System for measuring amount of consumed hydrogen

Abstract

Provided is a measurement system with which it is possible to precisely derive the amount of consumed hydrogen in a fuel cell without modifying a vehicle, etc., even when there is a possibility that leaked hydrogen is included in exhaust gas from the fuel cell or from a hydrogen engine. Provided is a system for measuring the amount of consumed hydrogen in a body under test, which is a moving body that is provided with a hydrogen reactor for chemically reacting hydrogen and that uses energy obtained through the chemical reaction, or which is a component of the moving body, the system for measuring the amount of consumed hydrogen comprising: an oxygen concentration sensor that measures the concentration of oxygen included in exhaust gas from the body under test; an oxidation catalyst disposed between the hydrogen reactor and the oxygen concentration sensor, the oxidation catalyst oxidizing hydrogen contained in the exhaust gas by using oxygen included in the exhaust gas; and a hydrogen consumption amount calculation unit that calculates the amount of consumed hydrogen on the basis of the oxygen concentration measured by the oxygen concentration sensor.

Description

Hydrogen Consumption Measurement System

[0001] The present invention relates to a hydrogen consumption measurement system for a fuel cell or the like.

[0002] As described in Non-Patent Document 1, fuel economy testing methods for fuel cell vehicles (hereinafter also referred to as fuel cell vehicles) include the mass method, pressure method, and flow method, as specified in the international standard ISO23828. However, all of these methods involve supplying hydrogen from outside the vehicle, and require vehicle modification to insert a hydrogen supply line that supplies hydrogen from outside the vehicle into the hydrogen supply line of the fuel cell vehicle. Meanwhile, the importance of finished vehicle inspections is increasing both domestically and internationally, and there is a demand for the establishment of a fuel economy testing method that does not require vehicle modification.

[0003] Therefore, the oxygen balance method has been proposed as a system for measuring the hydrogen consumption of a fuel cell without modifying the vehicle, as described in Non-Patent Documents 1 and 2. This oxygen balance method calculates the hydrogen consumption of a fuel cell by using an oxygen concentration sensor to measure the change in the oxygen concentration taken in by the fuel cell for the electrochemical reaction of hydrogen and the oxygen concentration contained in the exhaust gas emitted from the fuel cell after the reaction.

[0004] "Development of a fuel cell vehicle fuel economy test method that does not require vehicle modification - Investigation of issues with the oxygen balance method using a CVS", Masaru Yano, Takuya Shimosaka, Shigeyuki Ishidoya, JARI Research Journal 20200401; "Development of a fuel cell vehicle fuel economy test method that does not require vehicle modification - Verification experiment of the oxygen balance method", Masaru Yano, Eiji Kuroda, Automotive Research, Vol. 30, No. 7 (July 2008)

[0005] Focusing on the behavior of a fuel cell during the reaction, the hydrogen concentration stored on the anode side decreases as hydrogen is consumed as the fuel cell generates electricity. Therefore, in order to maintain a constant hydrogen concentration on the anode side, fuel cells periodically release all remaining gas on the anode side through an outlet and introduce new hydrogen into the fuel cell. This process is called purging. Furthermore, the phenomenon in which hydrogen permeates the membrane from the anode wall and moves toward the cathode side, resulting in the release of unreacted hydrogen from the fuel cell, is called cross leak. To calculate the hydrogen consumption of a fuel cell, it is necessary to calculate the hydrogen consumption amount, including not only the amount of hydrogen directly consumed in the electrochemical reaction, but also the amount of hydrogen leaked due to purging and cross leak.

[0006] However, the above-mentioned oxygen balance method cannot calculate the hydrogen consumption amount, including the amount of hydrogen leakage due to the above-mentioned purging, etc., solely from the oxygen concentration measurement by the oxygen concentration sensor. For this reason, Non-Patent Documents 1 and 2 describe a means for directly measuring the amount of hydrogen leakage using a separately provided hydrogen concentration sensor as a method for measuring the hydrogen consumption amount, including the amount of hydrogen leakage, using the oxygen balance method.

[0007] Non-Patent Document 1 states that, as mentioned above, a separate hydrogen concentration sensor is installed and hydrogen consumption is measured by the oxygen balance method, but the measurement error exceeds the target value, and therefore it is necessary to clarify the cause of the error and proceed with improvements. Furthermore, if improvement in measurement accuracy is required in measuring hydrogen consumption using a hydrogen concentration sensor, it is thought that a high-precision hydrogen concentration sensor will be required.

[0008] Non-Patent Document 2 lists an oxygen concentration sensor that uses the magnetic pressure method (hereinafter also referred to as a magnetic pressure oxygen concentration sensor) as an oxygen concentration sensor used in the oxygen balance method. The magnetic pressure method is a technique that uses the magnetic properties of oxygen (specifically, magnetic susceptibility) to convert the magnetic susceptibility of a target gas compared with an auxiliary gas (a type of reference gas) whose oxygen concentration is known, into an oxygen concentration.

[0009] The main objective of the present invention is to provide a measurement system that can accurately calculate the total amount of hydrogen consumed by a hydrogen reactor, such as a fuel cell, without the need to install a separate hydrogen concentration sensor or modify the vehicle, even when there is a possibility that the exhaust gas from the hydrogen reactor may contain leaked hydrogen due to purging or the like.

[0010] In other words, the hydrogen consumption measurement system of the present invention is a system that includes a hydrogen reactor that chemically reacts hydrogen and measures the hydrogen consumption in a test specimen that is a mobile body or part thereof that utilizes the energy obtained by the chemical reaction, and is characterized by including an oxygen concentration sensor that measures the oxygen concentration contained in the exhaust gas from the test specimen, an oxidation catalyst that is positioned between the hydrogen reactor and the oxygen concentration sensor and oxidizes the hydrogen contained in the exhaust gas with the oxygen contained in the exhaust gas, and a hydrogen consumption calculation unit that calculates the hydrogen consumption based on the oxygen concentration measured by the oxygen concentration sensor.

[0011] This hydrogen consumption measurement system is equipped with an oxidation catalyst that oxidizes hydrogen contained in exhaust gas with oxygen contained in the exhaust gas, so even if leaked hydrogen is contained in the exhaust gas, this leaked hydrogen can be oxidized by the oxygen contained in the exhaust gas. As a result, the total amount of hydrogen consumed by the fuel cell, including leaked hydrogen, can be accurately calculated without using a separate hydrogen concentration sensor to measure the amount of leaked hydrogen in order to improve errors in the oxygen balance method, as in the past.

