Physical quantity measurement system

Abstract

The present disclosure addresses the problem of detecting the presence or absence of an abnormality while reducing the possibility of moisture condensation occurring in a hygrometer. A physical quantity measurement system (1) includes a temperature / humidity sensor (16), a heat generation unit (17), and a detection unit (e.g., a second detection unit 209). A temperature / humidity sensor (16) measures the humidity and temperature of the mixed gas flowing through the flow channel (101). The heat generating unit (17) performs a heat generating operation to generate heat for heating the temperature / humidity sensor (16). The detection unit detects an abnormality in a heat generation operation of the heat generation unit (17). The detection unit detects that an abnormality has occurred when the heat generation unit (17) performs a heat generation operation and the humidity measurement value of the mixed gas measured by the temperature / humidity sensor (16) and the temperature measurement value of the mixed gas satisfy a predetermined condition.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to a physical quantity measurement system, and more particularly to a physical quantity measurement system that measures a target that is a mixed gas flowing through a flow passage. BACKGROUND

[0002] For example, a fuel cell system is known in the art as a system that measures a hydrogen concentration in a flow passage through which a mixed gas including hydrogen (mixed gas) flows using a physical quantity measurement system (see, for example, Patent Literature 1).

[0003] The fuel cell system of Patent Literature 1 teaches that when a mixed gas including three components, i.e., hydrogen, water vapor, and an impurity gas, flows through a flow passage, a hygrometer is provided to obtain a water vapor concentration using a detection result of the hygrometer.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2003-317752 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] According to the known method, when a water vapor concentration is obtained from a mixed gas including three components, i.e., hydrogen, water vapor, and an impurity gas, first, a water vapor pressure is measured using a detection result (humidity) measured by a hygrometer. If a system for measuring a physical quantity such as a water vapor concentration, i.e., a physical quantity measurement system, is used in a high humidity environment, condensation can occur in the hygrometer. In addition, it is also necessary to understand whether any abnormality has occurred to determine whether a measured value is a normal value or an abnormal value.

[0009] In view of the foregoing background, it is therefore an object of the present disclosure to provide a physical quantity measurement system that has the ability to detect the presence or absence of any abnormality while reducing the likelihood of condensation occurring in a sensor for measuring humidity.

[0010] A physical quantity measurement system according to one aspect of the present disclosure includes a temperature and humidity sensor, a heat generator, and a detector. The temperature and humidity sensor measures humidity and temperature of a mixed gas flowing through a flow passage. The heat generator performs a heat generation operation that heats the temperature and humidity sensor. The detector detects any abnormality in the heat generation operation of the heat generator. The detector detects occurrence of an abnormality when the heat generation operation is performed by the heat generator and a humidity measurement value of the mixed gas and a temperature measurement value of the mixed gas measured by the temperature and humidity sensor satisfy a predetermined condition. BRIEF DESCRIPTION OF DRAWINGS

[0011] [ Figure 1 ]Figure 1 is a block diagram showing a configuration of a physical quantity measurement system according to an example embodiment.

[0012] [ Figure 2 ] Figure 2 is a system diagram showing a configuration of a physical quantity measurement system.

[0013] [ Figure 3 ] Figure 3 is a cross-sectional view of a flow passage body included in the physical quantity measurement system, taken along the X-Z plane.

[0014] [ Figure 4 ] Figure 4 is a cross-sectional view of a flow passage body included in the physical quantity measurement system, taken along the X-Y plane.

[0015] [ Figure 5 ] Figure 5 is a flowchart showing an operation procedure of the physical quantity measurement system.

[0016] [ Figure 6 ] Figure 6 is a flowchart showing a procedure of a heat generation control process executed by the physical quantity measurement system.

[0017] [ Figure 7 ] Figure 7 is a flowchart showing a procedure of a third measurement process to be executed by the physical quantity measurement system.

[0018] [ Figure 8 ] Figure 8 is a flowchart showing a procedure of a first abnormality detection process to be executed by the physical quantity measurement system.

[0019] [ Figure 9 ] Figure 9 is a flowchart showing a procedure of a second abnormality detection process to be executed by the physical quantity measurement system.

[0020] [ Figure 10 ] Figure 10 is a flowchart showing a procedure of a concentration measurement process to be executed by the physical quantity measurement system.

[0021] [ Figure 11 ] Figure 11 is a flowchart showing a procedure of a sound velocity calculation process to be executed as part of the concentration measurement process.

[0022] [ Figure 12 ] Figure 12 is a flowchart showing a procedure of a hydrogen concentration calculation process to be executed as part of the concentration measurement process.

[0023] [ Figure 13 ]Figure 13 is a flowchart showing a procedure of a flow measurement process to be executed by the physical quantity measurement system.

[0024] [ Figure 14 ] Figure 14 is a flowchart showing a procedure of a flow coefficient calculation process to be executed as a part of the flow measurement process.

[0025] [ Figure 15 ] Figure 15 is a flowchart showing a procedure of a relative humidity measurement process to be executed by the physical quantity measurement system.

[0026] [ Figure 16 ] Figure 16 is a flowchart showing a procedure of a third measurement process according to a first modification example. DETAILED DESCRIPTION

[0027] Note that the embodiments to be described below and modifications thereof are merely exemplary embodiments and modifications of various embodiments and modifications of the present disclosure, and should not be construed as limiting the scope of the present disclosure. On the contrary, the exemplary embodiments and modifications thereof can be easily modified in various ways according to design selection or any other factors without departing from the true spirit and scope of the present disclosure.

[0028] (Embodiments)

[0029] A physical quantity measurement system 1 according to the present embodiment will be described with reference to Figures 1 to 15 .

[0030] (1) Overview

[0031] The physical quantity measurement system 1 according to the present embodiment is a system for measuring at least one of a water vapor pressure of water vapor as a specific gas or a relative humidity of a mixed gas in a mixed gas including a plurality of types of gases flowing through a flow passage 101 (refer to Figure 3 ).

[0032] The physical quantity measurement system 1 according to the present embodiment includes a temperature and humidity sensor 16, a heat generator 17, and a detector such as a second detector 209 as shown in Figure 1 . The temperature and humidity sensor 16 measures a humidity and a temperature of the mixed gas flowing through the flow passage 101. The heat generator 17 performs a heat generation to perform a heat generation operation to warm up the temperature and humidity sensor 16. The detector detects any abnormality in the heat generation operation of the heat generator 17. The detector detects an occurrence of the abnormality when the heat generator 17 performs the heat generation operation and a humidity measurement value of the mixed gas and a temperature measurement value of the mixed gas measured by the temperature and humidity sensor 16 satisfy a predetermined condition.

[0033] Even if the mixed gas flows through the flow passage in a high humidity environment, this configuration can reduce the possibility of condensation occurring in the temperature and humidity sensor 16 due to the heater 17 performing a heating operation. In addition, if the humidity measurement value of the mixed gas measured when the heater 17 performs a heating operation satisfies a predetermined condition, the detector detects the occurrence of an abnormality. Thus, the physical quantity measurement system 1 according to the present embodiment can detect the presence or absence of any abnormality while reducing the possibility of condensation occurring in the hygrometer.

[0034] (2) Configuration

[0035] The configuration of the physical quantity measurement system 1 will now be described with reference to Figures 1 to 4 The configuration of the physical quantity measurement system 1 will now be described with reference to

[0036] The physical quantity measurement system 1 includes a flow passage main body 10 and a processing device 20, as shown in Figure 1 The physical quantity measurement system 1 measures the concentration of hydrogen included in a mixed gas flowing through the flow passage main body 10 (hereinafter simply referred to as “hydrogen concentration”) as a physical quantity, the flow rate of the mixed gas, and the relative humidity thereof. In addition, the physical quantity measurement system 1 also measures the water vapor pressure of water vapor included in the mixed gas and the concentration of water vapor with respect to the mixed gas (hereinafter simply referred to as “water vapor concentration”) as physical quantities. In this case, the concentration measured by the physical quantity measurement system 1 can be, for example, a volume concentration.

[0037] Here, the X-axis, Y-axis, and Z-axis are defined with respect to the flow passage main body 10 (refer to Figure 2 ). Specifically, the X-axis is defined herein as an axis along the longitudinal axis of the flow passage main body 10, i.e., an axis defined along the direction in which the mixed gas flows. The Y-axis is an axis that intersects the X-axis at a right angle, and can be, for example, an axis defined along the depth of the flow passage main body 10. The Z-axis is an axis that intersects the X-axis and the Y-axis at right angles, and can be, for example, an axis defined along the height of the flow passage main body 10. Figure 3 is a cross-sectional view of the flow passage main body 10 taken along the X-Z plane. Figure 4 is a cross-sectional view of the flow passage main body 10 taken along the X-Y plane.

[0038] (2.1) Flow Passage Main Body

[0039] The mixed gas flows through the flow passage main body 10. The flow passage main body 10 includes a pair of ultrasonic transceivers 11, 12, a first temperature sensor 13, a second temperature sensor 14, a pressure sensor 15, a temperature and humidity sensor 16, a heater 17, and a switching unit 18, as shown in Figure 1 The flow passage main body 10 also includes a flow passage 21, as shown in Figure 2The main body 100 is shown. Note that in the following description, the ultrasonic transceiver 11 will hereinafter be sometimes referred to as "first ultrasonic transceiver 11", and the ultrasonic transceiver 12 will hereinafter be sometimes referred to as "second ultrasonic transceiver 12".

[0040] The main body 100 is formed in a substantially rectangular parallelepiped shape. A flow passage 101 through which a measured fluid (mixed gas) such as a mixed gas including hydrogen flows is provided to pass through the center of the main body 100 (refer to Figure 3 ). The first opening 110 and the second opening 111 are provided at two longitudinal end portions of the main body 100, respectively. The first opening 110 and the second opening 111 are provided through two side surfaces of the main body 100 facing each other along a longitudinal axis, respectively. The first opening 110 and the second opening 111 are connected to each other via the flow passage 101. The mixed gas flows in through the first opening 110, flows through the flow passage 101, and flows out through the second opening 111.

