A high and low temperature thermal shock test device and method for hydrogen fuel cells

Abstract

The present invention discloses a high and low temperature cold and hot shock test device and method for hydrogen fuel cells, the device includes: a flushing channel for clamping a sample to be tested; a first refrigerator and a second refrigerator connected in series, a first control valve is provided between the two, used to control the timing and flow rate of the medium flowing from the second refrigerator into the first refrigerator, the first refrigerator, the second refrigerator and the flushing channel form a cold shock circuit; a first heating machine and a second heating machine connected in series, a second control valve is provided between the two, used to control the timing and flow rate of the medium flowing from the second heating machine into the first heating machine, the first heating machine, the second heating machine and the flushing channel form a thermal shock circuit. The present invention controls the input and output of the flushing medium by setting a multi-stage cooling / heating mechanism, separates the reflux medium from the flushing medium, and realizes the alternating stable flushing of the medium below ‑20°C and the medium above 80°C, without causing temperature instability due to the influence of the reflux medium.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell plate detection, and in particular to a high and low temperature thermal shock testing device and method for a hydrogen fuel cell. Background Art

[0002] Hydrogen fuel cell bipolar plates are key components of hydrogen fuel cell stacks, and the main application scenarios of hydrogen fuel cell stacks are hydrogen fuel cell vehicles. During the use of hydrogen fuel cells, a large amount of heat will be generated due to the redox reaction of hydrogen and oxygen. Generally, the temperature during normal use is 50-70 degrees Celsius, and the peak temperature may exceed 90 degrees Celsius. This is mainly related to the different operating modes of hydrogen fuel cells. If it is a continuous and stable operation, the temperature is relatively stable, and a large amount of heat will be generated in a short time during the start and acceleration of the car. Therefore, the bipolar plate needs to be resistant not only to high temperatures, but also to temperature shocks, that is, large temperature changes in a short period of time. In addition, due to the vast land area of ​​my country, spanning multiple latitudes, and the obvious climate differences between the north and the south, hydrogen fuel cells will face the problem of cold start during use, that is, starting at -45 to -30°C. During this process, the temperature in the stack will quickly change from -30°C to 80°C. This process is a relatively large test for the key components of the fuel cell stack. During the product development process, it is necessary to switch between cold and hot media in a short period of time to conduct impact tests on the stack, so as to evaluate the stack's ability to withstand cold and hot shocks.

[0003] The hot and cold shock test requires that solutions at -20℃ or below and media at 80℃ or above be alternately added to the fuel cell stack and flushed for a period of time, which is generally 3 to 5 minutes. Because it is an alternating flushing, the hot medium is switched after the cold medium is flushed. Since the temperature of the tested sample is relatively low, the temperature of the hot medium will drop before entering the test sample (heat is neutralized in the transport channel, the channel where hot and cold meet); similarly, after the hot medium is flushed, the high temperature of the entire system causes the cold medium to heat up before entering the test sample, so the desired hot and cold flushing effect cannot be achieved.

[0004] In view of this, it is necessary to propose a new technical solution to solve the above technical problems. Summary of the invention

[0005] The purpose of the present invention is to provide a high and low temperature thermal shock testing device and method for hydrogen fuel cells. By setting up multi-stage cooling / heating, the system controls the input and output of the flushing medium, separates the reflux medium from the flushing medium, and realizes alternating and stable flushing of the medium at -20°C and below and the medium at 80°C and above, without causing temperature instability due to the influence of the reflux medium.

