Gas detector and leaked gas detection system

Abstract

To provide a gas detector that detects refrigerant gas present in a distant target space.SOLUTION: A gas detector 10 comprises a detection unit 22. The detection unit 22 detects refrigerant gas present in a target space by using a phenomenon that light in a predetermined wavelength within any one wavelength range of a plurality of wavelength ranges is absorbed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas detection device and a gas leakage detection system. [Background technology]

[0002] Patent Document 1 (JP 2006-275641 A) shows a gas concentration measurement device equipped with a detector gas cell that contains a gas to be detected and a reference gas cell that contains a reference gas. This device measures the concentration of methane gas in the detector gas cell using a photodetector that receives laser light that has passed through each gas cell. Summary of the Invention [Problem to be solved by the invention]

[0003] In refrigeration cycle devices such as air conditioners, refrigerants often circulate, but refrigerants can leak from the refrigerant circuit. When using refrigeration cycle devices in which 1,1,1-trifluoroethane (R143a), propane (R290), or trans-1,2-difluoroethylene (R1132(E)) is sealed in the refrigerant circuit, a device that detects the refrigerant gas concentration is required to detect refrigerant leaks.

[0004] Conventionally, infrared absorption spectroscopic devices or semiconductor devices have been used to measure the gas concentration by introducing gas into the device.

[0005] However, it is difficult for such devices to detect refrigerant gas near the ceiling of a room. Although a portable device can be carried near the ceiling, if it is desired to detect a specific gas in multiple locations in the space near the ceiling, the detection operation takes a long time. [Means for solving the problem]

[0006] A gas detection device according to a first aspect is a gas detection device for detecting a gas present in a remote target space, and includes a detection unit. The detection unit detects the gas by utilizing absorption of light of a predetermined wavelength. In the gas detection device according to the first aspect, the gas to be detected is 1,1,1-trifluoroethane (R143a), propane (R290), or trans-1,2-difluoroethylene (R1132(E)).

[0007] In the gas detection device of the first aspect, when the gas to be detected is 1,1,1-trifluoroethane (R143a), the predetermined wavelength is a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); A fourth wavelength range of 2236 to 2240 (nm), A fifth wavelength range of 2253 to 2257 (nm), A sixth wavelength range of 2319 to 2321 (nm), and The seventh wavelength range is 3294 to 3299 (nm). The wavelength range is either

[0008] In the gas detection device of the first aspect, when the gas to be detected is propane (R290), the predetermined wavelength is 11th wavelength range of 1685 to 1688 (nm), 12th wavelength range of 2276 to 2280 (nm), 13th wavelength range of 2325 to 2329 (nm), 14th wavelength range of 3137 to 3141 (nm), A 15th wavelength range of 3367 to 3372 (nm), and 16th wavelength range of 3819 to 3826 (nm), The wavelength range is either

[0009] In the gas detection device of the first aspect, when the gas to be detected is trans-1,2-difluoroethylene (R1132(E)), the predetermined wavelength is 21st wavelength range of 1634 to 1637 (nm), 22nd wavelength range of 2261 to 2267 (nm), 23rd wavelength range of 2287 to 2289 (nm), A 24th wavelength range of 3172 to 3177 (nm), and 25th wavelength range of 3209 to 3211 (nm), The wavelength range is either

[0010] A gas detection device of a second aspect is the gas detection device of the first aspect, further including an irradiation unit and a light receiving unit. The irradiation unit irradiates a first light and a second light onto the target space. The first light includes infrared light of the above-mentioned predetermined wavelength. The second light is light different from the first light. The light receiving unit receives the first passed light and the second passed light. The first passed light is light obtained by the first light passing through the target space. The second passed light is light obtained by the second light passing through the target space. The detection unit detects gas present in the target space based on the first passed light and the second passed light received by the light receiving unit.

[0011] The present inventors have come to recognize, through repeated testing using state-of-the-art high-resolution equipment, the existence of absorption wavelength bands for 1,1,1-trifluoroethane (R143a), propane (R290), and trans-1,2-difluoroethylene (R1132(E)) in wavelength ranges whose details had not been known until now. In light of this recognition, the present inventors have invented the gas detection device of the first aspect and the gas detection device of the second aspect described above. The present inventors have also found that this invention makes it possible to detect 1,1,1-trifluoroethane (R143a), propane (R290), and trans-1,2-difluoroethylene (R1132(E)).

[0012] A gas detection device according to a third aspect is the gas detection device according to the second aspect, wherein the detection unit has a calculation unit that calculates the concentration of the gas present in the target space based on the difference between the first transmitted light and the second transmitted light.

[0013] Here, not only can a predetermined gas present in the target space be detected, but the concentration of that gas can also be measured.

[0014] A gas detection device according to a fourth aspect is a gas detection device for detecting gas present in a remote target space, and includes an irradiation unit, a light receiving unit, and a detection unit. The irradiation unit irradiates a first light onto the target space. The first light is light whose emitted wavelength is modulated by current modulation using a predetermined fundamental frequency to include infrared light of a predetermined wavelength. The light receiving unit receives the first passing light. The first passing light is light that has passed through the target space. The detection unit detects gas present in the target space based on the first passing light received by the light receiving unit. The detection unit detects gas present in the target space based on a phase-sensitive detection signal of the fundamental frequency of the first passing light and a phase-sensitive detection signal of an integer multiple (the integer is an integer greater than or equal to 2) of the fundamental frequency of the first passing light. In the gas detection device of a fourth aspect, the gas to be detected is 1,1,1-trifluoroethane (R143a), propane (R290), or trans-1,2-difluoroethylene (R1132(E)).

