JP2019183862A - Hydrogen storage rate estimation system and hydrogen storage rate estimation method - Google Patents

Abstract

To provide a hydrogen storage rate estimation system capable of easily measuring a hydrogen storage amount at a hydrogen storage alloy tank at a high accuracy irrespective of a metal type or metal temperature.SOLUTION: This invention comprises a temperature sensor 14 for detecting a metal temperature of hydrogen storage alloy tank 11, a pressure sensor 15 for detecting a hydrogen pressure in the hydrogen storage alloy tank 11, a memory unit 17 storing an estimated equation for getting hydrogen concentration with the metal temperature and the hydrogen pressure being applied as parameters and a calculation unit 16 for calculating a hydrogen concentration by the estimated equation in reference to a detected value of the metal temperature obtained from the temperature sensor 14 and a detected value of hydrogen pressure obtained from the pressure sensor 15 and outputting an estimated value of the hydrogen storage rate from the calculated hydrogen concentration.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrogen storage rate estimation system and a hydrogen storage rate estimation method for estimating a hydrogen storage rate of a hydrogen storage alloy in a hydrogen storage alloy tank.

  The existing hydrogen storage method using compressed hydrogen gas and liquid hydrogen currently used in hydrogen stations and the like has a problem that it is difficult to apply in the vicinity of buildings in terms of energy density, required energy, safety, and handling. To do. One solution is a hydrogen storage alloy. Among the alloys that generate metal hydrides by the gas-solid phase reaction shown in the following formula, the hydrogen storage alloy has a relatively large amount of hydrogen storage and is reversible under a moderate temperature and hydrogen pressure. It is a general term for things that go on.

2M + xH2 ← → 2MHx + Q

  Here, M is a hydrogen storage alloy, MHx is a hydride, and Q is heat of reaction [kJ / mol].

  The hydrogen storage alloy is pulverized to a particle size of the order of μm or less due to the expansion and contraction of the volume accompanying the storage and release of hydrogen, and takes the form of powder particles. For this reason, in order to put it to practical use, the hydrogen storage alloy is used in a form stored in a tank.

  The characteristics of the hydrogen storage alloy are shown by a PCT (Pressure Composition Temperature) diagram. FIG. 11 is an example of a PCT diagram of a hydrogen storage alloy. The PCT diagram shows the relationship between the hydrogen pressure necessary and desorbable for hydrogen storage and the hydrogen storage amount at a constant temperature, and the Y-axis shows the hydrogen pressure at constant temperature (logarithmic equilibrium hydrogen pressure). The X axis shows the composition (hydrogen concentration) at a constant temperature. As shown in FIG. 11, the PCT diagram of the hydrogen storage alloy shows hysteresis characteristics that behave differently in the process of storing hydrogen and in the process of releasing hydrogen. In addition, a plateau region in which a substantially constant hydrogen pressure is present exists in the PCT diagram of the hydrogen storage alloy. The plateau region is not limited to one stage, and some metal species possess plateau regions in multiple stages. FIG. 12 is an example of a PCT diagram of a metal species having a multistage plateau region. In this example, there are two plateau regions of the first stage and the second stage.

  The hydrogen storage alloy can realize a very high hydrogen filling density per volume as compared with gas, and can be stored for a long time because it is a gas-solid reaction. In addition, although depending on the metal type, hydrogenation and dehydrogenation proceed under conditions of a hydrogen pressure of approximately 1 MPa or less and a temperature of 100 degrees or less, so that accidents due to sudden hydrogen leakage can be prevented. Does not require containers that require special specifications. For this reason, it can be said that the hydrogen storage alloy has the property of storing hydrogen safely and easily as compared with the conventional cylinder method and liquid hydrogen method.

  A problem in storing hydrogen using a hydrogen storage alloy is that the amount of stored hydrogen is difficult to understand. That is, the hydrogen storage alloy has a low hydrogen filling density per weight and is filled by a solid solution phenomenon and a chemical bond, so that it is difficult to understand the hydrogen storage amount at that time from the side.

  Prior art documents relating to the storage amount and storage rate estimation relating to the hydrogen storage alloy include those described in the following Patent Document 1, and Non-Patent Document 1 and Non-Patent Document 2.