[0006] To achieve the above purpose, the present invention adopts the following technical means:

[0007] A first aspect of the present invention provides a high and low temperature thermal shock test device for a hydrogen fuel cell, comprising:

[0008] A flushing channel, comprising an inlet end, an outlet end and a clamp connected between the inlet end and used for clamping a sample to be tested;

[0009] A first refrigerator and a second refrigerator are connected in series, the other end of the first refrigerator is connected to the outlet end of the flushing channel, and the other end of the second refrigerator is connected to the inlet end of the flushing channel; the first refrigerator, the second refrigerator and the flushing channel form a cold shock circuit;

[0010] A first heating machine and a second heating machine connected in series, the other end of the first heating machine is connected to the outlet end of the flushing channel, and the other end of the second heating machine is connected to the inlet end of the flushing channel; the first heating machine, the second heating machine and the flushing channel form a thermal shock circuit;

[0011] Wherein, the cold shock circuit is connected in parallel with the hot shock circuit, and the cold shock circuit and the hot shock circuit are provided with a plurality of valves;

[0012] A first control valve is provided between the first refrigerator and the second refrigerator, and the first control valve is used to control the timing and flow rate of the medium flowing from the second refrigerator into the first refrigerator;

[0013] A second control valve is provided between the first heating machine and the second heating machine, and the second control valve is used to control the timing and flow rate of the medium flowing from the second heating machine into the first heating machine.

[0014] As a further improvement, an air pump is also included, and the air pump is connected to the inlet end of the flushing channel.

[0015] As a further improvement, the two ends of the compensation pump are respectively connected to the return ends of the cold shock circuit and the hot shock circuit.

[0016] As a further improvement, a temperature sensor is provided at the inlet end of the flushing channel.

[0017] A second aspect of the present invention provides a method for performing an impact test using the device as described above, characterized in that it comprises the following steps:

[0018] The sample to be tested is clamped on the fixture of the flushing channel, and then cold flushing and hot flushing are performed alternately;

[0019] The single duration of the cold flushing and the hot flushing is 1-10 minutes, and the time interval between the cold flushing and the hot flushing does not exceed 10 seconds.

[0020] As a further improvement, the cold shock comprises the following steps:

[0021] After the refrigerated medium is cooled by the first refrigerator, the first control valve is opened to allow the medium to flow into the second refrigerator for secondary cooling.

[0022] Alternatively, after the reflux medium flows into the first refrigerator, the first control valve is opened to control the flow rate of the medium flowing into the second refrigerator, and the primary refrigeration and the secondary refrigeration are carried out simultaneously.

[0023] As a further improvement, the thermal shock comprises the following steps:

[0024] After the refluxed medium is heated by the first heating machine, the second control valve is opened to allow the medium to flow into the second heating machine for secondary heating.

[0025] Alternatively, after the reflux medium flows into the first heating machine, the second control valve is opened to control the flow of the medium into the second heating machine, and the primary heating and the secondary heating are performed simultaneously.

[0026] As a further improvement, the following steps are also included:

[0027] In the interval between the cold flushing and the hot flushing, the flushing channel is purged using an air pump.

[0028] As a further improvement, the following steps are also included:

[0029] The compensation pump is controlled to allow the medium to flow from the hot shock circuit into the cold shock circuit, so that the amount of the medium participating in the shock test of the two circuits is kept balanced.

[0030] As a further improvement, within the cold flushing time T, the first heating machine and the second heating machine work for time T / 2 respectively; within the hot flushing time T, the first refrigerator and the second refrigerator work for time T / 2 respectively.

[0031] Compared with the prior art, the present invention brings the following technical effects:

[0032] The present invention sets a cold shock circuit and a hot shock circuit in parallel at both ends of the flushing channel, wherein the cold shock circuit sets a first refrigerator and a second refrigerator in series, and a first control valve is set between the two; the hot shock circuit sets a first heating machine and a second heating machine in series, and a second control valve is set between the two; when performing a cold shock, the reflux medium is heated by the sample to be tested and the flushing channel, and the temperature of this part of the medium is firstly refrigerated in the first refrigerator. When the temperature of the medium reaches a preset temperature, the first control valve is opened, and the medium is allowed to flow into the second refrigerator for secondary refrigeration. At this time, the temperature is almost the same as the initial temperature, thereby ensuring that the medium entering the flushing channel always maintains a low temperature; the principle of the hot shock process is similar to that of the cold shock, thereby ensuring that the medium entering the flushing channel always maintains a high temperature. Such a cycle can ensure that the temperature mutation situation to which the sample to be tested is subjected during the cold and hot alternating shock test is consistent with the real scene, thereby ensuring the credibility of the test result. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 It shows a schematic structural diagram of a high and low temperature thermal shock test device for a hydrogen fuel cell according to a preferred embodiment of the present invention;