[0012] A hydrogen consumption measurement system configured as shown in FIG. 1 can calculate the hydrogen consumption in a hydrogen reactor as follows. First, in the configuration of FIG. 1, the piping between the oxidation catalyst and the oxygen concentration sensor is disconnected and opened, for example, to introduce air into the exhaust gas flow path, and the oxygen concentration (A) in the air is measured by the oxygen concentration sensor. Next, the hydrogen consumption measurement system is returned to the configuration of FIG. 1, and the exhaust gas from the hydrogen reactor is guided to the oxygen concentration sensor without passing through the oxidation catalyst, for example, by removing the oxidation catalyst from the exhaust gas flow path. The oxygen concentration (B) in the exhaust gas is measured by the oxygen concentration sensor. Furthermore, in the hydrogen consumption measurement system returned to the configuration of FIG. 1, the oxygen concentration (C) in the exhaust gas that has passed through the oxidation catalyst and been guided to the oxygen concentration sensor is measured. By applying the oxygen concentrations (A), (B), and (C) calculated in this way to the following equations, the amount of hydrogen consumed as fuel in a fuel cell that does not contain leaked hydrogen, the total amount of hydrogen consumed including leaked hydrogen, and the oxygen concentration difference corresponding to the amount of leaked hydrogen can be calculated. (Oxygen concentration equivalent to the amount of hydrogen excluding leaked hydrogen) = A - B (Oxygen concentration equivalent to the total amount of hydrogen including leaked hydrogen) = A - C (Oxygen concentration equivalent to the amount of leaked hydrogen) = (A - C) - (A - B)

[0013] As mentioned above, by using the oxidation catalyst, leaked hydrogen present in the sample gas can be converted into water through an oxidation reaction, and the amount of leaked hydrogen can be determined by knowing the amount of oxygen that has decreased before and after passing through the oxidation catalyst (the amount that has reacted with the leaked hydrogen through oxidation reaction).

[0014] Since the oxygen balance method requires measuring minute changes in oxygen concentration, when a magnetic pressure oxygen concentration sensor or the like is used as the oxygen concentration sensor, a standard gas is usually used as the auxiliary gas. However, even when air or the like is used as the auxiliary gas, if the difference between the oxygen concentration in the exhaust gas and the oxygen concentration in the auxiliary gas is calculated and the flow rate of the gas flowing into the oxygen concentration sensor is known, the amount of oxygen consumed in the hydrogen reactor can be accurately calculated by multiplying these values. Therefore, for example, in the case of Figure 1, the hydrogen consumption measurement system can further include a flow meter that measures the flow rate of gas flowing through the exhaust gas flow path.

[0015] The hydrogen consumption measurement system may further include a dilution mechanism that dilutes the exhaust gas with a dilution gas to produce a measurement gas and supplies the measurement gas to the oxygen concentration sensor, and a reference gas flow path that introduces the dilution gas as a reference gas to the oxygen concentration sensor. For example, it is preferable to use a magnetic pressure type oxygen concentration sensor.

[0016] To measure hydrogen consumption with higher accuracy, it is preferable that the dilution mechanism includes a sampling bag for collecting the dilution gas, and the reference gas flow path introduces the reference gas from the sampling bag into the oxygen concentration sensor. This configuration can more stabilize the oxygen concentration contained in the reference gas, for example, when air is used as the dilution gas. This configuration is particularly preferable when a magnetic pressure type oxygen concentration sensor is used.

[0017] In order to minimize the effect on oxygen concentration measurement of moisture generated when hydrogen is oxidized by the oxidation catalyst, it is preferable to further provide a dehumidifier that is placed between the oxidation catalyst and the oxygen concentration sensor and removes moisture contained in the measurement gas obtained by diluting the exhaust gas or the measurement gas that is part of the exhaust gas.

[0018] To further improve the measurement accuracy, the oxygen concentration sensor is preferably a magnetic pressure type oxygen sensor.

[0019] It is also possible to measure the amount of hydrogen leakage from the hydrogen reactor by measuring the oxygen concentration in the exhaust gas after it has passed through an oxidation catalyst, which oxidizes the hydrogen contained in the exhaust gas discharged from the hydrogen reactor with the oxygen contained in the exhaust gas, and the oxygen concentration in the exhaust gas that has not passed through the oxidation catalyst, and comparing these oxygen concentrations.

[0020] A specific example of a configuration for calculating the amount of hydrogen leakage is one that further includes a measurement gas flow path that guides the measurement gas to the oxygen concentration sensor via the oxidation catalyst, a bypass flow path that introduces the exhaust gas to the oxygen concentration sensor without passing through the oxidation catalyst, and a switching mechanism that switches the flow path connected to the oxygen concentration sensor between the measurement gas flow path and the bypass flow path.

[0021] Another configuration for calculating the amount of leaked hydrogen is to include a second oxygen concentration sensor arranged in parallel with the oxygen concentration sensor, and the oxidation catalyst oxidizes only the exhaust gas introduced into one of the two oxygen concentration sensors. Furthermore, if moisture meters are provided before and after the oxidation catalyst, the amount of leaked hydrogen can be calculated from the change in moisture content in the exhaust gas before and after passing through the oxidation catalyst.

[0022] The oxygen concentration sensor can also be calibrated by using a measurement system that includes an oxidation catalyst disposed between the hydrogen reactor and the oxygen concentration sensor, which oxidizes the hydrogen contained in the exhaust gas with the oxygen contained in the exhaust gas, and a hydrogen addition mechanism that adds a predetermined amount of hydrogen to the measurement gas before it flows into the oxidation catalyst.

[0023] As described above, according to the present invention, the total amount of hydrogen consumed in the hydrogen reactor, including leaked hydrogen, can be accurately calculated by the oxygen balance method, which does not require vehicle modification, without measuring leaked hydrogen with a separate hydrogen concentration sensor.

[0024] FIG. 1 is an overall schematic diagram of a hydrogen consumption amount measurement system according to one embodiment of the present invention. FIG. 2 is an overall schematic diagram of a hydrogen consumption amount measurement system according to a first embodiment of the present invention. FIG. 3 is an overall schematic diagram of a hydrogen consumption amount measurement system according to a second embodiment of the present invention. FIG. 4 is an overall schematic diagram of a hydrogen consumption amount measurement system according to a third embodiment of the present invention. FIG. 5 is an overall schematic diagram of a hydrogen consumption amount measurement system according to a fourth embodiment of the present invention. FIG. 6 is a graph relating to the calibration of an oxygen concentration sensor according to the fourth embodiment of the present invention. FIG. 7 is an overall schematic diagram of a hydrogen consumption amount measurement system according to a fifth embodiment of the present invention. FIG. 8 is an overall schematic diagram of a hydrogen consumption amount measurement system according to another embodiment of the present invention.

[0025] DESCRIPTION OF SYMBOLS 100 Hydrogen consumption measurement system 100C Calibration system AIR1 Air taken in by fuel cell vehicle AIR2 Dilution gas TV Fuel cell vehicle FV Fuel cell V Opening and closing valve 1 Gas exhaust path 2 Sampling mechanism (dilution mechanism) 21 Measurement gas sampling section 211 Dilution tunnel 212 Dilution gas supply path 213 Measurement gas sampling bag 214, 214a, 214b Measurement gas flow path 216 Outside vehicle atmosphere flow path 218 Bypass flow path 22 Dilution gas sampling section 221 Dilution gas sampling bag 222 Dilution gas flow path 223 Reference gas flow path 218 Bypass flow path 3 Oxygen concentration sensor 4 Calculation section 5 Oxidation catalyst 6 Dehumidifier 7 Switching mechanism 71 First switching valve 72 Second switching valve 73 Third switching valve 74 Fourth switching valve 8 Hydrogen addition mechanism 81 Hydrogen cylinder 82 Hydrogen addition flow path 83 Addition amount control unit 831 Flow control valve 832 Valve control unit 833 Inert gas flow control valve 84 Inert gas cylinder 85 Inert gas addition flow path 9 Moisture meter 9a Pre-dehumidifier moisture meter 9b Post-dehumidifier moisture meter 10 Cylinder 11 Vibration reduction mechanism 12 Memory unit FM Flow meter

[0026] A hydrogen consumption measurement system according to a first embodiment of the present invention will be described below with reference to the drawings. Note that the same reference numerals will be used to designate components that are the same in each embodiment, and descriptions thereof will be omitted.

