Zhang Yangjun

Comparative Study of Membrane Humidifier and Enthalpy Wheel Humidifier for Large Power Fuel Cell System

The performance of membrane humidifier (MH) and enthalpy wheel humidifier (EWH) for a large power proton exchange membrane fuel cell (PEMFC) system is compared using simulations and experiments. The MH model is based on one dimensional diffusion equation and the EWH model is based on the porous media surface diffusion equation. Simulation results agree well with experimental data. According to the results, the effect of intake air temperature has a lower effect on the MH performance than it does on the EWH performance while the air mass flow has a much higher effect on the MH performance than it does on the EWH performance. MH performs better than EWH at a low flow rate but worse at a high flow rate. Vapor transfer mechanism in the humidifiers is also studied.

Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel cell

Investigation into the formation and transport of liquid water in proton exchange membrane fuel cells (PEMFCs) is the key to fuel cell water management. A three-dimensional gas/liquid two-phase flow and heat transfer model is developed based on the multiphase mixture theory. The reactant gas flow, diffusion, and chemical reaction as well as the liquid water transport and phase change process are modeled. Numerical simulations on liquid water distribution and its effects on the performance of a PEMFC are conducted. Results show that liquid water distributes mostly in the cathode, and predicted cell performance decreases quickly at high current density due to the obstruction of liquid water to oxygen diffusion. The simulation results agree well with experimental data.