Study on Dynamic Pressure Effect of Gas Bearings in Fuel Cell Vehicles

2021 ◽  
Author(s):  
Chenxin ZHANG ◽  
Weirong Hong ◽  
Shuiying Zheng
Keyword(s):  
Fuel Cell ◽  
Pressure Effect ◽  
Dynamic Pressure ◽  
Fuel Cell Vehicles ◽  
Gas Bearings

scholarly journals Study on dynamic characteristics of gas films of spherical spiral groove hybrid gas bearings

2019 ◽  
Vol 233 (8) ◽  
pp. 1169-1181
Author(s):  
Chenhui Jia ◽  
Haijiang Zhang ◽  
Shijun Guo ◽  
Ming Qiu ◽  
Wensuo Ma ◽  
...  
Keyword(s):  
Pressure Effect ◽  
Dynamic Pressure ◽  
Iteration Algorithm ◽  
Unstable State ◽  
Gas Bearings ◽  
Damping Coefficients ◽  
The Stability ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Gas Bearing

According to the gas film force variation law, when the bearing axis is slightly displaced from the static equilibrium position, displacement and velocity disturbance relation expressions for the gas film force increment are constructed. Moreover, combined with the bearing rotor system motion equation, calculation model equations for the gas film stiffness and damping coefficients are established. The axial and radial vibration and velocity of the gas bearings during operation are collected. The instantaneous stiffness and damping coefficients of the gas film are calculated by the rolling iteration algorithm using MATLAB. The dynamic changes in the gas film stiffness and damping under different motion states are analyzed, and the mechanism of the gas film vortex and oscillation is studied. The results demonstrate the following: (1) When the gas bearing is running in the linear steady state in cycle 1, the dynamic pressure effect is enhanced and the stability is improved by increasing the eccentricity; when the gas supply pressure is increased, the static pressure effect is enhanced and the gas film vortex is reduced, but the oscillation is strengthened. (2) With the increase in rotational speed, the gas film vortex force gradually exceeds the gas film damping force, and the stability gradually worsens, causing a fluctuation in the gas film stiffness and damping, following which singularity occurs and a half-speed vortex is formed. Meanwhile, the gas film oscillation is intensified, and the rotor enters the nonlinear stable cycle 2 state operation. (3) As the fluctuation of the film force increases, the instantaneous stiffness and damping oscillation of the film intensifies, most of the stiffness and damping coefficients exhibit distortion, and the rotor operation will enter a chaotic or unstable state. Therefore, the gas bearing stiffness and damping variation characteristics can be used to study and predict the gas bearing operating state. Finally, measures for reducing the vortex and oscillation of the gas film and improving the stability of the gas bearing operation are proposed.

Study on Dynamic Pressure Effect of Gas Bearings in Fuel Cell Vehicles

2020 ◽  
Author(s):  
Chenxin Zhang ◽  
Weirong Hong ◽  
Shuiying Zheng
Keyword(s):  
Numerical Simulation ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Performance Test ◽  
Pressure Effect ◽  
Dynamic Pressure ◽  
Simulation Method ◽  
Dynamic Mesh ◽  
Gas Bearings ◽  
Cfd Numerical Simulation

Abstract The dynamic pressure effect can contribute to a better working performance of the gas bearing without changing its overall structure or increase its air supply pressure. To study the dynamic pressure effect of gas bearings, a new method of CFD numerical simulation with self-developed UDF dynamic mesh program was proposed. In this way, values of dynamic characteristics for gas bearings with different fluid fields and under different working conditions can be calculated. Based on the numerical simulation results, the influence law of rotational speed, gas film thickness, and radial eccentricity ratio on the dynamic characteristics (load-carrying capacity, stiffness and damping coefficients, static equilibrium position etc.) were obtained. Afterwards, a bearing’s performance test was conducted on a rotor-bearing system in the high-speed air compressor. Compared to the traditional methods, after the dynamic pressure effect was taken into account, the corresponding rotor dynamic calculation of critical speed is more in accordance with the experimental results, thus proved the credibility of the new CFD numerical simulation method with dynamic mesh.

Sensing advancement towards safety assessment of hydrogen fuel cell vehicles

2021 ◽  
Vol 489 ◽  
pp. 229450
Author(s):  
Sahar Foorginezhad ◽  
Masoud Mohseni-Dargah ◽  
Zahra Falahati ◽  
Rouzbeh Abbassi ◽  
Amir Razmjou ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Safety Assessment ◽  
Fuel Cell Vehicles ◽  
Hydrogen Fuel Cell ◽  
Hydrogen Fuel ◽  
Hydrogen Fuel Cell Vehicles

Catalyst boosts prospects for fuel-cell vehicles

2021 ◽  
Vol 99 (3) ◽  
pp. 4-4
Author(s):  
Mark Peplow, special to C&EN
Keyword(s):  
Fuel Cell ◽  
Fuel Cell Vehicles

scholarly journals A Review of Hydrogen Purification Technologies for Fuel Cell Vehicles

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Zhemin Du ◽  
Congmin Liu ◽  
Junxiang Zhai ◽  
Xiuying Guo ◽  
Yalin Xiong ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Emission ◽  
High Efficiency ◽  
Impurity Content ◽  
Fuel Cell Vehicle ◽  
Research Progress ◽  
Hydrogen Purification ◽  
Fuel Cell Vehicles ◽  
Low Carbon

Nowadays, we face a series of global challenges, including the growing depletion of fossil energy, environmental pollution, and global warming. The replacement of coal, petroleum, and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2) energy is considered the ultimate energy in the 21st century because of its diverse sources, cleanliness, low carbon emission, flexibility, and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission, they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops, H2 fuel supply, especially H2 quality, attracts increasing attention. Compared with H2 for industrial use, the H2 purity requirements for fuel cells are not high. Still, the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore, we analyze the causes and developing trends for the changes in these standards in detail. On the other hand, according to characteristics of H2 for fuel cell vehicles, standard H2 purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed.

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