[0027] The hydrogen consumption measurement system 100 of this embodiment determines the hydrogen consumption of a fuel cell FV, which is a hydrogen reactor that generates electricity through an electrochemical reaction between hydrogen, which is a fuel gas supplied to the anode side, and oxygen, which is an oxidant gas supplied to the cathode side. Examples of fuel cells FV include solid polymer fuel cells, solid oxide fuel cells, and phosphoric acid fuel cells.

[0028] <Basic Configuration of Hydrogen Consumption Measurement System> Specifically, the hydrogen consumption measurement system 100 measures the hydrogen consumption of the fuel cell FV equipped in a fuel cell vehicle TV that is a test specimen, and is used, for example, in a fuel efficiency evaluation device that mounts the fuel cell vehicle TV on a dynamometer to simulate driving conditions similar to road driving, and calculates the fuel efficiency of the fuel cell vehicle from the driving distance and driving load obtained from the dynamometer and the hydrogen consumption measured by the hydrogen consumption measurement system 100. In this embodiment, a vehicle TV equipped with a fuel cell FV is used as the test specimen, but the test specimen may be a part of a vehicle equipped with a fuel cell, or the fuel cell itself.

[0029] 2, the hydrogen consumption measurement system 100 according to this embodiment includes a gas exhaust path 1 through which exhaust gas from the fuel cell FV is discharged, a sampling mechanism 2 that samples the exhaust gas from the gas exhaust path 1, an oxygen concentration sensor 3 that measures the oxygen concentration in the exhaust gas sampled by the sampling mechanism 2, and a calculation unit 4 that calculates the amount of hydrogen consumed by the fuel cell based on the measurement value from the oxygen concentration sensor 3. Note that Air 1 in the figure represents the atmosphere or the like taken in by the fuel cell vehicle.

[0030] The gas exhaust path 1 is for discharging exhaust gas from the fuel cell FV to the outside, and may be provided with a flow meter and a dehumidifier (not shown).

[0031] The sampling mechanism 2 samples the exhaust gas flowing through the gas discharge passage 1, and in this embodiment, also functions as a dilution mechanism for diluting the exhaust gas.

[0032] The sampling mechanism 2 in this embodiment is a constant volume dilution sampling system (CVS) and includes a measurement gas sampling unit 21 that dilutes and samples exhaust gas, and a diluted gas sampling unit 22 that samples only the diluted gas. The measurement gas sampling unit 21 includes, for example, a dilution tunnel 211 connected to the gas exhaust line 1, a diluted gas supply line 212 that supplies diluted gas as Air 2 to the dilution tunnel 211, a measurement gas sampling bag 213 that collects the measurement gas diluted in the dilution tunnel 211, a measurement gas flow path 214 that guides the measurement gas collected in the measurement gas sampling bag 213 to the oxygen concentration sensor 3, and a measurement gas flow rate control unit (not shown) that controls the amount of measurement gas flowing through the measurement gas flow path 214.

[0033] The diluted gas sampling unit 22 includes, for example, a diluted gas sampling bag 221 that collects the diluted gas sampled from the diluted gas supply path 212, a diluted gas flow path 222 that guides the diluted gas collected in the diluted gas sampling bag 221 to the oxygen concentration sensor 3, and a diluted gas flow control unit (not shown) that controls the amount of gas flowing through the diluted gas flow path 222. The measurement gas flow control unit and the diluted gas flow control unit each include, for example, a pump P, an on-off valve V, a flow meter FM, etc., and an operation control unit (not shown) that controls the operation of these components.

[0034] In this embodiment, the measurement gas flow path 214 and the dilution gas flow path 222 merge upstream of the oxygen concentration sensor 3, and a first switching valve 71 is provided at this junction to switch which of these flow paths is led to the oxygen concentration sensor 3.

[0035] The oxygen concentration sensor 3 measures the oxygen concentration of the measurement gas, which is the diluted exhaust gas sampled by the measurement gas sampling unit 21, the diluted gas sampled by the diluted gas sampling unit 22, and a reference gas such as the surrounding atmosphere or air supplied from a cylinder as needed.

[0036] In this specification, the term "reference gas" refers to a gas used as a reference gas for comparison with the oxygen concentration in the measurement gas measured by the oxygen concentration sensor. It is used to determine the difference from the reference oxygen concentration, and includes the auxiliary gas used in the magnetic pressure oxygen sensor described above, a calibration gas with a known oxygen concentration used for calibration, including oxygen sensors other than the magnetic pressure oxygen sensor, and a reference gas used for comparison, such as the atmosphere during measurement. If the fluctuation in the oxygen concentration of the atmosphere is small enough to be acceptable for measurement accuracy, the atmosphere can also be used as the reference gas or auxiliary gas.

[0037] In this embodiment, a magnetic pressure type oxygen sensor is used as the oxygen concentration sensor 3. The oxygen concentration sensor 3 may be a magnetic dumbbell type oxygen meter, a galvanic type oxygen meter, a zirconia oxygen meter, or the like. It is preferable that the oxygen concentration sensor 3 is calibrated before measurement using a calibration gas, which is oxygen gas with a known concentration.

[0038] The calculation unit 4 functions as a hydrogen consumption calculation unit that calculates the amount of hydrogen consumed in the fuel cell FV by the oxygen balance method based on the detection value of the oxygen concentration sensor 3. Specifically, the calculation unit 4 calculates the amount of oxygen consumed in the fuel cell FV from the difference in oxygen concentration between the measurement gas and the dilution gas output from the oxygen concentration sensor and the flow rate through the dilution tunnel 211, and then calculates the amount of hydrogen consumed from this amount of oxygen consumed.

[0039] More specifically, the reaction formula between hydrogen and oxygen is as shown in equation (1) below. The concentration of hydrogen reacted and consumed in the fuel cell is equivalent to twice the difference (ΔO2 conc.) between the oxygen concentration before the reaction (oxygen concentration in the diluted gas) and the oxygen concentration in the exhaust gas after the reaction, as shown in equation (2). The amount of hydrogen consumed can be calculated by multiplying the hydrogen concentration calculated in this way by the amount of diluted exhaust gas (V total). During this calculation process, corrections such as partial pressure correction may be made to obtain more accurate concentration values. The functions of this calculation unit 4 are performed by a computer consisting of a CPU, memory, input / output interface, AD converter, etc. 2H ２ +O ２ =2H ２ O (1) ΔH ２ｃｏｎｃ (vol%) = ΔO ２ｃｏｎｃ (vol%)×2 (2) ΔV Ｈ２ (m ３ ) = ΔH ２ｃｏｎｃ (vol%) x V ｔｏｔａｌ (m ３ ) (3) The volumes in these equations (2) and (3) are all volumes under standard conditions. ｔｏｔａｌ is the flow rate measured by a flow meter installed just before the discharge pump located downstream of the dilution tunnel 211. ｔｏｔａｌ Alternatively, a flow meter for measuring the flow rate of the exhaust gas before dilution and sampling may be provided on the gas exhaust line 1, and the flow rate may be calculated from the flow rate of the exhaust gas flowing through this gas exhaust line and the flow rate of the diluted gas supplied to the dilution tunnel.

