四参数（流道脊部宽度、拔模角、圆角、压缩压强）模型评估计算金属双极板流道和气体扩散层受压下的变形和流阻增加现象

An engineering approach to optimal metallicbipolar plate designs reflecting gas diffusion layer compression effects

Ah－Reum Kim

Hye－Mi Jung

Sukkee Um

Abstract

GDL（Gas diffusion layer） intrusion into gas feeding channels narrows the effectivechannel cross－sectional area and eventually resultsin performance degradation of PEFCs （polymer electrolyte fuel cells）．Therefore， cross－sectional channel design of metallic bipolar plates should beoptimized to resolve this problem． In this study， effects of the cross－sectional configuration of metallic gas channelson pressure drops are numerically investigated for the comprehensive fluiddynamic analysis of channel flow． Multi－physics numerical systems combiningsolid mechanics and fluid dynamics are applied to figure out the GDL behavior．First， static structural analysis is performed to determine elastic deformationof GDLs under clamping forces． Subsequently， computational flow analysis in thedeformed regions is conducted to visualize flow patterns and estimatecorresponding pressure drops． Fourcross－sectional parameters are selected： channel to rib width ratio， draftangle， inner fillet radius and clamping pressure． Results are validatedagainst experimental data． The GDLintrusion is found to be greatly affected by draft angle and channel to ribratio． Cross－sectional area isreduced down to 45％ in the most shrunk channel， leading additional pressuredrop of 0．12 bar． It is suggested that fluid dynamics should be combinedwith solid mechanics for better accuracy in computational fuel cell modeling．

Fig． 1． Schematic diagrams of gas channel  cross－section （a） in a graphite bipolar plate and （b） in a metallic bipolar  plate．

Table 1 Design parameters used for the  analysis of gas diffusion layer intrusion．

遗漏了两个参数，实际脊部宽度尺寸，气体扩散层型号（力学性能、气体渗透特性）

SGL－10 BA was selected experimental  validation．

如果计算流体阻力还有若干参数：气体流量、流道深度、流道材料粗糙度、亲疏水性

Table 2 Mechanical and fluidic properties  for numerical modeling

Fig． 2． Boundary conditions with a  trapezoidal channel－rib geometry

For static analysis， 0．1 mm thick  channels were simulated to figure out the through－plane deformation of GDLs．这句话没有理解，从后面的仿真来看是0．5mm深度，0．1mm深度都小于碳纸的嵌入量。

Fig． 3． （a） Images of GDL intrusion into  channels at CR1， CR2 and CR3 by the experiment， and （b） comparison of  computed and measured penetration depths of GDL．

Fig． 3 shows experimental images of the  GDL intrusion and compares the computed penetration depth of GDLs with  experimental data for the various channel to rib ratios．

关键词：文献同时测量压缩压强、压缩位移、欧姆电阻评估气体扩散层的电阻、厚度、稳态和局部破坏［材料对标其四，设计因素其八］中使用tenting、这里有intrusion和penetration。

嵌入量约为气体扩散层厚度的100％。不知道占流道深度的百分比。

仿真和实际的偏差为8％－10％。

SGL－10 BA was selected experimental  validation．

Fig． 4． （a） Computed y－directional  （through－plane） deformation of GDLs and （b） predicted velocity vector  profiles in the z－direction of the shrunk channel for the reference geometry  case at CR＝1．1：1， 拔模角＝30度， R＝0．15 mm and Pc＝1．848 MPa．

Fig． 5． Computed profiles of pressure  drop and rate of pressure drop variation for various channel to rib ratios．

嵌入对流体阻力仿真的影响比仿真值大340％－530％。

Fig． 6． Average velocity and pressure  drop in the shrunk gas channel for various draft angles．

Fig． 7． Effects of inner fillet radius on  the GDL penetration and the rate of pressure drop variation．

Fig． 8． Predicted velocity vector  profiles for various clamping pressures．

不理解这里的eG代表什么

Fig． 9． Effects of clamping pressure on  the GDL penetration and the rate of pressure drop variation．

Conclusions

The influence of the metallic channel  cross－sectional structure on performance of PEFCs was investigated numerically  and experimentally． Multi－physics numerical systems combining solid mechanics  and fluid dynamics were applied to figure out the GDL intrusion with various  geometrical parameters． First， static structural analysis was performed to determine  elastic deformation of GDLs under clamping forces． Subsequently computational  flow analysis with the deformed fuel cell domains was conducted to visualize  flow patterns and estimate corresponding pressure drops．

Four cross－sectional parameters were  selected： channel to rib width ratio， draft angle， inner fillet radius and  clamping pressure． The calculated penetration depth was in good agreement  with the experimental data．

Numerical results showed that the increased  channel to rib ratio results in the higher penetration

depth and increased pressure drop． Particularly，  the pressure drop by the GDL intrusion causes almost twice in pressure drop compared  to a case without compression． Larger draft angles in channel designs with  less contacting areas between channels and GDLs narrowed cross－sectional flow  path of gas channels and increased reactant flow velocity． In addition， it  was found that the

inner fillet radius has negligible effects  on the GDL intrusion by 1％ and the increased stacking pressure results in the  linearly increasing penetration depth and the rate of pressure drop variation  from 240％ to 490％ compared with a geometry before compression． This study  suggests that fluid dynamics should be combined with solid mechanics for better  accuracy in computational fuel cell modeling and optimal designs of gas  feeding channels．

非常遗憾这篇文章没有流体阻力的试验论证，如果配有试验是一篇很不错的文章。

本来一名流体仿真工程师的工作变成一名气体扩散层工程师、一名力学仿真工程师、一名流体仿真工程师、一名试验工程师的工作。