[0041] A pair of ultrasonic transceivers 11, 12 transmits and receives ultrasonic waves. The pair of ultrasonic transceivers 11, 12 is configured to pass ultrasonic waves through the flow of the mixed gas along the flow passage 101. Specifically, the first ultrasonic transceiver 11 transmits ultrasonic waves toward the second ultrasonic transceiver 12. In addition, the first ultrasonic transceiver 11 also receives ultrasonic waves transmitted from the second ultrasonic transceiver 12. In the same manner, the second ultrasonic transceiver 12 transmits ultrasonic waves toward the first ultrasonic transceiver 11. In addition, the second ultrasonic transceiver 12 also receives ultrasonic waves transmitted from the first ultrasonic transceiver 11. The first ultrasonic transceiver 11 and the second ultrasonic transceiver 12 are configured at both lateral end portions of the flow passage 101 and at the upstream end portion and the downstream end portion to pass ultrasonic signals through the flow of the mixed gas. The first ultrasonic transceiver 11 and the second ultrasonic transceiver 12 are also configured on both side surfaces of the flow passage 101 facing each other along a lateral axis and at the upstream end portion and the downstream end portion to pass ultrasonic signals through the flow of the mixed gas. Specifically, the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12 are configured at the upstream end portion and the downstream end portion, respectively, in a manner facing each other (refer to Figures 2 to 4 ). An ultrasonic wave propagation path 106 for ultrasonic waves to propagate is formed in a direction in which the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12 face each other (refer to Figure 4 ). The ultrasonic wave propagation path 106 forms an inclination angle θ with respect to the flow passage 101 (refer to Figure 4 ).

[0042] The pressure sensor 15 is arranged in a central region of one of two main surfaces (hereinafter referred to as "upper surface") facing each other in a thickness direction defined with respect to the main body 100 (refer to Figure 2 and Figure 3 ). The pressure sensor 15 measures the pressure of the mixed gas flowing through the flow passage 101.

[0043] The first temperature sensor 13 is arranged on the upper surface in a manner positioned opposite the second opening 111 with respect to the pressure sensor 15 (refer to Figure 2 and Figure 3 ). That is, the first temperature sensor 13 is arranged at the upstream end portion of the flow passage 101. The first temperature sensor 13 can be, for example, a thermocouple, and measures the temperature of the mixed gas flowing through the flow passage 101.

[0044] The second temperature sensor 14 is arranged on the upper surface in a manner positioned opposite the first opening 110 with respect to the pressure sensor 15 (refer to Figure 2 and Figure 3 ). That is, the second temperature sensor 14 is arranged at the downstream end portion of the flow passage 101. The second temperature sensor 14 can be, for example, a thermocouple, and measures the temperature of the mixed gas flowing through the flow passage 101.

[0045] The temperature and humidity sensor 16 includes a humidity sensor and a temperature sensor. That is, the temperature and humidity sensor 16 measures the humidity and temperature of the mixed gas flowing through the flow passage 101. Of the two side surfaces facing each other along the lateral axis of the flow passage 101, the temperature and humidity sensor 16 is provided for the one side surface provided with the first ultrasonic transceiver 11. The temperature and humidity sensor 16 is provided at the downstream end portion of the flow passage 101. Further, the first temperature sensor 13 and the second temperature sensor 14, and the temperature and humidity sensor 16 are arranged separately along the flow passage 101.

[0046] A heater 17 is provided for the temperature and humidity sensor 16. The temperature and humidity sensor 16 and the heater 17 are housed in the same housing 160. The heater 17 performs a heat generating operation of generating heat, which causes the temperature and humidity sensor 16, particularly the humidity sensor thereof, to warm up. The heater 17 is provided for the temperature and humidity sensor 16. Therefore, the influence of the heat generated by the heater 17 on the second temperature sensor 14 is not as significant as the influence of the heat generated by the heater 17 on the temperature and humidity sensor 16. In other words, the second temperature sensor 14 measures the temperature of the mixed gas, and is arranged at a place where the influence of the heat generated by the heater 17 on the second temperature sensor 14 is small as compared with the temperature and humidity sensor 16.

[0047] The switch unit 18 is provided in the power supply unit 26 (refer to Figure 1) with the temperature and humidity sensor 16 and the heat generator 17. The control unit 26 supplies electric power to the temperature and humidity sensor 16 and the heat generator 17. The switching unit 18 can be, for example, a metal oxide semiconductor field effect transistor (MOSFET). Under the control of the processing device 20, the electric supply path between the electric supply unit 26 and the temperature and humidity sensor 16 and the heat generator 17 can be cut off, or the electric supply unit 26 can be electrically connected to the temperature and humidity sensor 16 and the heat generator 17 via the electric supply path. When the electric supply path between the electric supply unit 26 and the temperature and humidity sensor 16 and the heat generator 17 is cut off, electric power is no longer supplied to the temperature and humidity sensor 16 and the heat generator 17. This causes the temperature and humidity sensor 16 to stop measuring temperature and humidity and reduces heat generated by the heat generator 17. That is, the switching unit 18 is configured to be ready to stop the heat generator 17 from generating heat when any abnormality in the heat generation operation of the heat generator 17 is detected.

[0048] The flow passage main body 10 further includes one or more partitions 107. The one or more partitions 107 divide the flow passage 101 into a plurality of sections in the height direction H defined with respect to the flow passage 101. When the one or more partitions 107 divide the flow passage 101 into a plurality of sections, a multilayer flow passage 108 is formed in the flow passage 101. This configuration not only increases the aspect ratio of the flow passage cross section of each layer of the multilayer flow passage 108 to turn the flow into two-dimensional flow, but also reduces the Reynolds number to correct the flow and stabilize the turbulent flow.

[0049] Note that the one or more partitions 107 are not an essential constituent element. That is, the flow passage main body 10 (the physical quantity measurement system 1) does not necessarily include the partitions 107.

[0050] (2.2) Processing device

[0051] As Figure 1 shown, the processing device 20 includes a first communication unit 21, a second communication unit 22, a third communication unit 23, a fourth communication unit 24, and a control unit 25.

[0052] For example, the processing device 20 includes a computer system including one or more processors and a memory. The computer system executes the functions of the control unit 25 by causing the processor to execute a program stored in the memory. In the present embodiment, the program executed by the processor is stored in the memory in advance. Alternatively, the program can also be distributed after being stored in a non-transitory storage medium such as a memory card or downloaded via a telecommunication line such as the Internet.

[0053] The first communication unit 21 is a communication interface for communicating with the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12. The second communication unit 22 is a communication interface for communicating with the first temperature sensor 13, the second temperature sensor 14, the pressure sensor 15, and the temperature and humidity sensor 16. The third communication unit 23 is a communication interface for communicating with the heat generator 17 and the switching unit 18. The fourth communication unit 24 is a communication interface for communicating with the user device 30 (refer to Figure 2 ). The user device 30 is a device including a display unit such as a liquid crystal display to notify a user of, for example, a result of measurement by the physical quantity measurement system 1.

[0054] The control unit 25 includes a first signal processor 201, a second signal processor 202, a heat controller 203, a water vapor pressure measurer 204, a concentration measurer 205, a flow measurer 206, and a relative humidity measurer 207, as shown in Figure 1 The control unit 25 further includes a first detector 208 (an environmental abnormality detector) and a second detector 209 (a heat abnormality detector).

[0055] The first signal processor 201 performs processing regarding communication between the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12.

[0056] For example, when an ultrasonic wave is to be transmitted from the first ultrasonic transceiver 11 to the second ultrasonic transceiver 12, the first signal processor 201 outputs, to the first ultrasonic transceiver 11 via the first communication unit 21, a signal indicating that the first ultrasonic transceiver 11 transmits an ultrasonic wave. When an ultrasonic wave is to be transmitted from the second ultrasonic transceiver 12 to the first ultrasonic transceiver 11, the first signal processor 201 outputs, to the second ultrasonic transceiver 12 via the first communication unit 21, a signal indicating that the second ultrasonic transceiver 12 transmits an ultrasonic wave.

[0057] In addition, the first signal processor 201 also measures a first propagation time (i.e., a propagation time of an ultrasonic wave in a forward direction) t up of an ultrasonic wave transmitted from the first ultrasonic transceiver 11 to the second ultrasonic transceiver 12. Specifically, the first signal processor 201 measures the first propagation time t up based on a time at which an ultrasonic wave is transmitted from the first ultrasonic transceiver 11 and a time at which the ultrasonic wave transmitted from the first ultrasonic transceiver 11 is received at the second ultrasonic transceiver 12.

[0058] Furthermore, the first signal processor 201 also measures a second propagation time (i.e., a propagation time of an ultrasonic wave in a reverse direction) t dwSpecifically, the first signal processor 201 measures the second propagation time t2 based on the time at which the ultrasonic wave is transmitted from the second ultrasonic transceiver 12 and the time at which the ultrasonic wave transmitted from the second ultrasonic transceiver 12 is received at the first ultrasonic transceiver 11 dw .

[0059] The second signal processor 202 receives the output signals of the respective sensors, and subjects the received signals to predetermined processing. For example, upon receiving the output signal of the first temperature sensor 13, the second signal processor 202 subjects the thus-received signal to predetermined signal processing to obtain the first temperature value measured by the first temperature sensor 13. Upon receiving the output signal of the second temperature sensor 14, the second signal processor 202 subjects the thus-received signal to predetermined signal processing to obtain the second temperature value measured by the second temperature sensor 14.

[0060] Further, upon receiving the output signal of the pressure sensor 15, the second signal processor 202 subjects the thus-received signal to predetermined signal processing to obtain the pressure value measured by the pressure sensor 15.

[0061] Upon receiving the output signal of the humidity sensor of the temperature and humidity sensor 16, the second signal processor 202 subjects the thus-received signal to predetermined signal processing to obtain the humidity value (humidity measurement value) measured by the temperature and humidity sensor 16. Upon receiving the output signal of the temperature sensor of the temperature and humidity sensor 16, the second signal processor 202 subjects the thus-received signal to predetermined signal processing to obtain the temperature value (temperature measurement value) measured by the temperature and humidity sensor 16.