[0015] In the gas detection device of the fourth aspect, when the gas to be detected is 1,1,1-trifluoroethane (R143a), the predetermined wavelength is a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); A fourth wavelength range of 2236 to 2240 (nm), A fifth wavelength range of 2253 to 2257 (nm), A sixth wavelength range of 2319 to 2321 (nm), and The seventh wavelength range is 3294 to 3299 (nm). The wavelength range is either

[0016] In the gas detection device of the fourth aspect, when the gas to be detected is propane (R290), the predetermined wavelength is 11th wavelength range of 1685 to 1688 (nm), 12th wavelength range of 2276 to 2280 (nm), 13th wavelength range of 2325 to 2329 (nm), 14th wavelength range of 3137 to 3141 (nm), A 15th wavelength range of 3367 to 3372 (nm), and 16th wavelength range of 3819 to 3826 (nm), The wavelength range is either

[0017] In the gas detection device of the fourth aspect, when the gas to be detected is trans-1,2-difluoroethylene (R1132(E)), the predetermined wavelength is 21st wavelength range of 1634 to 1637 (nm), 22nd wavelength range of 2261 to 2267 (nm), 23rd wavelength range of 2287 to 2289 (nm), A 24th wavelength range of 3172 to 3177 (nm), and 25th wavelength range of 3209 to 3211 (nm), The wavelength range is either

[0018] The inventors of the present application have come to recognize, through repeated testing using the latest high-resolution equipment, the existence of absorption wavelengths of 1,1,1-trifluoroethane (R143a), propane (R290), and trans-1,2-difluoroethylene (R1132(E)) in wavelength ranges whose details had not been known until now. Based on this recognition, the inventors of the present application have found that a predetermined gas can be detected by irradiating a target space with first light containing infrared light of any wavelength within each of the above wavelength ranges and receiving the first light that has passed through the target space with a light-receiving unit.

[0019] A fifth aspect of the gas detection device is the gas detection device of the fourth aspect, wherein the detection unit includes a calculation unit that calculates the concentration of the gas present in the target space based on a predetermined ratio. The predetermined ratio is a ratio between a phase-sensitive detection signal of a fundamental frequency of the first passing light and a phase-sensitive detection signal of an integer multiple (the integer is 2 or greater) of the fundamental frequency of the first passing light.

[0020] Here, not only can the refrigerant gas present in the target space be detected, but the concentration of the refrigerant gas can also be measured.

[0021] A gas detection device of a sixth aspect is a gas detection device of any one of the second aspect to the fifth aspect, wherein the light receiving unit receives light reflected or scattered by an object located on the opposite side of the target space from the irradiating unit.

[0022] Here, the reflected or scattered light is received by the light receiving section, and since the predetermined wavelength of the first light is within the above range, absorption by the object is small, allowing for accurate gas detection.

[0023] A gas detection apparatus according to a seventh aspect is the gas detection apparatus according to any one of the second aspect to the fifth aspect, wherein when the gas to be detected is 1,1,1-trifluoroethane (R143a), the predetermined wavelength is The seventh wavelength range is 3294 to 3299 (nm). in the wavelength range of When the gas to be detected is propane (R290), the predetermined wavelength is: 14th wavelength range of 3137 to 3141 (nm), A 15th wavelength range of 3367 to 3372 (nm), and 16th wavelength range of 3819 to 3826 (nm), The wavelength range is either When the gas to be detected is trans-1,2-difluoroethylene (R1132(E)), the predetermined wavelength is: A 24th wavelength range of 3172 to 3177 (nm), and 25th wavelength range of 3209 to 3211 (nm), The wavelength range is either

[0024] Furthermore, since the gas detection device of the seventh aspect further comprises a wavelength conversion section, thermal noise in the light receiving section is also reduced, and the cooling device for removing that thermal noise can be simplified or omitted.

[0025] A gas detection apparatus according to an eighth aspect is the gas detection apparatus according to any one of the second aspect to the fifth aspect, wherein when the gas to be detected is 1,1,1-trifluoroethane (R143a), the predetermined wavelength is a first wavelength range of 1650 to 1653 (nm); Second wavelength range of 1662~1665(nm) a third wavelength range of 2207 to 2209 (nm); A fourth wavelength range of 2236 to 2240 (nm), A fifth wavelength range of 2253 to 2257 (nm), and A sixth wavelength range of 2319 to 2321 (nm), The wavelength range is either When the gas to be detected is propane (R290), the predetermined wavelength is: 11th wavelength range of 1685 to 1688 (nm), A 12th wavelength range of 2276 to 2280 (nm), and 13th wavelength range of 2325 to 2329 (nm), The wavelength range is either When the gas to be detected is trans-1,2-difluoroethylene (R1132(E)), the predetermined wavelength is: 21st wavelength range of 1634 to 1637 (nm), A 22nd wavelength range of 2261 to 2267 (nm), and 23rd wavelength range of 2287 to 2289 (nm), The wavelength range is either

[0026] Here, since the first light having a relatively short wavelength is used, the thermal noise in the light receiving section is also small, and the cooling device for removing the thermal noise can be simplified or omitted.

[0027] Generally, it takes time to start up the cooling device, and if the cooling device becomes large, the convenience of the gas detection device decreases.

[0028] A gas detection device according to a ninth aspect is the gas detection device according to any one of the second to eighth aspects, further comprising a condenser lens or a telescope. The condenser lens or telescope passes light received by the light receiving section.

[0029] Here, even if the amount of light is small, the light is received by the light receiving section.

[0030] A gas leakage detection system according to a tenth aspect includes an air conditioner and the gas detection device according to any one of the first to ninth aspects. The air conditioner has a heat exchanger through which a refrigerant flows and a casing that houses the heat exchanger. The refrigerant flowing through the heat exchanger is 1,1,1-trifluoroethane (R143a), propane (R290), or trans-1,2-difluoroethylene (R1132(E)). The gas detection device detects the refrigerant leaking from the air conditioner into a target space as a gas (refrigerant gas). At least the portion of the outer surface of the casing of the air conditioner that faces the target space has a lower infrared absorption rate than the refrigerant gas to be detected.

[0031] Here, a gas detection device is used to detect refrigerant gas leaking from an air conditioner into a target space. As described above, the irradiating unit of the gas detection device irradiates light onto the target space. The light that passes through the target space is then received by the light receiving unit. Therefore, if the outer surface of the air conditioner casing has a high infrared absorptivity, much of the light will be absorbed by the air conditioner casing, reducing the amount of light received by the light receiving unit.

