Physical amount measurement system

Abstract

The present disclosure addresses the problem of measuring hydrogen concentration with high accuracy even in a highly humid environment. A physical amount measuring system (1) includes a flow path, a pair of ultrasonic transceivers (11, 12), and a concentration measuring unit (204). A gas mixture including hydrogen and water vapor flows through the flow path. The pair of ultrasonic transceivers (11, 12) transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the gas mixture in the flow path. The concentration measuring unit (204) measures the gas concentration, which is the concentration of a gas that is included in the gas mixture and is different from water vapor. The concentration measuring unit (204) calculates the gas concentration using the pressure of the gas mixture, the density of the gas mixture, the temperature of the gas mixture, and the propagation time of ultrasonic waves obtained by transmitting and receiving ultrasonic waves between the pair of ultrasonic transceivers (11, 12).

Description

Physical Quantity Measurement System

[0001] The present disclosure generally relates to a physical quantity measurement system, and more particularly to a physical quantity measurement system that measures a gas mixture flowing through a flow path.

[0002] BACKGROUND ART Conventionally, there has been known a measurement method for measuring the concentration of a mixed gas containing hydrogen (mixed gas) by using ultrasonic waves (see, for example, Patent Document 1).

[0003] In Patent Document 1, the sound velocity of a mixed gas is calculated from the measured value of the propagation time of ultrasonic waves, and the average molecular weight of the mixed gas is calculated using this value and the measured temperature.Then, the concentration of hydrogen, which is a component gas, is calculated using the known molecular weights of each component gas.

[0004] A device for measuring the concentration of a mixed gas containing hydrogen (physical quantity measurement system) may be placed in a high-humidity environment. Patent Document 1 does not disclose how to calculate the hydrogen concentration in a high-humidity environment, and therefore, there is a possibility that the concentration of hydrogen contained in a mixed gas in a high-humidity state may not be measured accurately.

[0005] JP 2010-91489 A

[0006] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a physical quantity measurement system that can measure hydrogen concentration with high accuracy even in a high humidity environment.

[0007] A physical quantity measuring system according to one aspect of the present disclosure includes a flow path, a pair of ultrasonic transmitter-receivers, and a concentration measurement unit. A mixed gas containing hydrogen and water vapor flows through the flow path. The pair of ultrasonic transmitter-receivers transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the mixed gas in the flow path. The concentration measurement unit measures a gas concentration, which is the concentration of a gas contained in the mixed gas that is different from the water vapor. The concentration measurement unit calculates the gas concentration using the pressure of the mixed gas, the density of the mixed gas, the temperature of the mixed gas, and the propagation time of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves between the pair of ultrasonic transmitter-receivers.

[0008] FIG. 1 is a block diagram showing the configuration of a physical quantity measurement system according to one embodiment. FIG. 2 is a system diagram showing the configuration of the physical quantity measurement system according to the embodiment. FIG. 3 is a cross-sectional view in the XY plane of a flow path main body provided in the physical quantity measurement system according to the embodiment. FIG. 4 is a flowchart showing the operation of the physical quantity measurement system according to the embodiment. FIG. 5 is a flowchart showing the concentration measurement process performed by the physical quantity measurement system according to the embodiment. FIG. 6 is a flowchart showing the sound speed calculation process performed in the concentration measurement process according to the embodiment. FIG. 7 is a flowchart showing the concentration calculation process performed in the concentration measurement process according to the embodiment. FIG. 8 is a flowchart showing the flow rate measurement process performed by the physical quantity measurement system according to the embodiment. FIG. 9 is a system diagram showing the configuration of a physical quantity measurement system according to a fourth modification.

[0009] The embodiments and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiments and modifications. Various modifications other than the following embodiments and modifications are possible depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure.

[0010] (Embodiment) Hereinafter, a physical quantity measuring system 1 according to this embodiment will be described with reference to Figs.

[0011] (1) Overview A physical quantity measuring system 1 according to this embodiment is a system for measuring at least one of the concentrations of gases other than water vapor contained in a gas mixture containing multiple gases flowing through a flow path 101 (see FIG. 3). For example, a gas mixture containing hydrogen, nitrogen, and water vapor flows through the flow path 101.

[0012] As shown in FIG. 1 , the physical quantity measuring system 1 of this embodiment includes a flow path 101, a pair of ultrasonic transmitters and receivers 11 and 12, a pressure sensor 13, a temperature sensor 14, a density sensor 15, a concentration measurement unit 204, and a flow rate measurement unit 205. A mixed gas containing hydrogen and water vapor flows through the flow path 101. The pair of ultrasonic transmitters and receivers 11 and 12 transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the mixed gas through the flow path 101. The pressure sensor 13 measures the pressure of the mixed gas. The temperature sensor 14 measures the temperature of the mixed gas. The density sensor 15 measures the density of the mixed gas. The concentration measurement unit 204 measures the gas concentration, which is the concentration of a gas contained in the mixed gas that is different from water vapor. The concentration measurement unit 204 calculates the gas concentration using the pressure of the mixed gas measured by the pressure sensor 13, the density measured by the density sensor 15, the temperature measured by the temperature sensor 14, and the propagation time of the ultrasonic waves obtained by transmitting and receiving ultrasonic waves between a pair of ultrasonic transmitters and receivers 11 and 12.

[0013] With this configuration, the hydrogen concentration can be measured with high accuracy even in a high humidity environment.

[0014] (2) Configuration The detailed configuration of the physical quantity measuring system 1 will be described below with reference to FIGS. 1 to 3. FIG.

