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GB/T 38914-2020 English PDF (GBT38914-2020)

GB/T 38914-2020 English PDF (GBT38914-2020)

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GB/T 38914-2020: Evaluation method for lifetime of proton exchange membrane fule cell stack in vehicle application

This standard specifies the test and calculation method of the lifetime of the proton exchange membrane fuel cell stack in vehicle application. This standard applies to the test and evaluation of the lifetime of the proton exchange membrane fuel cell stack for road vehicles and non-road vehicles. Note: This standard does not consider the impact of the difference in ambient air quality between the laboratory and the road.
GB/T 38914-2020
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.070
K 82
Evaluation method for lifetime of proton exchange
membrane fuel cell stack in vehicle application
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Test equipment and conditions ... 5
4.1 Test object ... 5
4.2 Test platform and test object installation ... 6
4.3 Test environment and basic requirements ... 7
4.4 Special requirements ... 7
5 Test method of lifetime ... 8
5.1 General ... 8
5.2 Activation, testing and stability assessment ... 8
5.3 Test based on working conditions ... 10
5.4 Power generation performance test at the end of lifetime test ... 17 5.5 Determination of the cycle condition spectrum ... 17
5.6 Performance decay rate and calculation of fuel cell?€?s lifetime ... 18 6 Evaluation report ... 19
References ... 21
Evaluation method for lifetime of proton exchange
membrane fuel cell stack in vehicle application
1 Scope
This standard specifies the test and calculation method of the lifetime of the proton exchange membrane fuel cell stack in vehicle application.
This standard applies to the test and evaluation of the lifetime of the proton exchange membrane fuel cell stack for road vehicles and non-road vehicles. Note: This standard does not consider the impact of the difference in ambient air quality between the laboratory and the road.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.
GB/T 20042.1 Proton exchange membrane fuel cell - Part 1: Terminology
GB/T 23645-2009 Test methods of fuel cell power system for passenger cars GB/T 28183-2011 Test methods of fuel cell power system for bus
GB/T 29838-2013 Fuel cell modules
GB/T 36288-2018 Fuel cell electric vehicles - Safety requirement of fuel cell stack
GB/T 37244-2018 Fuel specification for proton exchange membrane fuel cell vehicles - Hydrogen
3 Terms and definitions
The terms and definitions as defined in GB/T 20042.1, GB/T 23645-2009, GB/T 28183-2011, GB/T 29838-2013 as well as the following terms and definitions apply to this document.
3.1
Idling current
The output current of the tested fuel cell stack corresponding to the fuel cell stack of the on-board fuel cell system under idling conditions. Under this current, the fuel cell stack can maintain the fuel cell system itself for a certain period of time, without outputting power externally.
3.2
Rated current
The output current of the tested fuel cell stack corresponding to the fuel cell stack of the on-board fuel cell system under the rated operating conditions. Under this current, the fuel cell stack can maintain operation for a certain period of time.
3.3
Reference current condition
Working conditions based on a specific current in the evaluation of the lifetime of fuel cell.
3.4
Operation mode cycle
The change history of operating conditions of the fuel cell stack during continuous operation from startup to shutdown of the tested fuel cell stack corresponding to the on-board fuel cell system.
3.5
Lifetime of fuel cell stack in vehicle application
The cumulative usage time of the fuel cell stack from the start of use to the time when the volt-ampere characteristic decays to the specified minimum under the cycle of vehicle operating conditions.
4 Test equipment and conditions
4.1 Test object
The test object is generally a single fuel cell stack or a combination of multiple fuel cell stacks. The tested cell stack, internal membrane electrodes and bipolar average voltage of each segment of fuel cell of 0.70 V after the initial activation is completed;
- Evaluation criteria for the lifetime of fuel cell stacks for vehicle applications: From the start volt-ampere curve to the final volt-ampere curve, the average voltage of each cell of the fuel cell decays by 10% at the reference current. 5 Test method of lifetime
5.1 General
