Gas measuring system, gas measuring method, and gas measuring program

Abstract

This gas measuring system comprises: a flowmeter for measuring a flow rate of a gas flowing through a pipe, to acquire flow rate information comprising time-series data; a first gas sensor for measuring a concentration of a prescribed gas component contained in the gas, to acquire first concentration information comprising time-series data; a second gas sensor for measuring the concentration of the prescribed gas component contained in the gas, to acquire second concentration information comprising time-series data; and a computing unit for calculating a time difference between measuring times of the concentrations of the prescribed gas component contained in the gas, on the basis of the first concentration information and the second concentration information, and correcting a time deviation in the first concentration information or the second concentration information with respect to the flow rate information on the basis of the calculated time difference.

Description

Gas measurement system, gas measurement method, and gas measurement program

[0001] The present invention relates to a gas measurement system, a gas measurement method, and a gas measurement program.

[0002] For example, Patent Document 1 discloses an exhaust gas measurement system that measures the concentrations and amounts of various components contained in exhaust gas emitted from an internal combustion engine of an automobile.

[0003] JP 2017-111123 A

[0004] In recent years, development has progressed in vehicles equipped with fuel cells (hereinafter referred to as FCVs (Fuel Cell Vehicles)) instead of internal combustion engines such as internal combustion engines. The oxygen balance method is known as a method for measuring the fuel efficiency of FCVs. The oxygen balance method is a method for determining the amount of hydrogen consumed by a fuel cell from the difference between the amount of oxygen contained in the air before the reaction in the fuel cell (i.e., the air taken in by the fuel cell, i.e., the ambient atmosphere) and the amount of oxygen contained in the gas discharged from the fuel cell via a pipe.

[0005] One method for sampling gas is the direct (measurement) method. The direct method involves continuously sampling gas flowing through a pipe and measuring the gas flow rate and the concentration of gas components (e.g., oxygen, hydrogen, and water) contained in the gas over time. Combining the direct method with the oxygen balance method makes it possible to continuously measure the hydrogen consumption in a fuel cell.

[0006] Here, for example, when measuring oxygen concentration, a time delay may occur with respect to the measured gas flow rate due to the responsiveness of the sensor. When this time delay occurs, it becomes difficult to accurately calculate oxygen consumption using the gas flow rate and oxygen concentration. One possible solution to this problem is to conduct a test in advance to determine the delay time in measuring the oxygen concentration, and then calculate the oxygen consumption rate taking this delay time into account. However, this method requires the preparation of equipment and labor for conducting the test.

[0007] The present invention has been made to solve the above problems, and its object is to provide a gas measurement system, a gas measurement method, and a gas measurement program that can accurately determine the consumption amount of gas components contained in gas flowing through a pipe using a simple technique.

[0008] A gas measurement system according to one aspect of the present invention includes a flow meter that measures the flow rate of gas flowing through a pipe and acquires flow rate information, which is time-series data; a first gas sensor that measures the concentration of a predetermined gas component contained in the gas and acquires first concentration information, which is time-series data; a second gas sensor that measures the concentration of the predetermined gas component contained in the gas and acquires second concentration information, which is time-series data; and a calculation unit that calculates a time difference between the measurement of the concentration of the predetermined gas component contained in the gas based on the first concentration information and the second concentration information, and corrects the time lag of the first concentration information or the second concentration information relative to the flow rate information based on the calculated time difference.

[0009] A gas measurement method according to another aspect of the present invention includes: a flow rate information acquisition step in which a flow meter measures the flow rate of gas flowing through a pipe and acquires flow rate information, which is time-series data; a first concentration information acquisition step in which a first gas sensor measures the concentration of a predetermined gas component contained in the gas and acquires first concentration information, which is time-series data; a second concentration information acquisition step in which a second gas sensor measures the concentration of the predetermined gas component contained in the gas and acquires second concentration information, which is time-series data; and a calculation step in which a calculation unit calculates a time difference between the measurement of the concentration of the predetermined gas component contained in the gas based on the first concentration information and the second concentration information, and corrects a time lag of the first concentration information or the second concentration information relative to the flow rate information based on the calculated time difference.

[0010] A gas measurement program according to yet another aspect of the present invention is a program for causing a computer to execute the following steps: a calculation step of calculating a time difference between measurements of the concentration of a predetermined gas component contained in a gas flowing through a pipe, based on first concentration information, which is time series data obtained by measuring the concentration of the predetermined gas component contained in the gas using a first gas sensor, and second concentration information, which is time series data obtained by measuring the concentration of the predetermined gas component contained in the gas using a second gas sensor; and a correction step of correcting a time difference between the first concentration information or the second concentration information relative to the flow rate information, based on the time difference.

[0011] According to the present invention, the consumption amount of a gas component contained in a gas flowing inside a pipe can be accurately determined by a simple method.