JP 2004-241261 A

Tomoki Maruoka, Junichiro Kadono, Shohei Shiomi, Yasumasa Kikuuchi “Study on Quantitative Hydrogen Analysis Using Hydrogen Storage Titanium”, Kyoto City Industrial Technology Research Institute Research Report, No.5, P7-11, 2015 廣 ▲ Seto Takehiko, “Study on Low Temperature Adsorption Type Hydrogen Storage Tank System for Fuel Cell Vehicles”, [online], 2015.11.18, Kyushu University, [March 19, 2018 search], Internet <URL: https: //catalog.lib.kyushu-u.ac.jp/opac_download_md/1500723/eng2458.pdf>

  As described above, the hydrogen storage alloy has a problem that the hydrogen storage amount at that time is difficult to understand from the side. The technique described in Non-Patent Document 1 is glow discharge emission analysis. However, it is considered that the emission spectroscopic analysis method is not suitable for estimating the hydrogen storage amount because it takes out and measures the thing in the tank.

  The technique described in Non-Patent Document 2 is quantification and estimation based on pressure and weight. Estimating by weight is difficult to measure accurately due to acceleration during operation, and the hydrogen concentration for the hydrogen storage alloy is currently 3 wt% at most, which is in the category of error. It seems that it is not suitable. Also, when measuring with a mass flow meter or the like, the actual measurement error is large and it is difficult to measure an accurate value.

  Further, it is known that the effective hydrogen storage amount of the hydrogen storage alloy depends on the pressure and temperature in addition to the metal species. In the method of Patent Document 1 using this, since the slope of the PCT diagram is a constant, it is not suitable for metal species whose slope depends on temperature. In addition, a metal species having a multistage plateau region in the use range as shown in FIG. 12 is not assumed.

  In view of the above-described problems, the present invention provides a hydrogen storage rate estimation system and a hydrogen storage rate estimation method capable of easily measuring the hydrogen storage amount of the hydrogen storage alloy in the hydrogen storage alloy tank with high accuracy regardless of the metal species or metal temperature. The purpose is to provide.

  In order to solve the above problems, a hydrogen storage rate estimation system according to an aspect of the present invention is a hydrogen storage rate estimation system that estimates a hydrogen storage rate of a hydrogen storage alloy in a hydrogen storage alloy tank, the hydrogen storage rate estimation system A temperature sensor for detecting the metal temperature of the hydrogen storage alloy in the alloy tank, a pressure sensor for detecting the hydrogen pressure in the hydrogen storage alloy tank, and a memory for storing an estimation formula for determining the hydrogen concentration using the metal temperature and the hydrogen pressure as parameters. A hydrogen concentration from the detected value of the metal temperature from the temperature sensor and the detected value of the hydrogen pressure from the pressure sensor, and an estimated value of the hydrogen storage rate from the calculated hydrogen concentration Is provided.

  A hydrogen storage rate estimation method according to an aspect of the present invention is a hydrogen storage rate estimation method for estimating a hydrogen storage rate of a hydrogen storage alloy in a hydrogen storage alloy tank, and includes a hydrogen storage alloy in the hydrogen storage alloy tank in advance. A step of calculating an estimation formula for obtaining a hydrogen concentration using a test specimen of the same composition using a metal temperature and a hydrogen pressure as parameters, a step of storing the estimation formula, a metal temperature of the hydrogen storage alloy in the hydrogen storage alloy tank, Detecting the hydrogen pressure of the hydrogen storage alloy tank, the detected value of the metal temperature of the hydrogen storage alloy of the hydrogen storage alloy tank, and the detected value of the hydrogen pressure of the hydrogen storage alloy tank according to the estimation formula Calculating a hydrogen concentration, and outputting an estimated value of a hydrogen storage rate from the calculated hydrogen concentration.

  According to the present invention, the hydrogen storage amount can be estimated easily and accurately by estimating the hydrogen storage rate of the hydrogen storage alloy using the estimation formula for obtaining the hydrogen concentration using the metal temperature and the hydrogen pressure as parameters. Further, according to the present invention, the hydrogen storage rate can be estimated even for a metal species that depends on temperature, a metal species having a multistage plateau region, and the like, and the hydrogen storage rate can be estimated regardless of the metal type.