[0040] <Characteristic Configuration of Hydrogen Consumption Measurement System> The hydrogen consumption measurement system 100 according to this embodiment is provided with an oxidation catalyst 5 that oxidizes hydrogen in the measurement gas and is disposed between the fuel cell FV and the oxygen concentration sensor 3. In this embodiment, the oxidation catalyst 5 is disposed between the first switching valve 71 and the oxygen concentration sensor 3.

[0041] The oxidation catalyst 5 oxidizes hydrogen contained in the measurement gas with oxygen contained in the measurement gas, and may be, for example, a platinum (Pt) catalyst. To remove water generated by the oxidation catalyst 5, a dehumidifier 6 is preferably disposed between the oxidation catalyst 5 and the oxygen concentration sensor 3.

[0042] Furthermore, a moisture meter 9 may be provided to measure the amount of moisture removed by the dehumidifier 6. If the amount of moisture removed by the dehumidifier 6 can be determined using the moisture meter 9, the amount of change in moisture partial pressure due to moisture removal by the dehumidifier 6 can be determined, allowing for a more accurate determination of the oxygen partial pressure measured by the oxygen concentration sensor 3. Furthermore, the amount of hydrogen oxidized by the oxidation catalyst 5, i.e., the amount of leaked hydrogen, can also be determined from this moisture amount. Note that in order to correct the oxygen concentration measurement value by the oxygen concentration sensor 3 for moisture partial pressure, it is only necessary to know the moisture partial pressure of the measurement gas introduced into the oxygen concentration sensor 3, and therefore at least one moisture meter 9 required for moisture partial pressure correction needs to be located immediately before the oxygen concentration sensor 3.

[0043] One method for determining the amount of moisture removed by the dehumidifier 6 using the moisture meter 9 is to provide moisture meters (a moisture meter 9a before the dehumidifier and a moisture meter 9b after the dehumidifier) ​​before and after the dehumidifier 6, and determine the partial pressure of the moisture reduced by removal by the dehumidifier from the difference in moisture concentration measured by these two moisture meters. If the dehumidifier is a thermoelectric cooler, one moisture meter 9a may be provided only before the dehumidifier, and the moisture concentration after the thermoelectric cooler may be calculated from the dew point corresponding to the cooling setting temperature of the thermoelectric cooler.

[0044] Furthermore, if the amount of leaked hydrogen is small and the amount of moisture generated by the oxidation catalyst is small, it is possible to provide only two dew point type moisture meters without providing the dehumidifier 6. Note that, when the amount of moisture generated by the oxidation catalyst 5 is to be accurately measured as described above, it is preferable to provide an additional dehumidifier upstream of the oxidation catalyst 5.

[0045] Furthermore, in this embodiment, a flow meter FM 3 that measures the flow rate of gas flowing into the oxygen concentration sensor 3 is provided between the dehumidifier 6 and the oxygen concentration sensor 3 .

[0046] The diluted gas sampling unit 22 further includes a reference gas flow path 223 that guides the diluted gas collected in the diluted gas sampling bag 221 as the reference gas to the oxygen concentration sensor 3. The reference gas flow path 223 is used when using an oxygen concentration sensor that requires an auxiliary gas such as a magnetic pressure oxygen sensor or a reference gas, but is not used with other sensors.

[0047] The calculation unit 4 obtains information about the load on the fuel cell, the oxygen concentration measured by the oxygen concentration sensor 3, and the flow rate of the gas flowing into the dilution tunnel 211 measured by the flow meter FM4, to determine the weight of oxygen consumed by the fuel cell FV from the oxygen concentration, and calculates the amount of consumed hydrogen based on this oxygen weight. The calculation unit 4 also obtains the moisture content from the moisture meters 9a and 9b described above to determine the amount of change in moisture partial pressure before and after the dehumidifier 6, and from this calculates the amount of moisture removed by the dehumidifier.

[0048] Effect of First Embodiment According to the hydrogen consumption measurement system 100 of this embodiment configured as described above, the leakage hydrogen discharged from the fuel cell FV is oxidized by the oxidation catalyst 5 by consuming oxygen contained in the measurement gas, so that the amount of leaked hydrogen can be reflected in the oxygen concentration measured by the oxygen concentration sensor 3. As a result, it is possible to measure the total amount of hydrogen consumed by the fuel cell FV without measuring the leakage hydrogen with a separate hydrogen concentration sensor or the like.

[0049] Furthermore, since a dehumidifier 6 is provided between the oxidation catalyst 5 and the oxygen concentration sensor 3, when a large amount of moisture is generated downstream of the oxidation catalyst, condensation in the gas flow path can be prevented and the influence of moisture on the measurement by the oxygen concentration sensor 3 can be reduced. Furthermore, since a moisture meter 9a is provided downstream of this oxidation catalyst 5, if another moisture meter (not shown) is provided upstream of the oxidation catalyst 5, the amount of leaked hydrogen can be calculated by the calculation unit 4 from the change in the amount of moisture measured by the moisture meter 9a before and after passing through the oxidation catalyst 5.

[0050] The diluted gas collected in the diluted gas sampling bag 221 provided in the constant volume dilution sampling device, which is the sampling mechanism 2, is used as the auxiliary gas for the magnetic pressure oxygen sensor, thereby improving the measurement accuracy of the oxygen concentration sensor 3 compared to conventional methods. This is thought to be because, compared to using the ambient air as the auxiliary gas, the influence of fluctuations in the oxygen concentration in the atmosphere on the measurement value can be minimized, and because the diluted gas that dilutes the measurement gas can be used as the auxiliary gas, drift in the measurement value due to differences in base gas can be suppressed.

[0051] Furthermore, since a magnetic pressure type oxygen concentration sensor is used as the oxygen concentration sensor 3, it is possible to measure the total amount of hydrogen consumed in the fuel cell FV with higher accuracy. Because leaked hydrogen contained in the exhaust gas is oxidized and removed by the oxidation catalyst, the effect of the magnetic susceptibility of hydrogen on oxygen concentration measurement can be reduced, further improving the accuracy of oxygen concentration measurement using a magnetic pressure type oxygen concentration sensor.

[0052] Second Embodiment Next, a hydrogen consumption amount measuring system according to a second embodiment will be described.

[0053] The hydrogen consumption amount measurement system 100A of the second embodiment functions as a hydrogen leakage amount measurement system that calculates not only the total amount of hydrogen consumption but also the amount of hydrogen leakage described above.

[0054] Specifically, as shown in Fig. 3, the hydrogen consumption measurement system 100A includes, in addition to the configuration of the above-described embodiment, a bypass flow path 218 that guides the measurement gas to the oxygen concentration sensor 3 without passing through the oxidation catalyst 5, and a switching mechanism 7 that switches the flow path connected to the oxygen concentration sensor 3 between the measurement gas flow path 214 and the bypass flow path 218. The switching mechanism 7 includes, for example, a second switching valve 72 such as a three-way valve, and a switching control unit (not shown) that controls the operation of the second switching valve 72. The functions of this switching control unit are fulfilled by a computer including a CPU, memory, an input / output interface, an AD converter, etc., and may also control the first switching valve described above.