[0062] The heat generation controller 203 controls the ON / OFF state of the heat generator 17 to change the state of the heat generator 17 from the ON state in which the heat generator 17 performs the heat generation operation to the OFF state in which the heat generator 17 stops performing the heat generation operation, and vice versa. The heat generation controller 203 controls the ON / OFF state of the heat generator 17 based on the comparison result between the humidity measurement value of the mixed gas that has been measured by the temperature and humidity sensor 16 and the first threshold value. That is, the heat generation controller 203 controls the heat generation operation of the heat generator 17 based on the comparison result between the humidity measurement value measured by the temperature and humidity sensor 16 and the first threshold value. As used herein, the "first threshold value" refers to a humidity value at which condensation does not occur in the temperature and humidity sensor 16. The first threshold value can be set to, for example, 70% as the humidity value at which condensation does not occur.

[0063] If the humidity measurement value measured by the temperature and humidity sensor 16 is greater than a first threshold value (threshold value), the heating controller 203 turns the heater 17 on. On the other hand, if the humidity measurement value measured by the temperature and humidity sensor 16 is equal to or less than the first threshold value, the heating controller 203 turns the heater 17 off. Specifically, if the humidity measurement value measured by the temperature and humidity sensor 16 is greater than the first threshold value, the heating controller 203 controls the periods during which the heater 17 is on and the periods during which the heater 17 is off through pulse width modulation (PWM), thereby alternately turning the heater 17 on and off. The heating controller 203 controls the pulse width of the pulse width modulation so that the greater the difference between the first threshold value and the humidity measurement value, the longer the on state lasts. On the other hand, if the humidity measurement value is equal to or less than the first threshold value, the heating controller 203 turns the heater 17 off. As used herein, the phrase "the heater 17 is in the on state" refers not only to a situation where the heater 17 remains in the on state, but also to a situation where the heater 17 is alternately turned on and off under pulse width modulation control.

[0064] The water vapor pressure measuring device 204 measures the water vapor pressure of the water vapor included in the mixed gas flowing through the flow channel. Regardless of the state of the heater 17, the water vapor pressure measuring device 204 measures the water vapor pressure P of the water vapor based on the humidity measurement value, which is the humidity value of the mixed gas measured by the temperature and humidity sensor 16, and the temperature measurement value, which is the temperature value of the mixed gas measured by the temperature and humidity sensor 16. W Specifically, the water vapor pressure measuring device 204 measures the water vapor pressure P by the following mathematical expression 1: W .

[0065] [Mathematical expression 1]

[0066]

[0067] Where T m is the temperature measurement, H m is the humidity measurement.

[0068] In this case, the water vapor pressure measuring device 204 calculates the water vapor pressure using different measurement methods according to the conditions satisfied based on the humidity measurement value. Specifically, the water vapor pressure measuring device 204 calculates the water vapor pressure P by the following mathematical expression 1 or the following mathematical expression 2 according to the conditions satisfied based on the humidity measurement value. W .

[0069] [Mathematical expression 2]

[0070]

[0071] Among them CW is a correction value of the water vapor pressure and is a value equal to or less than 1.

[0072] In the present embodiment, the water vapor pressure measurer 204 calculates the water vapor pressure P W based on the temperature measurement value and the humidity measurement value, that is, by using the mathematical expression 1, according to the first measurement method. According to the second measurement method, the water vapor pressure P W is calculated based on the temperature measurement value, the humidity measurement value, and the correction value corresponding to the first threshold value, that is, by using the mathematical expression 2. W

[0073] If the humidity measurement value exceeds the first threshold value when the mathematical expression 1 is used, the water vapor pressure measurer 204 changes the equation for calculating the water vapor pressure P W from the mathematical expression 1 to the mathematical expression 2. That is, if the humidity measurement value exceeds the first threshold value when the mathematical expression 1 is used, the water vapor pressure measurer 204 calculates the water vapor pressure P W using the mathematical expression 2. On the other hand, if the humidity measurement value is equal to or less than the first threshold value when the mathematical expression 1 is used, the water vapor pressure measurer 204 does not change the equation for calculating the water vapor pressure P W . That is, if the humidity measurement value is equal to or less than the first threshold value when the mathematical expression 1 is used, the water vapor pressure measurer 204 calculates the water vapor pressure P W using the mathematical expression 1. On the other hand, in the present embodiment, if the humidity measurement value is greater than the second threshold value when the mathematical expression 2 is used, the water vapor pressure measurer 204 does not change the equation for calculating the water vapor pressure P W . That is, if the humidity measurement value is greater than the second threshold value when the mathematical expression 2 is used, the water vapor pressure measurer 204 calculates the water vapor pressure P W using the mathematical expression 2. If the humidity measurement value decreases to a value equal to or less than the second threshold value when the mathematical expression 2 is used, the water vapor pressure measurer 204 changes the equation for calculating the water vapor pressure P W from the mathematical expression 2 to the mathematical expression 1. That is, if the humidity measurement value decreases to a value equal to or less than the second threshold value when the mathematical expression 2 is used, the water vapor pressure measurer 204 calculates the water vapor pressure P W using the mathematical expression 1. In this case, the second threshold value is a value less than the first threshold value. For example, if the first threshold value is set to 70% as a humidity value at which condensation does not occur, the second threshold value can be set to 60%.

[0074] ​That is, the water vapor pressure P is calculated using the mathematical expression 1 according to the measurement state. W The first state is to use mathematical expression 2 to calculate the water vapor pressure P W In the second state of the water vapor pressure measurement device 204, the threshold value used to determine whether to change the measurement method is changed. In the following description, the measurement method using Mathematical Expression 1 will be referred to as the "first measurement method" hereinafter, and the measurement method using Mathematical Expression 2 will be referred to as the "second measurement method" hereinafter.

[0075] If the humidity measurement value exceeds the first threshold value when the measurement state is in the first state using the first measurement method, water vapor pressure measurement device 204 changes the measurement state from the first state to the second state using the second measurement method. On the other hand, if the humidity measurement value is equal to or less than the first threshold value, water vapor pressure measurement device 204 maintains the measurement state in the first state. In other words, if the humidity measurement value exceeds the first threshold value when the measurement state is in the first state, water vapor pressure measurement device 204 changes the measurement method from the first measurement method to the second measurement method. On the other hand, if the humidity measurement value is equal to or less than the first threshold value, water vapor pressure measurement device 204 maintains the measurement method in the first measurement method.

[0076] If the humidity measurement value decreases to a value equal to or less than a second threshold value (the second threshold value is less than the first threshold value) while the measurement state is in the second state, water vapor pressure measurement device 204 changes the measurement state from the second state to the first state. On the other hand, if the humidity measurement value exceeds the second threshold value, water vapor pressure measurement device 204 maintains the measurement state in the second state. In other words, if the humidity measurement value decreases to a value equal to or less than the second threshold value while the measurement state is in the second state, water vapor pressure measurement device 204 changes the measurement method from the second measurement method to the first measurement method. On the other hand, if the humidity measurement value exceeds the second threshold value, water vapor pressure measurement device 204 maintains the measurement method in the second measurement method.

[0077] The concentration measuring device 205 calculates the pressure of the mixed gas based on the water vapor pressure measured by the water vapor pressure measuring device 204 and the pressure P of the mixed gas measured by the pressure sensor 15. m To measure the water vapor concentration x as the concentration of water vapor included in the mixed gas w Specifically, the concentration measurer 205 obtains the water vapor concentration x using the following mathematical expression 3: w .

[0078] [Mathematical expression 3]

[0079]

[0080] Further, the concentration measurer 205 measures a gas concentration that is a concentration of a gas included in the mixed gas and different from the water vapor based on the water vapor concentration thus obtained and the propagation time of the ultrasonic wave between the pair of ultrasonic transceivers (i.e., the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12). For example, the concentration measurer 205 measures a concentration of hydrogen included in the mixed gas (hereinafter simply referred to as "hydrogen concentration") based on the water vapor concentration x w thus obtained and the propagation time of the ultrasonic wave. In this case, the sound velocity c of the mixed gas, the molecular weight M of the mixed gas, the heat capacity ratio γ (= c p / c v ) of the mixed gas, the temperature T of the mixed gas, and the gas constant R satisfy the following mathematical expression 4.

[0081] [Mathematical Expression 4]

[0082]

[0083] where c p represents the molar heat capacity at constant pressure, c v represents the molar specific heat at constant volume.

[0084] In this case, it is assumed that the distance between the ultrasonic sensors (i.e., the length of the ultrasonic wave propagation path 106) is L. In this case, the sound velocity c is calculated based on the distance L and the average propagation time t up of the first propagation time t dw and the second propagation time t ave that have been measured. Therefore, the following mathematical expression 5 is satisfied.

[0085] [Mathematical Expression 5]

[0086]

[0087] In the present embodiment, hydrogen, nitrogen, and water vapor are included in the mixed gas. In this case, it is assumed that the molecular weight of hydrogen is M1, the specific heat at constant pressure thereof is c p1 , and the specific heat at constant volume thereof is c v1 ; the molecular weight of nitrogen is M2, the specific heat at constant pressure thereof is c p2 , and the specific heat at constant volume thereof is c v2 ; the molecular weight of water vapor is M w , the specific heat at constant pressure thereof is c pw , and the specific heat at constant volume thereof is c vw ; and the concentration of hydrogen is x1. In this case, the following mathematical expressions 6 to 8 are satisfied.

[0088] [Mathematical Expression 6]

[0089] M = x1M1+ (1 - x1- x w )M2+ x w M w

[0090] [mathematical expression 7]

[0091] c p = x1c p1 + (1 - x1- x w )c p2 + x w c pw

[0092] [mathematical expression 8]

[0093] c v = x1c v1 + (1 - x1- x w )c v2 + x w c vw

[0094] By using these mathematical expressions 6 to 8 and setting the temperature T to the temperature measurement value T m , the mathematical expression 4 can be transformed into the following mathematical expression 9.

