An efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials

Abstract

The invention discloses a high-efficiency automatic hydrogen charging and decharging method for PCT test of hydrogen storage materials, comprising the following steps: evacuating a test device with a hydrogen storage material sample placed thereon; performing a hydrogen charging and decharging PCT test; during the test, calculating the theoretical dosage of each hydrogen charging / decharging based on a mathematical model to obtain hydrogen charging / decharging dosage data; accurately controlling each hydrogen charging and decharging dosage of the test device through the hydrogen charging / decharging dosage data, and correcting the next hydrogen charging / decharging dosage data according to the last hydrogen absorption / decharging capacity of the hydrogen storage material, and after repeating the process of hydrogen charging and decharging for multiple times, obtaining the test data until the test is finished; according to the test data, a complete PCT curve can be obtained, and the hydrogen storage capacity of the hydrogen storage material can be calculated; the hydrogen storage test device using the method can not only make the distribution of the PCT curve data of the test uniform and reasonable, but also greatly improve the test efficiency of the PCT, and can significantly shorten the test time without affecting the test effect or even improving the test effect.

Description

Technical Field

[0001] The present invention relates to the technical field of PCT testing of hydrogen storage materials, and in particular to a high-efficiency automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials. Background Art

[0002] Among new energy sources, hydrogen energy is considered to be one of the most promising candidates, but hydrogen storage technology still needs new progress. Solid-state hydrogen storage technology has the advantages of high hydrogen storage volume density, good safety, and mature technology, and is widely favored by people. The core of solid-state hydrogen storage technology is to find hydrogen storage materials with good performance. However, the acquisition of hydrogen storage material performance requires the support of reliable testing equipment, which has promoted the innovation of hydrogen storage material testing equipment. There are usually several types of tests for hydrogen storage performance of hydrogen storage materials, such as PCT test, programmed temperature adsorption, programmed temperature desorption, kinetic test and cycle life test. Among them, the PCT test of hydrogen storage materials is a key test to evaluate whether it has commercial application value, and the accuracy of PCT test is higher than other hydrogen storage performance tests. In the PCT test, the hydrogen absorption and desorption of the sample is achieved by changing the hydrogen pressure in the gas storage chamber. When conducting the PCT test, the hydrogen in the gas storage chamber is gradually increased or decreased according to the pre-set dose until the maximum pressure or minimum pressure is reached.

[0003] At present, most PCT test equipment on the market is still manual or semi-automatic. Only a small part is automatic PCT test equipment. Although it is an automatic test equipment, its automatic test effect is not good, either the platform information of the PCT curve is not fully displayed, or the PCT test efficiency is not high. Generally speaking, manual or semi-automatic testing of PCT is not only time-consuming and labor-intensive, but also difficult to obtain good PCT curve data, especially for operators who are not familiar with such equipment or samples. The PCT test of this type of hydrogen storage material testing device usually adopts the ΔP or ΔC hydrogen charging and discharging method, which corresponds to the dynamic and static hydrogen charging and discharging methods respectively.

[0004] For the dynamic hydrogen charging and discharging method, the next hydrogen charging and discharging dosage of this method is calculated and determined based on the position of the equilibrium pressure of the previous reaction on the logarithmic coordinate. However, one disadvantage of the ΔP hydrogen charging and discharging method is that if the hydrogen absorption and dehydration platform of the metal hydride is very flat, the study of the platform information of its PCT curve may be incomplete or lack of information. In a more serious case, due to the use of the dynamic hydrogen charging and discharging method, the platform information of the measured PCT curve may be completely lost. For the static hydrogen charging and discharging method, a certain dose of hydrogen is calculated based on the temperature, pressure and cavity volume and filled into the gas storage chamber or the calculated hydrogen dose is removed from the gas storage chamber. Although the ΔC hydrogen charging and discharging method can well study the platform information of the PCT curve, there is a problem that the non-platform information of the PCT curve is ignored or the data points of the PCT curve platform are too dense (the test efficiency is too low). And both hydrogen charging and discharging methods require human intervention to obtain good test results. At present, there is an urgent need for an automatic hydrogen charging and discharging method that does not require human intervention and is efficient.

[0005] Therefore, in order to overcome the above-mentioned technical problems and develop more efficient, accurate, more widely applicable, better-performing and easier-to-operate fully automatic PCT testing equipment, we have developed a new efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the problems existing in the above-mentioned existing PCT test method for hydrogen storage materials, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to provide a highly efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials, which aims to solve the problems of long time, low efficiency and low degree of automation in PCT testing of existing hydrogen storage materials.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a highly efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials, the hydrogen charging and discharging method comprising the following steps:

[0010] S1: vacuumizing the test device on which the hydrogen storage material sample is placed;

[0011] S2: Carry out hydrogen charging and discharging PCT test;

[0012] S3: During the hydrogen charging and decharging PCT test, the theoretical dosage of each hydrogen charging and decharging is calculated based on the mathematical model to obtain the hydrogen charging and decharging dosage data; the hydrogen charging and decharging dosage of the test equipment is accurately controlled by the hydrogen charging and decharging dosage data, and the next hydrogen charging and decharging dosage data is corrected according to the last hydrogen absorption and decharging capacity of the hydrogen storage material. After repeating the hydrogen charging and decharging process for multiple times, the test data is obtained until the test is completed;

[0013] S4: Based on the test data, a complete PCT curve can be obtained, and the hydrogen storage capacity of the hydrogen storage material can be calculated;

[0014] The hydrogen charging and dehydration PCT test includes a hydrogen charging test and a hydrogen dehydration test. The hydrogen charging test is performed first. When the hydrogen charging test meets the conditions set for the hydrogen storage material to end hydrogen absorption, the hydrogen charging test is terminated. Then, the hydrogen dehydration test is performed. When the conditions set for the hydrogen storage material to end dehydration are met, the hydrogen dehydration test is completed.

[0015] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, wherein: in the hydrogen charging test, the model calculates the first hydrogen charging dose according to the influencing factors, and performs the first hydrogen charging to the test device, and the hydrogen storage material performs the first hydrogen absorption reaction;

[0016] Then, the initial hydrogen dosage required for the next hydrogen absorption reaction is obtained through the initial piecewise function. After the last hydrogen absorption reaction is completed, it is first determined whether the equilibrium pressure in the test device is below one atmosphere. If the equilibrium pressure is lower than one atmosphere, the current dosage is multiplied by the corresponding low pressure.

[0017] If the equilibrium pressure is higher than one atmosphere, it will directly enter the judgment of whether it has passed the platform area. If the position of the last PCT curve data point is judged to be in the platform area, the current calculated dosage will be adjusted for the platform; if the position of the last PCT curve data point is judged to be not in the platform area, no platform adjustment will be performed; the currently calculated hydrogen charging dosage will be directly output as the actual hydrogen charging dosage, and then the next hydrogen charging will be carried out to the test device, and the hydrogen storage material will carry out the next hydrogen absorption reaction;

[0018] During the hydrogen charging test cycle, if the current calculated hydrogen charging dose exceeds the upper limit dose of the hydrogen charging protection, the actual hydrogen charging dose is set to the upper limit dose of the hydrogen charging protection;

[0019] Finally, it is determined whether the hydrogen absorption reaction is completed. If the hydrogen absorption reaction is not completed, the process of obtaining the actual hydrogen charging dosage is continued to be circulated, otherwise the hydrogen charging test is terminated and the hydrogen release test is started;

[0020] The initial hydrogen charging / discharging dosage required for the next test is obtained by using the initial piecewise function, including:

[0021]

[0022] in, It is expressed as the initial dose of hydrogen for the kth time of charging and discharging in the gas storage chamber. Expressed as equilibrium pressure;

[0023] The actual hydrogen charging / discharging dosage is obtained, including:

[0024]

[0025] in, It is expressed as the actual dosage of hydrogen charging and discharging for the kth time, σ is expressed as the volume ratio coefficient, P min It is the pressure at which the desorption test is terminated. Expressed as the calculated dosage of the kth hydrogen charging and discharging, Indicates the upper limit dose for hydrogen charging protection.

