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ABSTRACT
The gas-water separator is an important auxiliary component of the hydrogen recirculation subsystem for the proton exchange membrane fuel cell (PEMFC) system. This study investigated three baffle separators with different structures used for a 75 kW PEMFC system by computational fluid dynamics (CFD) simulation and experimental validation. An Euler-Lagrange two-phase simulation model was established to investigate the gas-phase flow characteristics and the droplets trajectory and film distribution in separators. Moreover, an experimental bench was set up to test the overall performance of the separators. The results showed that the CFD model can predict the performance of the gas-water separator accurately. Through the comparison of air and mixed hydrogen, it was found that the density of the gas phase fluid has a great influence on the pressure drop. The local gas flow at the baffle bottom where the film fall directly is at high velocity in separator A, resulting in that the liquid film is broken easily to cause more fine droplets being entrained again into the outflow. Besides, thicker liquid film still formed in the top part of the separators A and B compared with separator C, which is not conducive for high separation performance. Thus, the separator C is preferred to be suggested for PEMFC systems.
Nomenclature
| A | = | Area, m2 |
| c | = | Liquid phase concentration, kg/m2 |
| m | = | Mass flow rate, kg/s |
| md | = | Droplet mass, kg/s |
| P | = | Operating power of the fuel cell stack, kW |
| p | = | Pressure, Pa |
| SR | = | Stoichiometric ratio of the fuel cell stack |
| Greek symbols | = | |
| ρ | = | Density, kg/s |
| ρl | = | Liquid density, kg/s |
| = | Separation efficiency | |
| Subscripts | = | |
| d | = | Droplet |
| in | = | Inlet of the separator |
| l | = | Liquid phase |
| out | = | Outlet of the separator |
| H2 | = | Hydrogen |
| Abbreviations | = | |
| CFD | = | Computational fluid dynamics |
| DPM | = | Discrete phase model |
| EWF | = | Euler Wall Film |
| PEMFC | = | Proton exchange membrane fuel cell |
Declaration of interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.