[0095] [mathematical expression 9]

[0096]

[0097] The concentration measurer 205 obtains the hydrogen concentration x1using this mathematical expression 9.

[0098] Further, in the mathematical expression 5 and the mathematical expression 9, if the average of the actually measured propagation time of hydrogen is t ave1 , the temperature thereof is T m1 , x1= 1, and x w = 0, the actual distance L between the ultrasonic sensors (= L1) can be obtained. This allows the concentration of hydrogen to be measured with high accuracy.

[0099] Further, in the mathematical expression 5 and the mathematical expression 9, if the average of the actually measured propagation time of nitrogen is t ave2 , the temperature thereof is T m2 , x1= 0, and x w = 0, the actual distance L between the ultrasonic sensors (= L2) can be obtained.

[0100] Ideally, L1=L2 is satisfied. However, in reality, a difference between the distance L2 and the distance L1 can occur due to a difference between a theoretical value and an actual measured value and a fixed error involved in conversion of the propagation time. In this case, the sound velocity is defined by the following mathematical expression 10 using the difference between the propagation time t ave and the propagation time t d . ave The corrected propagation time (t d ) calculated by subtracting the difference time t d from the propagation time t d .

[0101] [mathematical expression 10]

[0102]

[0103] By using this mathematical expression 10, t d and L satisfying L1=L2 can be determined. In this case, t d and L can be obtained by numerical analysis using t d =0 as an initial value under the condition that L1=L2 is satisfied. Alternatively, t d and L can also be obtained algebraically by the following mathematical expression 11 and mathematical expression 12.

[0104] [mathematical expression 11]

[0105]

[0106] [mathematical expression 12]

[0107]

[0108] If t d and L thus obtained are used for the calculation of the mathematical expression 9 and the mathematical expression 10, the concentration measurer 205 is allowed to measure the concentration more accurately.

[0109] The flow rate measurer 206 measures the flow rate of the mixed gas in the flow passage 101 using the propagation time of the ultrasonic wave, the water vapor concentration, and the gas concentration including the hydrogen concentration and the nitrogen concentration. The flow rate measurer 206 obtains the flow rate Q of the mixed gas using the following mathematical expression 13 and mathematical expression 14. The mathematical expression 13 is an equation for calculating a temporary flow rate Q0. The temporary flow rate Q0 is calculated by multiplying the cross-sectional area S of the flow passage 101 by the flow velocity V. In addition, based on the relationship between the flow velocity V, the length L of the ultrasonic wave propagation path 106 (i.e., the distance between the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12), the first propagation time t up , the second propagation time t dw , and the angle θ formed by the ultrasonic wave propagation path 106 with respect to the flow passage 101, "Q0=SV" can be deformed into the right side of the mathematical expression 13, where RK is a flow coefficient:

[0110] [mathematical expression 13]

[0111]

[0112] [mathematical expression 14]

[0113]

[0114] In addition, the flow coefficient R K is defined by the following mathematical expression 15 using the kinematic viscosity v, the characteristic length D, and the flow rate V m In mathematical expression 15, R e represents the Reynolds number. That is, the Reynolds number R e is given by the equation "R e = V m D / v". Note that the characteristic length D can be, for example, the length between a pair of the partitions 107 or the length between one side wall and the partition 107 closest to the one side wall, the one side wall being one of the two side walls forming the flow passage 101 that face each other in the height direction H. For example, if no partition 107 is provided, the characteristic length D can be equal to the height H. In addition, the function f(R e ) is a predefined function. The flow rate V m is a flow rate corresponding to a flow rate (hereinafter referred to as "reference flow rate") measured by a calibrator during a calibration process performed as a preliminary evaluation.

[0115] [mathematical expression 15]

[0116]

[0117] In this case, the kinematic viscosity v is a value depending on the temperature T in the flow passage 101, the concentrations of the respective gases (i.e., hydrogen, nitrogen, and water vapor) included in the mixed gas, and the pressure P m . In addition, since the kinematic viscosity v satisfies the equation "kinematic viscosity = viscosity / density", the kinematic viscosity v can be given by the following mathematical expression 16. In mathematical expression 16, the middle side is deformed to the right side according to the relationship expression #2 "density = (molecular weight M · pressure P m ) / (gas constant R · temperature T)" derived from the state equation of a gas "pressure P m · volume = number of moles · gas constant R · temperature T" and the relationship expression #1 "density = mass / volume". That is, the density p can be expressed by the molecular weight M, the pressure P m , the temperature T, and the gas constant R, as can be seen from the state equation of a gas and the relationship expression #1. In this case, the pressure P mis the pressure measured by pressure sensor 15. Temperature T is the average of the first temperature value measured by first temperature sensor 13 and the second temperature value measured by second temperature sensor 14. Furthermore, density ρ is determined by the concentration, temperature, and pressure of the gas. Therefore, in relational expression #2, molecular weight M is a function using concentration as a variable (see Mathematical Expression 6).

[0118] [Mathematical expression 16]

[0119]

[0120] In this mathematical expression 16, μ(x, T) can be determined based on the viscosity of each gas (i.e., hydrogen, nitrogen, and water vapor) included in the mixed gas. The viscosity of each gas can be obtained by a known method. The viscosity μ of the mixed gas can be determined by using the viscosity of each gas obtained by a known method and the concentration of each gas (i.e., hydrogen concentration, nitrogen concentration, and water vapor concentration) that has already been obtained.

[0121] The flow rate measuring device 206 obtains the standard flow rate Q of the mixed gas based on the flow rate Q of the mixed gas thus obtained. n , which is converted into a value corresponding to conditions including 0° C. and 1 atm.

[0122] The flow rate measuring device 206 uses the flow rate of the mixed gas to measure the flow rate of the gas. Specifically, the flow rate measuring device 206 obtains the standard flow rate Q based on the flow rate Q of the mixed gas. n The flow rate of the gas is measured by multiplying the concentration of the gas. The flow meter 206 measures the flow rate of the gas by the standard flow rate Q n The flow rate of hydrogen is obtained by multiplying the flow rate Q by the hydrogen concentration x1 as the gas concentration. Alternatively, the flow rate measurer 206 may obtain the flow rate of hydrogen by multiplying the flow rate Q by the hydrogen concentration x1 as the gas concentration.

[0123] Next, we will explain how to obtain the flow coefficient R K .

[0124] Flow coefficient R K By using temporary flow Q0 and reference flow Q m The following mathematical expression 17 represents that the reference flow rate Q m is the flow rate measured by the calibrator during calibration.

[0125] [Mathematical expression 17]

[0126]

[0127] In addition, the Reynolds number R e By using the reference flow Q mThe following mathematical expression 18 is expressed. In the mathematical expression 18, v represents the kinematic viscosity of the mixed gas, D represents the characteristic length, and S represents the cross-sectional area of ​​the flow channel 101. m It is the reference flow Q measured by the calibrator during calibration. m The corresponding flow rate.

[0128] [Mathematical expression 18]

[0129]

[0130] As a preliminary evaluation, the processing device 20 calculates a plurality of combinations (R e 、R K ), each combination is composed of the reference flow Q m The Reynolds number R under the changed e and the flow coefficient R obtained by using the temporary flow rate Q0 derived from the measured value K The processing device 20 obtains the Reynolds number R based on the calculation result. e and flow coefficient R K and store the relational expressions in advance.

[0131] Furthermore, the following mathematical expression 19 is also obtained by using mathematical expression 17 and mathematical expression 18 as the Reynolds number R e and flow coefficient R K The relationship expression between them is obtained. The characteristic length D and the cross-sectional area S are known values ​​of the physical quantity measurement system 1, and the kinematic viscosity v and the temporary flow rate Q0 are already calculated values. That is, the flow coefficient R K is expressed using the Reynolds number R e In other words, mathematical expression 19 is a linear function of the Reynolds number R e and flow coefficient R K , and is a linear function of the relationship between the temporary flow rate Q0 and the kinematic viscosity v of the mixed gas ((vS) / (Q0D)) as a coefficient.

[0132] [Mathematical expression 19]

[0133]

[0134] The flow rate measurement device 206 uses the Reynolds number R which has been obtained by the pre-evaluation. e and flow coefficient R K The relationship between the relational expression and the mathematical expression 19 is used to calculate the flow coefficient R KSpecifically, the flow rate measurer 206 calculates the flow rate coefficient R corresponding to the temporary flow rate Q0 by locating the intersection between the curve represented by the relational expression obtained by the pre-evaluation and the curve represented by the mathematical expression 19. K .

[0135] The flow rate measuring device 206 uses the flow rate coefficient R thus calculated K And mathematical expression 14 is used to calculate the flow rate Q.

[0136] In this case, the kinematic viscosity v has appeared in Mathematical Expression 15 and Mathematical Expression 18. That is, the flow coefficient R according to the present disclosure K is a value based on the kinematic viscosity v of the mixed gas. In addition, according to mathematical expression 18, the Reynolds number R e Use the kinematic viscosity v as the coefficient. That is, the flow coefficient R K By using the Reynolds number R e The value obtained by the linear function, Reynolds number R e A value based on the kinematic viscosity v of the mixed gas is used as the coefficient. More specifically, the flow coefficient R K It is a value obtained based on a linear function of the Reynolds number and a relational expression expressing the relationship between the Reynolds number and the flow coefficient obtained by preliminary evaluation, the Reynolds number using a value based on the kinematic viscosity v of the mixed gas as a coefficient.

[0137] Alternatively, the processing device 20 may also use a plurality of combinations (R e 、R K ) rather than the relational expression obtained by pre-evaluation, each combination is determined by the Reynolds number R that has been calculated by pre-evaluation. e and flow coefficient R K composition.