[0035] Figure 2 A schematic diagram showing the change in measured temperature of the medium in the first refrigerator and the second refrigerator over time during the cold flushing process of the present invention is shown. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0038] Embodiment 1

[0039] See also Figure 1 The present invention provides a high and low temperature thermal shock test device for a hydrogen fuel cell. The sample to be tested is a hydrogen fuel cell stack, and the medium used in the shock test is antifreeze.

[0040] The device includes:

[0041] The flushing channel 10 includes an inlet end, an outlet end, and a clamp 11 connected between the inlet end and the outlet end for clamping the sample to be tested;

[0042] A first refrigerator and a second refrigerator are connected in series, the other end of the first refrigerator is connected to the outlet end of the flushing channel 10, and the other end of the second refrigerator is connected to the inlet end of the flushing channel 10; the first refrigerator, the second refrigerator and the flushing channel 10 form a cold shock circuit; a first control valve 5 is provided between the first refrigerator and the second refrigerator, and the first control valve 5 is used to control the timing and flow rate of the medium flowing from the second refrigerator into the first refrigerator;

[0043] The first heating machine and the second heating machine are connected in series, the other end of the first heating machine is connected to the outlet end of the flushing channel 10, and the other end of the second heating machine is connected to the inlet end of the flushing channel 10; the first heating machine, the second heating machine and the flushing channel 10 form a thermal shock circuit; a second control valve 6 is provided between the first heating machine and the second heating machine, and the second control valve 6 is used to control the timing and flow rate of the medium flowing from the second heating machine to the first heating machine.

[0044] The cold shock circuit is connected in parallel with the hot shock circuit, and the cold shock circuit and the hot shock circuit are provided with a plurality of valves. Specifically, the cold shock circuit is provided with a valve 1 on the pipeline near the inlet end of the flushing channel 10, and a valve 2 on the pipeline near the outlet end of the flushing channel 10; the hot shock circuit is provided with a valve 3 on the pipeline near the inlet end of the flushing channel 10, and a valve 4 on the pipeline near the outlet end of the flushing channel 10.

[0045] It should be noted that the above-mentioned refrigerator, heater, valve, etc. are all connected to a controller and can operate normally under the unified control of the controller. This is the existing technology and there is no need to elaborate.

[0046] After the sample to be tested is clamped on the fixture 11, the hot and cold alternating shock test can be started. During the cold flushing, valves 1 and 2 are kept open, and valves 3 and 4 are kept closed. During the hot shock test, valves 3 and 4 are kept open, and valves 1 and 2 are kept closed.

[0047] Taking cold flushing as an example, the flow direction, temperature change and other details of the medium in the impact circuit of this embodiment are described in detail.

[0048] See also Figure 2, which shows a schematic diagram of the measured temperature change of the medium in the first refrigerator and the second refrigerator over time during the cold flushing process of the present invention. Specifically in this embodiment, a temperature sensor 9 is provided at the inlet end of the flushing channel 10, and the temperature of the medium in each refrigerator can also be monitored in real time by providing a temperature sensor.