[0026] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, wherein: the influencing factors include making the starting point and the end point of the PCT curve close to each other and the accuracy of the pressure sensor in the test device;

[0027] By multiplying the low pressure to avoid the PCT curve data points being too dense, the current calculated hydrogen dosage is adjusted according to the actual reaction of the last hydrogenation and the actual hydrogen dosage of the last hydrogenation, including:

[0028]

[0029] Among them, b k Expressed as the low-pressure multiplication factor, b k-1 It is expressed as the low-pressure multiplication factor of the last hydrogen charging and discharging dosage. is expressed as the equilibrium pressure of the current reaction, It is expressed as the actual hydrogen charging and discharging dosage in the gas storage chamber during the last reaction in the test device, and σ is expressed as the volume ratio coefficient;

[0030] The judgment condition for the hydrogen absorption process to pass the platform area is that the time taken for the two consecutive hydrogen absorption reactions is less than 94 seconds;

[0031] The condition for judging whether the hydrogen absorption reaction is finished is that the equilibrium pressure of the current hydrogen absorption test is greater than the set pressure for terminating the hydrogen absorption test;

[0032] The upper limit dose of hydrogen charging protection is determined by the equilibrium pressure of the hydrogen absorption reaction and the set pressure for terminating the hydrogen absorption test.

[0033] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, wherein: in the hydrogen discharging test, the initial hydrogen discharging dosage required by the test device is firstly obtained by calculating the initial piecewise function;

[0034] Then, it is determined whether the equilibrium pressure of the hydrogen release reaction is below one atmosphere. If the equilibrium pressure is lower than the atmospheric pressure, the test device is expanded at a corresponding low pressure. If the equilibrium pressure is higher than one atmosphere, it is determined whether it is a platform area.

[0035] If it is determined that the current reaction is in the platform area, the current calculated hydrogen release dosage is taken as the actual hydrogen release dosage, and then the test device is controlled to release hydrogen, and the hydrogen storage material performs a hydrogen desorption reaction;

[0036] If the current reaction is judged to be in the non-platform area, a judgment of the over-platform area or the quasi-platform area is performed; if it is judged to be in the over-platform area or the quasi-platform area, a corresponding over-platform or quasi-platform adjustment is performed. After the adjustment, the current calculated hydrogen release dosage is taken as the actual hydrogen release dosage, the test device is controlled to release hydrogen, and the hydrogen storage material performs a hydrogen desorption reaction;

[0037] Finally, it is determined whether the desorption reaction is completed. If the hydrogen desorption end condition is not met, the actual hydrogen desorption dosage acquisition process is continued, and then the test device is controlled to perform the next hydrogen desorption, and the hydrogen storage material performs the next hydrogen desorption reaction until the hydrogen desorption test is completed.

[0038] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, wherein: the low-pressure expansion is used to expand the gas storage chamber of the test device through an external container, and after the expansion, it is judged whether it is a platform area;

[0039] The judgment condition of whether it is a hydrogen release platform area is that the last hydrogen release reaction time is greater than or equal to 94s or the last hydrogen release desorption capacity is greater than or equal to 2.5 times the first hydrogen release desorption capacity;

[0040] The judgment condition for hydrogen discharge passing through the platform area is that the non-platform area before the platform area judgment condition is met for the first time is the platform area;

[0041] The judgment condition of the hydrogen release quasi-platform area is that the non-platform area after meeting the judgment condition of the platform area is the quasi-platform area;

[0042] The quasi-platform adjustment process is that when the hydrogen decomposition equilibrium pressure is less than the actual hydrogen decomposition dosage, the actual hydrogen decomposition dosage of the subsequent hydrogen decomposition reaction will not change until the end of the hydrogen decomposition test. If the hydrogen decomposition reaction meets the judgment conditions of the hydrogen decomposition platform area during the process, the actual hydrogen decomposition dosage will be changed accordingly.

[0043] The process of over-platform adjustment is to multiply the current hydrogen absorption and desorption dosage by the corresponding over-platform adjustment coefficient;

[0044] The condition for judging whether the desorption reaction is finished is that the equilibrium pressure of the hydrogen release reaction is less than the set pressure for terminating the hydrogen release test.

[0045] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, the PCT curve test efficiency is improved by over-platform adjustment, and the over-platform adjustment coefficient a is,

[0046]

[0047] Among them, m host and V rev are the mass of the sample body and the volume of the gas storage chamber, t reac_a and t reac_d are the reaction times for a single hydrogen absorption and a single hydrogen release, in seconds, C d,k represents the hydrogen desorption capacity of the kth step.

[0048] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of hydrogen storage materials described in the present invention, overcharging protection is used to avoid over-range damage to the pressure sensor, which includes:

[0049]

[0050] in, Expressed as the upper limit dose of hydrogen charging protection, P max It is the pressure at which the adsorption test is terminated. is represented as the equilibrium pressure of the test, and σ is represented as the volume proportionality coefficient.

[0051] As a preferred solution of the efficient automatic hydrogen charging and discharging method for the PCT test of the hydrogen storage material of the present invention, wherein: according to the test data, a complete PCT curve can be obtained, and the hydrogen storage capacity of the hydrogen storage material can be calculated, including:

[0052]

[0053] Where l represents the total number of steps of adsorption reaction, V rev and V tube Respectively represent the volume of hydrogen storage chamber and pipeline, P i,rev,k It is expressed as the initial pressure of the gas storage chamber before the kth adsorption, P f,rev,k It is expressed as the final pressure of the gas storage chamber after the kth adsorption, P f,tube,k-1 and P f,sc,k-1 are the final pressures of the pipeline and sample chamber after the k-1th adsorption, P f,tube,k and P f,sc,k are the final pressures of the pipeline and sample chamber after the kth adsorption, Z i,rev,k It is expressed as the initial compression factor of the gas storage chamber before the kth adsorption, Z f,rev,k It is expressed as the final compression factor of the gas storage chamber after the kth adsorption, Z f,tube,k-1 and Z f,sc,k-1are the final compression factors of the pipeline and sample chamber after the k-1th adsorption, Z f,tube,k and Z f,sc,k are the final compression factors of the pipeline and sample chamber after the kth adsorption, T i,rev,k It is expressed as the initial temperature of the gas storage chamber before the kth adsorption, T f,rev,k It is expressed as the final temperature of the gas storage chamber after the kth adsorption, T f,tube,k-1 and T f,sc,k-1 are the final temperatures of the pipeline and sample chamber after the k-1th adsorption, T f,tube,k and T f,sc,k are the final temperatures of the pipeline and sample chamber after the kth adsorption, It is the total molar amount of hydrogen absorbed and released by the hydrogen storage sample after l adsorption steps;

[0054] Finally, the molar amount of adsorption was converted to gravimetric storage capacity as follows,

[0055]

[0056] Among them, C wt％ The weight storage capacity is referred to as the hydrogen storage capacity, m host is the sample mass, M H2 is the molar mass of hydrogen.