[0012] FIG. 1 is an explanatory diagram showing a schematic configuration of a gas measurement system according to an embodiment of the present invention. FIG. 2 is a graph showing an example of flow rate information, first concentration information, and second concentration information. FIG. 3 is a graph showing the relationship between the flow rate information and the first concentration information. FIG. 4 is a graph showing the relationship between the flow rate information and the second concentration information. FIG. 5 is an explanatory diagram showing each parameter measured in an oxygen balance method. FIG. 6 is a flowchart showing the flow of operation in the gas measurement system. FIG. 7 is a graph showing the flow rate information, the first concentration information, and the corrected second concentration information together.

[0013] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

[0014] 1. Overview of the Gas Measurement System Fig. 1 is an explanatory diagram showing the general configuration of a gas measurement system 1 according to the present embodiment. The gas measurement system 1 is a system that measures the flow rate of gas emitted from a vehicle 100 under test and the concentration of gas components contained in the gas, and calculates the fuel consumption of the vehicle 100. In this embodiment, the vehicle 100 is considered to be a vehicle (FCV; Fuel Cell Vehicle) equipped with a fuel cell 101. In this case, the fuel consumption refers to hydrogen consumption.

[0015] The specimen may be the fuel cell 101 itself, or may be a part of the vehicle 100 equipped with the fuel cell 101. An example of a part of the vehicle 100 equipped with the fuel cell 101 could be an incomplete vehicle that is equipped with the fuel cell 101 but has not yet been manufactured to a state that makes it suitable for sale on the market.

[0016] The gas measurement system 1 includes a flow meter 2, a first gas sensor 3, a second gas sensor 4, an analyzer 5, a calculation unit 6, and a display unit 7.

[0017] The flow meter 2 acquires flow rate information by continuously measuring the flow rate of gas discharged from the vehicle 100 (particularly the fuel cell 101) via the pipe 102. An example of the flow rate information acquired by the flow meter 2 is shown in a graph of thin solid lines in Figure 2. The flow meter 2 is configured as, for example, an ultrasonic flow meter, but may also be configured as another type of flow meter (for example, a Pitot tube flow meter).

[0018] The first gas sensor 3 continuously measures the concentration of a predetermined gas component contained in the gas emitted from the vehicle 100 over time to obtain concentration information (first concentration information). An example of the first concentration information obtained by the first gas sensor 3 is shown in FIG. 2 by a thin dashed line graph. Here, oxygen is considered as the predetermined gas component. Therefore, the first gas sensor 3 is an oxygen meter that measures the concentration of oxygen. In particular, the first gas sensor 3 is configured as a zirconia oxygen sensor with excellent responsiveness.

[0019] The first gas sensor 3 is disposed near the flow meter 2. That is, the first gas sensor 3 is disposed closer to the flow meter 2 than the second gas sensor 4. This allows the measurement of the oxygen concentration by the first gas sensor 3 and the measurement of the gas flow rate by the flow meter 2 to be performed in approximately synchronized time. That is, the first concentration information and the flow rate information can be approximately synchronized in time. The first gas sensor 3 may be incorporated into the flow meter 2. That is, the first gas sensor 3 may be configured integrally with the flow meter 2. In this embodiment, the first gas sensor 3 is disposed downstream of the flow meter 2 in the flow direction of gas emitted from the vehicle 100, but it may also be disposed upstream.

[0020] The second gas sensor 4 continuously measures the concentrations of predetermined gas components contained in the gas emitted from the vehicle 100 over time to obtain concentration information (second concentration information). An example of the second concentration information obtained by the second gas sensor 4 is shown in Fig. 2 by a thick solid line graph. Here, the predetermined gas components whose concentrations are to be measured by the second gas sensor 4 are at least the same as the gas components measured by the first gas sensor 3. In this embodiment, the second gas sensor 4, like the first gas sensor 3, is also configured as an oxygen meter that measures the concentration of oxygen.

[0021] However, the second gas sensor 4 is a magnetic pressure oxygen sensor. Although a magnetic pressure oxygen sensor has a response time delay compared to a zirconia oxygen sensor, it has the advantage of being able to measure the oxygen concentration with high accuracy. The response delay of the second gas sensor 4 can be caused by factors such as sampling delay, the length of the piping through which the exhaust gas flows, or the use of a pump to suck in the exhaust gas.

[0022] The analyzer 5 continuously measures the flow rate and concentration of gas components other than the gas component (here, oxygen) whose concentration is measured by the first gas sensor 3 and the second gas sensor 4. Possible gas components other than oxygen that are the measurement target of the analyzer 5 include, for example, hydrogen, carbon dioxide, carbon monoxide, nitrogen oxides, hydrocarbons, ammonia, formaldehyde, particulate matter, solid particles, and water.