[0049] The -40℃ cold medium flows out from the second refrigerator, and the medium after flushing the battery stack will return to the first refrigerator instead of flowing directly into the second refrigerator. Specifically, in this process, cold flushing starts at 0s, and the cold medium is output from the second refrigerator. Since the reflux medium will not flow directly into the second refrigerator, the medium temperature in the second refrigerator will remain stable and the liquid volume will gradually decrease. In this process, both the first refrigerator and the second refrigerator are not working. When it switches to hot flushing after 300s, all the reflux medium is stored in the first refrigerator and continuous cooling begins. The medium temperature in the first refrigerator decreases linearly. This process lasts for 150s. At 450s, the medium temperature in the first refrigerator drops to about -15℃. At this time, the first control valve 5 is opened to transport the same amount of medium as the reflux medium to the second refrigerator and start the second refrigerator. Since the second refrigerator receives liquid with a higher temperature than itself, the overall temperature will rise. As the second refrigerator continues to cool, the temperature will gradually decrease and stabilize. At 600 seconds, the medium in the second refrigerator will be maintained at a temperature of about -30°C to -40°C, and then the next cold flush will begin.

[0050] The above is a description of the cold flushing process. The hot flushing process is similar:

[0051] The 80℃ hot medium flows out from the second heater, and after flushing the stack, the medium will return to the first heater instead of flowing directly into the second heater. Specifically, in this process, hot flushing starts at 300s, and the hot medium is output from the second heater. Since the reflux medium will not flow directly into the second heater, the medium temperature in the second heater will remain stable and the liquid volume will gradually decrease. In this process, both the first heater and the second heater do not work. After 600s, when it switches to cold flushing, all the reflux medium is stored in the first heater and continuous heating begins. The medium temperature in the first heater rises linearly. This process lasts for 150s. At 750s, the medium temperature in the first heater rises to about 60℃. At this time, the second control valve 6 is opened to transport the same amount of medium as the reflux medium to the second heater and start the second heater. Since the second heater receives a liquid with a lower temperature than itself, the overall temperature will decrease. As the second heater continues to heat, the temperature will gradually rise and stabilize. At 900s, the medium in the second heating machine will be maintained at a temperature of about 70°C to 80°C, and then the next thermal flush will begin.

[0052] This cycle realizes hot and cold alternating flushing. Specifically in this embodiment, the entire hot and cold alternating flushing cycle is 1000 rounds (cold flushing + hot flushing is one round). Capture the first 750 seconds of the flushing process and record the actions of various valves, refrigerators, heaters and other instruments and related parameter information as shown in the following table:

[0053]

[0054]

[0055] It should be noted that, in this embodiment, the volume of the output medium in each refrigerator is greater than 24L, and the capacity of the refrigerator is greater than or equal to 36L (the capacity is calculated as 150% of the medium volume), and the volume of the output medium in each heating machine is greater than 24L, and the capacity of the heating machine is greater than or equal to 36L (the capacity is calculated as 150% of the medium volume). The output flow rate recorded in the above table refers to the net output flow rate.

[0056] In this embodiment, a cold shock circuit and a hot shock circuit are arranged in parallel at both ends of the flushing channel 10, wherein the cold shock circuit is provided with a first refrigerator and a second refrigerator connected in series, and a first control valve 5 is arranged between the two; the hot shock circuit is provided with a first heating machine and a second heating machine connected in series, and a second control valve 6 is arranged between the two; when performing a cold shock, the reflux medium is heated by the sample to be tested and the flushing channel 10, and the part of the medium is firstly cooled in the first refrigerator, and when the temperature of the medium reaches a preset temperature, the first control valve 5 is opened, and then the medium is allowed to flow into the second refrigerator for secondary cooling. At this time, the temperature is almost the same as the initial temperature, thereby ensuring that the medium entering the flushing channel 10 always maintains a low temperature; the principle of the hot shock process is similar to that of the cold shock, thereby ensuring that the medium entering the flushing channel 10 always maintains a high temperature, and such a cycle can ensure that the temperature mutation situation of the sample to be tested during the cold and hot alternating shock test is consistent with the real scene, thereby ensuring the credibility of the test result.

[0057] In a preferred embodiment, the device further comprises an air pump 8, which is connected to the inlet end of the flushing channel 10. The function of the air pump 8 is to purge the flushing channel 10 during the interval of alternating cold and hot, and remove the residual medium in the channel to reduce the temperature impact of the residual medium on the next flushing process. In this embodiment, the time interval between the cold shock and the hot shock does not exceed 10 seconds, and the air pump 8 needs to complete the purge action within 10 seconds.