It is a block diagram which shows the structure of the hydrogen storage rate estimation system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the prior preparation system for producing an estimation formula. It is a flowchart which shows the pre-processing for creating an estimation formula. It is explanatory drawing of a process of observation data. It is a flowchart which shows the creation process of an approximate line. It is explanatory drawing of the creation process of an approximate line. It is a flowchart of the estimation process of the hydrogen storage rate in the hydrogen storage rate estimation system which concerns on the 1st Embodiment of this invention. It is explanatory drawing of a process in case it becomes a some estimation formula. It is a graph which shows the observation data in the case of hydrogen storage, and an approximate line. It is a graph which shows the observation data in the case of hydrogen discharge | release, and an approximate line. It is a graph in an example of a PCT diagram of a hydrogen storage alloy. It is a graph of an example of the PCT diagram of the metal seed | species with a multistage plateau area | region.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a hydrogen storage rate estimation system 1 according to the first embodiment of the present invention. As shown in FIG. 1, the hydrogen storage rate estimation system 1 according to the first embodiment of the present invention includes a hydrogen storage alloy tank 11, a hydrogen generation / supply device 12, a hydrogen consumption device 13, and a temperature sensor 14. , The pressure sensor 15, the calculation unit 16, the storage unit 17, and the display unit 18.

  The hydrogen storage alloy tank 11 stores a hydrogen storage alloy. There are various types of hydrogen storage alloys such as alkaline earth, rare earth, titanium, and solid solutions. In this embodiment, any hydrogen storage alloy can be used.

  The hydrogen generation / supply device 12 supplies hydrogen into the hydrogen storage alloy tank 11. Hydrogen in the hydrogen generation / supply device 12 may be generated by any method. For example, the hydrogen generation / supply device 12 electrolyzes water using surplus power to generate hydrogen. For example, the hydrogen generation / supply device 12 reforms methane, methanol, or the like to generate hydrogen.

  The hydrogen consuming device 13 consumes hydrogen extracted from the hydrogen storage alloy in the hydrogen storage alloy tank 11. The hydrogen extracted from the hydrogen storage alloy in the hydrogen storage alloy tank 11 may be consumed by the hydrogen consuming device 13 in any manner. For example, the hydrogen consuming apparatus 13 generates electric power from hydrogen taken out from the hydrogen storage alloy in the hydrogen storage alloy tank 11 using a fuel cell.

  The temperature sensor 14 detects the metal temperature of the hydrogen storage alloy in the hydrogen storage alloy tank 11. The metal temperature detected by the temperature sensor 14 is sent to the calculation unit 16.

  The pressure sensor 15 detects the hydrogen pressure in the hydrogen storage alloy tank 11. The hydrogen pressure detected by the pressure sensor 15 is sent to the calculation unit 16.

  The calculation unit 16 performs various calculations for estimating the hydrogen storage rate of the hydrogen storage alloy in the hydrogen storage alloy tank 11. As the calculation unit 16, a PC (Personal Computer) can be used. The storage unit 17 stores various data for estimating the hydrogen storage rate of the hydrogen storage alloy in the hydrogen storage alloy tank 11. The storage unit 17 may be the one in the PC constituting the calculation unit 16 or may be provided in an external database. In the present embodiment, the storage unit 17 stores in advance an estimation formula for obtaining the hydrogen concentration using the metal temperature and the hydrogen pressure as parameters. The calculation unit 16 calculates the hydrogen concentration from the detected value of the metal temperature from the temperature sensor 14 and the detected value of the hydrogen pressure from the pressure sensor 15 by this estimation formula, and calculates the hydrogen storage rate from the calculated hydrogen concentration. A process for outputting the estimated value is performed.

  The display unit 18 displays the hydrogen storage rate estimated by the calculation unit 16 to inform the user.

  Next, the hydrogen storage rate estimation method in the hydrogen storage rate estimation system 1 according to the first embodiment of the present invention will be described.

  The characteristics of the hydrogen storage alloy are represented by a PCT diagram. In the measurement of the PCT diagram, observation data indicating the hydrogen pressure and hydrogen concentration at a constant temperature is acquired. From this observation data, an approximate line indicating the relationship between hydrogen pressure and hydrogen concentration at each temperature can be created.

