Hydrogen Flow Concentration Meter

Abstract

To provide a measuring device capable of measuring flow rate and concentration of hydrogen even when a mixed gas containing hydrogen is in a high humidity state.SOLUTION: In a configuration that includes: ultrasonic transducers 2 and 3 that are arranged so as to cross the flow in a measurement channel 1; temperature sensors 9 and 10 for measuring the temperature, the pressure, and the relative humidity of mixed gas to be measured containing hydrogen in an ultrasonic propagation path 6 between the ultrasonic transducers 2 and 3; a pressure sensor 11; and a relative humidity sensor 13, the flow rate and concentration of hydrogen can be accurately measured even when the mixed gas to be measured is in high humidity conditions by using the propagation time between the ultrasonic transducers 2 and 3 and measured values by the temperature sensors 9 and 10, the pressure sensor 11, and the relative humidity sensor 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a configuration of a hydrogen flow concentration meter using ultrasonic waves. [Background technology]

[0002] In fields that use fuel cells, such as fuel cell vehicles (FCVs), there is a need to measure the hydrogen flow rate and concentration in high humidity hydrogen mixed gases.

[0003] Conventionally, a method that uses ultrasonic waves to measure the concentration of a mixed gas containing hydrogen is known (see, for example, Patent Document 1).

[0004] This device first calculates the speed of sound in the mixed gas from the measured propagation time of the ultrasonic waves, and then calculates the average molecular weight of the mixed gas using this value and the measured temperature. Next, the concentration of hydrogen, a component gas, is calculated using the known molecular weights of each component gas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-91489 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional configuration, when determining the concentration of hydrogen, which is a component gas, there is no description of how to calculate the hydrogen concentration when the target gas is in a high humidity state, making it difficult to measure the hydrogen concentration of a mixed gas in a high humidity state.

[0007] The present invention is devised to solve the above-mentioned problems in the conventional art, and aims to provide a measuring device that can accurately measure the flow rate and concentration of hydrogen in a mixed gas containing hydrogen, even if the mixed gas is in a high humidity state. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the hydrogen flow concentration meter of the present invention comprises a measurement flow path through which a mixed gas containing hydrogen flows, a pair of ultrasonic transmitters and receivers arranged in the measurement flow path so as to cross the flow of the mixed gas, a transmission / reception circuit for transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers, a first signal processing unit for processing signals from the transmission / reception circuit, a sensor unit for measuring the temperature, pressure, and humidity of the mixed gas, a second signal processing unit for obtaining measured values ​​of the temperature, pressure, and humidity of the mixed gas using the sensor unit, and a calculation unit for calculating the flow rate and concentration of hydrogen in the mixed gas using the propagation time between the ultrasonic transmitters and receivers obtained in the first signal processing unit and the measured values ​​of the temperature, pressure, and humidity obtained in the second signal processing unit. a flow path main body that houses the measurement flow path, the sensor unit including a relative humidity sensor that measures the relative humidity of the mixed gas, the relative humidity sensor being inserted into a relative humidity sensor mounting hole that is formed from an upper surface of the flow path main body toward the downstream side at an acute angle with respect to the flow direction of the mixed gas and that communicates with the measurement flow path, a gap-like outer peripheral path is formed on the outer periphery of the relative humidity sensor, and a communication path that communicates with the measurement flow path along a direction perpendicular to the insertion direction of the relative humidity sensor is formed in the relative humidity sensor mounting hole, and a bypass flow path is formed by the outer peripheral path and the communication path, Even if the fluid to be measured is in a high humidity state, the flow rate and concentration of hydrogen contained in the fluid to be measured can be measured with high accuracy, and a practical hydrogen flow concentration meter can be realized. Effect of the Invention

