a screw hole formed in the upper lid 13 at the lower end, and is fixed by a double nut 69. The ball 65 is normally pressed against the seat ring 66 to hold the pressure reducing valve 61 in a fully closed state, and is pushed up against the compression coil spring 67 when the pressure in the metal container 10 rises above a certain value. The pressure reducing valve 61 is opened. That is, the internal pressure in the metal container 10 increases by the saturated vapor pressure of the vaporized PCM 3, so that the pressure reducing valve 61 releases the increased pressure. The valve opening start operating pressure can be changed by adjusting the pressing force of the compression coil spring 67 against the ball 65 by the cap 64. This operating pressure is set to about 1.1 atm. A through hole 62 is formed in the lid 23 at a position facing the pressure reducing valve 61 (FIG. 10).

  The operating principle of the ozone gas concentration measuring device 60 is different in that sublimation heat Hs is used instead of the heat of fusion Hm shown in the first and second embodiments. However, since solid (powder) PCM3 is vaporized by sublimation and diffuses into the atmosphere via the pressure reducing valve 61, the amount of the PCM3 needs to be periodically replenished. is there.

  Also in such an ozone gas concentration measuring device 60, the temperature of the metal container 10 is fixed to the sublimation temperature until all of the solid PCM 3 is vaporized, so that the exposed portion of the gas detector 2 even in a hot region. The chemical concentration of the organic dye contained in 7 is not accelerated by the outside air temperature, and the ozone concentration can be measured accurately.

  FIG. 12 is an external perspective view of an ozone gas concentration measuring device 70 showing a fifth embodiment of the present invention. In this embodiment, the heat storage body A and the heat insulation container B are formed in a vertically long thin box shape and are used by being suspended from the neck by a string 71. The ozone gas concentration measuring device 70 constitutes a measuring device for a hot region using PCM that changes phase from a liquid to a gas as in the third embodiment.

  FIG. 13 is an external perspective view of an ozone gas concentration measuring device 80 showing a sixth embodiment of the present invention. In this embodiment, the heat storage body A and the heat insulating container B are similarly formed in a vertically long thin box shape, and are used by being fastened to clothes by pins 34 and clips 81. The ozone gas concentration measuring device 80 constitutes a measuring device for a hot region using PCM that changes phase from a liquid to a gas as in the third embodiment.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and combinations are possible. For example, in the above-described embodiment, a dye having an indigo ring is used as a dye that reacts with ozone gas. However, the present invention is not limited to this, and a triphenylmethane dye, a fuxoimine ring, or the like may be used.

Moreover, although the above-mentioned embodiment demonstrated the example applied to ozone gas concentration measuring device 1,40,60,70,80, all are not specified to this, For example, nitrogen dioxide gas is used as a detecting agent. When a gas detector in which a porous body is impregnated with a mixture of a diazotizing reagent that reacts with (NO ₂ ) and a coupling reagent is used, the present invention can also be applied to a nitrogen dioxide gas concentration measuring device.

  Furthermore, not only a gas concentration measuring device using a PCM that changes phase from liquid to solid, liquid to gas, and solid to gas, but from solid to liquid (for heat), from gas to liquid (for cold regions), from gas to solid ( It can also be applied to a gas concentration measuring device using a phase-changing substance (for cold regions). In that case, as described above, the metal container 10 may have a pressure-resistant structure or a compressor.

  Furthermore, the heat insulation container may be formed by integrally forming a plastic container and a heat insulation material container.

It is a figure for demonstrating the principle of operation of this invention. It is a disassembled perspective view of the ozone gas concentration measuring device which shows the 1st Embodiment of this invention. It is the III-III sectional view taken on the line of FIG. (A)-(c) is a figure which simulates and shows the one-dimensional heat conduction which passes a multilayer structure. It is sectional drawing of the ozone gas concentration measuring device which shows the 2nd Embodiment of this invention. It is a disassembled perspective view of the ozone gas concentration measuring device which shows the 3rd Embodiment of this invention. It is the VII-VII sectional view taken on the line of FIG. It is a pressure-volume diagram of a liquid phase change substance. It is a temperature-pressure diagram of a phase change substance. It is a disassembled perspective view of the ozone gas concentration measuring device which shows the 4th Embodiment of this invention. It is sectional drawing of a pressure reducing valve. It is an external appearance perspective view of the gas concentration measuring device which shows the 5th Embodiment of this invention. It is an external appearance perspective view of the gas concentration measuring device which shows the 6th Embodiment of this invention. It is a figure which shows the temperature dependence (Arrhenius plot) of the fading (or coloring) reaction rate of an organic dye.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ozone gas concentration measuring device, 2 ... Gas detector, 3 ... Phase change substance, 7 ... Exposed part, 10 ... Metal container, 11 ... Plastic container, 12 ... Heat insulation container, 17 ... Window, DESCRIPTION OF SYMBOLS 19 ... Opening part, 21 ... Color chart, 36 ... Microcapsule, 41 ... Evaporation part, 42 ... Evaporation hole, 43 ... Evaporation member, 40 ... Ozone gas concentration measuring device, 60 ... Ozone gas concentration measuring device, 61 ... Pressure reducing valve, 70, 80 ... ozone gas concentration measuring device, A ... heat storage, B ... heat insulation container.