  If an approximate line indicating the relationship between the hydrogen pressure and the hydrogen concentration at each temperature can be created, an estimation formula for obtaining the hydrogen concentration can be calculated from the approximate expression of the approximate line at each temperature using the metal temperature and the hydrogen pressure as parameters. If this estimation formula is created and stored in advance, the hydrogen concentration can be obtained from the detected value of the metal temperature and the detected value of the hydrogen pressure.

  Therefore, in the hydrogen storage rate estimation system 1 according to the first embodiment of the present invention, the hydrogen pressure and hydrogen at each temperature are measured using a test body having the same composition as the hydrogen storage alloy filled in the hydrogen storage alloy tank 11 in advance. An approximate line indicating the relationship with the concentration is created, and an estimation formula for obtaining the hydrogen concentration is calculated from the approximate formula of the approximate line at each temperature using the metal temperature and the hydrogen pressure as parameters.

  That is, FIG. 2 shows a configuration of a preparatory system for creating an estimation formula, and FIG. 3 is a flowchart showing a preliminary process for creating the estimation formula. As shown in FIG. 2, a PCT measurement device 51 and an analysis device 52 are prepared as a preliminary preparation system. The PCT measurement device 51 performs PCT measurement of the test body 53. The analysis device 52 uses the observation data obtained by the PCT measurement from the PCT measurement device 51 to calculate an estimation formula for obtaining the hydrogen concentration using the metal temperature and the hydrogen pressure as parameters. As the analysis device 52, for example, a PC (Personal Computer) can be used. Further, the analysis device 52 may be shared with the calculation unit 16 of the hydrogen storage rate estimation system 1.

  (Step S <b> 101) In the use region, the PCT measurement device 51 uses the test piece 53 having the same composition as the hydrogen storage alloy to be filled in the hydrogen storage alloy tank 11 to acquire observation data by creating a PCT diagram. As a method for creating a PCT diagram, the method described in (JIS H 7201: 2007) is used. According to this creation method, the PCT measurement device 51 acquires observation data indicating the hydrogen pressure and the hydrogen concentration at a predetermined constant temperature.

  (Step S102) The analysis device 52 plots the obtained observation data on coordinates where the X axis is the logarithm of the hydrogen pressure and the Y axis is the hydrogen concentration. FIG. 4 is an explanatory diagram of observation data processing. As shown in FIG. 4, the X axis is a logarithmic value of the hydrogen pressure, and the Y axis is the hydrogen concentration. This is an inverse function relationship in which the X axis and the Y axis are interchanged with respect to the PCT diagram with the hydrogen concentration as the X axis and the hydrogen pressure as the Y axis. Here, the inverse function with the X axis as the hydrogen pressure is used to create an estimation equation indicating the relationship between the hydrogen pressure with respect to the hydrogen concentration and the metal temperature in the processing shown in steps S103 to S106 described later. In the process of step S102, observation data d1, d2,... Are plotted on the XY plane as shown in FIG.

  (Step S103) When the observation data is plotted, the analysis device 52 creates an approximate line using the least square method. That is, as shown in FIG. 4B, the analysis device 52 creates the approximate line N1 so that the square sum of the residuals between the observation data d1, d2,. Here, it may be difficult to approximate the observation data d1, d2,... With one approximation line. In this case, as shown in FIG. 4C, approximation is performed using two approximate lines N1 and N2.

  (Step S104) If approximate lines can be created for one temperature, it is determined whether or not all temperatures have been measured. If not measured for all temperatures (step S104: No), the process proceeds to step S105. If all the temperatures have been measured (step S104: Yes), the process proceeds to step S106.

  (Step S105) The analysis device 52 sets the next temperature and returns the process to step S101. Then, by performing the processing from step S101 to step S104, an approximate line is created from the observation data at the next temperature by the least square method.

  (Step S106) When the measurement for each temperature is completed and an approximate line of the observation data of the PCT diagram can be created for each temperature (Step S104: Yes), the analyzer 52 calculates the approximate line for each temperature. From the approximate expression, the functions F (T) and G (T) are obtained, and an estimation expression for obtaining the hydrogen concentration is calculated using the metal temperature and the hydrogen pressure as parameters. That is, the estimation formula using the metal temperature and the hydrogen pressure as parameters takes the form shown in the formula (1).

x = F (T) × log P + G (T) (1)

  Here, P is the absolute pressure (atm) indicating the hydrogen pressure, T is the absolute temperature (K) indicating the metal temperature, x is the hydrogen concentration (wt%), F (T) and G (T) are the metal temperature T Is an arbitrary function. In step S106, the analysis device 52 obtains the functions F (T) and G (T) from the obtained approximate expression of the approximate line for each temperature, and calculates an estimation expression as shown in the expression (1).