[0015] 1, the physical quantity measurement system 1 includes a flow path main body 10 and a processing device 20. The physical quantity measurement system 1 measures the concentration of hydrogen contained in a mixed gas flowing through the flow path main body 10 (hydrogen concentration), the flow rate of the mixed gas, and relative humidity as physical quantities. Furthermore, the physical quantity measurement system 1 measures the water vapor pressure and the concentration of water vapor (water vapor concentration) contained in the mixed gas as physical quantities. Here, the concentration measured by the physical quantity measurement system 1 is, for example, volume concentration.

[0016] An X-axis, a Y-axis, and a Z-axis are defined for the flow path body 10 (see FIG. 2). The X-axis is an axis along the longitudinal direction of the flow path body 10, i.e., an axis along the direction in which the mixed gas flows. The Y-axis is an axis perpendicular to the X-axis, for example, an axis along the depth direction of the flow path body 10. The Z-axis is an axis perpendicular to both the X-axis and the Y-axis, for example, an axis along the height direction of the flow path body 10. FIG. 3 is a cross-sectional view of the flow path body 10 in the X-Y plane. Note that in FIG. 3, the pair of ultrasonic transmitter / receivers 11, 12 and the temperature sensor 14 are not shown in cross section.

[0017] (2.1) Flow Channel Main Body A mixed gas containing hydrogen, nitrogen, and water vapor flows through the flow channel main body 10. The second gas is, for example, nitrogen. As shown in FIG. 1 , the flow channel main body 10 has a pair of ultrasonic transmitters / receivers 11, 12, a pressure sensor 13, a temperature sensor 14, and a density sensor 15. Furthermore, as shown in FIG. 2 , the flow channel main body 10 has a main body portion 100. In the following description, the ultrasonic transmitter / receiver 11 may be referred to as the first ultrasonic transmitter / receiver 11, and the ultrasonic transmitter / receiver 12 may be referred to as the second ultrasonic transmitter / receiver 12.

[0018] The main body 100 is formed in a substantially rectangular shape. A flow path 101 through which a fluid to be measured (a mixed gas), such as a mixed gas containing hydrogen, flows is formed in the center of the main body 100 (see FIG. 3 ). A first opening 110 and a second opening 111 are provided at both ends in the longitudinal direction of the main body 100. Specifically, the first opening 110 and the second opening 111 are provided on both side surfaces of the main body 100 that face each other in the longitudinal direction. The first opening 110 and the second opening 111 are connected by the flow path 101. The mixed gas flows in through the first opening 110, passes through the flow path 101, and flows out from the second opening 111.

[0019] The pair of ultrasonic transmitters / receivers 11, 12 transmit and receive ultrasonic waves. The pair of ultrasonic transmitters / receivers 11, 12 are arranged so that the ultrasonic waves cross the flow of the mixed gas in the flow channel 101. Specifically, the first ultrasonic transmitter / receiver 11 transmits (transmits) ultrasonic waves toward the second ultrasonic transmitter / receiver 12. The first ultrasonic transmitter / receiver 11 receives (receives) ultrasonic waves transmitted from the second ultrasonic transmitter / receiver 12. The second ultrasonic transmitter / receiver 12 transmits (transmits) ultrasonic waves toward the first ultrasonic transmitter / receiver 11. The second ultrasonic transmitter / receiver 12 receives (receives) ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 11. The first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 are arranged upstream and downstream at both ends of the shorter side of the flow channel 101 so that the ultrasonic signals cross the flow of the mixed gas. The first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 are arranged upstream and downstream on opposing sides of the flow path 101 in the short direction so that ultrasonic signals cross the flow of the mixed gas. Specifically, the first ultrasonic transmitter / receiver 11 is arranged upstream and the second ultrasonic transmitter / receiver 12 is arranged downstream so as to face each other (see FIGS. 2 and 3). An ultrasonic propagation path 106 that propagates ultrasonic waves is formed in the opposing direction between the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 (see FIG. 3). The ultrasonic propagation path 106 is inclined at an angle θ with respect to the flow path 101 (see FIG. 3).

[0020] The pressure sensor 13 measures the pressure of the mixed gas flowing through the flow path 101 .

[0021] The temperature sensor 14 is, for example, a thermocouple, and measures the temperature of the gas mixture flowing through the flow path 101.

[0022] The density sensor 15 is, for example, a vibration type densitometer, and measures the density of the gas mixture flowing through the flow path 101.

[0023] (2.2) Processing Device As shown in FIG. 1 , the processing device 20 includes a first communication unit 21 , a second communication unit 22 , a third communication unit 23 , a storage unit 24 , and a control unit 25 .

[0024] The processing device 20 includes, for example, a computer system having one or more processors and a memory. The processor executes a program stored in the memory, causing the computer system to function as the control unit 25. The program executed by the processor is pre-recorded in the memory of the computer system here, but may also be provided by being recorded on a non-transitory recording medium such as a memory card, or via a telecommunications line such as the Internet.

[0025] The first communication unit 21 is a communication interface for communicating with the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12. The second communication unit 22 is a communication interface for communicating with the pressure sensor 13, the temperature sensor 14, and the density sensor 15. The third communication unit 23 is a communication interface for communicating with a user device (not shown) or the like. The user device has a display unit such as a liquid crystal display, and is a device for notifying a user of measurement results and the like in the physical quantity measurement system 1.

[0026] The storage unit 24 is configured by a device selected from a read-only memory (ROM), a random access memory (RAM), an electrically erasable programmable read-only memory (EEPROM), etc. The storage unit 24 stores information used for measuring physical quantities.

[0027] As shown in FIG. 1 , the control unit 25 has a first signal processing unit 201, a second signal processing unit 202, a conversion unit 203, a concentration measurement unit 204, a flow rate measurement unit 205, a water vapor pressure measurement unit 206, and a relative humidity measurement unit 207.

[0028] The first signal processing unit 201 performs processing related to communication between the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 .