[0138] The relative humidity measuring device 207 measures the water vapor pressure P measured by the water vapor pressure measuring device 204. W and the saturated water vapor pressure P corresponding to the temperature measured by the second temperature sensor 14 (ie, the temperature of the mixed gas). WS To measure the relative humidity of the mixed gas. More specifically, the relative humidity measurer 207 is based on the humidity measurement value H measured by the temperature and humidity sensor 16. m and temperature measurement value T mThe relative humidity H0 of the mixed gas is measured by the temperature of the mixed gas measured by the second temperature sensor 14 (second temperature value) as well. Specifically, the relative humidity measurer 207 obtains the relative humidity of the mixed gas by one of the following mathematical expression 20 and mathematical expression 21. If the measurement state is the first state, the relative humidity measurer 207 obtains the relative humidity of the mixed gas using the mathematical expression 20. If the measurement state is the second state, the relative humidity measurer 207 obtains the relative humidity of the mixed gas using the mathematical expression 21. In the mathematical expression 20 and the mathematical expression 21, P WS is the saturated water vapor pressure with respect to the temperature measured by the second temperature sensor 14. That is, P WS is the saturated water vapor pressure with respect to the temperature of the mixed gas. T n is also the temperature measured by the second temperature sensor 14 (second temperature value).

[0139] [mathematical expression 20]

[0140]

[0141] [mathematical expression 21]

[0142]

[0143] Alternatively, if the measurement state is the first state, the relative humidity measurer 207 can regard the humidity measurement value H m as the relative humidity H0 of the mixed gas.

[0144] The first detector 208 detects any abnormality in the measurement environment of the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state. That is, the first detector 208 functions as an environmental abnormality detector for detecting any abnormality in the measurement environment of the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state. The first detector 208 obtains the standard deviation σ of the humidity measurement value based on the humidity measurement value measured by the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state. In this case, the standard deviation σ obtained by the first detector 208 is the standard deviation in a predetermined period in the case where the heat generator 17 is in the ON state. The first detector 208 determines a reference value corresponding to the water vapor pressure P W measured by the water vapor pressure measurer 204. For example, the first detector 208 acquires (determines) the reference value corresponding to the water vapor pressure P WThe corresponding predetermined value is a reference value, and the predetermined value belongs to a plurality of predetermined values corresponding to a plurality of water vapor pressures stored in advance in the memory. If the standard deviation σ is greater than the reference value, the first detector 208 detects the occurrence of an anomaly in a case where the heat generator 17 is in an ON state. In the present embodiment, the first detector 208 detects that the temperature and humidity sensor 16, which is a measurement environment of the temperature and humidity sensor 16, has sunk into water.

[0145] Upon detecting that any anomaly has occurred in a case where the heat generator 17 is in an ON state, the first detector 208 outputs, to the user device 30 via the fourth communication unit 24, a first detection result indicating that an anomaly has occurred in the measurement environment of the temperature and humidity sensor 16.

[0146] The second detector 209 detects any anomaly in the heat generation operation of the heat generator 17. That is, the second detector 209 functions as a heat generation anomaly detector for detecting any anomaly in the heat generation operation. If the heat generation operation is performed by the heat generator 17 and the humidity measurement value of the mixed gas and the temperature measurement value of the mixed gas that have been measured by the temperature and humidity sensor 16 satisfy a predetermined condition, the second detector 209 detects the occurrence of an anomaly. That is, if the humidity measurement value of the mixed gas and the temperature measurement value of the mixed gas that have been measured by the temperature and humidity sensor 16 satisfy a predetermined condition in a case where the heat generation operation is performed by the heat generator 17, the second detector 209 detects the occurrence of an anomaly. Specifically, if a result calculated by subtracting the humidity measurement value from a first threshold value (a first difference value) is greater than a first comparison value, a result calculated by subtracting a temperature (a second temperature value) measured by the second temperature sensor 14 from the temperature measurement value (a second difference value) is greater than a second comparison value, and the temperature measurement value is greater than a predetermined third comparison value, the second detector 209 determines that the predetermined condition is satisfied and detects the occurrence of an anomaly in the heat generation operation.

[0147] In this case, the anomaly detected by the second detector 209 can be a communication error caused when a signal indicating that the heat generator 17 stops performing the heat generation operation is transmitted. Alternatively, the anomaly detected by the second detector 209 can also be an internal malfunction of the physical quantity measurement system 1. The internal malfunction of the physical quantity measurement system 1 can be, for example, a failure of the heat generator 17.

[0148] Upon detecting that any anomaly has occurred, the second detector 209 outputs, to the user device 30 via the fourth communication unit 24, a second detection result indicating that an anomaly has occurred in the heat generation operation.

[0149] Upon detecting an abnormality in the heating operation, the second detector 209 outputs a cutoff instruction signal to the switch unit 18 via the third communication unit 23, instructing the switch unit 18 to cut off the power supply path between the power supply unit 26 and the temperature and humidity sensor 16 and the heater 17. Upon receiving the cutoff instruction signal, the switch unit 18 cuts off the power supply path between the power supply unit 26 and the temperature and humidity sensor 16 and the heater 17. In this way, the heating operation of the heater 17 can be suspended.

[0150] If the result calculated by subtracting the humidity measurement value from the first threshold value (first differential value) is greater than the first comparison value, and the result calculated by subtracting the temperature measured by the second temperature sensor 14 (second temperature value) from the temperature measurement value (second differential value) is greater than the second comparison value, the second detector 209 can determine that the predetermined condition is met and detect the occurrence of an abnormality in the heating operation.

[0151] (3) Operation

[0152] In this section, how the physical quantity measuring system 1 operates will be described.

[0153] (3.1) Operation Overview

[0154] First, refer to Figure 5 An overview of the operation of the physical quantity measuring system 1 will be described.

[0155] The first signal processor 201 performs a first measurement process (in step S1). Specifically, the first signal processor 201 measures a first propagation time t of an ultrasonic wave transmitted from the first ultrasonic transceiver 11 to the second ultrasonic transceiver 12. up In addition, the first signal processor 201 also measures the second propagation time t of the ultrasonic wave transmitted from the second ultrasonic transceiver 12 to the first ultrasonic transceiver 11. dw .

[0156] The second signal processor 202 performs a second measurement process (in step S2). Specifically, the second signal processor 202 obtains a first temperature value measured by the first temperature sensor 13 based on the output signal of the first temperature sensor 13. Furthermore, the second signal processor 202 obtains a second temperature value measured by the second temperature sensor 14 based on the output signal of the second temperature sensor 14. Furthermore, the second signal processor 202 obtains a pressure value measured by the pressure sensor 15 based on the output signal of the pressure sensor 15. Furthermore, the second signal processor 202 obtains a humidity value (humidity measurement value) measured by the temperature and humidity sensor 16 and a temperature value (temperature measurement value) measured by the temperature and humidity sensor 16 based on the output signal of the humidity sensor of the temperature and humidity sensor 16.

[0157] The heat generation controller 203 executes a heat generation control process (in step S3). The heat generation controller 203 controls the ON / OFF state of the heat generator 17 to change the state of the heat generator 17 from the ON state in which the heat generator 17 performs a heat generation operation to the OFF state in which the heat generator 17 stops performing the heat generation operation, or vice versa.

[0158] The water vapor pressure measurer 204 executes a third measurement process (in step S4). The water vapor pressure measurer 204 executes the third measurement process to calculate the water vapor pressure and the water vapor concentration.

[0159] The first detector 208 executes a first abnormality detection process (in step S5). The first detector 208 executes the first abnormality detection process to detect any abnormality in the measurement environment of the temperature and humidity sensor 16.

[0160] The second detector 209 executes a second abnormality detection process (in step S6). The second detector 209 executes the second abnormality detection process to detect any abnormality in the heat generation operation of the heat generator 17.

[0161] The concentration measurer 205 executes a concentration measurement process (in step S7). The concentration measurer 205 executes the concentration measurement process to calculate the concentration of hydrogen flowing through the flow passage 101.

[0162] The flow rate measurer 206 executes a flow rate measurement process (in step S8). The flow rate measurer 206 executes the flow rate measurement process to calculate the flow rate of the mixed gas flowing through the flow passage 101 and the flow rate of hydrogen included in the mixed gas.

[0163] The relative humidity measurer 207 executes a relative humidity measurement process (in step S9). The relative humidity measurer 207 executes the relative humidity measurement process to calculate the relative humidity of the mixed gas flowing through the flow passage 101.

[0164] The processing device 20 (the control unit 25) notifies the user device 30 of at least one of the flow rate, the concentration, or the relative humidity of the mixed gas thus calculated via the fourth communication unit 24.

[0165] (3.2) Heat Generation Control Process

[0166] In this section, the heat generation control process in step S3 shown in FIG. 3 will be described with reference to FIG. 4. Figure 6 Explanation Figure 5 of FIG. 4.

[0167] The heat generation controller 203 acquires the humidity measurement value obtained by the second signal processor 202 (in step S51).

[0168] The heat generation controller 203 determines whether the humidity measurement value thus obtained is greater than the first threshold value (in step S52).

[0169] If the heating controller 203 determines that the humidity measurement value is greater than the first threshold value (if the answer in step S52 is yes), the heating controller 203 sets the operating state of the heater 17 to the ON state (in step S53). Specifically, if the humidity measurement value is greater than the first threshold value, the heating controller 203 controls the period during which the heater 17 is turned on and the period during which the heater 17 is turned off through pulse width modulation, thereby alternately turning the heater 17 on and off. The heating controller 203 controls the pulse width of the pulse width modulation so that the greater the difference between the first threshold value and the humidity measurement value, the longer the ON state becomes.

[0170] On the other hand, if the heating controller 203 determines that the humidity measurement value is not greater than the first threshold, ie, the humidity measurement value is equal to or less than the first threshold (if the answer in step S52 is No), the heating controller 203 turns off the heater 17 .

[0171] (3.3) Third Measurement Process

[0172] In this section, we will refer to Figure 7 illustrate Figure 5 The third measurement process in step S4 is shown.

[0173] The water vapor pressure measurer 204 determines whether the measurement state is the first state (in step S101 ).

[0174] If the water vapor pressure measurer 204 determines that the measurement state is the first state (if the answer is yes in step S101 ), the water vapor pressure measurer 204 determines whether the humidity measurement value obtained by the second signal processor 202 is greater than a first threshold (in step S102 ).