[0057] Beneficial effects of the present invention:

[0058] By using the hydrogen storage testing equipment of the present invention, the PCT test of hydrogen storage materials can be carried out efficiently, fully automatically, and without human intervention; the hydrogen storage testing equipment using this method can not only make the distribution of the tested PCT curve data uniform and reasonable, but also greatly improve the test efficiency of PCT, and it can significantly shorten the test time without affecting the test effect or even improve the test effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0060] Figure 1 It is a schematic diagram of the connection structure of the hydrogen storage material PCT testing device suitable for the efficient automatic hydrogen charging and discharging method of the hydrogen storage material PCT testing of the present invention.

[0061] Figure 2 Schematic diagram of the platform area division of the PCT curve of hydrogen storage materials.

[0062] Figure 3Schematic diagram of the automatic hydrogen charging implementation principle of the efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials of the present invention.

[0063] Figure 4 Schematic diagram of the automatic hydrogen release implementation principle of the efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials of the present invention.

[0064] Figure 5 Schematic diagram of the automatic hydrogen charging and discharging algorithm implementation flow of the efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials of the present invention.

[0065] Figure 6 La in the embodiment of the present invention 0.5 Ce 0.5 PCT isotherm of Ni4Co alloy.

[0066] Figure 7 LaNi in the embodiment of the present invention 4.25 Al 0.75 PCT isotherms of the alloys. DETAILED DESCRIPTION

[0067] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0068] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0069] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0070] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0071] Example

[0072] Reference Figure 1, which is an embodiment of the present invention, provides an efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials. This hydrogen charging and discharging method is suitable for hydrogen storage testing equipment. To facilitate the description of this hydrogen charging and discharging method, the following testing device is built:

[0073] The test device is attached Figure 1 As shown in the figure, its main structure includes temperature sensors (TT1~TT3), pressure sensors PT, pneumatic valves (PV1~PV5), cylinders GB (1~100ml), flow limiting gaskets FL, sample chambers SC, vacuum pumps VP, quick connectors QC, H2 supply, heating furnace and connecting gas pipes.

[0074] The air storage chamber rev is composed of the air pipe between the pneumatic valve (PV1~PV5) and the pressure sensor. Figure 1 The tube is composed of the air pipe between the pneumatic valve PV3 and the sample chamber SC. Figure 1 As shown in the dotted box on the upper left. The volume of the air storage chamber V rev The range is 10~20ml, and the pipeline volume V tube The range is 5~10ml, and the sample chamber volume V sc The range is 2 to 5 ml. Each part is connected by a trachea. The specific connection method is as follows Figure 1 shown.

[0075] Furthermore, the pneumatic valves (PV1 to PV5) are all normally closed and driven by air compressors. The pressure range of compressed air is 0.3 to 0.7 MPa. Pneumatic valve PV1 is used for controllable filling of hydrogen into the test device; pneumatic valve PV2 is used to control the usable volume of the gas storage chamber rev; pneumatic valve PV3 is used to control the flow of gas between the gas storage chamber rev and the sample chamber SC to control the reaction between the gas and the sample; pneumatic valve PV4 and pneumatic valve PV5 are used for controllable extraction of hydrogen from the test device. Pneumatic valve PV4 is used for slow and controllable extraction of hydrogen from the test device. Slow extraction is to avoid high-pressure gas from damaging the vacuum pump. It is used when the hydrogen pressure of the system is ≥0.32 MPa. Pneumatic valve PV5 is used for fast and controllable extraction of hydrogen from the test device. Fast extraction can shorten the vacuum extraction time and improve the test efficiency. It is used when the hydrogen pressure of the system is <0.40 MPa. Cylinder GB is used for gas storage chamber expansion. The flow limiting gasket FL is used to limit the extraction speed of hydrogen to prevent the vacuum pump VP from being damaged by excessive hydrogen extraction speed. The quick connector QC is used for the quick connection between the sample chamber SC and the system, which can achieve the quick connection between the sample chamber SC and the system without leakage.

[0076] Furthermore, the gas storage chamber rev and the pipeline tube are both in a room temperature environment, while the sample chamber SC is in a constant temperature environment of a heating furnace, and the constant temperature range of the heating furnace is room temperature to 800°C. Pressure sensors PT and temperature sensors TT1 are installed around the gas storage chamber rev, and temperature sensor TT2 is installed on the pipeline tube. A temperature sensor TT3 is installed at the bottom of the sample chamber SC. The temperature measurement range of the temperature sensors TT1 and TT2 is 0 to 50°C, and the temperature measurement range of TT3 is 0 to 600°C. The pressure measurement range of the pressure sensor PT is 0-10MPa, and its test error is 0.04%FS.

[0077] Furthermore, before the sample test, the test device is subjected to a leakage rate test; during the leakage rate test, the test device is kept sealed, and high-pressure hydrogen (the pressure is the maximum range of the pressure sensor) is filled into the test device for leakage rate test. The pressure and temperature data in the test device are repeatedly recorded within the next 24 hours to calculate the hydrogen leakage rate of the test device. Based on the recorded data, the hydrogen leakage rate of the test system in this embodiment is calculated to be 4.5×10 -10 g·s -1 , indicating that the system is well sealed.

[0078] Before the test begins, the gas storage chamber rev is expanded, specifically:

[0079] Open the pneumatic valve PV2 to expand the usable volume of the hydrogen storage chamber rev;

[0080] If the pressure of the air storage chamber rev after expansion is greater than one atmosphere, the pneumatic valve PV5 is opened to evacuate the air storage chamber rev to reduce the pressure of the air storage chamber rev after expansion to about one atmosphere, and the pneumatic valve PV5 is closed;

[0081] If the pressure of the gas storage chamber rev after expansion is less than one atmosphere, open the pneumatic valve PV1 to fill a certain amount of hydrogen to raise the pressure of the gas storage chamber rev to about one atmosphere, and close the pneumatic valve PV1;

[0082] Then close the pneumatic valve PV2;

[0083] Then the conventional PCT hydrogen absorption process is carried out. After the hydrogen absorption is completed, the hydrogen release test is carried out. When the hydrogen is released to the equilibrium pressure When the pressure is lower than one atmosphere, the pneumatic valve PV2 is opened to expand the gas storage chamber rev, and then the hydrogen desorption test is continued until the hydrogen desorption test is completed.

[0084] The PCT test is performed on the test sample in the test device by this hydrogen charging and discharging method:

[0085] S1: vacuumizing the test device on which the hydrogen storage material sample is placed;

[0086] Before the hydrogen filling test begins, open the pneumatic valves PV3, PV4 and PV5 to evacuate the entire connected system for more than half an hour, and then close all valves.

[0087] S2: Carry out hydrogen charging and discharging PCT test;

[0088] During the hydrogen charging process, keep all pneumatic valves closed, first open the pneumatic valve PV1; fill a certain amount of hydrogen into the gas storage chamber rev; close the pneumatic valve PV1, and after the hydrogen charging is completed, open the pneumatic valve PV3, and the hydrogen enters the sample chamber SC, and the hydrogen storage material produces an adsorption reaction on the hydrogen; after the reaction reaches a balanced state, close the pneumatic valve PV3. Repeat the above hydrogen charging process if the adsorption reaction end condition is not reached.

[0089] When the adsorption reaction end conditions are met, the hydrogen release process begins:

[0090] During the hydrogen release process, keep all pneumatic valves closed. After calculation, extract a certain amount of hydrogen from the gas storage chamber rev through the pneumatic valve PV4 (PV5), and then close the pneumatic valve PV4 (PV5). Then open the pneumatic valve PV3 to make the hydrogen storage material sample in the sample chamber SC produce a desorption reaction to release hydrogen; after the reaction reaches a balanced state, close the pneumatic valve PV3. Repeat the above hydrogen release process if the desorption reaction end condition is not reached.