[0023] The display unit 7 displays the results of measurements by the flow meter 2, the first gas sensor 3, the second gas sensor 4, and the analyzer 5, as well as the results of calculations by the calculation unit 6. Such a display unit 7 is configured, for example, by a liquid crystal display device.

[0024] 3 shows the relationship between the measurement value (first concentration information) of the first gas sensor 3 and the measurement value (flow rate information) of the flow meter 2. Here, the time shown on the horizontal axis is the elapsed time from the start of measurement, and is time information common to the first gas sensor 3 and the flow meter 2. Because the first gas sensor 3 is an analyzer with very little time lag, it can be assumed that there is no time lag between the measurement value of the first gas sensor 3 and the measurement value of the flow meter 2. Therefore, the time information of both measurement values ​​can be considered to be correct. However, the accuracy of the concentration information indicated by the first gas sensor 3 is low.

[0025] 4 shows the relationship between the measurement value (second concentration information) of the second gas sensor 4 and the measurement value (flow rate information) of the flow meter 2. Here, the time shown on the horizontal axis is the elapsed time from the start of measurement, and is time information common to the second gas sensor 4 and the flow meter 2. The measurement value (concentration value) of the second gas sensor 4 is a highly accurate value, but since the second gas sensor 4 is an analyzer that generates a time lag, there is a time lag between the measurement value of the second gas sensor 4 and the measurement value of the flow meter 2.

[0026] That is, in the flow rate information at a certain time, the time information that the measurement value should indicate is correct from the first gas sensor 3, and the concentration information that the measurement value should indicate is correct from the second gas sensor 4. The value (concentration information) indicated by the first gas sensor 3 is not as accurate as the value indicated by the second gas sensor 4, but behavior such as the maximum and minimum values ​​of the waveform can be detected. The reason why the waveforms of the first gas sensor 3 and the second gas sensor 4 may not necessarily be similar is thought to be due to the shape of the sensors, non-uniformity of exhaust gas components, etc.

[0027] The calculation unit 6 is configured with a calculation device such as a CPU (Central Processing Unit), and operates according to a predetermined operation program. The operation program is stored in a storage unit (not shown) within the calculation device.

[0028] Specifically, the arithmetic unit 6 functions as a calculation unit 11, a correction unit 12, and a processing unit 13. The calculation unit 11 calculates a time difference between measurements of the concentrations of a predetermined gas component contained in gas at the same flow rate, based on the first concentration information acquired by the first gas sensor 3 and the second concentration information acquired by the second gas sensor 4. For example, the calculation unit 11 calculates a delay time of one of the first concentration information and the second concentration information relative to the other as the time difference. The correction unit 12 corrects the time difference of the first concentration information or the second concentration information relative to the flow rate information acquired by the flowmeter 2, based on the time difference calculated by the calculation unit 11. Details of the processes performed by the calculation unit 11 and the correction unit 12 will be described later.

[0029] The processing unit 13 calculates the oxygen consumption rate based on the flow rate information and the corrected concentration information of the other gas component. The processing unit 13 then calculates the hydrogen consumption rate based on the calculated oxygen consumption rate and the concentration information of other gas components acquired by the analyzer 5. Furthermore, the processing unit 13 measures fuel economy using the hydrogen consumption rate and the mileage information of the test specimen. Mileage information can be obtained, for example, by mounting the vehicle on a dynamometer DY (see FIG. 5 ) and simulating driving conditions similar to road driving. The hydrogen consumption rate and / or mileage information may be acquired by driving the vehicle on the dynamometer DY in a predetermined driving mode. The predetermined driving mode in this case may be, for example, a worldwide harmonized test cycle known as the WLTC (Worldwide Harmonized Light Duty Test Cycle). If the test specimen is not capable of driving, the work load information of the test specimen may be converted into mileage information to measure fuel economy. Here, the work load information refers to information on the amount of work performed by the test specimen per unit time. For example, if it is known in advance that a test specimen will travel N (km) with a workload of K (W) per unit time, the fuel efficiency of the test specimen can be measured by calculating hydrogen consumption / N / K, i.e., the amount of gas consumed per unit workload of the test specimen can be measured.

[0030] The calculation of hydrogen consumption in the processing unit 13 is based on the oxygen balance method. Methods for measuring fuel economy in FCVs include the mass method, pressure method, and flow rate method. However, all of these methods require hydrogen to be supplied from outside the vehicle, and require modifications to the FCV's hydrogen supply line to insert an external test hydrogen supply line. The oxygen balance method is effective in that, in principle, it is possible to measure fuel economy without modifying the vehicle and it is possible to perform fuel economy tests on completed vehicles. Below, we will explain how to calculate hydrogen consumption using the oxygen balance method.