[0055] The switching mechanism 7 allows an arbitrary amount of the measurement gas sampled in the same measurement gas sampling bag 213 to flow into the measurement gas flow path 214, and the oxygen concentration is measured taking into account the amount of leaked hydrogen. Next, the remaining measurement gas is diverted to flow into the bypass flow path 218, making it possible to measure the oxygen concentration without taking into account the amount of leaked hydrogen.

[0056] The calculation unit 4 calculates the amount of hydrogen leakage based on the oxygen concentration in the measurement gas that has passed through the oxidation catalyst 5 and the oxygen concentration in the measurement gas that has not passed through the oxidation catalyst 5. In this case, the calculation unit 4 can be said to function as a hydrogen leakage amount calculation unit.

[0057] Effect of Second Embodiment With the hydrogen consumption measurement system 100A of this embodiment configured as described above, the flow rate connected to the oxygen concentration sensor 3 can be switched between the measurement gas flow path 214 and the bypass flow path 218, thereby making it possible to measure the difference in oxygen concentration between the measurement gas that has passed through the oxidation catalyst 5 and the measurement gas that has not passed through the oxidation catalyst 5. From this difference in oxygen concentration, the amount of leaked hydrogen can be calculated using the above-mentioned equations (1), (2), and (3).

[0058] Third Embodiment Next, a hydrogen consumption measurement system according to a third embodiment will be described. The hydrogen consumption measurement system 100B according to the third embodiment not only calculates the total amount of hydrogen consumption, as in the second embodiment, but also functions as a hydrogen leakage measurement system that calculates the amount of hydrogen leakage described above.

[0059] Specifically, as shown in FIG. 4 , the hydrogen consumption measurement system 100B includes an additional oxygen concentration sensor 3 in addition to the configuration of the first embodiment. The measurement gas flow path 214 is branched into two paths upstream of the oxidation catalyst 5, with the measurement gas flow path 214a, which passes through the oxidation catalyst 5, connected to one oxygen concentration sensor 3a, and the measurement gas flow path (without catalyst or dehumidifier) ​​214b, which does not pass through the oxidation catalyst 5, connected to the other oxygen concentration sensor 3b. The calculation unit 4 calculates the hydrogen leakage amount based on the oxygen concentration in the measurement gas that has passed through the oxidation catalyst 5 and the oxygen concentration in the measurement gas that has not passed through the oxidation catalyst 5, which are measured in this manner. In this case, the calculation unit 4 can be said to function as a hydrogen leakage amount calculation unit. If a significant difference is observed in the sensitivity of the two oxygen sensors, the hydrogen leakage amount may be calculated using the sensitivity ratio α of the other oxygen concentration sensor 3b to the one oxygen concentration sensor 3a, using equation (4) and the aforementioned equation (3). ΔH ２ｃｏｎｃ． (Leak concentration vol%) = 2ΔO ２ｃｏｎｃ． (Concentration value of 3a vol%) × α-2ΔO ２ｃｏｎｃ． (3b concentration value vol%) (4) ΔV Ｈ２（ m ３ ) = ΔH ２ｃｏｎｃ． (vol%) x V ｔｏｔａｌ (m ３ ) (3) However, if there is no significant difference in sensitivity between the two oxygen concentration sensors, α can be considered to be 1.

[0060] Effect of Third Embodiment In addition to the effects of the two previous embodiments, the hydrogen consumption measurement system 100B of this embodiment configured as described above can simultaneously measure the measurement gas that has passed through the oxidation catalyst 5 and the measurement gas that has not passed through the oxidation catalyst 5. Furthermore, in this embodiment, moisture meters 9b and 9c are provided immediately before the two oxygen concentration sensors 3a and 3b, respectively. Therefore, by using the moisture partial pressures measured by these two moisture meters 9b and 9c, the moisture partial pressures of the two oxygen concentration sensors 3a and 3b can be corrected, and the amount of hydrogen leakage can be determined more accurately.

[0061] Fourth Embodiment Next, a hydrogen consumption measurement system 100C (calibration system 100C) according to a fourth embodiment will be described. The calibration system 100C according to the fourth embodiment calibrates the oxygen concentration sensor 3 used in the above-described embodiments.

[0062] Specifically, as shown in FIG. 5, the calibration system 100C further includes a hydrogen addition mechanism 8 that adds a predetermined amount of hydrogen to the measurement gas flowing through the measurement gas flow path 214 described above.

[0063] The hydrogen addition mechanism 8 includes a hydrogen cylinder 81 containing hydrogen of a known concentration, a hydrogen addition flow path 82 connecting the hydrogen cylinder 81 to the measurement gas flow path 214 and adding hydrogen supplied from the hydrogen cylinder 81 to the measurement gas flow path 214 upstream of the oxidation catalyst 5, and an addition amount control unit 83 controlling the flow rate of hydrogen flowing through the hydrogen addition flow path 82. A fourth switching valve 74 may be further provided at the junction of the measurement gas flow path 214 and the hydrogen addition flow path 82. The addition amount control unit 83 includes, for example, a flow control valve 831 and a valve control unit 832 controlling the aperture of the flow control valve 831. The function of the valve control unit 832 is realized by a computer including a CPU, memory, an input / output interface, an AD converter, etc. By varying the amount of hydrogen supplied from the hydrogen cylinder 81 while maintaining a constant flow rate of the measurement gas supplied to the oxygen concentration sensor 3, the hydrogen concentration in the gas measured by the oxygen concentration sensor 3 can be changed in stages.

[0064] When it is desired to add a very small amount of hydrogen using the hydrogen addition mechanism 8, the hydrogen may be diluted with an inert gas (e.g., nitrogen gas) that does not affect the oxygen concentration measurement before being added. In this case, as shown in Fig. 5, a dilution inert gas cylinder 84 containing an inert gas for dilution, an inert gas addition flow path 85 connecting the inert gas cylinder 84 to the hydrogen addition flow path 82, and an inert gas flow control valve 833 on the inert gas addition flow path 85 for controlling the flow rate of the inert gas flowing through the inert gas addition flow path 85 may be further provided. The inert gas flow control valve 833 may be controlled by the valve control unit 832 described above, or may be provided with an independent inert gas valve control unit.

[0065] Effect of Fourth Embodiment The calibration system 100C of this embodiment configured as described above measures the oxygen concentration with the oxygen concentration sensor 3 while gradually increasing or decreasing the amount of hydrogen added to the measurement gas flow path 214 by the addition amount control unit 83. By using this procedure, the difference in oxygen concentration between the calibration atmosphere, in which oxygen has been consumed by the oxidation catalyst 5 and the oxygen concentration has been intentionally reduced, and the air used as the reference gas is measured while gradually changing the amount of hydrogen added, thereby calibrating the linearity of the measurement results by the oxygen concentration sensor 3 near the oxygen concentration in the air.

[0066] Specifically, for example, the calculation unit 4 predicts the change in oxygen concentration to be measured by the oxygen concentration sensor 3 based on the amount of hydrogen added by the hydrogen addition mechanism 8, and creates a calibration curve using this concentration and the change in oxygen concentration actually measured by the oxygen concentration sensor 3 to obtain a slope β from the calibration curve. This slope β can be used as a sensitivity coefficient of the oxygen concentration sensor 3 to correct the measurement results from the oxygen concentration sensor 3. As a result, the accuracy of measuring the hydrogen consumption rate of the fuel cell using the oxygen concentration sensor 3 can be further improved. A specific example of the calibration method according to this embodiment is one in which the amount of added hydrogen is changed in steps as shown in Table 1 to obtain a calibration curve such as that shown in FIG. 6. It is desirable to have two or more steps for changing the amount of added hydrogen to obtain a calibration curve.