[0091] S3: During the hydrogen charging and decharging PCT test, the theoretical dosage of each hydrogen charging / decharging is calculated based on the mathematical model to obtain the hydrogen charging / decharging dosage data; the hydrogen charging and decharging dosage of each test equipment is accurately controlled through the hydrogen charging / decharging dosage data, and the next hydrogen charging / decharging dosage data is corrected according to the previous hydrogen absorption / decharging capacity of the hydrogen storage material. After repeating the hydrogen charging and decharging process multiple times, the test data is obtained until the test is completed.

[0092] In the coordinates of the PCT curve, the horizontal axis is the hydrogen storage capacity C wt％ , the vertical axis is the equilibrium pressure In order to make relevant judgments on the platform area, it is necessary to divide the distribution of the PCT curve platform into different zones. Figure 2 shown. Figure 2It shows the complete PCT hydrogen absorption and desorption curves at two different test temperatures. The temperatures represented in the figure are T1 < T2. The higher the temperature, the smaller the plateau region and the lower the plateau pressure. The region enclosed between the two thicker dotted lines is relatively flat and is called the plateau region of the PCT curve; the left region represents the preparation for the hydrogen absorption and desorption reaction to reach the plateau region, which is defined as the quasi-plateau region; the right region represents the region where the hydrogen absorption and desorption reaction has passed the plateau region, which is defined as the post-plateau region. The hydrogen storage capacity at the last point of hydrogen absorption minus the hydrogen storage capacity at the first point of hydrogen desorption is defined as the desorption capacity of the first-step hydrogen desorption. The hydrogen storage capacity at the second point of hydrogen desorption minus the hydrogen storage capacity at the first point of hydrogen desorption is defined as the desorption capacity of the second-step hydrogen desorption, and so on.

[0093] In the PCT test, the hydrogen absorption and desorption of the test sample are achieved by changing the hydrogen pressure in the gas storage chamber, and the hydrogen in the gas storage chamber is increased or decreased step by step in a certain dose. The amount of hydrogen charging and discharging dose not only affects the test efficiency but also affects the test effect. If the hydrogen charging and discharging dose is too large, the test effect is not good; if the dose is too small, the test efficiency is not high. To overcome the above deficiencies, the dose control of this method is based on a new mathematical model, which can well control the hydrogen charging and discharging dose, not only enabling good test results in the PCT test but also ensuring high test efficiency.

[0094] This model considers many factors affecting the hydrogen charging and discharging dose, thereby defining variables such as the volume ratio coefficient σ, the adjustment coefficient a, and the low-pressure multiplication coefficient b. k and so on.

[0095] The variable of the volume ratio coefficient σ considers the influence of the relative sizes of the volumes of each chamber on the hydrogen charging and discharging dose. Since the control of the hydrogen charging and discharging dose is achieved by controlling the hydrogen pressure in the gas storage chamber, with the variable of the volume ratio coefficient σ, the indirect control of the hydrogen pressure of the overall system can be realized. Doing so can better relate the pressure in the gas storage chamber to the pressure of the system, thereby facilitating the simplification of the control algorithm.

[0096]

[0097] Among them, V rev 、V tube 、V sc are the volumes of the gas storage chamber, the pipeline, and the sample chamber respectively.

[0098] The adjustment coefficient a is used to consider the influence of the sample mass, the absolute size of the gas storage chamber volume, and whether the current hydrogen absorption and desorption reaction is at the plateau position on the hydrogen charging and discharging dose.

[0099]

[0100] Among them, m host is the main mass of the sample. t reac_a and t reac_dare the reaction times for single-step hydrogen absorption and single-step hydrogen release, respectively, in seconds. d,k It is expressed as the hydrogen desorption capacity of the kth step. In formula (2), the content in the left bracket is the judgment condition of the hydrogen absorption platform, and the content in the right bracket is the judgment condition of the desorption platform. These conditions are used to determine whether the current hydrogen absorption and desorption reaction is in the platform area. If the condition of formula (2-1) is met, it means that the current reaction is in the platform area; if the condition of formula (2-2) is met, it means that the current reaction is in the non-platform area.

[0101] In the PCT curve test of low-platform hydrogen storage materials, when the equilibrium pressure is lower than 0.1MPa, the low-pressure multiplication factor b k It is used to avoid the PCT curve data points being too dense to improve test efficiency.

[0102]

[0103] where b k-1 It is the low pressure multiplication factor of the last hydrogen charging and discharging dosage; is the current equilibrium pressure; It is the actual amount of hydrogen charged and discharged in the previous reaction in the gas storage chamber.

[0104] Because of the low pressure multiplication factor b k , then the automatic hydrogen charging and discharging method will have a certain adaptive function, and the hydrogen charging and discharging dosage this time will be adjusted according to the actual reaction situation last time.

[0105] Then construct the initial piecewise function to calculate the initial dosage of hydrogen charging and discharging. First, divide the function into two parts in the vertical direction (balance pressure) according to the properties of logarithmic coordinates with base 10. The three segments with equal distance in the direction correspond to [0, 0.1), [0.1, 1) and [1, 10) respectively. It can be seen that each segment corresponds to 10 -1 , 10 0 and 10 1 , then the interval interval can be regarded as 1. Then, according to the desired pressure interval of the actual PCT curve, j pressure data points are taken in each interval (in this embodiment, j=8), and 1 / 8=0.125 is obtained. Finally, combined with the characteristics of logarithmic coordinates, an initial piecewise function is proposed to calculate the initial dosage of hydrogen charging and discharging As shown in formula (4).

[0106]

[0107] in It is expressed as the initial dose of hydrogen for the kth time of charging and discharging in the gas storage chamber. This is the equilibrium pressure. The piecewise function of .

[0108] As shown in formula (5), the initial piecewise function combined with the low-pressure multiplication factor b k The calculated dosage of hydrogen charging and discharging can be obtained by the platform adjustment coefficient a. The calculated dosage of hydrogen charging and discharging is an intermediate variable, not the final actual dosage of hydrogen charging and discharging.

[0109]

[0110] in It is expressed as the calculated dosage of hydrogen for the kth time of charging and discharging in the gas storage chamber, and σ is expressed as the volume ratio coefficient. This is the equilibrium pressure The piecewise function of .

[0111] In order to prevent the pressure sensor PT from being damaged due to over-range, an overcharge protection mechanism is required. The protection mechanism is shown in the following formula (6).

[0112]

[0113] in It is the upper limit dose of hydrogen charging protection. max and P min are the pressures at which the adsorption / desorption test is terminated. Greater than P max The hydrogen absorption test ends; during the desorption reaction, when the equilibrium pressure Less than P min The hydrogen release test is then terminated.

[0114] In the adsorption reaction test, if the calculated dose of hydrogen is Exceeding the upper limit of hydrogen charging protection dose The actual dosage of hydrogen filling and discharging Set as the upper limit dose of the hydrogen charging protection

[0115] In order to make the order of magnitude of the starting point and the end point of the PCT test curve correspond (the starting point and the end point are close), the actual dose of the first hydrogen filling is Set to σP min , but if σP min Less than 5×10 -3 MPa is the actual dosage of the first hydrogen filling Should be set to 5×10 -3 MPa. Due to the limitation of the PT accuracy of the pressure sensor, it is necessary to set the lower limit of hydrogen charging and discharging, so as to avoid the valve opening and closing operation without any effect, which will cause the PCT test program to fall into an infinite loop. Therefore, the lower limit of hydrogen charging and discharging is set to 5×10 -3MPa. Finally, based on comprehensive consideration of all the above influences and the characteristics of the hydrogen storage test equipment, the actual dosage of hydrogen charging and discharging was obtained. As shown in formula (7):

[0116]

[0117] in, It is expressed as the actual dosage of the kth hydrogen filling, σ is expressed as the volume ratio coefficient, P min It is the pressure at which the desorption test is terminated. Expressed as the calculated dose of the kth hydrogen filling, Indicates the upper limit dose for hydrogen charging protection.