[0031] 2. Method for Calculating Hydrogen Consumption Amount Using Oxygen Balance Method FIG. 5 is an explanatory diagram showing the parameters measured in the oxygen balance method (particularly the direct method). The processing unit 13 calculates the hydrogen consumption amount based on the following formulas (1) to (4): ΔQ Ｏ２ = QA x CA Ｏ２ -QE x CE Ｏ２ 　　 = (QE x CE ＵＲＧ ) × (CA Ｏ２ / CA ＵＲＧ ) - (QE x CE Ｏ２ ) (1) QE Ｈ２ = QE x CE Ｈ２ (2) ΔQ Ｈ２ =ΔQ Ｏ２ ×2+QE Ｈ２ (3) However, QA × CA ＵＲＧ = QE x CE ＵＲＧ (4)

[0032] The breakdown of each parameter is as follows (all represent flow rate or concentration in a dry state): QA 　　 : Intake air flow rate [m ３ / min] CA Ｏ２ : Oxygen in the intake air (O ２ ) Concentration [vol.%] CA Ｈ２Ｏ　 : Moisture in intake air (H ２ O) Concentration [vol.%] CA ＵＲＧ　 ​QE: Non-reactive gas concentration in intake air [vol.%] 　　 : Exhaust gas flow rate [m ３ / min]CE Ｏ２ : Oxygen in exhaust gas (O ２ ) Concentration [vol.%] CE Ｈ２Ｏ　 : Moisture content in exhaust gas (H ２ O) Concentration [vol.%] CE ＵＲＧ　 : Non-reactive gas concentration in exhaust gas [vol.%] CE Ｈ２ : Hydrogen in exhaust gas (H ２ ) Concentration [vol.%] QE Ｈ２ : Hydrogen flow rate [m ３ / min] ΔQ Ｏ２ : Oxygen consumption [m ３ / min] ΔQ Ｈ２ : Hydrogen consumption [m ３ / min]

[0033] Here, the unreacted gas is nitrogen (N ２ ), argon (Ar), or carbon dioxide (CO ２ ) and other gases that do not contribute to the fuel cell reaction. From the viewpoint of conservation of mass, the amount of non-reactive gases is the same in intake and exhaust. That is, the amount of non-reactive gases in the intake air (QA x CA) ＵＲＧ ) is the amount of non-reactive gas in the exhaust gas (QE × CE ＵＲＧ ) (see formula (4)). Therefore, the amount of inhaled oxygen (QA × CA Ｏ２ ) is the amount of non-reactive gas in the exhaust gas (QE × CE ＵＲＧ ) and the ratio of oxygen concentration to non-reactive gas concentration in the intake air (CA Ｏ２ / CA ＵＲＧ ) It should be noted that when formula (4) is substituted into the first line of formula (1), the second line of formula (1) is obtained.

[0034] In addition, CA ＵＲＧ is calculated by subtracting the oxygen concentration and hydrogen concentration in the intake air from 100 vol.%. ＵＲＧ is calculated by subtracting the oxygen concentration and hydrogen concentration in the exhaust gas from 100 vol.%.

[0035] The fuel cell 101 shown in FIG. 1 performs purging, which involves discharging hydrogen at appropriate times, in order to maintain a constant level of hydrogen purity at the anode. The amount of purged hydrogen is simply measured using equation (2). The amount of hydrogen is measured using the analyzer 5. In other words, the analyzer 5 has at least a hydrogen meter. Since the fuel cell 101 consumes hydrogen with a molar volume twice that of oxygen to generate electricity, the final amount of hydrogen consumed is calculated using equation (3). The processing unit 13 performs calculations by substituting the acquired parameter values ​​into equations (1) to (4).

[0036] 2, the waveforms of the graphs showing the first and second concentration information are similar, but the positions of the concentration peaks are shifted in time. That is, there is a time delay between the measurement (concentration detection) by the first gas sensor 3 and the measurement (concentration detection) by the second gas sensor 4. This indicates that the responsiveness of the second gas sensor 4, which is a magnetic pressure oxygen sensor, is inferior to that of the first gas sensor 3, which is a zirconia oxygen sensor.

[0037] On the other hand, zirconia oxygen sensors are affected by combustible gases (e.g., hydrogen), making them unsuitable for use as oxygen meters to measure the concentration of oxygen in the exhaust gas of a fuel cell 101 (which is expected to contain hydrogen). However, as described above, zirconia oxygen sensors have excellent responsiveness, allowing them to accurately detect changes in oxygen concentration over time.