[0175] When it is determined that the humidity measurement value is not greater than the first threshold value, that is, when it is determined that the humidity measurement value is equal to or less than the first threshold value (if the answer in step S102 is no), the water vapor pressure measuring device 204 sets the measurement state to the first state (in step S103). After setting the measurement state to the first state in step S103, the water vapor pressure measuring device 204 performs a first water vapor pressure calculation process (in step S104). Specifically, the water vapor pressure measuring device 204 calculates the water vapor pressure P by the above-mentioned mathematical expression 1. W Thereafter, the concentration measurer 205 performs a first water vapor concentration calculation process (in step S105). The concentration measurer 205 uses the water vapor pressure P obtained in step S104 to calculate the water vapor concentration. W , the pressure P of the mixed gas obtained by the second signal processor 202 m and the above mathematical expression 3 to measure the water vapor concentration x of water vapor included in the mixed gas w.

[0176] When it is determined that the measurement state is not the first state, that is, when it is determined that the measurement state is the second state (if the answer in step S101 is No), the water vapor pressure measurer 204 determines whether the humidity measurement value obtained by the second signal processor 202 is greater than the second threshold value (in step S106).

[0177] When it is determined that the humidity measurement value is greater than the second threshold value (if the answer in step S106 is Yes), the water vapor pressure measurer 204 sets the measurement state to the second state (in step S107). After the measurement state is set to the second state in step S107, the water vapor pressure measurer 204 executes the second water vapor pressure calculation process (in step S108). Specifically, the water vapor pressure measurer 204 calculates the water vapor pressure P W Thereafter, the concentration measurer 205 executes the second water vapor concentration calculation process (in step S109). The concentration measurer 205 measures the water vapor concentration x W of the water vapor included in the mixed gas using the water vapor pressure P m obtained by the second signal processor 202, the pressure P w of the mixed gas, and the above-described mathematical expression 3.

[0178] When it is determined that the humidity measurement value is greater than the first threshold value in step S102 (if the answer in step S102 is Yes), the water vapor pressure measurer 204 sets the measurement state to the second state (in step S107). After the measurement state is set to the second state in step S107, the water vapor pressure measurer 204 executes the second water vapor pressure calculation process (in step S108). Thereafter, the concentration measurer 205 executes the second water vapor concentration calculation process (in step S109).

[0179] When it is determined that the humidity measurement value is not greater than the second threshold value in step S106, that is, when it is determined that the humidity measurement value is equal to or less than the second threshold value (if the answer in step S106 is No), the water vapor pressure measurer 204 sets the measurement state to the first state (in step S103). After the measurement state is set to the first state in step S103, the water vapor pressure measurer 204 executes the first water vapor pressure calculation process (in step S104). Thereafter, the concentration measurer 205 executes the first water vapor concentration calculation process (in step S105).

[0180] (3.4) First abnormality detection process

[0181] In this section, the Figure 8 explanation Figure 5The first abnormality detection process in step S5 shown.

[0182] The first detector 208 obtains a standard deviation σ of the humidity measurement value based on the humidity measurement value measured by the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state (in step S151).

[0183] The first detector 208 determines a reference value corresponding to the water vapor pressure P W measured by the water vapor pressure measurer 204 (in step S152). For example, the first detector 208 acquires (determines) as the reference value a predetermined value corresponding to the water vapor pressure P W measured by the water vapor pressure measurer 204, the predetermined value belonging to a plurality of predetermined values corresponding to a plurality of water vapor pressures, respectively.

[0184] The first detector 208 determines whether the standard deviation σ is greater than the reference value (in step S153).

[0185] If the first detector 208 determines that the standard deviation σ is not greater than the reference value (if the answer in step S153 is NO), the process ends. On the other hand, if the first detector 208 determines that the standard deviation σ is greater than the reference value (if the answer in step S153 is YES), the first detector 208 detects the occurrence of an abnormality in the measurement environment of the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state (in step S154). For example, the first detector 208 can detect that the temperature and humidity sensor 16 has sunk into water as an abnormality in the measurement environment of the temperature and humidity sensor 16.

[0186] When detecting that any abnormality has occurred in the measurement environment of the temperature and humidity sensor 16 in the case where the heat generator 17 is in the ON state, the first detector 208 outputs a first detection result indicating that an abnormality has occurred in the measurement environment of the temperature and humidity sensor 16 to the user device 30 (in step S155).

[0187] (3.5) Second Abnormality Detection Process

[0188] In this section, the second abnormality detection process in step S6 shown will be described with reference to Figure 9 Figure 5

[0189] The second detector 209 determines whether a result calculated by subtracting the humidity measurement value from the first threshold value (a first difference value) is greater than a first comparison value (in step S201).

[0190] ​​If the second detector 209 determines that the first difference value is not greater than the first comparison value (if the answer in step S201 is No), the processing ends. On the other hand, if the second detector 209 determines that the first difference value is greater than the first comparison value (if the answer in step S201 is Yes), the second detector 209 determines whether or not the result calculated by subtracting the temperature measured by the second temperature sensor 14 (second temperature value) from the temperature measurement value (second difference value) is greater than the second comparison value (in step S202).

[0191] If the second detector 209 determines that the second difference value is not greater than the second comparison value (if the answer in step S202 is No), the processing ends. On the other hand, if the second detector 209 determines that the second difference value is greater than the second comparison value (if the answer in step S202 is Yes), the second detector 209 determines whether or not the temperature measurement value is greater than the third comparison value (in step S203).

[0192] If the second detector 209 determines that the temperature measurement value is not greater than the third comparison value (if the answer in step S203 is No), the processing ends. On the other hand, if the second detector 209 determines that the temperature measurement value is greater than the third comparison value (if the answer in step S203 is Yes), the second detector 209 determines that the predetermined condition is satisfied and detects the occurrence of an abnormality of the heat generating operation (in step S204).

[0193] Upon detecting that any abnormality occurs in the heat generating operation, the second detector 209 outputs a second detection result indicating that an abnormality occurs in the heat generating operation to the user device 30 (in step S205).

[0194] Upon detecting that an abnormality occurs in the heat generating operation, the second detector 209 performs a cutoff processing (in step S206). The second detector 209 outputs a cutoff instruction signal to the switching unit 18 via the third communication unit 23. Upon receiving the cutoff instruction signal, the switching unit 18 cuts off the power supply path between the power supply unit 26 and the temperature and humidity sensor 16 and the heat generator 17. In this way, it is possible to suspend the heat generating operation of the heat generator 17.

[0195] (3.6) Concentration measurement processing

[0196] In this section, the concentration measurement processing in step S7 shown in FIG. 8 will be described with reference to Figure 10 Explanation Figure 5 FIG. 9.

[0197] The concentration measurer 205 performs the concentration measurement processing to measure the concentration of a gas, i.e., a gas included in the mixed gas and different from water vapor (for example, hydrogen in this example).

[0198] The concentration measurer 205 executes a sound velocity calculation process (in step S251). The concentration measurer 205 calculates the sound velocity based on the propagation times of the ultrasonic waves.

[0199] The concentration measurer 205 executes a hydrogen concentration calculation process (in step S252). The concentration measurer 205 calculates the hydrogen concentration using the water vapor concentration x w and the sound velocity calculated in the sound velocity calculation process.

[0200] (3.7) Sound velocity calculation process

[0201] In this section, the sound velocity measurement process in step S251 illustrated in Figure 11 will be described with reference to Figure 10 FIG. 9.

[0202] The concentration measurer 205 acquires the distance L (i.e., the distance between the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12) that has been stored in advance and the first propagation time t up and the second propagation time t dw measured by the first signal processor 201 (in step S261).

[0203] The concentration measurer 205 calculates the average propagation time t up using the first propagation time t dw and the second propagation time t ave (in step S262).

[0204] The concentration measurer 205 calculates the sound velocity using the distance L acquired in step S261, the average propagation time t ave calculated in step S262, and the above-described mathematical expression 5 (in step S263).

[0205] (3.8) Hydrogen concentration calculation process

[0206] In this section, the hydrogen concentration calculation process in step S252 illustrated in Figure 12 will be described with reference to Figure 10 FIG. 10.

[0207] The concentration measurer 205 acquires the temperature measurement value T m obtained by the second signal processor 202 (in step S271).

[0208] The concentration measurer 205 acquires the sound velocity c calculated in the sound velocity calculation process and the water vapor concentration x w calculated in the third measurement process (in step S272).

[0209] The concentration measurer 205 acquires each parameter that has been stored in advance (in step S273). Specifically, the concentration measurer 205 acquires, as respective parameters, the gas constant R, the molecular weight M1 of hydrogen, the molecular weight M2 of nitrogen, the molecular weight M3 of water vapor, w , the respective specific heat values of each gas (i.e., hydrogen, nitrogen, and water vapor) at constant volume, and the specific heat values of each gas (i.e., hydrogen, nitrogen, and water vapor) at constant volume.

[0210] The concentration measurer 205 calculates the hydrogen concentration xl (in step S274). Specifically, the concentration measurer 205 calculates the hydrogen concentration xl using the sound speed c, the temperature measurement value T m , the gas constant R, the water vapor concentration x w , the molecular weight M1 of hydrogen, the molecular weight M2 of nitrogen, the molecular weight M3 of water vapor, w , the respective specific heat values of each gas (i.e., hydrogen, nitrogen, and water vapor) at constant volume, the specific heat values of each gas (i.e., hydrogen, nitrogen, and water vapor) at constant volume, and the mathematical expression 9. That is, the concentration measurer 205 calculates the hydrogen concentration xl using the sound speed c, the temperature measurement value T m , the gas constant R, the molecular weight M of the mixed gas, the heat capacity ratio γ (= c p / c v ) of the mixed gas, and the mathematical expression 4.

[0211] (3.9) Flow rate measurement processing

[0212] In this section, the flow rate measurement processing in step S8 shown in Figure 13 will be described. Figure 5

[0213] The flow rate measurer 206 acquires the first propagation time t up and the second propagation time t dw that have been measured by the first signal processor 201 (in step S301).