[0009] The hydrogen flow concentration meter of the present invention can accurately measure the flow rate and concentration of hydrogen contained in the mixed gas being measured by using the measured values ​​of relative humidity, temperature, and pressure, even if the mixed gas being measured has a high humidity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a hydrogen flow concentration meter according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a portion of FIG. 1 according to the first embodiment of the present invention; [Diagram 3] FIG. 1 is an external perspective view of a flow path of a hydrogen flow concentration meter according to a first embodiment of the present invention; [Figure 4] FIG. 1 is an exploded assembly diagram of components of a hydrogen flow concentration meter according to a first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The first invention comprises a measurement flow path through which a mixed gas containing hydrogen flows, a pair of ultrasonic transmitters and receivers arranged in the measurement flow path so as to cross the flow of the mixed gas, a transmitter and receiver circuit for transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers, a first signal processing unit for processing signals from the transmitter and receiver circuit, a sensor unit for measuring the temperature, pressure, and humidity of the mixed gas, a second signal processing unit for obtaining measured values ​​of the temperature, pressure, and humidity of the mixed gas using the sensor unit, and a calculation unit for calculating the flow rate and concentration of hydrogen in the mixed gas using the propagation time between the ultrasonic transmitter and receivers obtained in the first signal processing unit and the measured values ​​of the temperature, pressure, and humidity obtained in the second signal processing unit, thereby calculating the flow rate and concentration of hydrogen contained in the flow, and even when the gas to be measured is in a high humidity state, the flow rate and concentration of hydrogen can be measured with high accuracy using the measured temperature, pressure, and relative humidity, thereby realizing a highly practical hydrogen flow concentration meter.

[0012] In the second invention, in the first invention, the measurement flow path is constructed of a multi-layer flow path separated by partitions, which straightens the flow and stabilizes turbulence, suppresses fluctuations in the measured physical quantities (temperature, pressure, relative humidity), and enables stable measurement of flow rate and concentration.

[0013] Hereinafter, the embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming more redundant than necessary and to facilitate understanding by those skilled in the art.

[0014] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] (Embodiment 1) The first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[0016] [1-1. Configuration] FIG. 1 is a configuration diagram showing a cross section of the main body and components of a hydrogen flow concentration meter in accordance with a first embodiment of the present invention, and FIG. 2 is a partial cross section showing the AA cross section of FIG.

[0017] 1 and 2, a measurement flow path 1 through which a fluid to be measured, such as a mixed gas containing hydrogen, flows is formed in the center of the flow path main body 17, and the measurement flow path 1 includes a pair of ultrasonic transmitters and receivers 2, 3 arranged upstream and downstream so as to intersect the flow of the fluid to be measured, a transmitter-receiver circuit 4a for transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers 2, 3, and a first signal processing unit 5a for processing the signal from the transmitter-receiver circuit 4a.

[0018] The transmission / reception circuit 4a is electrically connected to the ultrasonic transmitters and receivers 2 and 3 to transmit and receive signals, and the first signal processing unit 5a is connected to the transmission / reception circuit 4a to process signals. Symbols S1 and S2 written at the ends of the lines extending from the transmission / reception circuit 4a indicate connections to the ultrasonic transmitters and receivers 2 and 3, respectively.

[0019] An ultrasonic propagation path 6 for propagating ultrasonic waves is formed between the ultrasonic transmitters and receivers 2 and 3. can be.

[0020] In the first embodiment, the direction of height H of a rectangular cross section of the measurement flow path 1, which has a height H and a width W, is divided into six sections by five partition plates 7 to form a multi-layer flow path 8. This configuration increases the aspect ratio of the flow path cross section of each layer of the multi-layer flow path, making the flow two-dimensional, reducing the Reynolds number, straightening the flow, and stabilizing turbulence.

[0021] Also, it has a sensor section 4b for measuring the temperature, pressure, and humidity of the fluid to be measured, and the sensor section 4b is composed of a temperature sensor, a pressure sensor, and a relative humidity sensor, which will be described later.

[0022] In order to measure the temperature of the fluid to be measured in the ultrasonic propagation path 6, temperature sensors 9, 10 are provided on the inlet and outlet sides of the measurement flow path 1.

[0023] In addition, the pressure sensor 11 that measures the pressure of the measured fluid is disposed in the center of the ultrasonic propagation path 6 in the flow direction, and is configured to measure the pressure through a pressure connection hole 12 that communicates with the outermost layer of the ultrasonic propagation path 6 formed in multiple layers.