[0038] Therefore, in this embodiment, the concentration of oxygen contained in the exhaust gas is determined by the value of the concentration obtained by the magnetic pressure oxygen sensor (second gas sensor 4), which is capable of measuring the concentration with higher accuracy than the zirconia oxygen sensor. On the other hand, the time delay in the measurement by the second gas sensor 4 is corrected by observing the change in the oxygen concentration measured by the zirconia oxygen sensor (first gas sensor 3), which has excellent responsiveness. In this way, the flow rate information obtained by the flow meter 2 and the oxygen concentration information (second concentration information) obtained by the second gas sensor 4 are time-matched to determine the amount of oxygen contained in the exhaust gas ((QE×CE) in formula (1)). Ｏ２Therefore, the oxygen consumption rate and the hydrogen consumption rate can be calculated with high accuracy using the oxygen amount.

[0039] 4. Gas Measurement Method The following describes the operation of the gas measurement system 1 configured as described above, that is, the gas measurement method. Fig. 6 is a flowchart showing the flow of the operation of the gas measurement system 1 of this embodiment.

[0040] First, the flow meter 2 measures the flow rate of the gas flowing through the pipe 102 and acquires flow rate information, which is time-series data (S1: flow rate information acquisition step). Next, the first gas sensor 3 measures the concentration of a predetermined gas component (here, oxygen) contained in the gas flowing through the pipe 102 and acquires first concentration information, which is time-series data (S2: first concentration information acquisition step).

[0041] On the other hand, the second gas sensor 4 measures the concentration of a predetermined gas component (here, oxygen) contained in the gas flowing through the pipe 102, which is the same as the gas component measured by the first gas sensor 3, and acquires second concentration information, which is time-series data (S3; second concentration information acquisition process).

[0042] Next, the operation unit 6 (particularly the calculation unit 11) calculates a delay time ΔT between one of the first concentration information and the second concentration information and the other based on the first concentration information acquired in S2 and the second concentration information acquired in S3 (S4; delay time calculation step). Here, since the responsiveness of the second gas sensor 4 is inferior to that of the first gas sensor 3, the operation unit 6 (particularly the calculation unit 11) calculates the delay time ΔT between the second concentration information and the first concentration information.

[0043] For example, the calculation unit 6 calculates the delay time ΔT based on the position P1 of the concentration peak over time of the first concentration information and the position P2 of the concentration peak over time of the second concentration information shown in FIG. 2 . Note that each position P1 and P2 corresponds to the time point at which the oxygen concentrations (first concentration, second concentration) contained in gas at the same flow rate are measured. Because each position P1 and P2 corresponds to a local maximum of each graph (function) representing the first concentration information and the second concentration information, they can be determined based on the value obtained by differentiating each graph (first-order differential, second-order differential). Alternatively, the positions P1 and P2 may be estimated by the user's visual estimation. Once the positions P1 and P2 are determined, the calculation unit 6 can calculate the delay time ΔT (= t2 - t1) of the second concentration information relative to the first concentration information by subtracting the time t1 (sec) corresponding to position P1 from the time t2 (sec) corresponding to position P2. Note that the delay time ΔT information is stored in a memory (not shown) within the calculation unit 6.

[0044] Here, the calculation unit 6 may calculate the delay time ΔT based on the position where the concentration change over time in the first concentration information is minimal and the position where the concentration change over time in the second concentration information is minimal. Alternatively, the calculation unit 6 may calculate the delay time ΔT based on the change point where the concentration change over time in the first concentration information is steep and the change point where the concentration change over time in the second concentration information is steep. In other words, the calculation unit 6 may calculate the time difference (delay time ΔT) based on the waveform showing the concentration change over time in the first concentration information and the waveform showing the concentration change over time in the second concentration information.

[0045] Next, the calculation unit 6 (particularly the correction unit 12) corrects the time delay of the other concentration information (second concentration information) relative to the flow rate information based on the delay time ΔT calculated in S4 (S5; correction step). Note that S4 and S5 are collectively referred to as the calculation step. For example, the calculation unit 6 performs a correction to advance the other concentration information relative to the flow rate information by the delay time ΔT calculated in S4. FIG. 7 is a graph showing the flow rate information, the first concentration information, and the corrected second concentration information together. As shown in the figure, by advancing the second concentration information by the delay time ΔT, the concentration peak position P1 of the first concentration information and the concentration peak position P2 of the second concentration information coincide in time.

[0046] Thereafter, the calculation unit 6 (particularly the processing unit 13) calculates the amount of oxygen contained in the exhaust gas based on the flow rate information and the corrected second concentration information, and calculates the oxygen consumption amount ΔQ in the fuel cell 101. Ｏ２ Specifically, the processing unit 13 calculates the flow rate of the exhaust gas (corresponding to QE in the formula (1)) and the oxygen concentration measured by the second gas sensor 4 (CE in the formula (1)) at the same time (S6: oxygen consumption calculation step). Ｏ２ Then, the processing unit 13 calculates the amount of oxygen contained in the exhaust gas by multiplying the amount of oxygen consumed by the fuel cell 101 by the amount of oxygen consumed by the fuel cell 101 (corresponding to the amount of oxygen consumed by the fuel cell 101) based on the above-mentioned formula (1). Ｏ２ The concentration of non-reactive gases in the exhaust gas (CE ＵＲＧ ), oxygen concentration in intake air (CA Ｏ２ ), the concentration of non-reactive gases in the intake air (CA ＵＲＧ ) is assumed to be calculated in advance.