It is required to complete the following tests in sequence. It shall not adjust the test sequence. Unless otherwise specified. The loading and unloading process is generally completed according to the control method required by the client. When an unexpected shutdown occurs, the fuel cell stack?€?s voltage shall be reduced to below 0.3 V in each segment in time.
The following conditions can be determined as damage to the cell stack or end of lifetime, at this time the lifetime test can be ended:
- The fuel cell stack cannot operate stably;
- The voltage of a fuel cell under rated current is lower than 0.3 V (except for flooding);
- During the test, the volume concentration of hydrogen in the exhaust at the air side of the fuel cell stack is higher than 0.5%.
5.2 Activation, testing and stability assessment
5.2.1 Activation of fuel cell stack
Activate the fuel cell stack according to the method specified by the client. 5.2.2 Test of fuel cell stack performance and determination of current
parameters
After the activation is completed, test the power generation performance of the fuel cell stack. In the test, the fuel cell stack?€?s gas inlet temperature, inlet temperature, inlet pressure, gas supply stoichiometric ratio, coolant
temperature and coolant pressure, etc., are as specified by the client. Power generation performance?€?s test method: At idle speed to the average voltage of each segment of fuel cell of 0.60 V, measure at least 10 operating conditions; record the output current and voltage when each operating condition V?€? cycle2 - Linear fitting of the voltage points of measured reference current condition, in volts per time (V/time);
V' cycle1 - Under variable load conditions, Linear fitting of the measured voltage points, in volts per time (V/time).
5.3.6 Other working conditions
It will refer to the operating conditions with higher frequency extracted from the driving cycle specified by the client in addition to the above-mentioned operating conditions, for example, stable operating conditions such as 60% rated current, 120% rated current, as well as the variable conditions between these conditions.
For the test methods of other stable working condition, it may refer to the cycle test method of the rated working condition; for the test methods of other variable working conditions, it may refer to the cycle test method of variable load conditions.
5.4 Power generation performance test at the end of lifetime
test
Use the same method and test conditions as in 5.2.2 to test the power
generation performance of the fuel cell stack; record the voltage of each segment of fuel cell at the reference current.
5.5 Determination of the cycle condition spectrum
When calculating the lifetime index, it may choose "reference condition spectrum" or "self-defined condition spectrum". "Reference condition spectrum" is used to predict the lifetime of the fuel cell stack under a unified operating condition spectrum condition; "self-defined condition spectrum" is used to predict the lifetime of the fuel cell stack under other condition spectrum as specified by the client.
Reference condition spectrum parameters, including:
?€? Number of start-stop per hour n1 = 1 time;
?€? Loading times per hour n2 = 27 times, each loading process lasts for 30 s, unloading process lasts for 16 s;
?€? Idle running time per hour t1 = 21 min;
?€? Running time at rated operating conditions per hour t2 = 18 min.
U'2 - Voltage change rate of fuel cell as caused by rated conditions, in volt per hour (V/h);
t2 - Running hours at rated condition per hour, in minutes (min).
For more operating conditions, follow the formula (6) to calculate the
performance decay rate A of fuel cell stack:
Where:
V'i - Voltage decay rate of fuel cell stack as caused by other variable operating conditions, in volt per time (V/time);
ni - The number of other variable working conditions per hour, in times per hour (times/h);
U'j - Voltage decay rate of fuel cell stack as caused by other stable operating conditions, in volt per hour (V/h);
tj - Operating time in other stable conditions per hour, in minutes (min). Calculate the lifetime tLf of the fuel cell stack according to formula (7): Where:
tLf - Lifetime of fuel cell stack, in hours (h);
V0 - The initial voltage of the fuel cell stack, in volts (V).
6 Evaluation report
The evaluation report shall include the following:
?€? Cell stack?€?s model;
?€? Test conditions;
?€? Test unit;
?€? Test time;

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