[0029] For example, when transmitting ultrasonic waves from the first ultrasonic transmitter / receiver 11 to the second ultrasonic transmitter / receiver 12, the first signal processing unit 201 outputs a signal instructing the first ultrasonic transmitter / receiver 11 to transmit ultrasonic waves to the first ultrasonic transmitter / receiver 11 via the first communication unit 21. When transmitting ultrasonic waves from the second ultrasonic transmitter / receiver 12 to the first ultrasonic transmitter / receiver 11, the first signal processing unit 201 outputs a signal instructing the second ultrasonic transmitter / receiver 12 to transmit ultrasonic waves to the second ultrasonic transmitter / receiver 12 via the first communication unit 21.

[0030] The first signal processing unit 201 also calculates a first propagation time (forward propagation time of the ultrasonic waves) t ｕｐ Specifically, the first signal processing unit 201 measures the first propagation time t based on the time when the ultrasonic wave is transmitted from the first ultrasonic transmitter / receiver 11 and the time when the ultrasonic wave transmitted from the first ultrasonic transmitter / receiver 11 is received by the second ultrasonic transmitter / receiver 12. ｕｐ Measure.

[0031] The first signal processing unit 201 also calculates a second propagation time t of the ultrasonic wave transmitted from the second ultrasonic transmitter / receiver 12 to the first ultrasonic transmitter / receiver 11 (the propagation time of the ultrasonic wave in the reverse direction) ｄｗ Specifically, the first signal processing unit 201 measures the second propagation time t based on the time when the ultrasonic wave is transmitted from the second ultrasonic transmitter / receiver 12 and the time when the ultrasonic wave transmitted from the second ultrasonic transmitter / receiver 12 is received by the first ultrasonic transmitter / receiver 11. ｄｗ Measure.

[0032] The first signal processing unit 201 calculates the first propagation time t ｕｐ and the second propagation time t ｄｗ The average time between these is calculated as the propagation time t.

[0033] The second signal processing unit 202 receives signals output from each sensor and performs predetermined processing on the received signals. When the second signal processing unit 202 receives a signal output from the pressure sensor 13, it performs predetermined signal processing on the received signal to determine the pressure P measured by the pressure sensor 13. When the second signal processing unit 202 receives a signal output from the temperature sensor 14, it performs predetermined signal processing on the received signal to determine the temperature T measured by the temperature sensor 14. When the second signal processing unit 202 receives a signal output from the density sensor 15, it performs predetermined signal processing on the received signal to determine the density ρ measured by the density sensor 15.

[0034] The conversion unit 203 converts the calculated density ρ into a standard density ρ using the density ρ, temperature T, pressure P calculated by the second signal processing unit 202, and the following equation 1: ０ That is, the conversion unit 203 converts the density ρ measured by the density sensor 15 into the standard density ρ ０ Here, P ０ is the pressure (reference pressure) when the gas is in its standard state, and T ０ is the temperature (reference temperature) when the gas is in a standard state. The conversion unit 203 inputs the calculated density ρ, temperature T, and pressure P, and the reference pressure P into the middle of Equation 1. ０ and the reference temperature T ０ By substituting and, the density ρ can be converted to the standard density ρ ０ Here, the reference pressure P ０ and reference temperature T ０ is stored in advance in the storage unit 24. The standard state of gas refers to the state at 20° C. and 1 atm. １ " is the density of hydrogen contained in the gas mixture at standard state. "ρ ２ " is the density of nitrogen contained in the gas mixture at standard state. "ρ ｗ " is the density of water vapor contained in the mixed gas. Furthermore, "x" is the hydrogen concentration, and "x ｗ " is the concentration of water vapor. The density of hydrogen ρ １ , the density of nitrogen ρ ２ , and the density of water vapor ρ ｗis stored in advance in the storage unit 24.

[0035]

[0036] The concentration measurement unit 204 measures the gas concentration, which is the concentration of a gas that is contained in the mixed gas and is different from water vapor. For example, the concentration measurement unit 204 measures the concentration x of hydrogen (hydrogen concentration) as the gas concentration. Specifically, the concentration measurement unit 204 calculates the gas concentration (e.g., hydrogen concentration x) using the pressure P of the mixed gas measured by the pressure sensor 13, the density ρ measured by the density sensor 15, the temperature T measured by the temperature sensor 14, and the propagation time t of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves between the pair of ultrasonic transmitter / receivers 11 and 12. More specifically, the concentration measurement unit 204 calculates the gas concentration (e.g., hydrogen concentration x) using the standard density ρ converted by the conversion unit 203. ０ and the propagation time t of the ultrasonic waves are used to calculate the gas concentration (hydrogen concentration x).

[0037] The concentration measurement unit 204 calculates the water vapor concentration x of the mixed gas, which is the concentration of water vapor in the mixed gas, using the pressure P of the mixed gas measured by the pressure sensor 13, the density ρ measured by the density sensor 15, the temperature T measured by the temperature sensor 14, and the gas concentration (hydrogen concentration x). ｗ Calculate.

[0038] Here, in equation 1, x ｗ When solving for , the following equation 2 is obtained.

[0039]

[0040] Furthermore, the following equation 3 holds true for the sound speed c of the mixed gas.