[0032] However, in the gas leakage detection system of the tenth aspect, at least the portion of the outer surface of the casing of the air conditioner that faces the target space has a lower infrared absorption rate than the refrigerant gas, which increases the amount of light received by the light receiving unit and improves the accuracy of refrigerant gas detection. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of a gas leakage detection system including a gas detection device. [Figure 2] FIG. 1 is a schematic diagram of a gas detection device. [Figure 3A] 1 is a graph showing the infrared absorption spectrum of R143a. [Figure 3B] 1 is a graph showing the infrared absorption spectrum of R143a. [Figure 3C] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3D] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3E] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3F] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3G] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3H] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 3I] 1 is a graph showing the infrared absorption cross section of R143a. [Figure 4A] 1 is a graph showing the infrared absorption spectrum of R290. [Figure 4B] 1 is a graph showing the infrared absorption spectrum of R290. [Figure 4C] 1 is a graph showing the infrared absorption cross section of R290. [Figure 4D] 1 is a graph showing the infrared absorption cross section of R290. [Figure 4E] 1 is a graph showing the infrared absorption cross section of R290. [Figure 4F] 1 is a graph showing the infrared absorption cross section of R290. [Figure 4G] 1 is a graph showing the infrared absorption cross section of R290. [Figure 4H] 1 is a graph showing the infrared absorption cross section of R290. [Figure 5A] 1 is a graph showing the infrared absorption spectrum of R1132(E). [Figure 5B] 1 is a graph showing the infrared absorption spectrum of R1132(E). [Figure 5C]1 is a graph showing the infrared absorption cross section of R1132(E). [Figure 5D] 1 is a graph showing the infrared absorption cross section of R1132(E). [Figure 5E] 1 is a graph showing the infrared absorption cross section of R1132(E). [Figure 5F] 1 is a graph showing the infrared absorption cross section of R1132(E). [Figure 5G] 1 is a graph showing the infrared absorption cross section of R1132(E). DETAILED DESCRIPTION OF THE INVENTION

[0034] (1) The need for a portable gas detection device that can detect refrigerant gases remotely Ceiling-mounted air conditioning indoor units are often installed in buildings such as offices, hotels, and commercial facilities. The main body of this air conditioning indoor unit is installed above the ceiling, and the air outlet and air inlet of the air conditioning indoor unit are located in openings formed in the ceiling. If refrigerant gas leaks from a crack or loose connection in the heat exchanger or refrigerant piping of the air conditioning indoor unit, the refrigerant gas will diffuse from inside the air conditioning indoor unit through the air outlet and air inlet into the upper space of the room. When refrigerant gas leaks into the upper space of the room and the space below the air conditioning indoor unit, for example, the concentration of refrigerant gas in that space is expected to increase.

[0035] For this reason, there is a demand for a gas detection device that can accurately and remotely detect the location of a refrigerant leak from an apparatus that uses a refrigerant such as an air conditioner. Specifically, there is a demand for a gas detection device that can accurately and remotely detect a refrigerant leak from an apparatus that uses 1,1,1-trifluoroethane (R143a), propane (R290), or trans-1,2-difluoroethylene (R1132(E)) as a refrigerant.

[0036] R143a is the ASHRAE No. for 1,1,1-trifluoroethane. The molecular formula of R143a is C2H3F3. R290 is the ASHRAE No. for propane. The molecular formula of R290 is C3H8. R1132(E) is the ASHRAE No. for trans-1,2-difluoroethylene. The molecular formula of R1132(E) is C2H2F2.

[0037] (2) Gas leak detection system FIG. 1 shows a gas leakage detection system. The gas leakage detection system includes a ceiling-mounted air conditioner 90 and a gas detection device 10. The air conditioner 90 has a heat exchanger 91 and a casing 92 that houses the heat exchanger 91. The refrigerant that flows through the refrigerant circuit that includes the heat exchanger 91 is R143a, R290, or R1132(E). The gas detection device 10 detects refrigerant gas leaking from the air conditioner 90 into a target space RM. The target space RM is an indoor space in a room where the air conditioner 90 is installed, and is a space surrounded by a ceiling CE, side walls, and a floor FL.

[0038] Of the outer surface of the casing 92 of the air conditioner 90, at least the portion facing the target space RM has a lower infrared absorption rate than the refrigerant gas. Specifically, the infrared absorption rate is kept low by molding the panel of the casing 92 that is exposed to the room from a material containing metal powder or by plating the surface of the panel. However, even without using metal powder or plating, the outer surface of the casing 92 is solid, so the infrared absorption rate of the casing 92 is low.

[0039] Gas detection device 10, which will be described later, is a portable device carried by a service person for detecting refrigerant leaks. Gas detection device 10 irradiates a target space RM below an air conditioner 90 that is located at a distance from itself with infrared rays, receives light reflected or scattered from a casing 92 of air conditioner 90 or a ceiling CE, and performs calculations to detect the presence and concentration of refrigerant gas in the target space RM.

[0040] (3) Configuration of gas detection device Gas detector 10 shown in FIG. 2 is a gas detector based on laser sensing technology, and comprises main body 12, irradiation unit 13, light collecting tube 14, and switching unit 15.

[0041] The main body 12 has a light receiving unit 21, a detecting unit 22, and a switching unit 15 arranged therein.

[0042] The switching unit 15 is provided to switch the refrigerant gas to be detected, and allows the user to select the refrigerant (refrigerant gas) to be detected from three options: R143a, R290, and R1132(E). The switching unit 15 is realized by a plurality of switches, a slide switch, a selection button on a touch panel, or the like.

[0043] The irradiating unit 13 irradiates the target space RM with first light IR11 and second light IR12, which are laser beams. The first light IR11 includes infrared light with a predetermined wavelength. The second light IR12 is light with a different wavelength from the first light IR11.

[0044] The light collecting tube 14 is a collecting lens or a telescope, and passes light to be received by the light receiving unit 21, which will be described later. In this example, a Cassegrain telescope is used as the light collecting tube 14.

