A Method to Account for the Effects of Thermal Osmosis in PEM Fuel Cells

Abstract

In PEM fuel cells heat and water management are essential for fuel cell operation. Presently there are two agreed modes of water transport: electro-osmotic drag (EOD) and back diffusion (BD). EOD and BD are obtained from the Nernst-Planck equation. It can be shown that the Nernst Planck equation neglects the impact of thermal osmosis. It must be determined if this assumption on neglecting thermal osmosis is valid, or if thermal osmosis is a strong influencer of net water flow. Thermal osmosis (TO) is not fully understood, and some researchers have made conclusions about thermal osmosis but failed to properly isolate thermal osmosis from other modes of water transport. This work demonstrates that thermal osmosis is neglected in most fuel cell analysis and that thermal osmosis needs to be examined further.