[0041]

[0042] Here, "t" in Equation 3 is the propagation time of the ultrasonic wave. "L" is the distance between the pair of ultrasonic transducers 11 and 12. "γ" is the specific heat ratio of the mixed gas, "γ=c ｐ / c ｖ " relation holds. Here, "c ｐ " is the constant pressure molar specific heat, and "c ｖ " is the molar specific heat at constant volume. In addition, "M" in the formula 2 is the molecular weight, and "R" is the gas constant. "M １" is the molecular weight of hydrogen (first molecular weight). ｐ１ " is the constant pressure molar specific heat of hydrogen (first constant pressure molar specific heat). ｖ１ " is the isochoric molar specific heat of hydrogen (first isochoric molar specific heat). ２ " is the molecular weight of nitrogen (second molecular weight). ｐ２ " is the constant pressure molar specific heat of nitrogen (second constant pressure molar specific heat). ｖ２ " is the isochoric molar specific heat of nitrogen (second isochoric molar specific heat). "M ｗ " is the molecular weight of water vapor (third molecular weight). ｐｗ " is the constant pressure molar specific heat of water vapor (third constant pressure molar specific heat). ｖｗ ″ is the constant volume molar specific heat of water vapor (third constant volume molar specific heat). １ , first constant pressure molar specific heat c ｐ１ , first constant volume molar specific heat c ｖ１ , second molecular weight M ２ , second constant pressure molar specific heat c ｐ２ , second constant volume molar specific heat c ｖ２ , third molecular weight M ｗ , third constant pressure molar specific heat c ｐｗ , and the third constant volume molar specific heat c ｖｗ is stored in advance in the storage unit 24.

[0043] The concentration measurement unit 204 calculates the hydrogen concentration x using the pressure P measured by the pressure sensor 13, the temperature T measured by the temperature sensor 14, the density ρ of the mixed gas measured by the density sensor 15, the propagation time t of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves between the pair of ultrasonic transmitter-receivers, and Equations 1 to 3. That is, the concentration measurement unit 204 calculates the hydrogen concentration x using the standard density ρ converted by the conversion unit 203. ０ , the propagation time t of the ultrasonic waves, and Equations 2 and 3 are used to calculate the hydrogen concentration x.

[0044] Furthermore, the concentration measurement unit 204 calculates the water vapor concentration x using the pressure P, the temperature T, the density ρ of the mixed gas, the calculated hydrogen concentration x, and Equation 2. ｗ That is, the concentration measurement unit 204 calculates the standard density ρ converted by the conversion unit 203. ０ , the calculated hydrogen concentration x, and the water vapor concentration x using Equation 2 ｗThe concentration measurement unit 204 calculates the water vapor concentration x using the calculated hydrogen concentration x and Equation 3. ｗ may be calculated.

[0045] The density measurement unit 204 also measures the standard density ρ ０ Using the ultrasonic wave propagation time t, Equation 2 and Equation 3, first, the water vapor concentration x ｗ Calculate the standard density ρ ０ , the calculated water vapor concentration x ｗ , and Equation 2 to calculate the hydrogen concentration x. Alternatively, the concentration measurement unit 204 may calculate the water vapor concentration and then calculate the standard density ρ ０ , and Equation 3 may be used to calculate the hydrogen concentration x.

[0046] The flow rate measurement unit 205 measures the first propagation time t ｕｐ and the second propagation time t ｄｗ The flow rate measurement unit 205 measures the flow rate of the mixed gas in the flow path 101 using the following equation 4. ０ Calculate the provisional flow rate Q ０ is calculated by multiplying the cross-sectional area S of the flow path 101 by the flow velocity V. In addition, the flow velocity V, the length L of the ultrasonic propagation path 106 (the distance between the first ultrasonic transducer 11 and the second ultrasonic transducer 12), and the first propagation time t ｕｐ , the second propagation time t ｄｗ and the angle θ of the ultrasonic propagation path 106 with respect to the flow path 101, "Q = SV" can be transformed into the right side of Equation 4. Here, the cross-sectional area S of the flow path 101 and the angle θ of the ultrasonic propagation path 106 with respect to the flow path 101 are stored in advance in the storage unit 24.

[0047]

[0048] The flow rate measurement unit 205 stores, as information used for measuring the physical quantity, the distance L between the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12, the angle θ of the ultrasonic propagation path 106 with respect to the flow path 101, the cross-sectional area S, and the first propagation time t calculated by the first signal processing unit 201, which are stored in advance in the storage unit 24. ｕｐ and the second propagation time t ｄｗ Using the above equation 4, the tentative flow rate Q of the mixed gas is calculated. ０ Calculate.

[0049] The flow rate measurement unit 205 calculates the provisional flow rate Q ０ , and the flow rate Q is calculated using Equation 5. Here, the coefficient R ｋ is a flow coefficient (correction value) and is stored in advance in the storage unit 24.

[0050]

[0051] The water vapor pressure measuring unit 206 measures the water vapor concentration x ｗ and the pressure of the mixed gas P, the water vapor pressure P of the water vapor ｗ Specifically, the water vapor pressure measuring unit 206 measures the water vapor pressure P of the water vapor using the following equation 6: ｗ Calculate.

[0052]

[0053] The relative humidity measuring unit 207 measures the water vapor pressure P ｗ and the saturated water vapor pressure according to the temperature T. Specifically, the relative humidity measuring unit 207 calculates the relative humidity H of the mixed gas using the following equation 7.

[0054]

[0055] (3) Operation Here, the operation of the physical quantity measuring system 1 will be described.

[0056] (3.1) Overview of Operation Here, an overview of the operation of the physical quantity measuring system 1 will be described with reference to FIG.

[0057] The first signal processing unit 201 performs a first measurement process (step S1). Specifically, the first signal processing unit 201 measures a first propagation time t ｕｐ The first signal processing unit 201 also measures the second propagation time t ｄｗ Furthermore, the first signal processing unit 201 measures the first propagation time t ｕｐ and the second propagation time t ｄｗ The propagation time t is calculated as the average time between the

[0058] The second signal processing unit 202 performs a second measurement process (step S2). Specifically, the second signal processing unit 202 determines the pressure P measured by the pressure sensor 13 based on the signal output from the pressure sensor 13. The second signal processing unit 202 determines the temperature T measured by the temperature sensor 14 based on the signal output from the temperature sensor 14. The second signal processing unit 202 determines the density ρ measured by the density sensor 15 based on the signal output from the density sensor 15.