[0047] Here, the intake air refers to the air in the test room, but the oxygen concentration value in the intake air may be a predetermined oxygen concentration value in an atmospheric gas cylinder. The amount of fluctuation in the oxygen concentration in the air in the test room is limited to a range that does not interfere with measurement using the oxygen balance method. The oxygen concentration in the intake air may be measured using an oxygen concentration meter designed for indoor use or a magnetic oxygen sensor. Furthermore, the oxygen concentration value in the intake air may be determined by referring only to the oxygen concentration value measured before the test. If a gas cylinder adjusted to a predetermined concentration is used instead of air, the oxygen concentration value printed on the gas cylinder may be used.

[0048] Next, the calculation unit 6 (particularly the processing unit 13) calculates the oxygen consumption ΔQ obtained in S7. Ｏ２ From the above, based on the formula (3), the hydrogen consumption amount ΔQ in the fuel cell 101 is calculated. Ｈ２ (S7: hydrogen consumption calculation step). Ｈ２ is calculated by the analyzer 5. Finally, the processing unit 13 calculates the hydrogen consumption amount ΔQ calculated in S7. Ｈ２ The fuel efficiency of the vehicle 100 is calculated by dividing the calculated fuel efficiency by the work load information or the travel distance information (S8). The results of S5 to S8 are displayed on the display unit 7 (see FIG. 1).

[0049] In this embodiment, the reasons for selecting the positions P1 and P2 when calculating the delay time ΔT are as follows. A magnetic pressure oxygen sensor is expected to obtain more accurate measurement values ​​the closer it is to the same oxygen concentration (approximately 20 vol%) as the reference gas. Therefore, it is considered necessary to select the change point by focusing on the waveform near the concentration of the reference gas.

[0050] On the other hand, with zirconia oxygen sensors, the accuracy of oxygen concentration measurement may decrease if the measured gas contains a large amount of moisture. It is believed that the formation of water droplets on the sensor surface reduces its sensitivity to oxygen, and as is clear from position P3, the absolute value of the oxygen concentration decreases. However, as can be seen from positions P1, P3, P5, and P7, when we focus on the behavior of large changes in oxygen concentration, we can see that the behavior of the concentration change in the zirconia oxygen sensor follows the behavior of the concentration change in the magnetic pressure oxygen sensor. Therefore, even with zirconia oxygen sensors, the highest possible oxygen concentration value should be selected as the change point.

[0051] In determining the validity of the change points, positions P1 and P2 have peak positions that match well (in the time axis direction) after correction, and other combinations of change points (e.g., P3 and P4, P5 and P6, P7 and P8) also have peak positions that match well (in the time axis direction) after correction. From this, it is believed that the combination of positions P1 and P2 can be trusted, and in this embodiment, positions P1 and P2 were selected when calculating the delay time ΔT.

[0052] There are also transition points that are detected by the magnetic pressure oxygen sensor but not by the zirconia oxygen sensor (e.g., P11 and P12 of the magnetic pressure oxygen sensor). These are in concentration ranges slightly outside the range of the reference gas (oxygen concentration of approximately 8-9 vol%), so it is difficult to expect the concentration values ​​to be as accurate as would be expected within the range of the reference gas. It is considered best not to select these relatively small waveforms as transition points.

[0053] [5. Effects] As described above, the calculation unit 6 (correction unit 12) corrects the time delay of the other concentration information (second concentration information) relative to the flow rate information, thereby enabling the flow rate information and the other concentration information to be time-aligned, as shown in FIG. 7 . This makes it possible to accurately determine the amount of gas component (oxygen) contained in the exhaust gas, and therefore the consumption amount of the gas component, using the flow rate information and the other concentration information. Furthermore, the above correction by the calculation unit 6 eliminates the need to manually perform a test in advance to time-align the flow rate information and the other concentration information. In other words, according to the gas measurement system and gas measurement method of this embodiment, the consumption amount of the gas component contained in the gas flowing through the pipe 102 can be accurately determined using a simple calculation method.

[0054] In particular, the calculation unit 6 performs a correction to advance the other concentration information (second concentration information) in time relative to the flow rate information by the calculated delay time ΔT, thereby enabling the flow rate information and the other concentration information to be synchronized in time.

[0055] Furthermore, by the calculation unit 6 determining the position P1 of the concentration peak of the first concentration information and the position P2 of the concentration peak of the second concentration information, the relative delay time ΔT between the first concentration information and the second concentration information can be reliably calculated.