[0067] The method for calculating the change in oxygen concentration predicted from the amount of hydrogen added is expressed by the following formula (5) taking into consideration the flow rate L1 flowing through the measurement gas flow path 214, the flow rate L2 flowing through the hydrogen addition flow path 82, the flow rate L3 flowing through the inert gas addition flow path 85, the hydrogen purity γ [vol%] written on the hydrogen cylinder, and formula (1). Ｏ２ (Change in oxygen concentration predicted from the amount of added hydrogen [g / cm 3 ]) = 1 / 2×(γ / 100)×(L2 / (L1+L2+L3)) (5)

[0068]

[0069] Fifth Embodiment Next, a hydrogen consumption measurement system according to a fifth embodiment will be described. The hydrogen consumption measurement system 100D according to the fifth embodiment does not use an exhaust gas dilution mechanism, and functions as a hydrogen leakage measurement system that calculates not only the total amount of hydrogen consumption but also the amount of hydrogen leakage described above.

[0070] As shown in FIG. 7 , when a dilution mechanism is not used, the measurement gas flowing through a measurement gas flow path 214 branched from the gas exhaust path 1 may be directly measured by an oxygen concentration sensor 3. In the example shown in FIG. 7 , two oxygen concentration sensors 3 are provided, along with two measurement gas flow paths 214 and 215 connecting the oxygen concentration sensors 3a and 3b to the gas exhaust path 1, respectively. One of the two measurement gas flow paths 214 and 215, the measurement gas flow path 214, is provided with an oxidation catalyst 5, a moisture meter 9a, a dehumidifier 6, and another moisture meter 9b. The other measurement gas flow path 215 is provided with a moisture meter 9c and a flow meter FM. The reference gas for the two oxygen concentration sensors 3a and 3b may be atmospheric air, or, as shown in FIG. 7 , a cylinder 10 filled with air may be used. In the example shown in FIG. 7 , it is preferable to connect the reference gas flow paths of the two oxygen concentration sensors 3a and 3b to a single cylinder 10. According to the hydrogen consumption amount measurement system shown in FIG. 7, the hydrogen consumption amount can be calculated, for example, as follows.

[0071] First, a case where the oxygen concentration of the reference gas contained in the cylinder 10 in Fig. 7 is known will be described. In this case, since a reference gas with a known oxygen concentration is used, the oxygen concentration value (instantaneous value) indicated by each oxygen concentration sensor is a value that is as reliable as the oxygen concentration of the reference gas.

[0072] The relationship between the oxygen concentration O2(conc3b) obtained by the oxygen concentration sensor 3b, the oxygen concentration O2(conc.Air) in the atmosphere, and the change in oxygen concentration ΔO2(FV) consumed by the test specimen FV in the chemical reaction during power generation can be expressed as the following equation (6): O2(conc3b) = O2(conc.Air) - ΔO2(FV) (6)

[0073] The relationship between the oxygen concentration obtained by the oxygen concentration sensor 3a, the atmospheric oxygen concentration O2(conc. Air), the change ΔO2(FV), and the amount of oxygen consumed by reaction with leaked hydrogen in the test specimen FV ΔO2(leak) can be expressed as the following equation (7): O2(conc. 3a) = O2(conc. Air) - ΔO2(FV) - ΔO2(leak) (7)

[0074] By subtracting equation (7) from equation (6), ΔO2(leak) can be calculated as follows: O2(conc3b) - O2(conc3a) = ΔO2(leak) (8)

[0075] Furthermore, when a correction coefficient α is used to correct the sensitivity of each of the oxygen concentration sensors 3a and 3b, the above formula (8) becomes the following formula: O2(conc3b) × α − O2(conc3a) = ΔO2(leak) (9)

[0076] Next, a case will be described in which the oxygen concentration of the reference gas contained in the cylinder 10 in Fig. 7 is unknown. In this case, the oxygen concentration values ​​(displayed values) measured and displayed by the oxygen concentration sensors 3a and 3b are relative concentration information compared with the reference gas (here, the oxygen concentration of the reference gas is denoted as X) having an unknown oxygen concentration. However, for example, according to the procedure described below, the amount of hydrogen consumed and the amount of leaked hydrogen in the specimen FV can be calculated based on the displayed values ​​of the oxygen concentration sensors 3a and 3b.

[0077] The oxygen concentration display value (Display) of each oxygen concentration sensor can be expressed as the following equations (10) and (11): (Display_3a) = X - (O2(conc.Air) - ΔO2(FV) - ΔO2(leak)) (10) (Display 3b) = X - (O2(conc.Air) - ΔO2(FV)) (11)

[0078] Therefore, by subtracting the displayed values ​​of these oxygen concentration sensors 3a and 3b as calculated in the above equation (8) or equation (9), the unknown concentration term of the reference gas can be canceled, and the amount of oxygen ΔO2(leak) consumed by reacting with the leaked hydrogen in the test specimen FV can be obtained.

[0079] Specifically, the display values ​​of the oxygen concentration sensors 3a and 3b are subtracted. That is, equation (10) is subtracted from equation (11) to obtain equation (12). (Display 3b) - (Display 3a) = ΔO2(leak) (12)

[0080] As shown in this equation (12), even if the absolute value of the oxygen concentration measured by each oxygen concentration sensor 3a 3b is unknown, the amount of oxygen ΔO2(leak) consumed by reacting with leaked hydrogen in the test specimen FV can be calculated.

[0081] The above formula (9) or formula (12) is used to find the instantaneous value of the oxygen concentration corresponding to the amount of hydrogen leaked in the test specimen FV.

[0082] 7, if the change in the oxygen concentration in the atmosphere over time during the test of the FV under test is considered to be negligible, the oxygen concentration O2(conc. Air) of the atmosphere may be measured in advance. For example, while the FV under test is stopped, air may be drawn in backward from the outlet of the exhaust pipe 1 and measured by the oxygen concentration sensor 3b.

[0083] If it is desired to simultaneously measure the oxygen concentration of the atmosphere during the test of the specimen FV, a third oxygen concentration sensor 3c (not shown) may be provided. When the oxygen concentration sensor 3c (not shown) is provided and atmospheric gas with an unknown oxygen concentration is used as the reference gas, the displayed value of the oxygen concentration measured by the oxygen concentration sensor 3c can be expressed by the following equation (13): (Display 3c) = X - O2(conc.Air) (13)

[0084] By subtracting equation (11) from equation (13), the terms for concentration X and O2(conc. Air) can be eliminated, just like equation (12), and the oxygen concentration consumed in the chemical reaction in the specimen FV can be calculated using equation (14) below: (Display 3c) - (Display 3b) = ΔO2(FV) (14)

[0085] So far we have described how to calculate the instantaneous value of oxygen concentration, but when using the configuration of Figure 7, the total amount of hydrogen consumption can be calculated as follows. The instantaneous concentration values ​​of ΔO2(FV) and ΔO2(leak) at a certain time t are set as ΔO2(FV)_t [vol%] and ΔO2(leak)_t [vol%], respectively. The instantaneous exhaust volume V_t [m 3 ] (instantaneous value of flow meter FM8), the total amount of oxygen consumed during the test time T from 0 to t can be expressed by the following equation (15).