[0058] In a preferred embodiment, the device further comprises a compensation pump 7, and the two ends of the compensation pump 7 are respectively connected to the heat shock circuit and the return end of the heat shock circuit. The purpose of this setting is that the flushing medium is antifreeze, and under low temperature conditions, the transmission resistance increases. During the process of alternating hot and cold flushing, since the inlet and outlet are switched at the same time, there will be a phenomenon of antifreeze accumulating in the heat shock circuit, so it is necessary to transfer it to prevent the heating machine from overflowing due to the inability to fit, especially when the flushing time is long. The compensation pump 7 can be set to timely transfer the antifreeze in the heat shock circuit to the cold shock circuit, thereby ensuring that the medium of the two circuits remains balanced.

[0059] Embodiment 2

[0060] This embodiment is suitable for working conditions where the single flushing time is long and the flushing flow rate is large, and the single output medium volume (storage volume of cold medium and hot medium) of the second refrigerator and the second heating machine is less than the medium volume required for flushing within the cycle (the capacity of the second refrigerator and the second heating machine is less than 150% of the medium volume required for a single flushing).

[0061] In this embodiment, no matter in the cold flushing process or the hot flushing process, the first control valve 5 and the second control valve 6 always remain in the open state, that is, the reflux medium will directly flow into the second refrigerator or the second heating machine. By controlling the opening and closing size of the first control valve 5 and the second control valve 6, the flow rate of the reflux medium entering the second refrigerator or the second heating machine is smaller than the output flow rate of the corresponding machine, thereby achieving the purpose of the invention.

[0062] Specifically in this embodiment, the entire cold and hot alternating flushing cycle is 1000 rounds (cold flushing + hot flushing is one round), and the first 25 minutes of the flushing process are captured to record the actions of various valves, refrigerators, heaters and other instruments and related parameter information as shown in the following table:

[0063]

[0064] It should be noted that, in this embodiment, the volume of the output medium in each refrigerator is greater than 50L, the capacity of the first refrigerator is greater than or equal to 100L, and the capacity of the second refrigerator is greater than or equal to 75L (the capacity is calculated as 150% of the medium volume); the volume of the output medium in each heating machine is greater than 50L, the capacity of the first refrigerator is greater than or equal to 100L, and the capacity of the second heating machine is greater than or equal to 75L (the capacity is calculated as 150% of the medium volume), and the output flow rate recorded in the above table refers to the net output flow rate.

[0065] In this embodiment, a thermal shock circuit and a cold shock circuit are arranged in parallel at both ends of the flushing channel 10, wherein the cold shock circuit is provided with a first refrigerator and a second refrigerator connected in series, and a first control valve 5 is arranged between the two; the thermal shock circuit is provided with a first heating machine and a second heating machine connected in series, and a second control valve 6 is arranged between the two; when performing a cold shock, the reflux medium is heated by the sample to be tested and the flushing channel 10, and the part of the medium is firstly cooled in the first refrigerator, and at the same time, the first control valve 5 is opened and the flow rate is adjusted to half of the output flow rate of the second refrigerator. After flushing for a period of time (the time is less than the time of the cold flushing cycle), the temperature of the medium in the first refrigerator approaches the set temperature due to the neutralization of the medium temperature and continuous cooling. At this time, the first control valve 5 is increased and the flow rate is adjusted, and after the cold flushing is completed, the medium is continuously transported from the first refrigerator to the second refrigerator to ensure the amount of the medium in the second refrigerator. The flushing process can ensure that the medium entering the flushing channel 10 always maintains a low temperature; the principle of the thermal shock process is similar to that of the thermal shock, thereby ensuring that the medium entering the flushing channel 10 always maintains a high temperature. Such a cycle can ensure that the temperature mutation conditions to which the sample to be tested is subjected during the thermal alternating shock test are consistent with the actual scenario, thereby ensuring the credibility of the test results.