[0118] Combined with Figure 3 As shown in the figure, the test device is charged with hydrogen, and the hydrogen storage material undergoes a hydrogen adsorption reaction:

[0119] In the hydrogen charging test, the first hydrogen charging dosage is set according to the influencing factors, and then the test device is charged with hydrogen for the first time, and the hydrogen storage material undergoes the first adsorption reaction.

[0120] Then, the initial piecewise function is used to determine the amount of hydrogen required for the next test device; then, it is determined whether the hydrogen absorption equilibrium pressure in the test device is below one atmosphere. If the equilibrium pressure is lower than one atmosphere, the current dose is multiplied by the corresponding low pressure; if the equilibrium pressure is higher than one atmosphere, it directly enters the judgment process of whether it has passed the platform area; if the position of the last PCT curve data point is judged to be in the platform area, the current dose is adjusted to pass the platform; if the position of the last PCT curve data point is judged to be not in the platform area, no platform adjustment is performed, and the currently calculated hydrogen charging dose is directly output as the actual hydrogen charging dose; then the test device is charged with hydrogen for the next time, and the hydrogen storage material performs the next adsorption reaction.

[0121] Finally, it is determined whether the adsorption reaction is completed. If the adsorption reaction is not completed, the process of obtaining the actual hydrogen charging dose is continued to cycle, otherwise the hydrogen charging test is terminated and the hydrogen release test is started.

[0122] Specifically, the gas storage chamber rev is first charged with hydrogen. Considering that in order to make the starting point and the end point of the PCT curve close to each other, the actual hydrogen dosage for the first time is Let σP min Considering the accuracy limit of the pressure sensor PT, in order to avoid the valve from having no effect and causing the program to fall into an infinite loop, the minimum dose is set to 0.005MPa. min ≥0.005MPa, then the first hydrogen filling dose σP min , if σP min<0.005MPa, then the first hydrogen filling dose The minimum dosage is 0.005MPa. The specific actions are: open the pneumatic valve PV1; fill the air storage chamber rev with σP min MPa of hydrogen; close the pneumatic valve PV1. After the hydrogen filling is completed, open the pneumatic valve PV3 to carry out the hydrogen absorption reaction; after the reaction is completed, close the pneumatic valve PV3.

[0123] Then continue the hydrogen filling dosage acquisition process, first determine the approximate initial dosage through the initial segmentation function. Then enter the judgment process of whether it is lower than the atmospheric pressure to judge the current equilibrium pressure Is it under one atmosphere? If the pressure is balanced If the pressure is lower than one atmosphere, the current dose will be multiplied accordingly (as shown in Formula 3). The main function of low-pressure multiplication is to avoid the problem of too dense data points on the hydrogen absorption PCT curve, which will lead to low test efficiency. The multiplication factor b k It has a certain adaptive function, which can adjust the actual hydrogen filling dosage this time according to the actual reaction situation last time.

[0124] If the pressure is balanced If the pressure is higher than one atmosphere, the system will directly enter the judgment process of whether it has passed the platform area. If the last PCT data point position is judged to be in the platform area, the current dose will be adjusted to pass the platform, and the hydrogen charging dose will be increased to improve the test efficiency. The judgment condition for passing the platform area is that the time used for the last two consecutive (k-2) and (k-1) hydrogen absorption reactions is less than 94 seconds. The requirement that the reaction time is less than 94 seconds for two consecutive times is to reduce the possibility of misjudgment. If the last PCT data point position is judged to be not in the platform area, no platform adjustment will be performed, and the currently calculated hydrogen charging dose will be used as the actual hydrogen charging dose. Direct output.

[0125] During the kth hydrogen filling process, the specific actions are as follows: first open the pneumatic valve PV1; fill the actual dose into the gas storage chamber rev MPa of hydrogen; close the pneumatic valve PV1. After the hydrogen filling is completed, open the pneumatic valve PV3, and the hydrogen enters the sample chamber SC again, and the hydrogen storage material undergoes the kth adsorption reaction; after the reaction reaches the equilibrium state, close the pneumatic valve PV3.

[0126] Finally, it is determined whether the hydrogen storage material has finished adsorbing hydrogen. The condition for the end of the adsorption reaction is the equilibrium pressure. Greater than the pressure P at which the adsorption test is terminated max .

[0127] The specific operation of the last hydrogen filling is: open the pneumatic valve PV1; fill the gas storage chamber rev MPa of hydrogen; close the pneumatic valve PV1. After the hydrogen filling is completed, open the pneumatic valve PV3, hydrogen enters the sample chamber SC, and the hydrogen storage material undergoes an adsorption reaction; after the reaction is completed, close the pneumatic valve PV3.

[0128] If the hydrogen absorption is not completed, the actual hydrogen dosage acquisition cycle continues, otherwise the hydrogen charging process ends and the hydrogen release process begins.

[0129] Combined with Figure 4 As shown in , during the dehydrogenation process of the test device, the hydrogen storage material undergoes a hydrogen desorption reaction:

[0130] First, the hydrogen desorption dosage required by the test device is calculated through the initial piecewise function.

[0131] Then determine whether the equilibrium pressure in the test device is below one atmosphere. If the equilibrium pressure is lower than the atmospheric pressure, the test device is expanded at a low pressure accordingly. If the equilibrium pressure is higher than one atmosphere, directly enter the judgment process of whether it is a platform area. If it is determined that the current reaction is in the platform area, directly take the currently calculated hydrogen release dosage as the actual hydrogen release dosage. If it is determined that the current reaction is in the non-platform area, perform an over or quasi-platform area judgment. If it is determined to be an over or quasi-platform area, perform the corresponding over or quasi-platform adjustment process. Then, hydrogen is released into the test device once, and the hydrogen storage material undergoes a desorption reaction.

[0132] Finally, it is determined whether the desorption reaction is completed. If the hydrogen desorption completion condition is not met, the process of obtaining the actual hydrogen desorption dosage is continued to cycle until the hydrogen desorption is completed.

[0133] Specifically, in the hydrogen release test phase, the initial piecewise function process is performed first. The initial piecewise function is the same as that in the hydrogen absorption phase and can be used to calculate the initial hydrogen release dosage.

[0134] Then enter the process of judging whether it is lower than the atmospheric pressure. If the hydrogen is released to balance the pressure If the pressure is lower than the atmospheric pressure, the corresponding low-pressure expansion process is carried out. The judgment of whether the pressure is lower than the atmospheric pressure and the corresponding low-pressure expansion process must be checked before the PCT test. If the low-pressure expansion is not checked, the process will not be carried out, and the judgment process of whether it is a platform area will be directly entered. The low-pressure expansion process is used for the PCT hydrogen release test of hydrogen storage test materials with a hydrogen absorption and desorption platform lower than one atmospheric pressure. When the hydrogen release balance pressure This process is enabled when the pressure is below one atmosphere. This low pressure expansion process is used to solve the inefficiency problem of hydrogen desorption testing of low plateau pressure materials. This inefficiency problem is caused by the fact that when the hydrogen desorption balance pressure This is caused by too many data points when the pressure is below atmospheric pressure.