[0059] The conversion unit 203 performs a standard density calculation process (step S3). The conversion unit 203 converts the density ρ into the standard density ρ using the density ρ, temperature T, and pressure P obtained in the second measurement process and the above-mentioned equation 1. ０ Convert to.

[0060] The concentration measurement unit 204 performs a concentration measurement process (step S4). The concentration measurement unit 204 measures the water vapor concentration x ｗ , and the gas concentration that is the concentration of a gas that is contained in the mixed gas and is different from water vapor. In this embodiment, the concentration measurement unit 204 measures the water vapor concentration x ｗ and hydrogen concentration x. Specifically, the concentration measurement unit 204 calculates the gas concentration (e.g., hydrogen concentration x) using the pressure P of the mixed gas measured by the pressure sensor 13, the density ρ measured by the density sensor 15, the temperature T measured by the temperature sensor 14, and the propagation time t of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves between the pair of ultrasonic transmitter-receivers 11 and 12. That is, the concentration measurement unit 204 calculates the gas concentration (e.g., hydrogen concentration x) using the standard density ρ converted by the conversion process. ０ , and the propagation time t of the ultrasonic waves, and Equation 2 and Equation 3 to calculate the hydrogen concentration x. Furthermore, the concentration measurement unit 204 calculates the hydrogen concentration x using the calculated gas concentration (hydrogen concentration x), standard density ρ ０ and using Equation 2, the water vapor concentration x ｗ Calculate.

[0061] The flow rate measurement unit 205 executes a flow rate measurement process to calculate the flow rate Q of the mixed gas (step S5).

[0062] The water vapor pressure measurement unit 206 performs a water vapor pressure measurement process (step S6). The water vapor pressure measurement unit 206 calculates the water vapor pressure P using the pressure P calculated in the second measurement process, the water vapor concentration xw calculated in the concentration measurement process, and Equation 6. ｗ Calculate.

[0063] The relative humidity measurement unit 207 performs a relative humidity measurement process (step S7). The relative humidity measurement unit 207 calculates the water vapor pressure P ｗ and the saturated water vapor pressure according to the temperature T. Specifically, the relative humidity measuring unit 207 calculates the relative humidity H of the mixed gas using the following equation 7.

[0064] (3.2) Density Measurement Processing Here, the density measurement processing shown in step S4 of FIG. 4 will be described with reference to FIG.

[0065] The concentration measurement unit 204 executes the concentration measurement process to measure the concentration x of water vapor contained in the mixed gas. ｗ , and a gas concentration (hydrogen concentration x) which is the concentration of a gas other than water vapor (here, hydrogen) is measured.

[0066] The concentration measurement unit 204 performs a sound speed calculation process (step S101). The concentration measurement unit 204 calculates the sound speed c based on the propagation time t of the ultrasonic wave.

[0067] The concentration measurement unit 204 performs a concentration calculation process (step S102). The concentration measurement unit 204 calculates the sound velocity c calculated based on the propagation time t of the ultrasonic wave, the standard density ρ converted by the conversion process, and the concentration of the ultrasonic wave. ０ , using Equation 2 and Equation 3, the hydrogen concentration x and the water vapor concentration x ｗ Calculate.

[0068] (3.3) Sound Speed ​​Calculation Processing Here, the sound speed calculation processing shown in step S101 of FIG. 5 will be described with reference to FIG.

[0069] The concentration measurement unit 204 receives the pre-stored distance L (the distance between the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12) and the first propagation time t ｕｐ and the second propagation time t ｄｗ and are acquired (step S151).

[0070] The concentration measurement unit 204 measures the first propagation time t ｕｐ and the second propagation time t ｄｗ The propagation time t, which is the average time between the time and the time (step S152).

[0071] The concentration measurement unit 204 calculates the sound speed c using the distance L acquired in step S151, the propagation time t calculated in step S152, and Equation 3 described above (step S153).

[0072] (3.4) Density Calculation Processing Here, the density calculation processing shown in step S102 of FIG. 5 will be described with reference to FIG.

[0073] The concentration measurement unit 204 acquires the temperature T obtained in the second measurement process (step S161).

[0074] The concentration measurement unit 204 calculates the sound velocity c calculated in the sound velocity calculation process and the standard density ρ calculated in the conversion process. ０ is obtained (step S162).

[0075] The concentration measurement unit 204 acquires each parameter stored in advance (step S163). The concentration measurement unit 204 acquires the gas constant R, the molecular weight of hydrogen (first molecular weight) M １ , the molecular weight of nitrogen (second molecular weight) M ２ , the molecular weight of water vapor (third molecular weight) M ｗ , the constant pressure molar specific heat (c ｐ１ , c ｐ２ , c ｐｗ ), the constant volume molar specific heat (c ｖ１ , c ｖ２ , c ｖｗ ), and the density of each gas (hydrogen, nitrogen, water vapor) (ρ １ , ρ ２ , ρ ｗ ) are taken as parameters.

[0076] The concentration measurement unit 204 measures the hydrogen concentration x and the water vapor concentration x ｗ The concentration measurement unit 204 calculates the temperature T acquired in step S161, the sound speed c acquired in step S162, and the standard density ρ ０Using the parameters acquired in step S163, Equation 2, and Equation 3, the hydrogen concentration x and the water vapor concentration x ｗ Specifically, the concentration measurement unit 204 calculates the hydrogen concentration x using the temperature T acquired in step S161, the sound speed c acquired in step S162, the parameters acquired in step S164, and Equations 2 and 3. Furthermore, the concentration measurement unit 204 calculates the hydrogen concentration x using the standard density ρ acquired in step S162. ０ Using the calculated hydrogen concentration x and Equation 2, the water vapor concentration x ｗ Calculate.