[0045] The light receiving unit 21 receives, via the light collecting tube 14, the first light and the second light (hereinafter referred to as the first passing light IR21 and the second passing light IR22) that pass through the target space RM and are reflected or scattered by the casing 92 of the air conditioner 90 or the ceiling CE. The light receiving unit 21 is an infrared detection element that receives infrared light and converts it into an electrical signal. Here, an MCT (HgCdTe) infrared detection element is used as the infrared detection element.

[0046] The detection unit 22 detects the refrigerant gas present in the target space RM based on the first passing light IR21 and the second passing light IR22 received by the light receiving unit 21. The detection unit 22 includes a signal amplifier and a calculation unit 22a.

[0047] The calculation unit 22a is realized by a computer. The calculation unit 22a includes a control calculation device and a storage device. A processor such as a CPU or a GPU can be used as the control calculation device. The control calculation device reads a program stored in the storage device and performs predetermined image processing and calculation processing in accordance with the program. Furthermore, the control calculation device can write calculation results to the storage device and read information stored in the storage device in accordance with the program.

[0048] The calculation unit 22a receives the electrical signal from the light receiving unit 21 and calculates the concentration of the refrigerant gas present in the target space RM. The calculation of the concentration of the refrigerant gas is performed based on the difference between the first passing light IR21 and the second passing light IR22 received by the light receiving unit 21.

[0049] (3-1) Irradiation light when the refrigerant gas to be detected is R143a When R143a is selected by the switching unit 15 as the refrigerant gas to be detected, the predetermined wavelength of the infrared light contained in the first light IR11 is in the wavelength range of 1650 to 1653 (nm).

[0050] The second light IR12 is near-infrared light, a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); A fourth wavelength range of 2236 to 2240 (nm), A fifth wavelength range of 2253 to 2257 (nm), A sixth wavelength range of 2319 to 2321 (nm), and The seventh wavelength range is 3294 to 3299 (nm). The wavelength band other than the infrared (700 to 2500 (nm)) is near infrared.

[0051] As will be described later, when refrigerant gas (R143a) is present in the target space RM, a portion of the first light IR11 is absorbed, and the second light IR12 is not absorbed.

[0052] (3-2) Irradiation light when the refrigerant gas to be detected is R290 When R290 is selected by the switching unit 15 as the refrigerant gas to be detected, the predetermined wavelength of the infrared light contained in the first light IR11 is in the wavelength range of 1685 to 1688 (nm).

[0053] The second light IR12 is near-infrared light, 11th wavelength range of 1685 to 1688 (nm), 12th wavelength range of 2276 to 2280 (nm), 13th wavelength range of 2325 to 2329 (nm), 14th wavelength range of 3137 to 3141 (nm), A 15th wavelength range of 3367 to 3372 (nm), and 16th wavelength range of 3819 to 3826 (nm), The wavelength band other than the infrared (700 to 2500 (nm)) is near infrared.

[0054] As will be described later, when refrigerant gas (R290) is present in the target space RM, a portion of the first light IR11 is absorbed, and the second light IR12 is not absorbed.

[0055] (3-3) Irradiation light when the refrigerant gas to be detected is R1132(E) When R1132(E) is selected by the switching unit 15 as the refrigerant gas to be detected, the predetermined wavelength of the infrared light contained in the first light IR11 is in the wavelength range of 1634 to 1637 (nm).

[0056] The second light IR12 is near-infrared light, 21st wavelength range of 1634 to 1637 (nm), 22nd wavelength range of 2261 to 2267 (nm), 23rd wavelength range of 2287 to 2289 (nm), A 24th wavelength range of 3172 to 3177 (nm), and 25th wavelength range of 3209 to 3211 (nm), The wavelength band other than the infrared (700 to 2500 (nm)) is near infrared.

[0057] As will be described later, when refrigerant gas (R1132(E)) is present in the target space RM, a portion of the first light IR11 is absorbed, and the second light IR12 is not absorbed.

[0058] (4) Operation of the gas detection device In the gas leakage detection system, a service person uses a portable gas detection device 10 that he or she carries to check whether refrigerant is leaking from an air conditioner 90 installed in the ceiling CE of a room in a building such as an office. The service person determines that the space below the air conditioner 90 near the ceiling CE is a target space RM for gas detection (see FIG. 1 ), and irradiates laser light (first light IR11 and second light IR12) toward the target space RM.

[0059] As shown in FIG. 1, if refrigerant gas is leaking from a heat exchanger 91 of an air conditioner 90 or a crack 90a in a refrigerant pipe, a predetermined concentration of refrigerant gas will be present in the target space RM. In this case, the first light IR11 of the laser light is partially absorbed by the refrigerant gas, and the second light IR12 is hardly absorbed by the refrigerant gas. Therefore, a difference occurs in the detection levels of the light reflected from the casing 92 of the air conditioner 90 and the ceiling CE (the first passing light IR21 and the second passing light IR22) at the light receiving unit 21. Based on this difference, the calculation unit 22a calculates the concentration of refrigerant gas in the target space RM.

[0060] 2, the first passing light IR21 and the second passing light IR22, which are the light (reflected light) obtained when the first light IR11 and the second light IR12 pass through the target space RM, enter the light receiving unit 21 via the light collecting tube 14. The light collecting tube 14 collects the reflected or scattered light over a wide area. Therefore, the light receiving unit 21 can detect even a small amount of the first passing light IR21 that has been absorbed.

[0061] (5) Infrared absorption characteristics of three types of refrigerant gases The inventors of the present application have come to recognize the existence of absorption wavelength bands of 1,1,1-trifluoroethane (R143a), propane (R290), and trans-1,2-difluoroethylene (R1132(E)) in wavelength ranges whose details had not been known until now, through repeated tests using modern high-resolution equipment.