[0135] Then proceed to the process of judging whether it is a platform area. If it is judged to be a platform area, the current calculated dose is directly taken as the actual dose of hydrogen release. The judgment conditions for the platform area in the hydrogen release stage are more relaxed. As long as one of the conditions is met, the current reaction is considered to be in the platform area. The two conditions for meeting the platform area in the hydrogen release stage are: the last (k-1) hydrogen release reaction time t reac_d ≥94s or the last (k-1) hydrogen desorption capacity C d,k-1 ≥2.5 times the initial hydrogen desorption capacity C d,1 (The desorption capacity is calculated using formulas 18 and 19.) Because it is necessary to promptly discover the location of the hydrogen release platform and promptly or in advance enter the platform area process, the judgment conditions for the hydrogen release platform area need to be relatively easy to achieve, so as to better avoid the appearance of PCT test curves with incomplete platform information.

[0136] If the platform area determines that the current reaction is in the non-platform area, then the over-platform or quasi-platform area judgment is performed. If it is determined to be in the over-platform or quasi-platform area, the corresponding over-platform or quasi-platform adjustment process is performed. The functions used for hydrogen release over-platform adjustment and hydrogen absorption over-platform adjustment are the same. The hydrogen release quasi-platform adjustment is to improve the efficiency of hydrogen release testing. Specifically: when the hydrogen release equilibrium pressure Less than the actual hydrogen release dose When , the actual hydrogen release dose of the subsequent hydrogen release reaction is No change will occur until the end of the hydrogen release test, unless the hydrogen release reaction meets the hydrogen release platform judgment conditions. If the current reaction is judged to be in the hydrogen release platform area, the currently calculated hydrogen release dosage is used as the actual hydrogen release dosage. Just output it without going through any over or quasi-platform adjustment process.

[0137] Finally, it is determined whether the dehydrogenation process is completed. The judgment condition for the end of dehydrogenation is the equilibrium pressure. Less than the pressure P at which the hydrogen discharge test is terminated min If the hydrogen discharge end condition is not met, the hydrogen discharge dosage acquisition process will continue to cycle until the hydrogen discharge is completed. The implementation principle of the above automatic hydrogen charging and discharging method combined with the specific algorithm implementation process obtained by the mathematical model is as follows: Figure 5 shown.

[0138] The specific process of hydrogen release without expansion: for the kth hydrogen release, when the equilibrium pressure in the test device ( ), open the pneumatic valve PV4 (PV5); draw out air into the air storage chamber rev MPa of hydrogen, close the pneumatic valve PV4 (PV5). Then open the pneumatic valve PV3 to make the hydrogen storage material sample in the sample chamber SC produce a desorption reaction to release hydrogen; after the reaction is completed, close the pneumatic valve PV3.

[0139] The specific process of expanding hydrogen discharge capacity is as follows: when the system balance pressure When the system balance pressure is When (balance pressure ), open the pneumatic valve PV4 (PV5); draw out air into the air storage chamber rev MPa of hydrogen; close the pneumatic valve PV4 (PV5). After the hydrogen is released, open the pneumatic valve PV3 to make the hydrogen storage material sample in the sample chamber SC produce a desorption reaction to release hydrogen; after the reaction is completed, close the pneumatic valve PV3.

[0140] The specific process of the automatic hydrogen charging and discharging method is realized automatically by a program based on LabVIEW software. The program includes multiple modules: initial piecewise function module, low-pressure multiplication module, platform area judgment module, over-platform area judgment module, quasi-platform area judgment module, low-pressure expansion module, overcharge protection mechanism module, over-platform adjustment module and quasi-platform adjustment module. The initial hydrogen charging and discharging dosage can be obtained through the initial piecewise function module. The function is divided into three intervals, corresponding to different expressions, as shown in formula (4). The low-pressure multiplication module is used for hydrogen absorption test. When the balance pressure When it is lower than 0.1MPa, the initial dose calculated by the initial piecewise function is multiplied according to the last (k-1) actual hydrogen charging dose and the actual reaction situation, thereby improving the efficiency of the low-pressure hydrogen absorption test of the low-platform hydrogen storage material. The platform area judgment module is used to determine whether the current reaction is in the platform area. If it is in the platform area, the change rate of the hydrogen charging and dehydration dose will decrease. When the hydrogen dehydration equilibrium pressure When the pressure is lower than the atmospheric pressure, the low-pressure expansion module is used to improve the hydrogen release test efficiency of the hydrogen storage material in the low platform area. The cylinder GB is used to expand the usable volume of the hydrogen storage chamber rev, so that more hydrogen is released in each reaction to achieve the purpose of improving efficiency. The overcharge protection mechanism is to ensure the balance pressure during the hydrogen absorption stage. Will not exceed the end adsorption test pressure P max Too much, and also avoid excessive hydrogen pressure causing the pressure sensor to be damaged due to over-range. The cross-platform adjustment module is used to increase the hydrogen charging and decharging dosage in the cross-platform area of ​​the hydrogen absorption and desorption reaction to improve the test efficiency of the cross-platform area of ​​the hydrogen absorption and desorption reaction. The quasi-platform adjustment module is used to improve the test efficiency of the quasi-platform area of ​​hydrogen desorption. The principle is that when the hydrogen desorption reaction reaches the quasi-platform area, if the actual hydrogen desorption dosage Greater than the equilibrium pressure The dose-unchanged strategy is then implemented in the subsequent quasi-platform area until a new platform area appears or the hydrogen release test is completed.

[0141] S4: Based on the test data, a complete PCT curve can be obtained, and the hydrogen storage capacity of the hydrogen storage material can be calculated.

[0142] By using the real-time data collected by the temperature and pressure sensors and the calibrated volumes of each cavity, based on the existing gas state equation, the molar amount of gaseous hydrogen in each cavity can be calculated in real time, and then the molar amount of hydrogen absorption and desorption of the material can be calculated.

[0143] PV=nZRT(8)

[0144] Where P is the gas pressure, V is the cavity volume, n is the molar amount, Z is the gas compressibility factor, R is the gas constant, and T is the absolute temperature. The error of the gas state equation depends on the error of the gas compressibility factor. For the selection of the compression factor, the compression factor of the Leachman state equation newly recommended by NIST is selected in this embodiment. Because compared with the previous state equation, it has higher accuracy in a wider temperature and pressure range. And the uncertainty of the compression factor of the Leachman state equation is significantly smaller than the uncertainty of other state equations.

[0145]

[0146] Among them, ρ m is the molar density, α r is the remainder of the Helmholtz free energy, l = 7, m = 9 and n = 14. The parameter d i ,N i ,t i ,p i ,φ i ,D i ,β i and γ i Please refer to Table 1 and Table 2 for details.

[0147] Table 1 The residual contribution parameters of Leachman EOS normal hydrogen to the reduction of Helmholtz free energy

[0148]

[0149] Table 2 Residual contribution parameters of Leachman EOS normal hydrogen to the reduction of Helmholtz free energy

[0150]

[0151] Under the condition that the leakage rate of the equipment meets the requirements, the molar density of gaseous hydrogen in each part and the compression factor of each state can be calculated by using the above formula through the collected data and the volume of the cavity. The dead volume V of the sample chamber used to calculate the amount of hydrogen storage material absorbing and desorbing hydrogen dead_cell Calculated by formula (12).

[0152]

[0153] Among them, V sc and V dead_cell They are the sample chamber volume and the dead volume of the sample chamber. The dead volume of the sample chamber is the volume of the sample chamber after removing the volume occupied by the sample. and are the mass and density of the sample after the (k-1)th adsorption, respectively. is the total molar amount of hydrogen absorbed by the sample after the (k-1)th adsorption. The mass of the sample is calculated by formula (13).