[0086] The total amount of oxygen reacted in the specimen FV, including the oxygen reacted with leaked hydrogen, calculated as above, O2total (m 3 ) into equation (2), the total amount of hydrogen consumed, including leaked hydrogen, during the test time T from 0 to t can be calculated. It goes without saying that it is also possible to calculate only the amount of leaked hydrogen by performing integration in a similar manner. In the method of calculating hydrogen consumption described above, the moisture meter 9b and flow meter FM6 provided in the dehumidifier 6 and oxygen concentration sensor 3a in FIG. 7 are not necessarily required components and may be omitted.

[0087] Effect of Fifth Embodiment With the hydrogen consumption measurement system 100D of this embodiment configured as described above, leaked hydrogen discharged from the fuel cell FV is oxidized by the oxidation catalyst 5 by consuming oxygen contained in the measurement gas, so that the amount of leaked hydrogen can be reflected in the instantaneous value of the oxygen concentration measured by the oxygen concentration sensor 3. As a result, it is possible to measure the instantaneous value of the hydrogen consumption rate in the fuel cell FV without measuring the leaked hydrogen with a separate hydrogen concentration sensor or the like. Furthermore, since the hydrogen consumption measurement system 100D of this embodiment does not use a dilution mechanism, it is possible to measure the instantaneous value of the difference in oxygen concentration between the measurement gas that has passed through the oxidation catalyst 5 and the measurement gas that has not passed through the oxidation catalyst 5.

[0088] Other Embodiments The hydrogen consumption measurement system according to the present invention may be an on-board system that measures the hydrogen consumption of a fuel cell vehicle while it is traveling on the road. In this case, for example, as shown in FIG. 8 , three oxygen sensors may be provided. Two of these three oxygen concentration sensors may be connected to the gas exhaust passage 1, as in the fifth embodiment, to directly measure the instantaneous value of the oxygen concentration of exhaust gas sampled from the vehicle exhaust pipe and the instantaneous value of the oxygen concentration including the leaked hydrogen concentration. Furthermore, the remaining oxygen concentration sensor may be connected to the outside-vehicle air flow passage 216 through which the outside-vehicle air Air1 flows, to measure the oxygen concentration of the outside-vehicle air simultaneously with the measurements by the two oxygen concentration sensors. The instantaneous value of the hydrogen consumption rate and the amount of leaked hydrogen may be calculated from these three oxygen concentrations.

[0089] In the case of an on-board oxygen concentration sensor, if the measured value of the oxygen concentration sensor is affected by vibrations of the vehicle, a vibration reduction mechanism 11 such as a vibration isolation table that reduces vibrations from the vehicle may be further provided. Also, a memory unit that stores information on the temperature, humidity, atmospheric pressure, vehicle speed, or mileage outside the vehicle may be further provided.

[0090] It is also possible to calculate fuel efficiency using the hydrogen consumption amount obtained in the present invention and the distance traveled by the vehicle. The fuel efficiency can be calculated, for example, using the following formula: (Distance traveled by the vehicle [km]) / (Amount of hydrogen consumed [kg]) = Fuel efficiency [km / kg]

[0091] When using magnetic oxygen concentration sensors as oxygen concentration sensors in an on-board hydrogen consumption measurement system such as that shown in Figure 8, it is not necessary to provide three oxygen concentration sensors as described above. For example, if air is used as an auxiliary gas for the magnetic oxygen concentration sensor, it is possible to determine the hydrogen consumption of the test specimen with only one oxygen concentration sensor. Providing two magnetic oxygen concentration sensors is preferable because it also makes it possible to determine the amount of hydrogen leakage.

[0092] In the above-described embodiment, the calculation unit provided in the hydrogen consumption measurement system calculates the hydrogen consumption amount and hydrogen leak amount, but this is not limited to this. For example, a person may calculate the hydrogen consumption amount, hydrogen leak amount, etc. based on measurement values ​​obtained from an oxygen concentration sensor, etc.

[0093] The accuracy of oxygen concentration measurement can be further improved by obtaining a stable concentration signal from multiple concentration signal data acquired at regular time intervals using noise processing or by obtaining a moving average of the concentration signal, thereby obtaining a concentration value with little time fluctuation. Examples of noise processing include calculating the average of multiple acquired concentration signal data and, in the process of obtaining the average as the concentration value, excluding concentration signals that deviate from the average by more than a predetermined percentage from the calculation, and using the average of the remaining concentration signal data as the concentration value. In particular, in the cases of the first to fourth embodiments described above, the diluted gas collected in the diluted gas sampling bag provided in the constant-volume dilution sampling device is used, and combining this with the above-described noise processing can sufficiently stabilize the concentration signal output from the oxygen concentration sensor. On the other hand, for example, the method of the fifth embodiment is primarily intended to obtain a concentration value with good responsiveness in real time. Therefore, although the above-described noise processing or smoothing of the concentration signal data using a moving average may be performed, this is not a required step.

[0094] The calibration of the oxygen concentration sensor may be performed within a specific oxygen concentration range, or within a range from a completely oxygen-free state to an oxygen concentration equivalent to that of atmospheric air. More specifically, when a fixed-volume dilution sampling device is provided to narrow the oxygen concentration range measured by the oxygen concentration sensor to a certain extent, as in the first to fourth embodiments, the oxygen concentration range may be set to 18 to 21%, for example, for calibration. Furthermore, when exhaust gas from a fuel cell is directly supplied, as in the fifth embodiment, the oxygen concentration is expected to fluctuate significantly, so the oxygen concentration may be set to 0 to 21% for calibration. Note that the resolution of the concentration value displayed by the oxygen concentration sensor increases as the concentration range narrows, so it is preferable to set the oxygen concentration range for calibration as narrow as possible.

[0095] It should be noted that, while the methods according to the first to fourth embodiments dilute the sample gas, the method according to the fifth embodiment does not. Due to these differences in configuration, the amount of change in oxygen concentration and the measurement range differ depending on the dilution ratio in each of these methods. Therefore, depending on which method is used, the measurement range of the oxygen concentration sensor and the displayed value of the oxygen concentration must be adjusted appropriately. In this regard, for example, by using an oxygen concentration sensor that has the ability to automatically adjust the measurement range, it is possible to use a single oxygen concentration sensor as a hydrogen consumption measurement system compatible with both the methods according to the first to fourth embodiments and the method according to the fifth embodiment.

[0096] In addition, one of the main effects of the present invention is that the air or a dilution gas can be used as a reference gas in the oxygen balance method, without using a standard gas that has traditionally been considered essential, and an oxidation catalyst is not necessarily an essential component to achieve this effect.

[0097] In the above embodiments, the test specimen is described as a fuel cell-equipped automobile. However, the test specimen may be, for example, another type of vehicle or ship, such as a train equipped with a fuel cell, or a part of such a vehicle or ship, or the fuel cell itself. Furthermore, the test specimen is not limited to a vehicle equipped with a fuel cell. It may be a hydrogen engine vehicle or part thereof equipped with a hydrogen engine as a hydrogen reactor, or the hydrogen engine itself. Like fuel cells, hydrogen engines use hydrogen as fuel and are powered by the energy generated by a combustion reaction with oxygen in the atmosphere. Therefore, hydrogen consumption can be determined using the oxygen balance method. Furthermore, in hydrogen engines, not all of the hydrogen introduced for combustion reacts with oxygen within the engine. Some hydrogen remains unreacted after the combustion process and is discharged from the engine as exhaust. This unreacted hydrogen can cause errors in the total hydrogen consumption measured using the oxygen balance method, similar to the problem with fuel cells.