  (Step S107) From the use region, the analyzer 52 sets the hydrogen pressure at the hydrogen storage rate (y = 0) as the reference hydrogen concentration x1, and the hydrogen concentration at the hydrogen storage rate (y = 100) as the reference hydrogen concentration. Set as x2 (x1 <x2). The reference hydrogen concentrations x1 and x2 are used for conversion from the hydrogen concentration x to the hydrogen storage rate y (where x1 <x <x2). Conversion from the hydrogen concentration x to the hydrogen storage rate y can be performed by the following equation.

y = ((x−x1) / (x2−x1)) × 100 (2)

  (Step S108) The analysis device 52 stores the estimation formula obtained in Step S106 and the reference hydrogen concentrations x1 and x2 set in Step S107 in the storage unit 17 of the hydrogen storage rate estimation system 1.

  In addition, the estimation formula at the time of hydrogen occlusion or hydrogen release is produced | generated by the process of the above-mentioned step S101-S108. Since the PCT curve has a hysteresis characteristic, the processing in steps S101 to S108 described above is performed at the time of hydrogen storage and at the time of hydrogen release, and the storage unit 17 stores the estimation formula at the time of hydrogen storage and the estimation at the time of hydrogen release. The formula is stored.

  As shown in FIG. 4C, in the present embodiment, a plurality of approximate lines are created depending on the dispersion of the observation data. For this reason, there may be a plurality of estimation equations. Thereby, it can respond also to the metal seed | species which has a multistage plateau area | region in the use range. That is, FIG. 5 is a flowchart showing the approximate line creation processing in step S103, and FIG. 6 is an explanatory diagram thereof.

  (Step S201) First, the analysis device 52 initializes a variable N for identifying an approximate line to 1.

  (Step S202) The analysis device 52 acquires three points of observation data from the first observation data. For example, when the observation data is acquired as shown in FIG. 6, the analysis device 52 first acquires the first observation data d1, d2, and d3.

  (Step S203) The analysis device 52 estimates the approximate line N1 so that the sum of squares of the deviation between the approximate line and the observation data d1, d2, and d3 is minimized.

  (Step S204) The analysis device 52 determines whether there is a next observation point. If there is no next observation point (step S204: No), the process proceeds to step S205, and if there is a next observation point (step S204: Yes), the process proceeds to step S206.

  (Step S205) The analysis device 52 stores the approximate expression representing the obtained approximate line in the storage unit 17, and ends the processing.

  (Step S206) The analysis device 52 determines whether or not the deviation between the inclination of the current observation point and the next observation point and the inclination of the approximate line exceeds a threshold value. That is, assuming that the observation data dn in FIG. 6 is the current observation point and the observation data dn + 1 is the next observation point, the slope between the current observation point and the next observation point is b. In contrast, it is assumed that the slope of the approximate line N1 is a. The analysis device 52 determines whether or not the residual between the inclination b of the current observation point and the next observation point and the inclination a of the approximate line N1 exceeds a predetermined threshold value. If the deviation between the slope of the current observation point and the next observation point and the slope of the approximate expression does not exceed the threshold value (step S206: No), the process proceeds to step S207, and the current observation point and the next observation point are observed. If the deviation between the slope of the point and the slope of the approximate expression exceeds the threshold (step S206: Yes), the process proceeds to step S208.

  If the PCT diagram is only in the plateau region, the slope of the approximate line is substantially constant. Accordingly, in step S206, it is determined that the deviation between the inclination of the data at the current observation point and the next observation point and the inclination of the approximate line does not exceed the threshold value. If the deviation between the inclination of the data at the current observation point and the next observation point and the inclination of the approximate line does not exceed the threshold (step S206: No), the process proceeds to step S207.

  (Step S207) The analysis device 52 acquires the observation data of the next observation point, and returns the process to step S203.

  By repeating steps S203, S204, S206, and S207, one approximate line N1 that minimizes the sum of squares of the deviation between each observation data and the approximate line is obtained.