[0214] The flow rate measurer 206 acquires each parameter that has been stored in advance (in step S302). Specifically, the flow rate measurer 206 acquires, as respective parameters, the cross-sectional area S of the flow passage 101, the length L of the ultrasonic wave propagation path 106 (i.e., the distance L between the first ultrasonic transceiver 11 and the second ultrasonic transceiver 12), and the inclination angle θ defined by the ultrasonic wave propagation path 106 with respect to the flow passage 101.

[0215] The flow rate measurer 206 performs temporary flow rate calculation processing (in step S303). Specifically, the flow rate measurer 206 calculates the flow rate using the first propagation time t up and the second propagation time t dw ​, the cross-sectional area S, the length L, and the angle θ that have been acquired in step S302 , and mathematical expression 13 are used to calculate the provisional flow rate Q0 (in step S303 ).

[0216] The flow rate measuring device 206 performs a flow rate coefficient calculation process (in step S304). The flow rate measuring device 206 calculates the flow rate coefficient R by performing the flow rate coefficient calculation process. K .

[0217] The flow rate measuring device 206 uses the temporary flow rate Q0 and the flow coefficient R thus calculated. K and Mathematical Expression 14 to calculate the flow rate Q (in step S305).

[0218] The flow rate measuring device 206 calculates the standard flow rate Q of the mixed gas based on the flow rate Q thus calculated. n , the standard flow Q n is converted into a value corresponding to the conditions including 0° C. and 1 atm (in step S306 ).

[0219] The flow rate measuring device 206 obtains the hydrogen concentration x1 calculated in step S274 and converts the thus calculated standard flow rate Q n The hydrogen concentration x1 thus acquired is multiplied to calculate the flow rate of hydrogen (in step S307). Alternatively, the flow rate measurer 206 may also obtain the flow rate of hydrogen by multiplying the flow rate Q thus calculated by the hydrogen concentration x1 as the gas concentration.

[0220] (3.10) Flow coefficient calculation process

[0221] In this section, we will refer to Figure 14 illustrate Figure 13 The flow coefficient calculation process in step S304 is shown.

[0222] The flow meter 206 obtains the temperature T and pressure P m (In step S351 ) The temperature T is an average value of a first temperature value measured by the first temperature sensor 13 and a second temperature value measured by the second temperature sensor 14 .

[0223] The flow rate measuring device 206 obtains the concentrations of water vapor, hydrogen, and nitrogen included in the mixed gas (in step S352). That is, the flow rate measuring device 206 obtains the concentration of hydrogen x1, the concentration of nitrogen x2, and the concentration of water vapor x w (=x3). In this case, the nitrogen concentration x2 is given by 1-x1-x w given.

[0224] The flow meter 206 obtains the pre-stored parameters (in step S353). Specifically, the flow meter 206 obtains the characteristic length D and the cross-sectional area S of the flow channel 101 as the corresponding parameters. In addition, the flow meter 206 also obtains the viscosity of each gas included in the mixed gas (i.e., hydrogen, nitrogen, and water vapor).

[0225] The flow rate meter 206 uses the respective viscosities of hydrogen, nitrogen, and water vapor, the water vapor concentration x w , hydrogen concentration x1, and nitrogen concentration x2 to calculate the viscosity μ of the mixed gas including hydrogen, nitrogen, and water vapor (in step S354).

[0226] The flow rate measurement device 206 uses the water vapor concentration x w , hydrogen concentration x1, nitrogen concentration x2 and Mathematical Expression 16 to calculate the kinematic viscosity v of the mixed gas including hydrogen, nitrogen and water vapor (in step S355).

[0227] The flow rate measurer 206 calculates the flow rate coefficient R corresponding to the temporary flow rate Q0 by locating the intersection A0 between the curve represented by the relational expression obtained by the pre-evaluation and the curve represented by the mathematical expression 19. K (In step S356).

[0228] (3.11) Relative humidity measurement processing

[0229] In this section, we will refer to Figure 15 illustrate Figure 5 The relative humidity measurement process in step S9 is shown.

[0230] The relative humidity measurer 207 determines whether the measurement state is the first state (in step S401 ).

[0231] When it is determined that the measurement state is the first state (if the answer in step S401 is yes), the relative humidity measurer 207 performs the first humidity measurement process (in step S402). Specifically, the relative humidity measurer 207 uses the water vapor pressure P calculated by using Mathematical Expression 1 W , the saturated water vapor pressure P relative to the temperature measured by the second temperature sensor 14 WS And the above mathematical expression 20 is used to obtain the relative humidity of the mixed gas.

[0232] When it is determined that the measurement state is not the first state, that is, when it is determined that the measurement state is the second state (if the answer in step S401 is no), the relative humidity measurer 207 performs the second humidity measurement process (in step S403). Specifically, the relative humidity measurer 207 uses the water vapor pressure P calculated by using Mathematical Expression 2 Wthe saturated water vapor pressure P with respect to the temperature measured by the second temperature sensor 14 WS and the above mathematical expression 21 to obtain the relative humidity of the mixed gas.

[0233] (4) Advantages

[0234] As can be seen from the foregoing description, the physical quantity measurement system 1 according to the present embodiment includes the temperature and humidity sensor 16, the heat generator 17, and the detector such as the second detector 209. The temperature and humidity sensor 16 measures the humidity and the temperature of the mixed gas flowing through the flow passage 101. The heat generator 17 performs a heat generation operation to warm up the temperature and humidity sensor 16. The detector detects any abnormality in the heat generation operation of the heat generator 17. The detector detects the occurrence of the abnormality when the heat generation operation is being performed by the heat generator 17 and the humidity measurement value of the mixed gas and the temperature measurement value of the mixed gas measured by the temperature and humidity sensor 16 satisfy a predetermined condition.

[0235] Even if the mixed gas flows through the flow passage under a high humidity environment while the heat generator 17 is performing the heat generation operation, this configuration can reduce the possibility of condensation occurring in the temperature and humidity sensor 16. In addition, if the humidity measurement value of the mixed gas measured when the heat generator 17 performs the heat generation operation satisfies the predetermined condition, the detector detects the occurrence of the abnormality. Thus, the physical quantity measurement system 1 according to the present embodiment can detect the presence or absence of any abnormality while reducing the possibility of condensation occurring in the sensor for measuring humidity (e.g., the temperature and humidity sensor 16 in the present embodiment).

[0236] (5) Variants

[0237] Next, variants will be listed one by one. Note that the variants to be explained below can be appropriately combined for adoption.

[0238] (5.1) First variant

[0239] In the above exemplary embodiment, the processing device 20 is configured to change the measurement state using the first threshold value and the second threshold value, i.e., is configured to change the measurement method using the first threshold value and the second threshold value. However, this configuration is merely an example and should not be construed as limiting.

[0240] Alternatively, the processing device 20 can also change the measurement method using only one threshold value. A third measurement process according to this first variant will now be explained with reference to Figure 16

[0241] The water vapor pressure measurer 204 determines whether the humidity measurement value obtained by the second signal processor 202 is greater than a predetermined threshold value (in step S501). For example, the predetermined threshold value can be the above-mentioned second threshold value. ​

[0242] When it is determined that the humidity measurement value is not greater than the predetermined threshold value (second threshold value), that is, when it is determined that the humidity measurement value is equal to or less than the second threshold value (if the answer in step S501 is No), the water vapor pressure measurer 204 executes a first water vapor pressure calculation process (in step S502). Specifically, the water vapor pressure measurer 204 calculates the water vapor pressure P W Thereafter, the concentration measurer 205 executes a first water vapor concentration calculation process (in step S503). The concentration measurer 205 measures the water vapor concentration x W of the water vapor included in the mixed gas using the water vapor pressure P m obtained in step S502, the pressure P w of the mixed gas which has been obtained by the second signal processor 202, and the above-described mathematical expression 3.

[0243] When it is determined that the humidity measurement value is greater than the predetermined threshold value (second threshold value) (if the answer in step S501 is Yes), the water vapor pressure measurer 204 executes a second water vapor pressure calculation process (in step S504). Specifically, the water vapor pressure measurer 204 calculates the water vapor pressure P W Thereafter, the concentration measurer 205 executes a second water vapor concentration calculation process (in step S505). The concentration measurer 205 measures the water vapor concentration x W of the water vapor included in the mixed gas using the water vapor pressure P m obtained in step S504, the pressure P w of the mixed gas which has been obtained by the second signal processor 202, and the above-described mathematical expression 3.

[0244] Further, according to the first modification example, if the processing device 20 executes the relative humidity measurement process, the relative humidity measurer 207 determines whether the humidity measurement value is greater than the predetermined threshold value in step S401, instead of determining whether the measurement state is the first state. When it is determined that the humidity measurement value is not greater than the predetermined threshold value (second threshold value), that is, when it is determined that the humidity measurement value is equal to or less than the second threshold value, the relative humidity measurer 207 executes the first humidity measurement process shown in step S402. On the other hand, when it is determined that the humidity measurement value is greater than the predetermined threshold value (second threshold value), the relative humidity measurer 207 executes the second humidity measurement process shown in step S403.

[0245] Alternatively, when it is determined in step S501 that the humidity measurement value is greater than the predetermined threshold value (second threshold value), the water vapor pressure measurer 204 can set the measurement state to the second measurement state. On the other hand, when it is determined in step S501 that the humidity measurement value is not greater than the predetermined threshold value (second threshold value), the water vapor pressure measurer 204 can set the measurement state to the first measurement state. In this case, it is not necessary to change step S401 of the relative humidity measurement process described above.

[0246] (5.2) Second Modified Example

[0247] When any abnormality in the heat generation operation is detected, the control unit 25 of the processing device 20 can control the power supply unit 26 to suspend supply of electric power to at least the heat generator 17 among the heat generators 17 and each sensor provided for the flow passage 101.

[0248] (5.3) Third Modified Example

[0249] In the above-described example embodiment, a so-called "Z-path" in which the pair of ultrasonic transceivers 11, 12 is configured to form an inclined angle θ with respect to the flow passage 101 is used as the ultrasonic wave propagation path 106. However, this configuration is merely an example and should not be construed as limiting.