[0062] (5-1) Infrared absorption characteristics of R143a 3A and 3B are graphs plotting the wavelength of infrared light on the horizontal axis and the absorbance of infrared light at each wavelength when passing through a space containing a predetermined concentration of R143a on the vertical axis. Specifically, Fig. 3A shows the absorbance of infrared light when the concentration of R143a is 100%, the temperature is 27°C, the enclosed pressure is 760 Torr, the optical path length is 20.7 cm, and the wavenumber resolution is 0.01 cm. -13B is a graph showing the infrared absorption spectrum of R143a at a concentration of 0.25%, a temperature of 25°C, a sealed pressure of 760 Torr, an optical path length of 20.7 cm, and a wavenumber resolution of 0.01 cm. -1 1 is a graph showing the infrared absorption spectrum of R143a in

[0063] In Figures 3C to 3I, the horizontal axis represents the wavelength of infrared light, and the vertical axis represents the absorption cross section of R143a (cm 2 As can be seen from these graphs, the test results revealed the existence of absorption wavelengths of R143a, particularly in the near-infrared and mid-infrared bands, as well as their transmittance and absorption cross section. Specifically, the existence of the following seven absorption wavelength bands where the infrared absorption cross section of R143a shows peaks was discovered. a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); A fourth wavelength range of 2236 to 2240 (nm), A fifth wavelength range of 2253 to 2257 (nm), A sixth wavelength range of 2319 to 2321 (nm), and The seventh wavelength range is 3294 to 3299 (nm).

[0064] Based on this new knowledge, in the gas detection device 10, when the refrigerant gas to be detected is R143a, infrared light in the wavelength range of 1650 to 1653 (nm) is used as the first light IR11, and is irradiated from the irradiation unit 13 toward the target space RM.

[0065] The infrared wavelength range marked "water vapor" in Figures 3A and 3B is an infrared wavelength range where it is difficult to eliminate the presence of water vapor within the system of a measurement device such as a gas cell. The measurement results shown in Figures 3A and 3B contain the characteristics of water vapor. In Figures 3A and 3B, the term "water vapor" is used to avoid confusion with the characteristics of R143a.

[0066] (5-2) Infrared absorption characteristics of R290 4A and 4B are graphs plotting the wavelength of infrared light on the horizontal axis and the absorbance of infrared light at each wavelength when passing through a space containing a predetermined concentration of R290 on the vertical axis. Specifically, Fig. 4A shows the absorbance of infrared light at each wavelength when the R290 concentration is 100%, the temperature is 23°C, the enclosed pressure is 760 Torr, the optical path length is 20.7 cm, and the wavenumber resolution is 0.01 cm. -1 4B is a graph showing the infrared absorption spectrum of R290 at an R290 concentration of 0.4%, a temperature of 23°C, a sealed pressure of 760 Torr, an optical path length of 20.7 cm, and a wavenumber resolution of 0.01 cm. -1 1 is a graph showing the infrared absorption spectrum of R290 in

[0067] In Figures 4C to 3H, the horizontal axis represents the wavelength of infrared light, and the vertical axis represents the absorption cross section of R290 (cm 2 As can be seen from these graphs, the test results revealed the existence of absorption wavelengths of R290, particularly in the near-infrared and mid-infrared bands, as well as their transmittance and absorption cross section. Specifically, the existence of the following six absorption wavelength bands where the infrared absorption cross section of R290 shows peaks was discovered. 11th wavelength range of 1685 to 1688 (nm), 12th wavelength range of 2276 to 2280 (nm), 13th wavelength range of 2325 to 2329 (nm), 14th wavelength range of 3137 to 3141 (nm), A 15th wavelength range of 3367 to 3372 (nm), and 16th wavelength range: 3819~3826(nm).

[0068] Based on this new knowledge, in the gas detection device 10, when the refrigerant gas to be detected is R290, infrared light in the wavelength range of 1685 to 1688 (nm) is used as the first light IR11, and is irradiated from the irradiation unit 13 toward the target space RM.

[0069] The infrared wavelength range marked "water vapor" in Figures 4A and 4B is an infrared wavelength range where it is difficult to eliminate the presence of water vapor within the system of a measurement device such as a gas cell. The measurement results shown in Figures 4A and 4B contain the characteristics of water vapor. In Figures 4A and 4B, the term "water vapor" is used to avoid confusion with the characteristics of R290.

[0070] (5-3) Infrared absorption characteristics of R1132(E) 5A and 5B are graphs plotting the infrared wavelength on the horizontal axis and the infrared absorbance at each wavelength when passing through a space containing a predetermined concentration of R1132(E) on the vertical axis. Specifically, Fig. 5A shows the infrared absorbance at each wavelength when the concentration of R1132(E) is 100%, the temperature is 24°C, the enclosed pressure is 760 Torr, the optical path length is 20.7 cm, and the wavenumber resolution is 0.01 cm. -1 5B is a graph showing the infrared absorption spectrum of R290 at a concentration of R1132(E) of 5%, a temperature of 24°C, a sealed pressure of 760 Torr, an optical path length of 20.7 cm, and a wavenumber resolution of 0.01 cm. -1 1 is a graph showing the infrared absorption spectrum of R1132(E) in

[0071] 5C to 5G, the horizontal axis represents the infrared wavelength, and the vertical axis represents the absorption cross section (cm) of R1132(E). 2 As can be seen from these graphs, the test results revealed the existence of absorption wavelengths of R1132(E), particularly in the near-infrared and mid-infrared bands, as well as their transmittance and absorption cross section. Specifically, the existence of the following five absorption wavelength bands where the infrared absorption cross section of R1132(E) shows peaks was discovered. 21st wavelength range of 1634 to 1637 (nm), 22nd wavelength range of 2261 to 2267 (nm), 23rd wavelength range of 2287 to 2289 (nm), A 24th wavelength range of 3172 to 3177 (nm), and 25th wavelength range: 3209-3211 (nm).

[0072] Based on this new knowledge, in the gas detection device 10, when the refrigerant gas to be detected is R1132(E), infrared light in the wavelength range of 1634 to 1637 (nm) is used as the first light IR11, and is irradiated from the irradiation unit 13 toward the target space RM.

[0073] The infrared wavelength range marked "water vapor" in Figures 5A and 5B is an infrared wavelength range where it is difficult to eliminate the presence of water vapor within the system of a measurement device such as a gas cell. The measurement results shown in Figures 5A and 5B contain the characteristics of water vapor. In Figures 5A and 5B, the term "water vapor" is used to avoid confusion with the characteristics of R1132(E).