  If the plateau region of the PCT diagram is completed before the processing is completed for all observation point data, the slope of the approximate line changes greatly. Therefore, in step S206, it is determined that the deviation between the slope of the data at the current observation point and the next observation point and the slope of the approximate line exceeds the threshold value. If the deviation between the slope of the data at the current observation point and the next observation point and the slope of the approximate line exceeds the threshold (step S206: Yes), the process proceeds to step S208.

(Step S208) The analysis device 52 stores the approximate expression of the approximate line N1 obtained so far in the storage unit 17, and advances the processing to Step S209.

(Step S209) The analysis device 52 advances the processing to step S210 using the current observation data as the first observation data.

(Step S210) The analysis device 52 increments the variable N for identifying the approximate line, and returns the process to Step S202.

  Thereafter, steps S203, S204, S206, and S207 are repeated to obtain an approximate line N2 that minimizes the sum of squares of the deviations between the respective observation data and the approximate line. As a result, a second approximate line N2 is created. When processing is completed for all observation point data, it is determined in step S204 that there is no next observation point data. If it is determined in step S204 that there is no next observation point data (step S204: No), the analysis device 52 stores the approximate line N2 in the storage unit 17 and ends the process.

  Thus, in this embodiment, a new approximate line is created when the characteristic changes greatly from the boundary of the plateau region. Further, even when a multi-stage plateau region is included, the same processing is repeated from the boundary of the region, and a new approximate line is created. When there are a plurality of approximate lines indicating the relationship between the hydrogen pressure and the hydrogen concentration at each temperature, there are a plurality of estimation formulas calculated from the approximate lines indicating the relationship between the hydrogen pressure and the hydrogen concentration at each temperature.

  As described above, according to the present embodiment, an estimation equation using the metal temperature and the hydrogen pressure as parameters as shown in the equation (1) is created by pre-processing at the time of hydrogen storage and hydrogen release. Further, as described above, in the present embodiment, there may be a plurality of estimation equations.

  Next, a process for estimating the hydrogen storage rate of the hydrogen storage alloy in the hydrogen storage alloy tank 11 will be described.

  FIG. 7 is a flowchart of hydrogen storage rate estimation processing in the hydrogen storage rate estimation system 1 according to the first embodiment of the present invention. As described above, an estimation formula using the metal temperature and the hydrogen pressure as parameters is created by the pre-processing at the time of hydrogen storage and hydrogen release, and this estimation formula is stored in the storage unit 17. Reference hydrogen concentrations x1 and x2 are stored in the storage unit 17. FIG. 8 is an explanatory diagram of processing when a plurality of estimation equations are used. In the example of FIG. 8, there are two approximate lines N1 and N2 as approximate lines indicating the relationship between the hydrogen pressure and the hydrogen concentration at a predetermined temperature. In this case, two estimation formulas are calculated from the two approximate lines N1 and N2, and the two estimation formulas are stored in the storage unit 17.

  (Step S301) The computing unit 16 acquires the metal temperature T and the hydrogen pressure P from the detection value of the temperature sensor 14 and the detection value of the pressure sensor 15.

  (Step S <b> 302) The computing unit 16 calls the estimation formula using the metal temperature and the hydrogen pressure as parameters and the reference hydrogen concentrations x <b> 1 and x <b> 2 from the storage unit 17.

  (Step S303) The computing unit 16 determines whether there are a plurality of estimation formulas using the metal temperature and the hydrogen pressure as parameters. If there are not a plurality of estimation formulas (step S303: No), the process proceeds to step S304. If there are a plurality of estimation formulas (step S303: Yes), the process proceeds to step S305.

  (Step S304) The computing unit 16 calculates the hydrogen concentration x by substituting the metal temperature T and the hydrogen pressure P into the estimation formula using the metal temperature and the hydrogen pressure as parameters, and advances the process to step S307.

  (Step S305) The computing unit 16 substitutes the metal temperature T and the hydrogen pressure P into N estimation equations using the metal temperature and the hydrogen pressure as parameters, calculates the N hydrogen concentrations xn, and performs the process. The process proceeds to S306.