[0077] (3.5) Flow Rate Measurement Processing Here, the flow rate measurement processing shown in step S5 of FIG. 4 will be described with reference to FIG.

[0078] The flow rate measurement unit 205 calculates the first propagation time t ｕｐ and the second propagation time t ｄｗ and are acquired (step S201).

[0079] The flow rate measurement unit 205 acquires each parameter stored in advance (step S202). The flow rate measurement unit 205 acquires the cross-sectional area S of the flow path 101, the length L of the ultrasonic propagation path 106 (the distance L between the first ultrasonic transducer 11 and the second ultrasonic transducer 12), the angle θ at which the ultrasonic propagation path 106 is inclined with respect to the flow path 101, and the flow coefficient R ｋ are acquired as parameters.

[0080] The flow rate measurement unit 205 performs a tentative flow rate calculation process (step S203). Specifically, the flow rate measurement unit 205 calculates the first propagation time t ｕｐ and the second propagation time t ｄｗ Using the cross-sectional area S, length L, and angle θ obtained in step S202 and equation 4, the provisional flow rate Q ０ Calculate.

[0081] The flow rate measurement unit 205 calculates the flow rate coefficient R ｋ and the provisional flow rate Q calculated in step S203 ０ and Equation 5 to calculate the flow rate Q (step S204).

[0082] (4) Advantages As described above, the physical quantity measuring system 1 of this embodiment includes the flow path 101, a pair of ultrasonic transmitters / receivers 11 and 12, a pressure sensor 13, a temperature sensor 14, a density sensor 15, and a concentration measurement unit 204. A mixed gas containing hydrogen and water vapor flows through the flow path 101. The pair of ultrasonic transmitters / receivers 11 and 12 transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the mixed gas through the flow path 101. The pressure sensor 13 measures the pressure of the mixed gas. The temperature sensor 14 measures the temperature of the mixed gas. The density sensor 15 measures the density of the mixed gas. The concentration measurement unit 204 measures the gas concentration, which is the concentration of a gas contained in the mixed gas that is different from water vapor. The concentration measurement unit 204 calculates the gas concentration using the pressure of the mixed gas measured by the pressure sensor 13, the density measured by the density sensor 15, the temperature measured by the temperature sensor 14, and the propagation time of the ultrasonic waves obtained by transmitting and receiving ultrasonic waves between a pair of ultrasonic transmitters and receivers 11 and 12.

[0083] According to this configuration, the physical quantity measurement system 1 uses the temperature and propagation time of the mixed gas as well as the density measured by the density sensor 15 to measure the gas concentration (hydrogen concentration), so that the gas concentration (hydrogen concentration) can be measured with high accuracy even in a high humidity environment.

[0084] (5) Modifications Modifications are listed below. The modifications described below can be applied in appropriate combination with the above-described embodiment.

[0085] (5.1) Modification 1 The flow channel body 10 may further include one or more partition plates. The one or more partition plates divide the flow channel 101 into multiple sections in the height direction (Z direction) of the flow channel 101. By dividing the flow channel 101 into multiple sections with the one or more partition plates, a multi-layer flow channel is formed in the flow channel 101. This configuration increases the aspect ratio of the flow channel cross section of each layer of the multi-layer flow channel, thereby making the flow two-dimensional and rectifying the flow and stabilizing turbulence.

[0086] (5.2) Modification 2 The flow path main body 10 may have a plurality of temperature sensors 14. That is, the physical quantity measuring system 1 may be provided with a plurality of temperature sensors 14. When the flow path main body 10 has a plurality of temperature sensors 14, the second signal processing unit 202 calculates the average value of the temperatures measured by the plurality of temperature sensors 14 as the temperature T of the mixed gas.

[0087] (5.3) Modification 3 The first ultrasonic transmitter / receiver 11 is arranged upstream and the second ultrasonic transmitter / receiver 12 is arranged downstream, facing each other, i.e., the arrangement direction of the first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 intersects with the X direction, but this configuration is not limited to this.

[0088] The first ultrasonic transmitter / receiver 11 and the second ultrasonic transmitter / receiver 12 may be arranged along the X direction, but not intersect with the X direction.

[0089] In this case, the ultrasonic waves output from the first ultrasonic transmitter / receiver 11 are reflected within the flow path 101, and the reflected ultrasonic waves are input to the second ultrasonic transmitter / receiver 12. Furthermore, the ultrasonic waves output from the second ultrasonic transmitter / receiver 12 are reflected within the flow path 101, and the reflected ultrasonic waves are input to the first ultrasonic transmitter / receiver 11. That is, the path of the ultrasonic waves is V-shaped and crosses the flow of the mixed gas in the flow path 101. That is, in the third modification as well, the pair of ultrasonic transmitters / receivers 11, 12 are arranged so that the ultrasonic waves cross the flow of the mixed gas in the flow path 101.

[0090] (5.4) Modification 4 In the present disclosure, at least one of the pressure sensor 13, the temperature sensor 14, and the density sensor 15 is not an essential component of the physical quantity measuring system 1.

[0091] 9 . In other words, if the pressure of the mixed gas flowing through the flow path 101 is known by another means, the physical quantity measurement system 1 does not necessarily need to include the pressure sensor 13. The physical quantity measurement system 1 may obtain the pressure of the mixed gas flowing through the flow path 101, which is known by another means, from the external device 30 and use it as a measurement value.