[0074] (6) Features (6-1) As described above, the inventors of the present application have conducted repeated tests and discovered that refrigerant gases have absorption wavelengths in previously unrecognized wavelength ranges. Specifically, the inventors discovered the existence of a first wavelength range of 1650-1653 nm for R143a, an eleventh wavelength range of 1685-1688 nm for R290, and a 21st wavelength range of 1634-1637 nm for R1132(E).

[0075] In the gas detection device 10 according to the above embodiment, the wavelength of the first light IR11 is set to 1650 to 1653 (nm) when detecting R143a, 1685 to 1688 (nm) when detecting R290, and 1634 to 1637 (nm) when detecting R1132(E), making it possible to detect each refrigerant gas present in the remote target space RM.

[0076] It should be noted that discovering previously unrecognized infrared absorption wavelengths for each refrigerant gas was impossible using previous tests that used low-resolution measuring equipment. By repeating the tests using the latest high-resolution measuring equipment, we were able to obtain the findings shown in Figures 3A to 3I, 4A to 4H, and 5A to 5G.

[0077] (6-2) In the gas detection device 10, the wavelength of the first light IR11 is set to a wavelength within the wavelength range of near-infrared rays (electromagnetic waves with wavelengths of 700 to 2500 (nm)) depending on the type of refrigerant. 1650~1653(nm) 1685~1688(nm) or 1634~1637(nm) Therefore, compared to when mid-infrared (2500-4000 (nm)) or far-infrared (over 4000 (nm)) is selected, cooling for thermal noise removal can be omitted or simplified. This reduces manufacturing costs and also prevents the deterioration of convenience caused by the time it takes for the cooling device to stabilize after startup.

[0078] In order to perform the minimum necessary cooling, for example, a Peltier element can be used as a cooling device for the infrared detection element.

[0079] (6-3) In gas detection device 10, light reflected or scattered by an object (such as air conditioner 90 or ceiling CE) located on the opposite side of target space RM from irradiator 13 is received by light receiving unit 21. Therefore, irradiator 13 and light receiving unit 21 can be placed close to each other, making gas detection device 10 easy to carry.

[0080] (6-4) Generally, the absorption wavelengths of building materials and structures are in the 3 μm band for materials such as PP (polypropylene), PS (polystyrene), ABS (acrylonitrile butadiene styrene), and AS (acrylonitrile styrene), and in the 9 μm band for materials such as PS (polystyrene), paper ceilings, and wood. If the wavelength of the infrared light emitted from the gas detection device is selected from the 3 μm or 9 μm band, the light absorption by the building materials and structures may incorrectly identify the presence of refrigerant gas unless it matches the absorption wavelength of the building materials and structures or the absorption cross section is sufficiently small compared to the refrigerant gas.

[0081] However, in gas detection device 10, the wavelength of first light IR11 is changed depending on the type of refrigerant. 1650~1653(nm) 1685~1688(nm) or 1634~1637(nm) This makes it less susceptible to the effects of light absorption by building materials and structures.

[0082] (6-5) In the above-described leak gas detection system, the gas detection device 10 is used to detect refrigerant gas leaking from the air conditioner 90 into the target space RM. As described above, the irradiator 13 of the gas detection device 10 irradiates the target space RM with the first light IR11 and the second light IR12. The first passing light IR21 and the second passing light IR22 that pass through the target space RM are then received by the light receiving device 21. Therefore, if the infrared absorptivity of the outer surface of the casing 92 of the air conditioner 90 is high, much of the first light IR11 will be absorbed by the casing 92 of the air conditioner 90, reducing the amount of light received by the light receiving device 21.

[0083] However, in the above-described leakage gas detection system, at least the portion of the outer surface of the casing 92 of the air conditioner 90 that faces the target space RM has a lower infrared absorption rate than any of the refrigerant gases (R143a, R290, R1132(E)). Specifically, the panel of the casing 92 that is exposed to the interior of the room is molded from a material containing metal powder, or the surface of the panel is plated.

[0084] As a result, the amount of reflected or scattered light received by gas detection device 10 increases, improving the accuracy of refrigerant gas detection.

[0085] Even if measures such as molding the panel from a material containing metal powder or plating the panel surface are not taken, the outer surface of the casing 92 is solid, so the infrared absorption rate of the casing 92 is low.

[0086] (7) Variations (7-1) Variation 1A In the gas detection device 10, the predetermined wavelength of the infrared light included in the first light IR11 is adjusted according to the type of refrigerant. 1650~1653(nm) 1685~1688(nm) or 1634~1637(nm) The wavelength range is set to

[0087] Instead, the wavelength of the first light is changed depending on the type of refrigerant. Second wavelength range of 1662 to 1665 (nm) (for detecting R143a), The third wavelength range of 2207 to 2209 (nm) (for detecting R143a), The fourth wavelength range of 2236 to 2240 (nm) (for detecting R143a), The fifth wavelength range of 2253 to 2257 (nm) (for detecting R143a), The sixth wavelength range of 2319 to 2321 (nm) (for detecting R143a), 12th wavelength range of 2276-2280 (nm) (for detecting R290), 13th wavelength range of 2325 to 2329 (nm) (for detecting R290), 22nd wavelength range of 2261 to 2267 (nm) (for detecting R290), or 23rd wavelength range of 2287 to 2289 (nm) (for detecting R1132 (E)), As described above, infrared rays in these wavelength ranges also match the infrared absorption wavelengths of the refrigerant gases and are easily absorbed by the refrigerant gases. Therefore, good refrigerant gas detection accuracy can be expected.

[0088] Furthermore, these wavelength ranges are also in the near-infrared wavelength region, making it possible to omit or simplify cooling for thermal noise removal.