  (Step S306) The computing unit 16 determines the minimum hydrogen concentration xmin among the determined N hydrogen concentrations xn, and sets the minimum hydrogen concentration xmin as the hydrogen concentration x. That is, as shown in FIG. 8, when there are two approximate lines N1 and N2, when the hydrogen pressure is smaller than p1, the hydrogen concentration obtained from the approximate line N1 is greater than the hydrogen concentration obtained from the approximate line N2. Get smaller. Therefore, when the hydrogen pressure is smaller than p1, if the minimum hydrogen concentration xmin is determined and the hydrogen concentration is selected, the hydrogen concentration obtained from the approximate line N1 is selected. When the hydrogen pressure exceeds p1, the hydrogen concentration obtained from the approximate line N2 becomes smaller than the hydrogen concentration obtained from the approximate line N1. Therefore, when the hydrogen pressure exceeds p1, when the minimum hydrogen concentration xmin is determined and the hydrogen concentration is selected, the hydrogen concentration obtained by the approximate line N2 is selected.

  (Step S307) The computing unit 16 converts the calculated hydrogen concentration x into a hydrogen storage rate y using the reference hydrogen concentrations x1 and x2. Conversion from the hydrogen concentration x to the hydrogen storage rate y can be performed by the aforementioned equation (2).

  (Step S308) The computing unit 16 displays the obtained hydrogen storage rate on the display unit 18.

  As described above, in the hydrogen storage rate estimation system 1 according to the first embodiment of the present invention, the hydrogen storage rate of the hydrogen storage alloy can be accurately estimated from the hydrogen pressure and the metal temperature for the hydrogen storage alloy. Further, in the present embodiment, since the estimation formula at the time of hydrogen storage and the estimation formula at the time of hydrogen release are respectively created, estimation is possible even when the PCT diagram has hysteresis characteristics. In the present embodiment, the hydrogen storage rate can be estimated even for metal species that depend on temperature, metal species having a multistage plateau region, and the like, and can be estimated regardless of the metal species.

  As an example, an example using a Ti-based alloy as a hydrogen storage alloy is shown. The physical properties of this Ti-based alloy are as follows. The molar heat capacity and below are estimated from the composition using the Neumann-Kopp rule. This alloy has a two-stage plateau region.

Hydrogen filling rate per weight: 2wt%
Molar heat capacity: 25.18 J / molK
Specific heat: 0.48 J / gK
Thermal conductivity: 42.52 W / mK

  FIG. 9 shows observation data and approximate lines in the case of hydrogen storage. The metal temperature T is 20 ° C. (293 ° K), 30 ° C. (303 ° K), 60 ° C. (333 ° K), and the observation data at 20 ° C. are represented by diamonds, and the observation at 30 ° C. Data is represented by a square, and observation data at 60 ° C. is represented by a triangle. As described above, the estimation equation is expressed by equation (1). In the case of hydrogen storage, the following formula (3) was used as an estimation formula.

x = (3.7368-0.0035 x T) x logP + (12.646-0.0428 x T) (3)
F (T) = 3.7368-0.0035 × T
G (T) = 12.646-0.0428 × T

  In the case of hydrogen storage, observation data at T = 20 ° C., 30 ° C., and 60 ° C. is dispersed as shown in FIG.

  In the case of T = 20 ° C., an expression representing an approximate line is as follows, and the approximate line is indicated by A1.

x = 2.7108 x logP + 0.0992

  In the case of T = 30 ° C., the equation representing the approximate line is as follows, and the approximate line is indicated by A2.

x = 2.6758 × logP-0.3288

  In the case of T = 60 ° C., the equation representing the approximate line is as follows, and the approximate line is indicated by A3.

x = 2.5708 × logP-1.6128

  FIG. 10 shows observation data and approximate lines in the case of hydrogen release. The metal temperatures are 20 ° C, 30 ° C, and 60 ° C, the observation data at 20 ° C is represented by diamonds, the observation data at 30 ° C is represented by squares, and the observation data at 60 ° C is represented by triangles. ing. In the case of hydrogen release, the PCT diagram has a multistage plateau, and there are two estimation equations for the first and second stages. In the first stage, the following equation (4) was used as an estimation equation.

x = (6.2058-0.0106 × T) × logP + (14.526-0.0466 × T) (4)
F (T) = 6.2058-0.0106 × T
G (T) = 14.526-0.0466 × T

  In the second stage, the following equation (5) was used as an estimation equation.

x = (2.1673-0.0018 × T) × logP + (9.4414-0.0291 × T) (5)
F (T) = 2.1673-0.0018 × T
G (T) = 9.4414-0.0291 × T

  In the case of hydrogen release, the observation data at T = 20 ° C., 30 ° C., and 60 ° C. are dispersed as shown in FIG.