[0250] Alternatively, as the ultrasonic wave propagation path, a path involving reflection, such as a so-called "V-path", i.e., a path formed by configuring the pair of ultrasonic transceivers 11, 12 so that the ultrasonic wave passes through the flow of the mixed gas twice in the flow passage 101, can be employed.

[0251] (5.4) Fourth Modified Example

[0252] In the above-described embodiment, it is assumed that the mixed gas includes nitrogen as an additional component in the mixed gas other than hydrogen. However, this configuration is merely an example and should not be construed as limiting. Optionally, the mixed gas can also include a hydrocarbon (HC) such as methane, carbon dioxide, helium, argon, and oxygen as a gas other than hydrogen, not just nitrogen.

[0253] (Other Modified Examples)

[0254] Note that the above-described embodiment is merely an example embodiment among various embodiments of the present disclosure and should not be construed as limiting. Rather, the example embodiment can be easily modified in various ways according to design selection or any other factor without departing from the scope of the present disclosure.

[0255] The functions of the physical quantity measurement system 1 can also be realized as, for example, an anomaly detection method, a computer program, or a non-transitory storage medium storing the program. The anomaly detection method according to an aspect is designed for the physical quantity measurement system 1 including the temperature and humidity sensor 16 and the heat generator 17. The temperature and humidity sensor 16 measures the humidity and temperature of the mixed gas flowing through the flow passage 101. The heat generator 17 performs a heat generation operation to warm up the temperature and humidity sensor 16. The anomaly detection method includes a detection step. The detection step includes detecting any anomaly in the heat generation operation by the heat generator 17. The detection step includes detecting the occurrence of an anomaly when the measured value of the humidity of the mixed gas and the measured value of the temperature of the mixed gas measured by the temperature and humidity sensor 16 while the heat generation operation is performed by the heat generator 17 satisfy a predetermined condition. The program according to another aspect is designed to cause a computer system to function as an implementer that performs the above-described anomaly detection method.

[0256] The physical quantity measurement system 1 according to the present disclosure includes a computer system. The computer system includes a processor and a memory as its main hardware components. The computer system performs the functions of the physical quantity measurement system 1 according to the present disclosure by causing the processor to execute a program stored in the memory of the computer system. The program can be stored in advance in the memory of the computer system. Alternatively, the program can also be downloaded through a telecommunication line, or distributed after having been recorded in some non-transitory storage medium such as a memory card, an optical disc, or a hard disk drive, any of which is readable by the computer system. The processor of the computer system can be composed of a single or multiple electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). As used herein, an “integrated circuit” such as an IC or an LSI is referred to by different names according to its degree of integration. Examples of the integrated circuit such as an IC or an LSI include integrated circuits referred to as “system LSI,” “very large scale integration (VLSI),” and “ultra large scale integration (ULSI).” Alternatively, a field programmable gate array (FPGA) to be programmed after manufacturing the LSI or a reconfigurable logic device allowing reconfiguration of the connections or circuitry inside the LSI can also be employed as the processor. These electronic circuits can be integrated together on a single chip, or distributed on multiple chips as appropriate. These multiple chips can be aggregated together in a single device or distributed in multiple devices, but are not limited thereto. As used herein, a “computer system” includes a microcontroller including one or more processors and one or more memories. Thus, the microcontroller can also be realized as a single or multiple electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0257] In the above-described embodiments, the plurality of functions of the physical quantity measurement system 1 are integrated together in a single housing. However, this is not a necessary configuration of the physical quantity measurement system 1. Alternatively, those constituent elements of the physical quantity measurement system 1 can be distributed in a plurality of different housings. Still alternatively, at least some of the functions of the physical quantity measurement system 1 can also be implemented as a cloud computing system.

[0258] (SUMMARY)

[0259] As can be seen from the foregoing description, the physical quantity measurement system (1) according to the first aspect includes a temperature and humidity sensor (16), a heat generator (17), and a detector such as the second detector 209. The temperature and humidity sensor (16) measures the humidity and temperature of the mixed gas flowing through the flow passage (101). The heat generator (17) performs a heat generation operation to warm up the temperature and humidity sensor (16). The detector detects any abnormality in the heat generation operation of the heat generator (17). The detector detects the occurrence of an abnormality when the heat generation operation is performed by the heat generator (17) and the humidity measurement value of the mixed gas measured by the temperature and humidity sensor (16) and the temperature measurement value of the mixed gas satisfy a predetermined condition.

[0260] This aspect can reduce the possibility of condensation being generated in the temperature and humidity sensor (16) even when the mixed gas flows through the flow passage under a high humidity environment while the heat generator (17) is performing the heat generation operation. In addition, the detector detects the occurrence of an abnormality if the humidity measurement value of the mixed gas measured when the heat generator (17) performs the heat generation operation satisfies the predetermined condition. Thus, the physical quantity measurement system (1) can detect the presence or absence of any abnormality while reducing the possibility of condensation being generated in the hygrometer.

[0261] The physical quantity measurement system (1) according to the second aspect which can be implemented in combination with the first aspect further includes a temperature sensor such as the second temperature sensor 14. The temperature sensor measures the temperature of the mixed gas and is arranged at a place where the temperature sensor is not significantly affected by heat generated by the heat generator (17) in comparison with the temperature and humidity sensor (16). The detector determines that the predetermined condition is satisfied and detects the occurrence of an abnormality when the first difference value is greater than the first comparison value and the second difference value is greater than the second comparison value. The first difference value is calculated by subtracting the humidity measurement value from the first threshold value. The second difference value is calculated by subtracting the temperature measured by the temperature sensor from the temperature measurement value of the mixed gas measured by the temperature sensor (16).

[0262] This aspect allows the occurrence of any abnormality to be detected based on the comparison result between the first difference value and the first comparison value and the comparison result between the second difference value and the second comparison value.

[0263] In the physical quantity measurement system (1) according to the third aspect which can be implemented in combination with the second aspect, when the temperature measurement value is greater than the third comparison value, the detector further determines that the predetermined condition is satisfied and detects the occurrence of the anomaly.

[0264] This aspect allows the occurrence of any anomaly to be detected not only based on the comparison result between the first difference value and the first comparison value and the comparison result between the second difference value and the second comparison value, but also based on the comparison result between the temperature measurement value and the third comparison value.

[0265] In the physical quantity measurement system (1) according to the fourth aspect which can be implemented in combination with any one of the first aspect to the third aspect, the anomaly is a communication error caused when a signal instructing the heat generator (17) to stop performing the heat generating operation is being transmitted.

[0266] This aspect allows a communication error to be detected as an anomaly in the heat generating operation.

[0267] In the physical quantity measurement system (1) according to the fifth aspect which can be implemented in combination with any one of the first aspect to the fourth aspect, the anomaly is an internal malfunction of the physical quantity measurement system (1).

[0268] This aspect allows an internal malfunction of the physical quantity measurement system (1) to be detected as an anomaly in the heat generating operation.

[0269] In the physical quantity measurement system (1) according to the sixth aspect which can be implemented in combination with the fifth aspect, the internal malfunction of the physical quantity measurement system (1) is a failure of the heat generator (17).

[0270] This aspect allows a failure of the heat generator (17) to be detected as an anomaly in the heat generating operation.

[0271] The physical quantity measurement system (1) according to the seventh aspect which can be implemented in combination with any one of the first aspect to the sixth aspect further includes a switching unit (18). The switching unit (18) is configured to be ready to instruct the heat generator (17) to stop performing the heat generating operation when the occurrence of the anomaly is detected.

[0272] This aspect allows the heat generating operation of the heat generator (17) to be forcibly suspended when any anomaly is detected.

[0273] Explanation of Reference Numerals

[0274] 1 physical quantity measurement system

[0275] 13 first temperature sensor

[0276] 14 second temperature sensor (temperature sensor)

[0277] 16 temperature and humidity sensor

[0278] 17 heat generator

[0279] 18 switch unit

[0280] 101 flow passage

[0281] 204 water vapor pressure measurer

[0282] 208 first detector

[0283] 209 second detector (detector)

Claims

1. A physical quantity measurement system comprising: a temperature and humidity sensor configured to measure humidity and temperature of a mixed gas flowing through a flow passage; a heat generator configured to perform a heat generation operation that generates heat to warm up the temperature and humidity sensor; and a detector configured to detect any abnormality in the heat generation operation of the heat generator, the detector being configured to detect occurrence of the abnormality when a humidity measurement value of the mixed gas measured by the temperature and humidity sensor and a temperature measurement value of the mixed gas measured by the temperature and humidity sensor satisfy a predetermined condition while the heat generation operation is performed by the heat generator.

2. The physical quantity measurement system according to claim 1, further comprising a temperature sensor configured to measure temperature of the mixed gas, the temperature sensor being disposed at a place where the temperature sensor is not significantly affected by heat generated by the heat generator as compared with the temperature and humidity sensor, wherein the detector is configured to determine that the predetermined condition is satisfied and detect occurrence of the abnormality when a first difference value calculated by subtracting the humidity measurement value from a first threshold value is larger than a first comparison value and a second difference value calculated by subtracting a temperature measured by the temperature sensor from the temperature measurement value is larger than a second comparison value.

3. The physical quantity measurement system according to claim 2, wherein the detector is configured to further determine that the predetermined condition is satisfied and detect occurrence of the abnormality when the temperature measurement value is larger than a third comparison value.

4. The physical quantity measurement system according to any one of claims 1 to 3, wherein the abnormality is a communication error caused when a signal instructing the heat generator to stop performing the heat generation operation is being transmitted.

5. The physical quantity measurement system according to any one of claims 1 to 4, wherein the abnormality is an internal malfunction of the physical quantity measurement system.

6. The physical quantity measurement system according to claim 5, wherein the internal malfunction of the physical quantity measurement system is a failure of the heat generator.

7. The physical quantity measurement system according to any one of claims 1 to 6, further comprising a switching unit configured to be ready to instruct the heat generator to stop performing the heat generation operation when the occurrence of the abnormality is detected. ​

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