[0089] (7-2) Variation 1B In the gas detection device 10, the predetermined wavelength of the infrared light included in the first light IR11 is adjusted according to the type of refrigerant. 1650~1653(nm) 1685~1688(nm) or 1634~1637(nm) The wavelength range is set to

[0090] Instead, the wavelength of the first light is changed depending on the type of refrigerant. The seventh wavelength range of 3294 to 3299 (nm) (for detecting R143a), 14th wavelength range of 3137 to 3141 (nm) (for detecting R290), 15th wavelength range of 3367-3372 (nm) (for detecting R290), 16th wavelength range of 3819 to 3826 (nm) (for detecting R290), 24th wavelength range of 3172 to 3177 (nm) (for detecting R1132 (E)), or 25th wavelength range of 3209 to 3211 (nm) (for detecting R1132 (E)), In this case, there are some disadvantages, such as the need for cooling to remove thermal noise, but the infrared absorption cross section of the refrigerant gas is large. Therefore, it is possible to detect refrigerant gas at lower concentrations than when near-infrared light is used as the first light.

[0091] (7-3) Variation 1C In the above-described gas leakage detection system, gas detection device 10 is provided with switching unit 15, so that any of the three types of refrigerant, R143a, R290, and R1132(E), can be detected. However, instead of gas detection device 10, a gas detection device dedicated to detecting only R143a, a gas detection device dedicated to detecting only R290, and a gas detection device dedicated to detecting only R1132(E) may be prepared, and the service person may select and carry a gas detection device depending on the type of refrigerant gas to be detected.

[0092] (7-4) Variation 1D The gas detection device 10 described above employs a configuration in which the irradiating unit 13 irradiates the first light IR11 and the second light IR12.

[0093] Alternatively, a configuration in which only the first light is irradiated from the irradiating unit may be adopted. In this case, the irradiating unit irradiates the target space with the first light, the emitted wavelength of which is modulated by current modulation using a predetermined fundamental frequency to include infrared light of a predetermined wavelength. The first light becomes first transmitted light, which is light (reflected light) that passes through the target space, and is received by the light receiving unit. The detecting unit detects the refrigerant gas present in the target space based on a phase-sensitive detection signal of the fundamental frequency of the first transmitted light and a phase-sensitive detection signal of an integer multiple (the integer is an integer greater than or equal to 2) of the fundamental frequency of the first transmitted light.

[0094] Preferably, the detection unit further includes a calculation unit that calculates the concentration of the refrigerant gas present in the target space based on a ratio between a phase-sensitive detection signal of the fundamental frequency of the first passing light and a phase-sensitive detection signal of an integer multiple (the integer is 2 or more) of the fundamental frequency of the first passing light.

[0095] (7-5) Variation 1E As in the above-described modification 1B, when mid-infrared light is irradiated from the irradiating unit as the first light, it is preferable to further provide a wavelength converting unit in the gas detection device. If the wavelength converting unit converts the wavelength of the reflected or scattered light and the light receiving unit receives the wavelength-converted light, it is possible to simplify measures against thermal noise.

[0096] The wavelength conversion section may be a wavelength conversion device such as a nonlinear optical crystal.

[0097] (7-6) Variation 1F The gas detection device 10 described above employs a configuration in which the irradiating unit 13 irradiates the first light IR11 and the second light IR12.

[0098] Alternatively, the wavelength may be changed by changing the output of the laser from the irradiation unit, and light of two wavelengths may be detected by inserting or removing the wavelength-selective film. The wavelength-selective film is inserted or removed before the detector.

[0099] Furthermore, instead of inserting and removing a wavelength-selective film, a wavelength conversion crystal such as lithium niobate (PPLN) can be used. If a wavelength conversion crystal can be used to convert the wavelength, for example, from mid-infrared to visible light or near-infrared, cooling using liquid nitrogen or the like becomes unnecessary, and refrigerant gas can be detected at room temperature without thermal noise.

[0100] Furthermore, an LED may be used as the light source of the irradiating unit instead of a laser. In this case, the multi-wavelength LED light emitted from the irradiating unit is split by a half mirror, and the refrigerant gas can be detected by performing a two-wavelength difference.

[0101] (7-7) Variation 1G In the above-described leakage gas detection system, the space around air conditioner 90 is set as target space RM, and irradiation from irradiation unit 13 of gas detection device 10 is performed therein.

[0102] If an air conditioner is installed on the side wall of a room in a building, the refrigerant (refrigerant gas) leaking from the air conditioner will diffuse into the space near the side wall, so the target space will be the space along the side wall rather than near the ceiling.If the air conditioner is a floor-standing type, the target space will be the space near the floor.

[0103] (Addendum) Although the embodiments of the gas detection device and the gas leakage detection system have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0104] 10 Gas detection equipment 13 Irradiation unit 14 Condenser tube (condenser lens, telescope) 21 Light receiving part 22 Detection unit 22a Arithmetic unit 90 Air conditioner 91 Heat exchanger 92 Casing IR11 1st light IR12 2nd light IR21 First passing light (light that passes through the target space) IR22 Second passing light (light that has passed through the target space) RM target space [Prior art documents] [Patent documents]

[0105] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-275641

Claims

1. A gas detection device (10) for detecting a gas present in a remote target space, comprising: a detection unit (22) that detects the gas by utilizing absorption of light of a predetermined wavelength; Equipped with The gas to be detected is 1,1,1-trifluoroethane (R143a), and the predetermined wavelength is: a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); a fourth wavelength range of 2236 to 2240 (nm); a fifth wavelength range of 2253 to 2257 (nm); a sixth wavelength range of 2319 to 2321 (nm); and a seventh wavelength range of 3294 to 3299 (nm); in any of the wavelength ranges Or, The gas to be detected is propane (R290), and the predetermined wavelength is: an eleventh wavelength range of 1685 to 1688 (nm); a twelfth wavelength range of 2276 to 2280 (nm); a thirteenth wavelength range of 2325 to 2329 (nm); a 14th wavelength range of 3137 to 3141 (nm); a 15th wavelength range of 3367 to 3372 (nm); and A 16th wavelength range of 3819 to 3826 (nm), in any of the wavelength ranges Or, The gas to be detected is trans-1,2-difluoroethylene (R1132(E)), and the predetermined wavelength is: A 21st wavelength range of 1634 to 1637 (nm), a 22nd wavelength range of 2261 to 2267 (nm); a 23rd wavelength range of 2287 to 2289 (nm); A 24th wavelength range of 3172 to 3177 (nm), and A 25th wavelength range of 3209 to 3211 (nm), in any of the wavelength ranges Gas detection equipment.