[0092] When the physical quantity measurement system 1 does not include the temperature sensor 14, it may acquire the temperature of the mixed gas flowing through the flow path 101 from the external device 30. That is, when the temperature of the mixed gas flowing through the flow path 101 is known by another means, the physical quantity measurement system 1 does not necessarily need to include the temperature sensor 14. The physical quantity measurement system 1 may acquire the temperature of the mixed gas flowing through the flow path 101, which is known by another means, from the external device 30 and use it as a measurement value.

[0093] When the physical quantity measurement system 1 does not include the density sensor 15, it may acquire the density of the mixed gas flowing in the flow path 101 from the external device 30. That is, when the density of the mixed gas flowing in the flow path 101 is known by another means, the physical quantity measurement system 1 does not necessarily need to include the density sensor 15. The physical quantity measurement system 1 may acquire the density of the mixed gas flowing in the flow path 101, which is known by another means, from the external device 30 and use it as a measurement value.

[0094] The concentration measurement unit 204 of the physical quantity measurement system 1 of the fourth modification calculates the water vapor concentration using the pressure, density, and temperature of the mixed gas.

[0095] In this case, if the physical quantity measurement system 1 of variant example 4 does not have any of the pressure sensor 13, temperature sensor 14, and density sensor 15, the concentration measurement unit 204 of variant example 4 acquires all of the pressure, density, and temperature of the mixed gas from the external device 30.

[0096] Alternatively, the physical quantity measurement system 1 of Modification 4 may measure one or two of the pressure, temperature, and density of the mixed gas. In this case, the physical quantity measurement system 1 of Modification 4 further includes one or two sensors that perform measurements according to one or two of the measurement targets of the mixed gas pressure, temperature, and density. That is, the physical quantity measurement system 1 of Modification 4 further includes one or two sensors from the pressure sensor 13 that measures the pressure of the mixed gas, the temperature sensor 14 that measures the temperature of the mixed gas, and the density sensor 15 that measures the density of the mixed gas, according to one or two of the measurement targets of the mixed gas pressure, temperature, and density of the mixed gas. The concentration measurement unit 204 of Modification 4 externally acquires the pressure, temperature, and density of the mixed gas that are not the measurement targets. With this configuration, some of the pressure, temperature, and density of the mixed gas can be acquired from the sensors, and the rest can be acquired externally.

[0097] (Other Modifications) The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design and the like as long as the object of the present disclosure can be achieved.

[0098] Furthermore, functions similar to those of the physical quantity measurement system 1 may be embodied as a physical quantity measurement method, a computer program, a non-transitory recording medium on which a program is recorded, or the like. A physical quantity measurement method according to one aspect is used in a physical quantity measurement system 1 including a flow path 101 and a pair of ultrasonic transmitters / receivers 11 and 12. A mixed gas containing hydrogen and water vapor flows through the flow path 101. The pair of ultrasonic transmitters / receivers 11 and 12 transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the mixed gas in the flow path 101. The physical quantity measurement method includes a concentration measurement step. The concentration measurement step measures a gas concentration, which is the concentration of a gas contained in the mixed gas and different from water vapor. In the concentration measurement step, the gas concentration is calculated using the pressure of the mixed gas, the density of the mixed gas, the temperature of the mixed gas, and the propagation time of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves between the pair of ultrasonic transmitters / receivers 11 and 12. A program according to one aspect causes a computer system to function as the above-described physical quantity measurement method.

[0099] The physical quantity measurement system 1 according to the present disclosure includes a computer system. The computer system is primarily composed of a processor and a memory as hardware. The processor executes a program stored in the memory of the computer system to realize the functions of the physical quantity measurement system 1 according to the present disclosure. The program may be pre-recorded in the memory of the computer system, provided via a telecommunications line, or provided in a non-transitory recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs and LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large-scale integrations (VLSIs), or ultra-large-scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices that allow the reconfiguration of internal connections or internal circuit partitions of the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0100] Furthermore, it is not essential for the physical quantity measurement system 1 that multiple functions are integrated into one housing, and the components of the physical quantity measurement system 1 may be distributed across multiple housings. Furthermore, at least some of the functions of the physical quantity measurement system 1 may be realized by the cloud (cloud computing) or the like.

[0101] (Summary) As described above, the physical quantity measuring system (1) of the first aspect includes a flow path (101), a pair of ultrasonic transmitters and receivers (11, 12), and a concentration measuring unit (204). A mixed gas containing hydrogen and water vapor flows through the flow path (101). The pair of ultrasonic transmitters and receivers (11, 12) transmit and receive ultrasonic waves and are arranged so that the ultrasonic waves cross the flow of the mixed gas in the flow path (101). The concentration measuring unit (204) measures a gas concentration, which is the concentration of a gas contained in the mixed gas that is different from water vapor. The concentration measuring unit (204) calculates the gas concentration using the pressure of the mixed gas, the density of the mixed gas, the temperature of the mixed gas, and the propagation time of ultrasonic waves obtained by transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers (11, 12).

[0102] According to this embodiment, the density of the mixed gas, in addition to the temperature and propagation time of the mixed gas, is used to measure the gas concentration (hydrogen concentration), so that the gas concentration (hydrogen concentration) can be measured with high accuracy even in a high humidity environment.

[0103] The physical quantity measurement system (1) of the second aspect is the same as that of the first aspect, but further includes a pressure sensor (13), a temperature sensor (14), and a density sensor (15). The pressure sensor (13) measures the pressure of the gas mixture. The temperature sensor (14) measures the temperature of the gas mixture. The density sensor (15) measures the density of the gas mixture.

[0104] According to this embodiment, the gas concentration (hydrogen concentration) can be measured with high accuracy even in a high humidity environment.

[0105] The physical quantity measurement system (1) of the third aspect is the same as that of the first aspect, and further includes one or two sensors that perform measurements according to one or two measurement targets among the pressure, temperature, and density of the mixed gas. The concentration measurement unit (204) acquires the pressure, temperature, and density of the mixed gas that are not the measurement targets from an external source.