[0024] In addition, the relative humidity sensor 13 is positioned downstream of the ultrasonic propagation path 6 so as not to affect the flow in the ultrasonic propagation path 6, and is inserted obliquely from the top surface of the flow path main body 17 toward the downstream side at an acute angle θ with respect to the flow direction.

[0025] A gap-like outer peripheral path 15a is formed on the outer periphery of the relative humidity sensor 13, and a communication path 16 that communicates with the multilayer flow path 8 is formed in the relative humidity sensor mounting hole 15. This communication path 16 is provided in a direction substantially perpendicular to the relative humidity sensor mounting hole 15. As a result, a bypass flow path is formed by the communication path 16 that extends obliquely upward from the multilayer flow path 8 and the outer peripheral path 15a that opens on the downstream side of the multilayer flow path 8.

[0026] The temperature, pressure and humidity are measured by the sensor section 4b, which is made up of the temperature sensors 9, 10, the pressure sensor 11 and the relative humidity sensor 13, and the obtained signals are processed by the second signal processing section 5b.

[0027] Although the electrical signals from each sensor are connected to the sensor unit 4b by separate wiring, they are shown here as a single line for convenience. Also, the symbols Tp1, Tp2, Pr, and Hu written at the ends of the branches from the line represent connections to the temperature sensors 9 and 10, the pressure sensor 11, and the relative humidity sensor 13, respectively.

[0028] The calculation section 30 performs calculation processing based on the signal from the first signal processing section 5a and the signal from the second signal processing section 5b.

[0029] In the above configuration, by arranging temperature sensors 9 and 10 on the upstream and downstream sides of the ultrasonic propagation path 6, the fluid temperature in the ultrasonic propagation path 6 can be accurately estimated without affecting the ultrasonic propagation or flow.

[0030] Also, by disposing the pressure sensor 11 at the center of the ultrasonic propagation path 6 and arranging it in the outermost layer of the multi-layer flow path 8, the influence of the pressure connection hole 12 on the flow can be reduced from spreading to other multi-layer flow paths of the ultrasonic propagation path 6, and the fluid pressure in the ultrasonic propagation path can be estimated without significantly affecting the ultrasonic propagation and the flow.

[0031] In such measurement of relative humidity, if moisture in the fluid to be measured adheres to the relative humidity sensor 13 due to condensation or the like, it will interfere with the measurement. To avoid such a situation, from the multi-layer flow path 8 A bypass passage is formed that communicates with the downstream side of the multi-layer flow path through the communication passage 16 and via the gap-like outer peripheral path 15a on the outer peripheral side of the relative humidity sensor 13.

[0032] Thereby, even if dew condensation occurs around the relative humidity sensor 13, it can be made to flow out without staying. When the flow velocity is high, the bypass passage can blow the droplets to the downstream side. Also, even when the flow velocity is low, since both the relative humidity sensor 13 and the surrounding outer peripheral path 15a and the communication passage 16 are inclined with respect to the flow direction in the measurement flow path 1, even if the measurement flow path 1 is placed in a horizontal state as shown in FIG. 1, the droplets will drip due to gravity.

[0033] Also, since the inclination directions of the outer peripheral path 15a and the communication passage 16 are inclined in opposite directions with respect to the vertical direction of the measurement flow path 1, even if the outlet of the measurement flow path 1 is inclined upward or downward, either the outer peripheral path 15a or the communication passage 16 will be inclined downward, so that dripping due to gravity is ensured.

[0034] Note that, in order to further promote gravity dripping, in order to facilitate dripping to the side of the communication passage 16 with a larger cross-sectional area, it is preferable to install the measurement flow path 1 such that its outlet side is upward. In some cases, the measurement flow path 1 may be installed such that its outlet side is upward and the measurement flow path 1 is vertical. [1-2. Operation] Next, the operation of the hydrogen flow rate and concentration meter of the present invention will be described.