[0056] Furthermore, by using a zirconia oxygen sensor with excellent response as the first gas sensor 3, the calculation unit 6 can accurately calculate the delay time ΔT of the second concentration information relative to the first concentration information, and can accurately synchronize the flow rate information and the second concentration information in terms of time.

[0057] Furthermore, although the magnetic pressure oxygen sensor is slower in response than the zirconia oxygen sensor, it can measure the oxygen concentration more accurately (it has better detection accuracy) than the zirconia oxygen sensor. Therefore, by using a magnetic pressure oxygen sensor as the second gas sensor 4, the amount of oxygen in the exhaust gas, and therefore the oxygen consumption rate, can be determined with high accuracy by synchronizing the flow rate information and the second concentration information in time.

[0058] When the exhaust gas emitted from the vehicle 100 as a test specimen is oxygen, the calculation unit 6 (particularly the processing unit 13) calculates the oxygen consumption of the vehicle 100 by the oxygen balance method using the flow rate information acquired by the flow meter 2 and the corrected second concentration information, calculates the hydrogen consumption of the vehicle 100 from the oxygen consumption, and determines the gas amount per unit work using the hydrogen consumption and work amount information. This makes it possible to calculate the final fuel efficiency of the vehicle 100.

[0059] In particular, the calculation unit 6 uses the flow rate information acquired by the flow meter 2 and the corrected second concentration information to calculate the oxygen consumption of the vehicle 100 using the oxygen balance method, calculates the hydrogen consumption of the vehicle 100 from the oxygen consumption, and can easily calculate fuel efficiency information of the vehicle 100 by using the hydrogen consumption and the mileage information of the vehicle 100 or the mileage information calculated from the work amount information.

[0060] [6. Program] The calculation unit 6 of the gas measurement system 1 of this embodiment can be configured as a computer on which an operating program (application software) is installed. By having the computer (e.g., the calculation unit 6) read and execute the program, each component of the calculation unit 6 (the calculation unit 11, the correction unit 12, and the processing unit 13) can be operated to execute the above-described processes (each step). Such a program is acquired, for example, by downloading it from an external source via a network and stored in the memory of the calculation unit 6. The program may be recorded on a computer-readable recording medium such as a CD-ROM (Compact Disk-Read Only Memory), and the program may be read from the recording medium and stored in the memory. In other words, the gas measurement program of this embodiment is a program for causing a computer to execute steps S4 to S7 of the gas measurement method of this embodiment described above. Furthermore, the recording medium of this embodiment is a computer-readable recording medium on which the above-described gas measurement program is recorded.

[0061] [7. Supplementary Information] The gas measurement system 1 described in this embodiment can also be expressed as a gas analysis device or gas analysis system that analyzes gas emitted from a test specimen. Here, the test specimen is, as described above, the fuel cell 101, the vehicle 100 including the fuel cell 101, or a part of the vehicle 100. In this case, the gas emitted from the test specimen is water vapor generated by the power generation reaction in the fuel cell, consumed oxygen, etc.

[0062] The vehicle 100 may be a vehicle other than an FCV. For example, the vehicle 100 may be a vehicle equipped with an engine fueled by gasoline or diesel. Therefore, the test specimen may be an engine fueled by gasoline or diesel, or a vehicle equipped with such an engine or a part of such a vehicle. In this case, the gases emitted from the test specimen may include carbon dioxide, nitrogen oxides, ammonia, formaldehyde, etc.

[0063] Even if vehicle 100 is a vehicle other than an FCV, when calculating the fuel consumption of vehicle 100, if the response of a sensor that measures the concentration of a specific gas component contained in the exhaust gas from vehicle 100 is low, the configuration of the gas measurement system described in this embodiment can be applied (in combination with a sensor with excellent response) to accurately calculate the fuel consumption.

[0064] In this embodiment, the second concentration information is delayed in time compared to the first concentration information, so a correction is made to advance the second concentration information in time. However, if the first concentration information is delayed in time compared to the second concentration information due to the responsiveness of the sensor, a correction can be made to advance the first concentration information in time.

[0065] The first gas sensor 3 and the second gas sensor 4 may be located either upstream or downstream in the gas flow direction with respect to the flow meter 2. However, if the first gas sensor 3 and the second gas sensor 4 are located upstream with respect to the flow meter 2, the first gas sensor 3 and the second gas sensor 4 may draw in gas to measure the oxygen concentration, which may change the flow rate of the gas flowing downstream and change the flow rate measurement value of the flow meter 2. Therefore, from the perspective of accurately measuring the flow rate with the flow meter 2, it is desirable that the first gas sensor 3 and the second gas sensor 4 be located downstream with respect to the flow meter 2.