[0106] According to this embodiment, the gas concentration (hydrogen concentration) can be measured with high accuracy even in a high humidity environment.

[0107] The physical quantity measuring system (1) of a fourth aspect is any one of the first to third aspects, further comprising a conversion unit (203). The conversion unit (203) converts the density of the mixed gas into a standard density, which is the density of the mixed gas at a standard state, using the pressure and temperature of the mixed gas. The concentration measuring unit (204) calculates the gas concentration using the standard density and the propagation time of ultrasonic waves obtained by transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers (11, 12).

[0108] According to this embodiment, the gas concentration (hydrogen concentration) can be measured with high accuracy even in a high humidity environment.

[0109] A fifth aspect of the physical quantity measurement system (1) is the physical quantity measurement system (1) of any one of the first to fourth aspects, further comprising a water vapor pressure measurement unit (206). The water vapor pressure measurement unit (206) measures the water vapor pressure of water vapor. The concentration measurement unit (204) further calculates a water vapor concentration, which is the concentration of water vapor, using the pressure, density, temperature, and gas concentration of the mixed gas. The water vapor pressure measurement unit (206) calculates the water vapor pressure using the water vapor concentration and the pressure of the mixed gas.

[0110] According to this embodiment, the water vapor pressure can be measured with high accuracy.

[0111] The physical quantity measuring system (1) of a sixth aspect is the fifth aspect, further comprising a relative humidity measuring unit (207). The relative humidity measuring unit (207) measures the relative humidity of the mixed gas based on the water vapor pressure and the saturated water vapor pressure according to the temperature.

[0112] According to this aspect, the relative humidity of the mixed gas is measured using the water vapor pressure measured by the water vapor pressure measuring unit (206), so that the relative humidity of the mixed gas can be measured more accurately.

[0113] The physical quantity measuring system (1) of a seventh aspect is the physical quantity measuring system (1) of any one of the first to sixth aspects, further including a flow rate measuring unit (205). The flow rate measuring unit (205) measures the flow rate of the mixed gas in the flow path (101) using a first propagation time of an ultrasonic wave transmitted from a first ultrasonic transmitter / receiver (11) to a second ultrasonic transmitter / receiver (12) of the pair of ultrasonic transmitter / receivers (11, 12) and a second propagation time of an ultrasonic wave transmitted from the second ultrasonic transmitter / receiver (12) to the first ultrasonic transmitter / receiver (11).

[0114] According to this embodiment, the flow rate of the mixed gas can be measured with high accuracy.

[0115] REFERENCE SIGNS LIST 1 Physical quantity measurement system 11 Ultrasonic transducer (first ultrasonic transducer) 12 Ultrasonic transducer (second ultrasonic transducer) 13 Pressure sensor 14 Temperature sensor 15 Density sensor 20 Processing device 101 Flow path 203 Conversion unit 204 Concentration measurement unit 205 Flow rate measurement unit 206 Water vapor pressure measurement unit 207 Relative humidity measurement unit

Claims

1. A flow path through which a mixture of hydrogen and water vapor flows, A pair of ultrasonic transducers that transmit and receive ultrasonic waves, and are arranged such that the ultrasonic waves cross the flow of the mixed gas in the channel, The system includes a concentration measuring unit that measures the gas concentration of a gas contained in the mixed gas and which is different from the water vapor, The concentration measuring unit is The gas concentration is calculated using the pressure of the gas mixture, the density of the gas mixture, the temperature of the gas mixture, and the propagation time of the ultrasonic waves obtained by transmitting and receiving ultrasonic waves in the pair of ultrasonic transducers. A system for measuring physical quantities.

2. A pressure sensor for measuring the pressure of the mixed gas, A temperature sensor for measuring the temperature of the mixed gas, The system further comprises a density sensor for measuring the density of the mixed gas, The physical quantity measurement system according to claim 1.

3. The system further comprises one or two sensors that perform measurements according to one or two of the following measurement targets: the pressure of the gas mixture, the temperature of the gas mixture, and the density of the gas mixture. The concentration measuring unit obtains from an external source the pressure of the gas mixture, the temperature of the gas mixture, and the density of the gas mixture, which are not to be measured. The physical quantity measurement system according to claim 1.

4. The system further includes a conversion unit that converts the density of the mixed gas to a standard density, which is the density of the mixed gas under standard conditions, using the pressure and temperature of the mixed gas. The concentration measuring unit calculates the gas concentration using the standard density and the propagation time of the ultrasonic waves obtained by transmitting and receiving the ultrasonic waves in the pair of ultrasonic transducers. A physical quantity measurement system according to any one of claims 1 to 3.

5. The system further comprises a water vapor pressure measuring unit for measuring the water vapor pressure of the water vapor, The concentration measuring unit further calculates the water vapor concentration, which is the concentration of water vapor, using the pressure of the gas mixture, the density of the gas mixture, the temperature of the gas mixture, and the gas concentration. The water vapor pressure measuring unit calculates the water vapor pressure of the water vapor using the water vapor concentration and the pressure of the mixed gas. A physical quantity measurement system according to any one of claims 1 to 3.

6. The system further includes a relative humidity measuring unit that measures the relative humidity of the mixed gas based on the water vapor pressure and the saturated water vapor pressure corresponding to the temperature. The physical quantity measurement system according to claim 5.

7. The system further includes a flow rate measuring unit that measures the flow rate of the mixed gas in the flow path using the first propagation time of the ultrasonic waves transmitted from the first ultrasonic transducer to the second ultrasonic transducer, and the second propagation time of the ultrasonic waves transmitted from the second ultrasonic transducer to the first ultrasonic transducer. A physical quantity measurement system according to any one of claims 1 to 3.