  In the first stage, when T = 20 ° C., an equation representing an approximate line is as follows, and the approximate line is indicated by B1.

x = 3.0984 × logP + 0.8652

  In the case of T = 30 ° C., the equation representing the approximate line is as follows, and the approximate line is indicated by B2.

x = 2.9924 × logP + 0.3992

  In the case of T = 60 ° C., the equation representing the approximate line is as follows, and the approximate line is indicated by B3.

x = 2.6744 × logP-0.9988

  In the second stage, when T = 20 ° C., an expression representing an approximate line is as follows, and the approximate line is indicated by C1.

x = 1.6395 × logP + 0.9107

  In the case of T = 30 ° C., an expression representing an approximate line is as follows, and the approximate line is indicated by C2.

x = 1.6216 × logP + 0.6197

  In the case of T = 60 ° C., an expression representing an approximate line is as follows, and the approximate line is indicated by C3.

x = 1.5676 × logP-0.2533

  You may make it implement | achieve all or one part of the hydrogen storage rate estimation system 1 in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. It may be realized using a programmable logic device such as an FPGA.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

11: Hydrogen storage alloy tank, 12: Hydrogen generation / supply device, 13: Hydrogen consumption device, 14: Temperature sensor, 15: Pressure sensor, 16: Calculation unit, 17: Storage unit, 18: Display unit

Claims (6)

A hydrogen storage rate estimation system for estimating a hydrogen storage rate of a hydrogen storage alloy in a hydrogen storage alloy tank,
A temperature sensor for detecting a metal temperature of the hydrogen storage alloy in the hydrogen storage alloy tank;
A pressure sensor for detecting a hydrogen pressure in the hydrogen storage alloy tank;
A storage unit for storing an estimation formula for obtaining the hydrogen concentration using the metal temperature and the hydrogen pressure as parameters;
From the detected value of the metal temperature from the temperature sensor and the detected value of the hydrogen pressure from the pressure sensor, the hydrogen concentration is calculated by the estimation formula, and the estimated value of the hydrogen storage rate is output from the calculated hydrogen concentration. A hydrogen storage rate estimation system comprising a calculation unit. The hydrogen storage rate estimation system according to claim 1, wherein the storage unit stores an estimation formula for storing hydrogen and an estimation formula for releasing hydrogen. The estimation formula is obtained by using a specimen having the same composition as the hydrogen storage alloy in the hydrogen storage alloy tank, obtaining observation data by creating a PCT diagram, and calculating an approximation line for each temperature by the least square method from the observation data. The hydrogen storage rate estimation system according to claim 1, wherein the hydrogen storage rate estimation system is created and calculated. When creating the approximate line, determine the deviation between the slope of the approximate line obtained up to the previous time and the slope of the continuous observation data, and the slope of the approximate line obtained up to the previous time and the slope of the continuous observation data The hydrogen storage rate estimation system according to claim 3, wherein a new approximate line is created if the deviation from the above is a predetermined threshold value or more. The hydrogen storage rate estimation system according to claim 1, wherein when there are a plurality of estimation formulas, the calculation unit estimates a hydrogen storage rate by selecting a hydrogen concentration at which a calculation result is minimum. A hydrogen storage rate estimation method for estimating a hydrogen storage rate of a hydrogen storage alloy in a hydrogen storage alloy tank,
A step of calculating an estimation formula for obtaining a hydrogen concentration using a test piece having the same composition as the hydrogen storage alloy in the hydrogen storage alloy tank in advance using the metal temperature and the hydrogen pressure as parameters,
Storing the estimation equation;
Detecting the metal temperature of the hydrogen storage alloy in the hydrogen storage alloy tank and the hydrogen pressure in the hydrogen storage alloy tank;
From the detected value of the metal temperature of the hydrogen storage alloy of the hydrogen storage alloy tank and the detected value of the hydrogen pressure of the hydrogen storage alloy tank, the hydrogen concentration is calculated by the estimation formula, and hydrogen storage is performed from the calculated hydrogen concentration. A hydrogen storage rate estimation method comprising: outputting an estimated rate value.

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