[0098] To further improve the accuracy of hydrogen consumption measurement using a hydrogen reactor, it is better to also consider the reaction between hydrocarbons in the atmosphere and oxygen in the oxidation catalyst. For example, by measuring the total hydrocarbon (THC) concentration in the atmosphere and calculating the concentration of oxygen consumed by the reaction with the hydrocarbons, and using this calculation result when calculating the hydrogen consumption, the hydrogen consumption in the hydrogen reactor can be determined more accurately. Furthermore, since oxygen consumption may occur due to the generation of thermal NOx in hydrogen engines, the hydrogen consumption in a hydrogen engine can be calculated more accurately by measuring NOx in the exhaust gas and correcting the oxygen consumption. Various modifications and combinations of the embodiments may be made as long as they do not deviate from the spirit of the present invention.

[0099] According to the present invention, even if there is a possibility that the exhaust gas from a hydrogen reactor such as a fuel cell may contain leaked hydrogen due to purging or the like, the total amount of hydrogen consumed by the hydrogen reactor can be accurately calculated without installing a separate hydrogen concentration sensor or modifying the vehicle.

Claims

1. A system for measuring hydrogen consumption in a test specimen that is a moving object or a part thereof, the system comprising: a hydrogen reactor that chemically reacts hydrogen; and a moving object that utilizes energy obtained by the chemical reaction, the system comprising: an oxygen concentration sensor for measuring an oxygen concentration contained in exhaust gas from the test specimen; an oxidation catalyst disposed between the hydrogen reactor and the oxygen concentration sensor, which oxidizes hydrogen contained in the exhaust gas with oxygen contained in the exhaust gas; and a hydrogen consumption calculation unit that calculates a hydrogen consumption amount based on the oxygen concentration measured by the oxygen concentration sensor.

2. The exhaust gas from the test specimen is introduced into the oxygen concentration sensor as a measurement gas, with or without dilution, The hydrogen consumption measurement system further includes a flow meter for measuring a flow rate of the exhaust gas after dilution or before dilution, The hydrogen consumption measurement system of claim 1, wherein the hydrogen consumption calculation unit calculates the amount of hydrogen consumed that has reacted with oxygen based on the difference between the oxygen concentration in the measurement gas measured by the oxygen concentration sensor and the oxygen concentration in a reference gas used for comparison, and the flow rate of the exhaust gas measured by the flow meter.

3. 3. The hydrogen consumption measurement system according to claim 1, further comprising a dehumidifier disposed between the oxidation catalyst and the oxygen concentration sensor for removing moisture contained in the measurement gas.

4. 4. The hydrogen consumption measurement system according to claim 3, further comprising a moisture meter for measuring a moisture concentration of the measurement gas introduced into the oxygen concentration sensor, and performing moisture partial pressure correction based on the moisture concentration measured by the moisture meter.

5. the hydrogen reactor is a fuel cell or a hydrogen engine; 5. The hydrogen consumption measurement system according to claim 1, wherein the oxygen concentration sensor is a magnetic pressure type oxygen sensor.

6. a second oxygen concentration sensor arranged in parallel with the oxygen concentration sensor; 6. The hydrogen consumption measurement system according to claim 1, wherein the oxidation catalyst oxidizes only the exhaust gas introduced into one of the two oxygen concentration sensors.

7. a measurement gas flow path that guides the exhaust gas to the oxygen concentration sensor via the oxidation catalyst; a bypass flow path that introduces the exhaust gas into the oxygen concentration sensor without passing through the oxidation catalyst; 7. The hydrogen consumption measurement system according to claim 1, further comprising a switching mechanism that switches a flow path connected to the oxygen concentration sensor between the measurement gas flow path and the bypass flow path.

8. a dilution mechanism that dilutes the exhaust gas with a dilution gas and supplies the diluted exhaust gas to the oxygen concentration sensor; 8. The hydrogen consumption measurement system according to claim 1, further comprising a measurement gas flow path that introduces the measurement gas diluted with the dilution gas into the oxygen concentration sensor.

9. a dilution mechanism that dilutes the exhaust gas with a dilution gas and supplies the diluted exhaust gas to the oxygen concentration sensor; 9. The hydrogen consumption measurement system according to claim 1, further comprising a reference gas flow path that introduces the dilution gas as a reference gas to the oxygen concentration sensor.

10. the dilution mechanism includes a sampling bag that collects the diluted gas; 10. The hydrogen consumption measurement system according to claim 9, wherein the reference gas flow path introduces the reference gas from the sampling bag to the oxygen concentration sensor.

11. A system for measuring an amount of hydrogen leakage from a hydrogen reactor using an oxidation catalyst and an oxygen concentration sensor provided in the hydrogen consumption measurement system according to claim 1, the oxygen concentration sensor measures an oxygen concentration in a measurement gas that has passed through the oxidation catalyst and an oxygen concentration in a measurement gas that has not passed through the oxidation catalyst; a hydrogen leak amount calculation unit that calculates the amount of hydrogen leak from the difference between the oxygen concentration in the exhaust gas that has passed through the oxidation catalyst, measured by the oxygen concentration sensor, and the oxygen concentration in the exhaust gas that has not passed through the oxidation catalyst.

12. A system for measuring an amount of hydrogen leakage from a hydrogen reactor using an oxidation catalyst and an oxygen concentration sensor provided in the hydrogen consumption measurement system according to claim 1, A hydrogen leak amount measurement system comprising: a dehumidifier disposed between the oxidation catalyst and the oxygen concentration sensor for removing moisture generated by the oxidation catalyst; and a hydrogen leak amount calculation unit for calculating the amount of hydrogen leak from the difference in moisture concentration before and after the oxidation catalyst.

13. A system for calibrating an oxygen concentration sensor provided in the hydrogen consumption measurement system according to claim 1, comprising: A calibration system comprising a hydrogen addition mechanism that adds a predetermined amount of hydrogen to exhaust gas before it flows into the oxidation catalyst.

14. A method for measuring hydrogen consumption in a test specimen that is a moving object or a part thereof, the test specimen comprising a hydrogen reactor that chemically reacts hydrogen and utilizes energy obtained by the chemical reaction, the method comprising the steps of: A hydrogen consumption measurement method, characterized in that hydrogen contained in exhaust gas from the test specimen is oxidized by oxygen contained in the exhaust gas, and then the oxygen concentration contained in the exhaust gas is measured.

15. A hydrogen leakage measurement method comprising: a hydrogen reactor for chemically reacting hydrogen; measuring the oxygen concentration in exhaust gas after the exhaust gas has passed through an oxidation catalyst which oxidizes hydrogen contained in the exhaust gas from a test specimen, which is a mobile body or part thereof that utilizes the energy obtained by the chemical reaction, with oxygen contained in the exhaust gas, and measuring the oxygen concentration in the exhaust gas that has not passed through the oxidation catalyst; and comparing these oxygen concentrations to measure the amount of hydrogen leaking from the hydrogen reactor.