Microscopic leakage rate prediction method for sealing interface of hydrogen fuel cell

Abstract

The invention relates to a method for predicting the microcosmic leakage rate of a sealing interface of a hydrogen fuel cell. The method comprises the following steps: 1) establishing a microcosmic contact pair model of the sealing interface of the hydrogen fuel cell with random characteristics through a G-W surface topography description model; 2) carrying out a sealing compression numerical simulation experiment on the hydrogen fuel cell sealing interface microscopic contact pair model to simulate a pre-tightening load and a compression state of a sealing element in an assembling process of a hydrogen fuel cell, and thus obtaining a microscopic gap between contact pairs after the sealing compression numerical simulation experiment, namely a fluid leakage region; and 3) carrying out a gas flow leakage simulation experiment on the fluid leakage region, simulating gas leakage of the sealing interface of the hydrogen fuel cell, and obtaining the leakage rate of the microcosmic sealing unit of the sealing interface of the hydrogen fuel cell. Compared with the prior art, the method has the advantages of high interface microstructure expression precision, short fluid mechanics simulation period, low cost, intuition, easiness in observation and the like.

Description

technical field [0001] The invention relates to the field of hydrogen fuel cell seal detection, in particular to a hydrogen fuel cell leakage rate calculation and prediction method that takes into account the characteristics of the random surface topography of the sealing interface and the principle of compression and gas flow of the seal on a microscopic scale. Background technique [0002] With the increasingly serious problems of environmental pollution and energy security, it is imminent to find alternative energy sources for fossil fuels. Hydrogen energy is regarded as "future energy" because of its high efficiency, cleanliness, economy, and safety. Fuel cells are the means to release hydrogen energy. The main place is a generating device that converts internal energy into electrical energy; it is the fourth largest power generation technology after hydropower, thermal power, and atomic power, and is considered to be the first choice for clean and efficient power generat...

AI Technical Summary

Problems solved by technology

[0004] Leakage affects the performance and safety of the entire hydrogen fuel stack, and is an important indicator for judging whether the stack can work safely and effectively. As an essential reaction gas for hydrogen fuel cells, hydrogen has a small molecular structure, light weight, and lively properties. Features, once a leak occurs, the hydrogen will be lost from the reaction space quickly, the pressure of the anode gas of the hydrogen fuel cell will drop rapidly, and the efficiency of the stack will decrease until it fails; and hydrogen is very flammable and explosive, and it is likely to become a combustion gas after it leaks out. , explosion and other hazards, directly endangering production safety

[0005] Hydrogen fuel cell cells have the output characteristics of "high current, low voltage". In order to make them suitable for practical engineering use, generally 300-500 single cells are connected in series to form a stack. For the whole stack system, its series characteristics determine If there is a problem with any one component, the electrical efficiency of the whole stack will be greatly reduced or even shut down due to failure. However, there are hundreds of thousands of sealing surfaces in a hydrogen fuel cell stack, and any leakage or intrusion of any sealing surface will seriously affect The electrical efficiency of the whole stack may even cause vicious safety accidents such as fire and explosion

[0006] To sum up, it can be seen that it is particularly important to predict the sealing performance of hydrogen fuel cells. Unstable, the parameters such as the shape and size of the gas leakage channel become difficult to predict, which greatly reduces the accuracy of the hydrogen fuel cell leakage rate model

[0007] In industrial production, special leak detection equipment is used to measure the leakage rate of the entire stack of hydrogen fuel cells. These leak detection devices are generally heavy and bulky, and can only be fixed somewhere. It is difficult to carry out leak detection on the spot in real time when there is a leak; secondly, in order to obtain an accurate leak rate, it is necessary to ensure that the stack and the leak detection equipment are in normal operation for a long time at the same time, which has a long cycle and is easily disturbed by external factors; furthermore, the hydrogen fuel cell When the leakage rate is actually measured, the leak detection equipment must work together with systems such as air supply, humidification, cooling, dust prevention, and post-processing. When the working conditions of the stack are unstable and the external load changes greatly, the shortcomings of poor flexibility and low efficiency of this traditional leak detection system will become more obvious, and this leak detection method for the entire stack of hydrogen fuel cells, It is impossible to specifically identify the leakage point, let alone predict and control the leakage rate from the perspective of practicality and safety

[0008] In theoretical research, the current hydrogen fuel cell seal leakage rate calculation model is mainly derived from traditional mechanical seal leakage theory, including parallel plate gap flow theory, surface fractal theory, Persson rough surface penetration theory, Lattice Boltzmann Method (Lattice Boltzmann Method, LBM) and Greenwood-Williamson (hereinafter referred to as G-W) random contact surface contact models are more commonly used. Through the theoretical prediction model of hydrogen fuel cell leakage rate, the leakage rate under different working conditions and time points can be obtained. The actual measurement method, the theoretical calculation method has a short cycle, low cost, and is easy to change the boundary conditions and implement flexibly. However, the prediction results of the leakage rate of the above-mentioned hydrogen fuel cell leakage calculation models are quite different and cannot be unified, and the leakage rate calculation models are mostly composed of mathematical methods. It is deduced that the relationship between it and the macroscopic method is not close enough. Most importantly, there is a huge scale difference between the macroscopic leak rate measurement method used in the project and the microscopic calculation results of the theoretical model, and it is difficult for the two to fit and verify each other. difficulty

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