[0035] The fluid to be measured is a mixed gas containing hydrogen, and flows in from the direction indicated by the white arrow in FIG. 1 in a high humidity state.

[0036] At this time, ultrasonic waves are transmitted and received between the ultrasonic transmitters and receivers 2 and 3 via the ultrasonic propagation path 6, and the forward propagation time (tup) of the ultrasonic waves (from downstream to upstream) and the reverse propagation time (tdw) of the ultrasonic waves (from downstream to upstream) during this period are measured by the transmission / reception circuit 4a and the first signal processing unit 5a.

[0037] Based on the propagation time thus obtained, the flow velocity is calculated by the calculation unit 30 using a known method, and the flow rate can be calculated by multiplying it by the cross-sectional area of ​​the measurement flow path 1.

[0038] This value is corrected using the temperature obtained from temperature sensors 9 and 10 and the pressure obtained from pressure sensor 11, which will be described later, to obtain the flow rate (Q) under standard conditions.

[0039] Furthermore, among the flow rates (Q) calculated as described above, the flow rate of hydrogen alone can be calculated by multiplying the flow rate (Q) by the hydrogen concentration, which will be described later.

[0040] The temperature of the fluid to be measured is measured by measuring the upstream temperature (T1) by the temperature sensor 9 on the upstream side of the measurement flow path 1, and the downstream temperature (T2) by the temperature sensor 10 provided on the downstream side. These upstream temperature signal and downstream temperature signal are taken into the second signal processing unit 5b and processed, and then sent as the respective temperatures to the calculation unit 30. Based on these two temperatures, the calculation unit 30 determines an average temperature (measurement temperature Tm).

[0041] The pressure of the fluid to be measured is measured by a pressure sensor 11 placed at the center in the flow direction of the ultrasonic propagation path 6, the flow of which is stabilized by the multilayer flow path 8. A signal from the pressure sensor 11 is taken into the second signal processing unit 5b and processed, and then sent to the calculation unit 30 as pressure (p).

[0042] The relative humidity of the fluid to be measured is measured by a relative humidity sensor 13 arranged downstream of the ultrasonic propagation path 6. A signal from the relative humidity sensor 13 is taken into the second signal processing unit 5b and processed, and then sent to the calculation unit 30 as a relative humidity value (h).

[0043] [1-3. Method of measuring concentration] The method of calculating the hydrogen concentration using the physical quantities (transit time, temperature, pressure, and relative humidity) of the fluid being measured thus obtained will be described below.

[0044] First, the concentration of two types of mixed gas can be calculated by the following procedure.

[0045] The following relationship exists between the speed of sound c, molecular weight M, specific heat ratio γ, absolute temperature T, and gas constant R of a gas.

[0046]

number

[0047] Here, the sound speed c is calculated by the distance L between the ultrasonic sensors and the measured propagation time t up , t dw The average value of t ave and is calculated as follows:

[0048]

number

[0049] In addition, the physical properties of the two gases are as follows: Gas 1 (molecular weight M 1 , specific heat at constant pressure C p1 , specific heat at constant volume C v1 ) and gas 2 (molecular weight M 2 , specific heat at constant pressure C p2 , specific heat at constant volume C v2 ) and the concentration of gas 1 is x, the molecular weight and specific heat ratio of the mixed gas can be written as follows:

[0050]

number

[0051]

number

[0052] The concentration x can be obtained by substituting equations (2) to (4) and the measurement temperature Tm, converted into absolute temperature T, into equation (1) and solving for x.

[0053] Now, suppose that the mixed gas consists of three components: hydrogen, nitrogen, and water vapor. The molecular weight, specific heat at constant volume, and specific heat at constant pressure are known.

[0054] First, the water vapor concentration in the mixed gas can be calculated from the measured relative humidity (h), water vapor partial pressure (p), and measured temperature (Tm). In this case, the molecular weight and specific heat ratio of the mixed gas are written in the same way as in equations (3) and (4), and the hydrogen concentration is x. By solving equation (1) for x, the hydrogen concentration x can be calculated.

