Session: 13-01: Hydrogen and Fuel Cells

Paper Number: 156310

156310 - Modeling and Analysis of Pemfc and Recirculation System in Air-Independent Environment 

Abstract: 

Efforts are underway to reduce fossil fuel usage to mitigate global warming, with hydrogen emerging as a viable alternative fuel. Hydrogen can be converted into electrical energy via fuel cells, which are categorized by their specific purposes and functions. Especially, The characteristics of the Proton Exchange Membrane Fuel Cell (PEMFC), which is fast responsiveness and operation at a relatively low temperature, are suitable for vehicles, which is the main cause of greenhouse gas emissions. However, they face cost challenges, primarily because platinum is used as a catalyst, and effective moisture management of the membrane is crucial, necessitating additional components and resulting in high costs. Key strategies to lower these costs include adopting alternative catalysts or reducing the number of system components. This study investigates the impact of an external membrane humidifier, one of the key components for moisture management in PEMFC. The system has been compared through differences in how it is configured with or without a humidifier. Moreover, a configuration using pure oxygen instead of air as the oxidizing agent was adopted to prevent nitrogen accumulation during recirculation. Using pure oxygen as an oxidizing agent is particularly applicable in environments where air supply is constrained, such as underwater or in space. The study was conducted with Aspen Plus®, a chemical process simulation program, and since no model in the library can properly simulate a membrane humidifier and a fuel cell for air-independent, the two components were modeled using Aspen Custom Modeler® which is a compatible library-making program. First, the fuel cell stack model was divided into several nodes along the inlet-outlet direction to indicate the flow of the fluid. Therefore, by setting the target average current density, local current density, flow rate change, and water transport can be monitored. The temperature of the stack can be controlled through coolant water, and a heat transfer model through fins is applied to the channel. Then, the liquid-to-gas membrane humidifier was applied to the external membrane humidifier, and a shell-and-tube shape was applied to allow the reactant gases to pass through the tube and the coolant water of the PEMFC Stack to the shell. It was also divided into nodes to monitor fluid flow, temperature, and water transport changes. The system configuration consisted of Aspen Plus®, and components not mentioned were used in the built-in library. Finally, the results and conclusions were made based on differences in stack operating conditions and system configuration.

Presenting Author: Byeongrok Chu Chungnam National University

Presenting Author Biography: Byeongrok Chu is currently Master's Student at the Chungnam National University in Republic of Korea
Major is Mechanical Engineering, and studies in Fuel cell Systems and heat transfer.