[0154]

[0155] Among them, the main mass m of the sample can be directly measured by a balance host ; is the molar mass of a hydrogen molecule.

[0156] The approximate density of the sample can be obtained according to the average density formula of the mixture (14). After a large number of experimental verifications, it is shown that the density obtained by this method differs from the actual sample density by less than 5%.

[0157]

[0158] Where t is the number of sample elements; and ρ s are the mass fraction of the sample element and the density of the sample element respectively; and ρ H is the mass fraction of solid hydrogen and the density of solid hydrogen.

[0159] The sum of all mass fractions is 1, as shown in formula (15). The variable details of the mixture average density formula (14) are shown in formulas (16) and (17).

[0160]

[0161] in It is the initial mass fraction of the single element in the test sample, which refers to the molar mass fraction of the single element in the sample that has not been adsorbed.

[0162]

[0163] Substituting the compression factor calculated by equation (11) and the related variables of equations (12), (13), (14), (16) and (17) into equation (18), the molar amount of hydrogen absorption and desorption of the sample can be obtained.

[0164]

[0165] Where l represents the total number of steps of adsorption reaction, Vrev and V tube Respectively represent the volume of hydrogen storage chamber and pipeline, P i,rev,k It is expressed as the initial pressure of the gas storage chamber before the kth adsorption, P f,rev,k is the final pressure of the gas storage chamber after the kth adsorption, P f,tube,k-1 and P f,sc,k-1 are the final pressures of the pipeline and sample chamber after the k-1th adsorption, P f,tube,k and P f,sc,k are the final pressures of the pipeline and sample chamber after the kth adsorption, Z i,rev,k It is expressed as the initial compression factor of the gas storage chamber before the kth adsorption, Z f,rev,k It is expressed as the final compression factor of the gas storage chamber after the kth adsorption, Z f,tube,k-1 and Z f,sc,k-1 are the final compression factors of the pipeline and sample chamber after the k-1th adsorption, Z f,tube,k and Z f,sc,k are the final compression factors of the pipeline and sample chamber after the kth adsorption, T i,rev,k It is expressed as the initial temperature of the gas storage chamber before the kth adsorption, T f,rev,k It is expressed as the final temperature of the gas storage chamber after the kth adsorption, T f,tube,k-1 and T f,sc,k-1 are the final temperatures of the pipeline and sample chamber after the k-1th adsorption, T f,tube,k and T f,sc,k are the final temperatures of the pipeline and sample chamber after the kth adsorption, It is the total molar amount of hydrogen absorbed and released by the hydrogen storage sample after l adsorption steps;

[0166] Finally, the adsorbed molar amount was converted to the gravimetric storage capacity as shown in Equation (19).

[0167]

[0168] Among them, C wt％ The desorption hydrogen storage capacity of the hydrogen storage material in the current reaction is used to determine the next desorption hydrogen dosage.

[0169] Experimental Examples

[0170] Weigh 1.6194 g of La 0.5 Ce 0.5The Ni4Co alloy was placed in the sample chamber SC, and then the sample chamber SC carrying the alloy was connected to the system through the quick connector QC, and then the sample chamber SC was placed in the heating furnace. First, the entire system was evacuated at room temperature, and then the sample was degassed at 473K for 1h. Finally, in order to activate the sample, the sample chamber SC was heated to 373K at a heating rate of 10K / min, and then naturally cooled to 313K in a hydrogen atmosphere of 9MPa. 0.5 Ce 0.5 The pretreatment process of Ni4Co alloy sample is completed. After completing similar preparation work, 1.7384gLaNi 4.25 Al 0.75 The alloy samples were activated with 6 MPa hydrogen at room temperature.

[0171] PCT test equipment based on automatic hydrogen charging and discharging method to test La 0.5 Ce 0.5 The PCT curves of Ni4Co alloy at 293K and 313K are shown in the attached figure. Figure 6 As shown in the attached figure, the alloy has been previously tested for 1000 cycles, so the hydrogen storage capacity of the alloy has decreased. Figure 6 As shown, the curve is fully displayed and the data points are evenly and reasonably distributed, indicating that the automatic hydrogen charging and discharging method is effective in the PCT test of high platform pressure hydrogen storage materials.

[0172] In order to verify the effectiveness of the automatic hydrogen charging and discharging method in the PCT test of low platform pressure hydrogen storage materials, the PCT test equipment based on the automatic hydrogen charging and discharging method was used to test LaNi 4.25 Al 0.75 The PCT curves of the alloy at 363K and 403K. Figure 7 As shown in the figure, not only the hydrogen absorption and desorption curves are complete, but also the data points are evenly distributed and not dense. The results show that the automatic hydrogen charging and desorption method has a good effect in the PCT test of low platform pressure hydrogen storage materials.

[0173] The hydrogen storage test equipment using the automatic hydrogen charging and discharging method in the above embodiment can implement PCT testing efficiently, fully automatically and without human intervention. 0.5 Ce 0.5 The two PCT tests of Ni4Co alloy took only about 6 hours each. 4.25 Al 0.75 The alloy underwent two PCT tests, each of which took about 5.5 hours. For existing PCT testing equipment, under the same conditions, the test of the same material generally takes more than 10 hours. This automatic hydrogen filling and discharging method greatly reduces the PCT test cycle and improves test efficiency.

[0174] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials, characterized by: The following steps are included: Vacuum the test device containing the hydrogen storage material sample; Carry out PCT test of hydrogen charging and discharging; During the PCT test of hydrogen charging and discharging, the theoretical dosage of each hydrogen charging / discharging is calculated based on the mathematical model to obtain the hydrogen charging / discharging dosage data; The hydrogen charging and dehydrogenating dosage of the test equipment is accurately controlled through the hydrogen charging and dehydrogenating dosage data, and the hydrogen charging and dehydrogenating dosage data for the next time is corrected according to the hydrogen storage material's last hydrogen absorption and dehydrogenating capacity. After repeating the hydrogen charging and dehydrogenating process for multiple times, the test data is obtained until the test is completed; According to the test data, a complete PCT curve can be obtained and the hydrogen storage capacity of the hydrogen storage material can be calculated; The hydrogen charging and dehydration PCT test includes a hydrogen charging test and a hydrogen dehydration test. The hydrogen charging test is performed first. When the hydrogen charging test satisfies the hydrogen storage material's set hydrogen absorption end condition, the hydrogen charging test is terminated. Then, the hydrogen dehydration test is performed. When the set hydrogen storage material dehydration end condition is met, the hydrogen dehydration test is completed. In the hydrogen charging test, the model calculates the first hydrogen charging dosage according to the influencing factors, and performs the first hydrogen charging to the test device, and the hydrogen storage material performs the first hydrogen absorption reaction; Then, the initial hydrogen dosage required for the next hydrogen absorption reaction is obtained through the initial piecewise function. After the last hydrogen absorption reaction is completed, it is first determined whether the equilibrium pressure in the test device is below one atmosphere. If the equilibrium pressure is lower than one atmosphere, the current dosage is multiplied by the corresponding low pressure. If the equilibrium pressure is higher than one atmosphere, the system directly enters the judgment of whether it has passed the plateau area. If the position of the last PCT curve data point is judged to be in the plateau area, the current calculated dose is adjusted to pass the plateau area. If the last PCT curve data point position is judged as a non-platform area, no platform adjustment is performed; The currently calculated hydrogen charging dosage is directly output as the actual hydrogen charging dosage, and then the test device is charged with hydrogen for the next time, and the hydrogen storage material performs the next hydrogen absorption reaction; During the hydrogen charging test cycle, if the current calculated hydrogen charging dose exceeds the upper limit dose of the hydrogen charging protection, the actual hydrogen charging dose is set to the upper limit dose of the hydrogen charging protection; Finally, it is determined whether the hydrogen absorption reaction is completed. If the hydrogen absorption reaction is not completed, the process of obtaining the actual hydrogen charging dosage is continued to be circulated, otherwise the hydrogen charging test is terminated and the hydrogen release test is started; The initial charging / discharging hydrogen dosage required for the next test is obtained through the initial piecewise function. include, in, It is expressed as the initial dose of hydrogen for the kth time of charging and discharging in the gas storage chamber. Expressed as balanced pressure; The actual hydrogen charging / discharging dosage is obtained, including: in, It is expressed as the actual dosage of hydrogen charging and discharging for the kth time, σ is expressed as the volume ratio coefficient, P min It is the pressure at which the desorption test is terminated. Expressed as the calculated dosage of the kth hydrogen charging and discharging, Indicates the upper limit dose for hydrogen charging protection.

2. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 1 is characterized in that: The influencing factors include making the starting point and the end point of the PCT curve close to each other and the accuracy of the pressure sensor in the test device; By multiplying the low pressure to avoid the PCT curve data points being too dense, the current calculated hydrogen dosage is adjusted according to the actual reaction of the last hydrogenation and the actual hydrogen dosage of the last hydrogenation, including: Among them, b k Expressed as the low-pressure multiplication factor, b k-1 It is expressed as the low-pressure multiplication factor of the last hydrogen charging and discharging dosage. is expressed as the equilibrium pressure of the current reaction, It is expressed as the actual hydrogen charging and discharging dosage in the gas storage chamber during the last reaction in the test device, and σ is expressed as the volume ratio coefficient; The judgment condition for the hydrogen absorption process to pass the platform area is that the time taken for the two consecutive hydrogen absorption reactions is less than 94 seconds; The condition for judging whether the hydrogen absorption reaction is finished is that the equilibrium pressure of the current hydrogen absorption test is greater than the set pressure for terminating the hydrogen absorption test; The upper limit dose of hydrogen charging protection is determined by the equilibrium pressure of the hydrogen absorption reaction and the set pressure for terminating the hydrogen absorption test.

3. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 2 is characterized in that: In the hydrogen release test, the initial hydrogen release dosage required by the test device is firstly obtained by calculating the initial piecewise function; Then, it is determined whether the equilibrium pressure of the hydrogen release reaction is below one atmosphere. If the equilibrium pressure is lower than the atmospheric pressure, the test device is expanded at a corresponding low pressure. If the equilibrium pressure is higher than one atmosphere, it is determined whether it is a platform area. If it is determined that the current reaction is in the platform area, the current calculated hydrogen release dosage is taken as the actual hydrogen release dosage, and then the test device is controlled to release hydrogen, and the hydrogen storage material performs a hydrogen desorption reaction; If the current reaction is judged to be in the non-platform area, a judgment of the over-platform area or the quasi-platform area is performed; if it is judged to be in the over-platform area or the quasi-platform area, a corresponding over-platform or quasi-platform adjustment is performed. After the adjustment, the current calculated hydrogen release dosage is taken as the actual hydrogen release dosage, the test device is controlled to release hydrogen, and the hydrogen storage material performs a hydrogen desorption reaction; Finally, it is determined whether the desorption reaction is completed. If the hydrogen desorption end condition is not met, the actual hydrogen desorption dosage acquisition process is continued, and then the test device is controlled to perform the next hydrogen desorption, and the hydrogen storage material performs the next hydrogen desorption reaction until the hydrogen desorption test is completed.

4. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 3 is characterized in that: The low-pressure expansion is to expand the gas storage chamber of the test device through an external container, and after the expansion, it is determined whether it is a platform area; The judgment condition of whether it is a hydrogen release platform area is that the last hydrogen release reaction time is greater than or equal to 94s or the last hydrogen release desorption capacity is greater than or equal to 2.5 times the first hydrogen release desorption capacity; The judgment condition for hydrogen discharge passing through the platform area is that the non-platform area before the platform area judgment condition is met for the first time is the platform area; The judgment condition of the hydrogen release quasi-platform area is that the non-platform area after meeting the judgment condition of the platform area is the quasi-platform area; The quasi-platform adjustment process is that when the hydrogen decomposition equilibrium pressure is less than the actual hydrogen decomposition dosage, the actual hydrogen decomposition dosage of the subsequent hydrogen decomposition reaction will not change until the end of the hydrogen decomposition test. If the hydrogen decomposition reaction meets the judgment conditions of the hydrogen decomposition platform area during the process, the actual hydrogen decomposition dosage will be changed accordingly. The process of over-platform adjustment is to multiply the current hydrogen absorption and desorption dosage by the corresponding over-platform adjustment coefficient; The condition for judging whether the desorption reaction is finished is that the equilibrium pressure of the hydrogen release reaction is less than the set pressure for terminating the hydrogen release test.

5. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 4 is characterized in that: The PCT curve test efficiency is improved by over-platform adjustment, and the over-platform adjustment coefficient a is: Among them, m host and V rev are the mass of the sample body and the volume of the gas storage chamber, t reac_a and t reac_d are the reaction times for a single hydrogen absorption and a single hydrogen release, in seconds, C d,k represents the hydrogen desorption capacity of the kth step.

6. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 5, characterized in that: Overcharge protection is used to prevent the pressure sensor from being damaged by over-range, which includes: in, Expressed as the upper limit dose of hydrogen charging protection, P max Expressed as the pressure at which the adsorption test is terminated, is represented as the equilibrium pressure of the test, and σ is represented as the volume proportionality coefficient.

7. The efficient automatic hydrogen charging and discharging method for PCT testing of hydrogen storage materials according to claim 6, characterized in that: According to the test data, a complete PCT curve can be obtained, and the hydrogen storage capacity of the hydrogen storage material can be calculated, including: Where l represents the total number of steps of adsorption reaction, V rev and V tube Respectively represent the volume of hydrogen storage chamber and pipeline, P i,rev,k It is expressed as the initial pressure of the gas storage chamber before the kth adsorption, P f,rev,k It is expressed as the final pressure of the gas storage chamber after the kth adsorption, P f,tube,k-1 and P f,sc,k-1 are the final pressures of the pipeline and sample chamber after the k-1th adsorption, P f,tube,k and P f,sc,k are the final pressures of the pipeline and sample chamber after the kth adsorption, Z i,rev,k It is expressed as the initial compression factor of the gas storage chamber before the kth adsorption, Z f,rev,k It is expressed as the final compression factor of the gas storage chamber after the kth adsorption, Z f,tube,k-1 and Z f,sc,k-1 are the final compression factors of the pipeline and sample chamber after the k-1th adsorption, Z f,tube,k and Z f,sc,k are the final compression factors of the pipeline and sample chamber after the kth adsorption, T i,rev,k It is expressed as the initial temperature of the gas storage chamber before the kth adsorption, T f,rev,k It is expressed as the final temperature of the gas storage chamber after the kth adsorption, T f,tube,k-1 and T f,sc,k-1 are the final temperatures of the pipeline and sample chamber after the k-1th adsorption, T f,tube,k and T f,sc,k are the final temperatures of the pipeline and sample chamber after the kth adsorption, It is the total molar amount of hydrogen absorbed and released by the hydrogen storage sample after l adsorption steps; Finally, the molar amount of adsorption was converted to gravimetric storage capacity as follows, Among them, C wt％ The weight storage capacity is referred to as the hydrogen storage capacity, m host is the sample mass, is the molar mass of hydrogen.

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