[0055] [1-4. Effects] As described above, the present invention includes a measurement flow path 1 through which a mixed gas containing hydrogen flows, a pair of ultrasonic transmitters and receivers 2 and 3 arranged in the measurement flow path 1 so as to cross the flow of the mixed gas, a transmission / reception circuit 4a for transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers 2 and 3, a first signal processing unit 5a for processing signals from the transmission / reception circuit 4a, a sensor unit 4b for measuring the temperature, pressure, and humidity of the mixed gas, a second signal processing unit 5b for acquiring measured values ​​of the temperature, pressure, and humidity of the mixed gas using the sensor unit 4b, and a calculation unit 30 for calculating the flow rate and concentration of hydrogen in the mixed gas using the propagation time between the ultrasonic transmitters and receivers 2 and 3 obtained in the first signal processing unit 5a and the measured values ​​of the temperature, pressure, and humidity obtained in the second signal processing unit 5b. This makes it possible to ensure the measurement accuracy of the hydrogen concentration in a mixed gas containing hydrogen even in a high humidity environment, and to realize practical flow rate and concentration measurements.

[0056] Furthermore, by dividing the measurement flow path 1 with partition plates 7 to form a multi-layered configuration, the flow can be straightened, thereby suppressing fluctuations in the physical quantities to be measured (temperature, pressure, relative humidity), enabling stable and accurate measurements.

[0057] In this embodiment, two temperature sensors are installed on the upstream and downstream sides of the ultrasonic propagation path, but the temperature in the ultrasonic propagation path can be estimated with just one of them.

[0058] Furthermore, if the shape has little effect on the flow or ultrasonic propagation, it can be inserted into the ultrasonic propagation path.

[0059] In addition, although the pressure sensor is shown to be directly open to the ultrasonic wave propagation path, it is also possible to use a pressure communication path to place the pressure sensor at a position away from the flow path. In addition, in this embodiment, the pressure sensor is placed on the top surface of the outermost layer of the multi-layer flow path, but it is also possible to place it on the side, which allows measurement across multiple layers to obtain an average pressure.

[0060] In addition, although the configuration in which the relative humidity sensor is placed on the downstream side of the ultrasonic propagation path has been shown, it is also possible to place the relative humidity sensor at a position away from the flow path by using a communication path. Furthermore, it is also possible to place two small, compact, and low-cost relative humidity sensors on the upstream and downstream sides of the ultrasonic propagation path and use the average value.

[0061] [1-5. Assembly configuration] Figures 3 and 4 show the assembly configuration of the hydrogen flow concentration meter shown in Figures 1 and 2, with Figure 3 being an external oblique view of the flow path section 14 of the hydrogen flow concentration meter 100, and Figure 4 being an overall exploded assembly view of the hydrogen flow concentration meter 100 in Figure 3.

[0062] 3 is an external perspective view of a flow path section 14 in which ultrasonic transmitters and receivers 2 and 3, temperature sensors 9 and 10, a pressure sensor 11, and a relative humidity sensor 13 are arranged. A flow path section main body 17 houses the measurement flow path 1 as shown in FIG. 1, and is provided with an inlet connection section 18 on the inlet side of the measurement flow path 1 for piping connection, and an outlet connection section 19 on the outlet side.

[0063] Fig. 4 is an exploded view of the components of the hydrogen flow concentration meter 100. The flow path main body 17 houses the measurement flow path 1, and has mounting holes 20a, 20b, and 20c above it for inserting the temperature sensor 9, pressure sensor 11, and relative humidity sensor 13. A mounting hole 20d for inserting the ultrasonic transmitter / receiver 3 is arranged on the front side of Fig. 4, and a plurality of mounting parts 22 are provided for mounting a control board 21 on which the transmission / reception circuit 4a, the first signal processing unit 5a, and the second signal processing unit 5b are arranged. A mounting hole 20e (not shown) for inserting the ultrasonic transmitter / receiver 2 is arranged on the back side of Fig. 4.

