Numerical research on liquid water removal mechanism and the influence of pore structure on water removal rate based on real pore GDL structure during shutdown purge of fuel cell

Abstract

This paper establishes a two-phase flow model of the real pore structure to explore the liquid water removal process during the shutdown purge. The Monte Carlo algorithm is used to randomly throw circles in the rectangular region to simulate the two-dimensional interface of the real GDL pore structures. The real pore structure with different porosity is established by change the number of random circles to explore the influence of porosity on the liquid water removal process. A solid mechanical model is established to explore the variation of GDL under the effect of assembly force. The equivalent model of the compressed real pore GDL is established to explore the effect of the assembly force on the removal of liquid water during the shutdown purge stage. The results show that the liquid water under the ribs is difficult to remove during the removal of liquid water, affecting the speed of liquid water removal. The reduction of GDL porosity is conducive to the diffusion of air and the displacement of liquid water, thus improving the removal speed of liquid water. The assembly force can reduce the porosity below the rib, and effectively promote the removal speed of liquid water below the rib.