[0066] Furthermore, for example, if the first gas sensor 3 is located upstream of the flow meter 2 and the second gas sensor 4 is located further upstream than the first gas sensor 3, the second concentration information acquired by the second gas sensor 4 may be shifted forward in time relative to the flow rate information acquired by the flow meter 2. In this case, the calculation unit 6 (particularly the correction unit 12) performs a correction based on the time difference between the first concentration information and the second concentration information to delay the second concentration information by the time difference, thereby enabling the flow rate information and the second concentration information to be synchronized in time.

[0067] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and the invention can be expanded or modified without departing from the spirit of the invention.

[0068] The present invention can be used, for example, in a system for determining the consumption amount of a gas component contained in a gas flowing through a pipe.

[0069] REFERENCE SIGNS LIST 1 Gas measurement system 2 Flow meter 3 First gas sensor 4 Second gas sensor 6 Calculation unit 100 Vehicle (test specimen) 101 Fuel cell (test specimen) 102 Pipe ΔT Delay time (time lag)

Claims

1. a flow meter that measures the flow rate of gas flowing through a pipe and acquires flow rate information as time-series data; a first gas sensor that measures a concentration of a predetermined gas component contained in the gas and acquires first concentration information that is time-series data; a second gas sensor that measures the concentration of the predetermined gas component contained in the gas and acquires second concentration information that is time-series data; a calculation unit that calculates a time difference when measuring the concentration of the specified gas component contained in the gas based on the first concentration information and the second concentration information, and corrects a time lag of the first concentration information or the second concentration information relative to the flow rate information based on the calculated time difference.

2. The gas measurement system according to claim 1 , wherein the first gas sensor is disposed closer to the flow meter than the second gas sensor.

3. 3. The gas measurement system according to claim 2, wherein the calculation unit calculates a delay time of the second concentration information relative to the first concentration information as the time difference, and corrects the time delay of the second concentration information relative to the flow rate information based on the calculated delay time.

4. 4. The gas measurement system according to claim 3, wherein the calculation unit performs a correction to advance the second concentration information in time relative to the flow rate information by the calculated delay time.

5. 5. The gas measurement system according to claim 1, wherein the calculation unit calculates the time difference based on a waveform representing a change in concentration over time of the first concentration information and a waveform representing a change in concentration over time of the second concentration information.

6. the first gas sensor is a zirconia oxygen sensor; The gas measurement system according to claim 1 , wherein the calculation unit calculates, as the time difference, a delay time of the second concentration information relative to the first concentration information.

7. 7. The gas measurement system according to claim 6, wherein the second gas sensor is a magnetic pressure type oxygen sensor.

8. The gas is exhaust gas emitted from a test specimen, The exhaust gas contains oxygen, 2. The gas measurement system according to claim 1, wherein the calculation unit calculates the oxygen consumption of the specimen by an oxygen balance method using the flow rate information acquired by the flow meter and the first concentration information or the second concentration information after correcting for the time lag, calculates the hydrogen consumption of the specimen from the oxygen consumption, and determines the amount of gas per unit work using the hydrogen consumption and work amount information indicating the amount of work performed by the specimen.

9. The gas is exhaust gas emitted from a test specimen, The exhaust gas contains oxygen, 2. The gas measurement system according to claim 1, wherein the calculation unit calculates the oxygen consumption of the specimen by an oxygen balance method using the flow rate information acquired by the flow meter and the first concentration information or the second concentration information after correcting for the time lag, calculates the hydrogen consumption of the specimen from the oxygen consumption, and calculates fuel efficiency information of the specimen using the hydrogen consumption and mileage information indicating a mileage of the specimen or mileage information calculated from the work amount information.

10. 9. The gas measurement system according to claim 8, wherein the test object is any one of a fuel cell, a vehicle equipped with the fuel cell, and a part of a vehicle equipped with the fuel cell.

11. a flow rate information acquisition step of measuring the flow rate of gas flowing through the pipe and acquiring flow rate information which is time series data; a first concentration information acquisition step of measuring the concentration of a predetermined gas component contained in the gas and acquiring first concentration information which is time-series data; a second concentration information acquisition step of measuring the concentration of the predetermined gas component contained in the gas and acquiring second concentration information which is time-series data; a calculation step of calculating a time difference between measurements of the concentration of the predetermined gas component contained in the gas based on the first concentration information and the second concentration information, and correcting a time lag of the first concentration information or the second concentration information relative to the flow rate information based on the calculated time difference.

12. a calculation step of calculating a time difference between measurements of the concentration of a predetermined gas component contained in the gas flowing through the pipe, based on first concentration information, which is time-series data obtained by measuring the concentration of the predetermined gas component contained in the gas using a first gas sensor, and second concentration information, which is time-series data obtained by measuring the concentration of the predetermined gas component contained in the gas using a second gas sensor; and a correction step of correcting a time lag of the first concentration information or the second concentration information relative to the flow rate information based on the time difference.