[0066] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom still fall within the scope of protection of the present invention.

Claims

1. A high and low temperature thermal shock test device for hydrogen fuel cells, characterized in that: include: A flushing channel, comprising an inlet end, an outlet end and a clamp connected between the inlet end and used for clamping a sample to be tested; A first refrigerator and a second refrigerator are connected in series, the other end of the first refrigerator is connected to the outlet end of the flushing channel, and the other end of the second refrigerator is connected to the inlet end of the flushing channel; the first refrigerator, the second refrigerator and the flushing channel form a cold shock circuit; A first heating machine and a second heating machine connected in series, the other end of the first heating machine is connected to the outlet end of the flushing channel, and the other end of the second heating machine is connected to the inlet end of the flushing channel; the first heating machine, the second heating machine and the flushing channel form a thermal shock circuit; Wherein, the cold shock circuit is connected in parallel with the hot shock circuit, and the cold shock circuit and the hot shock circuit are provided with a plurality of valves; A first control valve is provided between the first refrigerator and the second refrigerator, and the first control valve is used to control the timing and flow rate of the medium flowing from the second refrigerator into the first refrigerator; A second control valve is provided between the first heating machine and the second heating machine, and the second control valve is used to control the timing and flow rate of the medium flowing from the second heating machine into the first heating machine.

2. The high and low temperature thermal shock test device for hydrogen fuel cells according to claim 1, characterized in that: An air pump is also included, and the air pump is connected to the inlet end of the flushing channel.

3. The high and low temperature thermal shock test device for hydrogen fuel cells according to claim 1, characterized in that: It also includes that two ends of the compensation pump are respectively connected to the return ends of the cold shock circuit and the hot shock circuit.

4. The high and low temperature thermal shock test device for hydrogen fuel cells according to claim 1, characterized in that: A temperature sensor is provided at the inlet end of the flushing channel.

5. A method for performing an impact test using the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: The sample to be tested is clamped on the fixture of the flushing channel, and then cold flushing and hot flushing are performed alternately; The single duration of the cold flushing and the hot flushing is 1-10 minutes, and the time interval between the cold flushing and the hot flushing does not exceed 10 seconds.

6. The high and low temperature thermal shock test method for a hydrogen fuel cell according to claim 5, characterized in that: The cold shock comprises the following steps: After the refrigerated medium is cooled by the first refrigerator, the first control valve is opened to allow the medium to flow into the second refrigerator for secondary cooling. Alternatively, after the reflux medium flows into the first refrigerator, the first control valve is opened to control the flow rate of the medium flowing into the second refrigerator, and the primary refrigeration and the secondary refrigeration are carried out simultaneously.

7. The high and low temperature thermal shock test method for a hydrogen fuel cell according to claim 5 or 6, characterized in that: The thermal shock comprises the following steps: After the refluxed medium is heated by the first heating machine, the second control valve is opened to allow the medium to flow into the second heating machine for secondary heating. Alternatively, after the reflux medium flows into the first heating machine, the second control valve is opened to control the flow of the medium into the second heating machine, and the primary heating and the secondary heating are performed simultaneously.

8. The high and low temperature thermal shock test method for a hydrogen fuel cell according to claim 5, characterized in that: The method further comprises the following steps: using an air pump to purge the flushing channel during an interval between the cold flushing and the hot flushing.

9. The high and low temperature thermal shock test method for a hydrogen fuel cell according to claim 5, characterized in that: The following steps are also included: controlling the compensation pump to allow the medium to flow from the hot shock circuit into the cold shock circuit, so that the amount of the medium participating in the shock test of the two circuits is kept balanced.

10. The high and low temperature thermal shock test method for a hydrogen fuel cell according to claim 5, characterized in that: During the cold flushing time T, the first heating machine and the second heating machine work for a time T / 2 respectively; during the hot flushing time T, the first refrigerator and the second refrigerator work for a time T / 2 respectively.

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