[0064] The ultrasonic transmitter / receivers 2, 3, temperature sensors 9, 10, pressure sensor 11, and relative humidity sensor 13 are airtightly attached to the flow path main body 17 via airtight seal members 23, respectively, to form the flow path 14. The entire device is then assembled by fastening the control board 21 to the attachment parts 22 with screws 26 and assembling the exterior case 24 to cover the flow path 14 from above. Note that wiring between the ultrasonic transmitter / receivers 2, 3, temperature sensors 9, 10, pressure sensor 11, and relative humidity sensor 13 and the control board 21, and wiring between the connectors 27, 28 for connecting to the outside and the control board 21 are omitted in Figures 3 and 4.

[0065] In this way, the ultrasonic transmitters 2, 3, temperature sensors 9, 10, pressure sensor 11, relative humidity sensor 13 and control board 21 are attached to the top and both side surfaces of flow path main body 17, and exterior case 24 is attached from above, realizing a compact device. This configuration makes assembly easier and improves productivity.

[0066] As described above, in the embodiment of the present invention, the measurement flow path 1 is configured to have multiple layers, but it can also be configured to have a single layer without being divided by the partition plate 7. In addition, the cross-sectional shape of the measurement flow path 1 is not limited to a rectangular cross section, and may be a circular cross section or a nearly circular cross section. [Industrial Applicability]

[0067] As described above, the hydrogen flow concentration meter of the present invention can accurately measure the flow rate and concentration of hydrogen even when the mixed gas containing hydrogen is in a high humidity state, and can therefore be widely used as a control measuring component in various applications that use fuel cells, including fuel cells and fuel cell vehicles, where such conditions occur. [Explanation of symbols]

[0068] 1 Measurement flow path 2, 3 Ultrasonic Transducer 4a Transmitter / receiver circuit 4b Sensor section 5a First signal processing section 5b Second signal processing section 6 Ultrasonic propagation path 7 Partition 8 Multilayer channel 9, 10 Temperature Sensor 11 Pressure Sensor 12 Pressure connection hole 13 Relative Humidity Sensor 14 Flow path 15 Relative humidity sensor mounting hole 15a Outer path 16 Communication path 17 Flow passage body 18 Inlet Connection 19 Outlet Connection 20a, 20b, 20c, 20d, 20e Mounting holes 21 Control board 22 Mounting part 23 Airtight seal material 24 Outer case 30 Arithmetic section 100 Hydrogen flow concentration meter

Claims

1. a measurement flow path through which a mixed gas containing hydrogen flows; a pair of ultrasonic transducers disposed in the measurement flow path so as to cross the flow of the mixed gas; a transmission / reception circuit for transmitting and receiving ultrasonic waves between the pair of ultrasonic transmitters and receivers; a first signal processing unit for processing a signal from the transmission / reception circuit; A sensor unit for measuring the temperature, pressure, and humidity of the mixed gas; a second signal processing unit that acquires measurement values ​​of a temperature, a pressure, and a humidity of the mixed gas using the sensor unit; a calculation unit that calculates a flow rate and a concentration of hydrogen in the mixed gas by using a propagation time between ultrasonic transmitters and receivers obtained in the first signal processing unit and the measured values ​​of the temperature, the pressure, and the humidity obtained in the second signal processing unit; A flow path main body that accommodates the measurement flow path, the sensor unit includes a relative humidity sensor for measuring a relative humidity of the mixed gas, the relative humidity sensor is inserted into a relative humidity sensor mounting hole that is formed at an acute angle from an upper surface of the flow path body toward a downstream side with respect to a flow direction of the mixed gas and that communicates with the measurement flow path, A gap-like outer peripheral path is formed on the outer peripheral portion of the relative humidity sensor, a communication passage is formed in the relative humidity sensor mounting hole along a direction perpendicular to an insertion direction of the relative humidity sensor, the communication passage being in communication with the measurement flow path; A hydrogen flow concentration meter in which a bypass flow path is formed by the outer peripheral path and the communication path.

2. 2. The hydrogen flow concentration meter according to claim 1, wherein the measurement flow path is configured as a multi-layer flow path separated by partition plates.

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