2. an irradiation unit (13) that irradiates the target space (RM) with first light (IR11) including infrared light of the predetermined wavelength and second light (IR12) different from the first light; a light receiving unit (21) that receives first transmitted light (IR21) that is light obtained by the first light (IR11) passing through the target space and second transmitted light (IR22) that is light obtained by the second light (IR12) passing through the target space; Furthermore, the detection unit detects the gas present in the target space based on the first passed light and the second passed light received by the light receiving unit.

2. The gas detection device according to claim 1.

3. the detection unit has a calculation unit, The calculation unit a difference between the first transmitted light and the second transmitted light received by the light receiving unit; Calculating the concentration of the gas present in the target space based on the 3. The gas detection device according to claim 2.

4. A gas detection device for detecting a gas present in a remote target space, an irradiation unit that irradiates the target space with first light whose emission wavelength is modulated by current modulation using a predetermined fundamental frequency, the first light including infrared light of a predetermined wavelength; a light receiving unit that receives first transmitted light, the first light being light that has passed through the target space; a detection unit that detects the gas present in the target space based on the first passing light received by the light receiving unit; Equipped with The detection unit a phase-sensitive detection signal of the fundamental frequency of the first transmitted light; and, a phase-sensitive detection signal of an integer multiple (the integer is an integer of 2 or more) of the fundamental frequency of the first passing light; Detecting the gas present in the target space based on the The gas to be detected is 1,1,1-trifluoroethane (R143a), and the predetermined wavelength is: a first wavelength range of 1650 to 1653 (nm); a second wavelength range of 1662 to 1665 (nm); a third wavelength range of 2207 to 2209 (nm); a fourth wavelength range of 2236 to 2240 (nm); a fifth wavelength range of 2253 to 2257 (nm); a sixth wavelength range of 2319 to 2321 (nm); and a seventh wavelength range of 3294 to 3299 (nm); in any of the wavelength ranges Or, The gas to be detected is propane (R290), and the predetermined wavelength is: an eleventh wavelength range of 1685 to 1688 (nm); a twelfth wavelength range of 2276 to 2280 (nm); a thirteenth wavelength range of 2325 to 2329 (nm); a 14th wavelength range of 3137 to 3141 (nm); a 15th wavelength range of 3367 to 3372 (nm); and A 16th wavelength range of 3819 to 3826 (nm), in any of the wavelength ranges Or, The gas to be detected is trans-1,2-difluoroethylene (R1132(E)), and the predetermined wavelength is: A 21st wavelength range of 1634 to 1637 (nm), a 22nd wavelength range of 2261 to 2267 (nm); a 23rd wavelength range of 2287 to 2289 (nm); A 24th wavelength range of 3172 to 3177 (nm), and A 25th wavelength range of 3209 to 3211 (nm), in any of the wavelength ranges Gas detection equipment.

5. the detection unit has a calculation unit, The calculation unit a ratio of a phase-sensitive detection signal of the fundamental frequency of the first passing light to a phase-sensitive detection signal of an integer multiple (the integer is an integer greater than or equal to 2) of the fundamental frequency of the first passing light; Calculating the concentration of the gas present in the target space based on the 5. The gas detection device according to claim 4.

6. The light receiving unit receives light reflected or scattered by an object located on the opposite side of the target space from the irradiation unit.

6. The gas detection device according to claim 2.

7. The gas to be detected is 1,1,1-trifluoroethane (R143a), and the predetermined wavelength is: a seventh wavelength range of 3294 to 3299 (nm); in the wavelength range of Or, The gas to be detected is propane (R290), and the predetermined wavelength is: a 14th wavelength range of 3137 to 3141 (nm); a 15th wavelength range of 3367 to 3372 (nm); and A 16th wavelength range of 3819 to 3826 (nm), The wavelength range is either Or, The gas to be detected is trans-1,2-difluoroethylene (R1132(E)), and the predetermined wavelength is: A 24th wavelength range of 3172 to 3177 (nm), and A 25th wavelength range of 3209 to 3211 (nm), The wavelength range is either a wavelength conversion unit that converts the wavelength of light received by the light receiving unit; The gas detection device according to claim 2 , further comprising:

8. The gas to be detected is 1,1,1-trifluoroethane (R143a), and the predetermined wavelength is: a first wavelength range of 1650 to 1653 (nm); Second wavelength range of 1662 to 1665 (nm) a third wavelength range of 2207 to 2209 (nm); a fourth wavelength range of 2236 to 2240 (nm); a fifth wavelength range of 2253 to 2257 (nm); and a sixth wavelength range of 2319 to 2321 (nm); in any of the wavelength ranges Or, The gas to be detected is propane (R290), and the predetermined wavelength is: an eleventh wavelength range of 1685 to 1688 (nm); a twelfth wavelength range of 2276 to 2280 (nm); and a thirteenth wavelength range of 2325 to 2329 (nm); in any of the wavelength ranges Or, The gas to be detected is trans-1,2-difluoroethylene (R1132(E)), and the predetermined wavelength is: A 21st wavelength range of 1634 to 1637 (nm), a 22nd wavelength range of 2261 to 2267 (nm); and a 23rd wavelength range of 2287 to 2289 (nm); in any of the wavelength ranges 6. The gas detection device according to claim 2.

9. a condenser lens or telescope (14) for transmitting light received by the light receiving section; The gas detection device according to claim 2 , further comprising:

10. an air conditioner (90) having a heat exchanger (91) through which the 1,1,1-trifluoroethane (R143a), the propane (R290), or the trans-1,2-difluoroethylene (R1132(E)) flows as a refrigerant, and a casing (92) accommodating the heat exchanger; The gas detection device according to any one of claims 2 to 5, which detects the refrigerant leaking from the air conditioner into the target space as the gas; Equipped with At least a portion of the outer surface of the casing facing the target space has a lower infrared absorption rate than the gas. Gas leak detection system.

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