Claims (18)

A gas detector having an exposed portion that changes color in response to a specific gas, a heat storage body that keeps the temperature of the gas detector constant, and a heat insulating container that houses the heat storage body and the gas detection body,
The heat storage body is composed of a phase change material that changes phase by latent heat in a certain temperature range under atmospheric pressure, and a metal container that stores the phase change material,
The gas detector is housed in the heat insulating container in close contact with the surface of the metal container, and an opening is provided in the heat insulating container to expose the exposed portion of the gas detector to the outside. Gas concentration measuring instrument. A gas detector having an exposed portion that changes color in response to a specific gas, a heat storage body that keeps the temperature of the gas detector constant, and a heat insulating container that houses the heat storage body and the gas detection body,
The heat storage body is composed of a phase change material that changes phase by latent heat in a certain temperature range under atmospheric pressure, and a metal container that stores the phase change material,
The heat insulating container is made of a plastic container having a window and containing the metal container and the gas detector, and a heat insulating material having an opening corresponding to the window and containing the plastic container. With a container of
The gas detector is disposed in a gap between the metal container and the plastic container in a state of being in close contact with the metal container, and the exposed portion is disposed outside the heat insulating container from the window and the opening. Gas concentration measuring device characterized by being exposed to The gas concentration measuring device according to claim 1 or 2,
The gas concentration is characterized in that the phase change substance is any one of a substance that changes phase from solid to liquid, liquid to solid, liquid to gas, gas to liquid, solid to gas, and gas to solid. Measuring instrument. The gas concentration measuring device according to claim 1 or 2,
The metal container has a sealed structure,
A gas concentration measuring device characterized in that the phase change material is made of solid or powder, and the temperature of the gas detector is kept constant by the heat of fusion. The gas concentration measuring device according to claim 1 or 2,
The metal container has a sealed structure,
A gas concentration measuring device characterized in that the phase change substance is made of a liquid and the temperature of the gas detector is kept constant by the heat of solidification. The gas concentration measuring device according to claim 1 or 2,
The phase change substance is a liquid, and the temperature of the gas detector is kept constant by the heat of vaporization,
A gas concentration measuring device, wherein a transpiration unit for sucking up the phase change material and evaporating it outside the container is provided in the metal container. The gas concentration measuring device according to claim 1 or 2,
The phase change material is a solid, and the temperature of the gas detector is kept constant by sublimation heat.
A gas concentration measuring device characterized in that a pressure reducing valve is provided in the metal container for releasing the internal pressure when the internal pressure becomes higher than a predetermined value. The gas concentration measuring device according to claim 1 or 2,
The phase change material is an n-paraffin hydrocarbon, an organic compound, an organic solvent in which a fragrance is dissolved, a hydrate or a hydrate to which a phase separation inhibitor is added, or a hydrate to which a supercooling inhibitor is added. A gas concentration measuring device characterized by being one of them. The gas concentration measuring device according to claim 1 or 2,
The gas storage device according to claim 1, wherein the heat storage body is configured by storing the phase change material in a microcapsule and filling the microcapsule as a powder into a metal container. The gas concentration measuring device according to claim 9, wherein
A heat storage plate is formed by coating the microcapsules with a resin, and a metal film is formed on the surface of the heat storage plate. The gas concentration measuring device according to claim 8, wherein
The phase change material is at least one paraffin selected from the group consisting of n-eicosane, n-nonadecane, n-octadecane, n-heptadecane, n-hexadecane, n-pentadecane, n-tetradecane, and n-tridecane. Gas concentration measuring device characterized by being a hydrocarbon. The gas concentration measuring device according to claim 8, wherein
The hydrate or the hydrate added with the phase separation inhibitor or the hydrate added with the supercooling inhibitor is hydrated calcium chloride, hydrous lithium nitrate, sodium sulfate decahydrate, hydrated carbonic acid. Of sodium, disodium hydrogen phosphate dodecahydrate, zinc nitrate hexahydrate, calcium bromide hexahydrate, zinc sulfate heptahydrate, iron bromide hexahydrate Any one of the gas concentration measuring devices. The gas concentration measuring device according to claim 8, wherein
The organic solvent in which the organic compound or fragrance is dissolved is trimyristin, methyl palmitate, capric acid, d-form-lactic acid, glycerin, acetic acid, caprylic acid, ethylenediamine, formic acid, n-pentane, isopentane, neopentane, n-butane , 1-pentene, acetaldehyde, ethyl methyl ether, diethyl ether, ethylene oxide, R11, R21, dichloromethane, carbonyl chloride, R114, lauric acid, p-nitrophenol, o-nitroaniline, ε-caprolactam The gas concentration measuring device characterized by being. The gas concentration measuring device according to claim 1 or 2,
The metal container is made of any one of copper, aluminum, silver, tungsten, and zinc, and the inner surface is coated with a corrosion-resistant protective film, and further, a metal piece having a good thermal conductivity or a substantially spherical fine particle or A gas concentration measuring device characterized in that fibrous fine particles are filled in a container. The gas concentration measuring device according to claim 14, wherein
A gas concentration measuring device, wherein the fine particles to be filled are any one of alumina fine particles and silica fine particles. The gas concentration measuring device according to claim 14, wherein
The gas concentration measuring device, wherein the corrosion-resistant protective film is a surface coat film of plastic, glass or fluororesin. In the gas concentration measuring device according to any one of claims 1 to 16,
A gas concentration measuring device, wherein a sheet on which a color chart indicating a color corresponding to a specific gas concentration is attached is attached to a surface where an opening of the heat insulating material container is formed. The gas concentration measuring device according to claim 6, wherein
A gas concentration measuring device comprising: a transpiration hole provided in a metal container with the transpiration portion; and a liquid-absorbing transpiration member inserted into the transpiration hole and projecting at one end to the outside of the container.

Images