Thermal behavior and performance evaluation of a 5-cell PEMFC stack operating with and without active cooling

This study presents a detailed experimental investigation of the performance characteristics of a 5-cell Proton Exchange Membrane Fuel Cell (PEMFC) stack, with each cell having an active area of 100 cm², under two operating conditions: with and without active cooling. A liquid cooling system using deionized (DI) water and a heat exchanger was employed to regulate the stack temperature. Without active cooling, the stack temperature rose to 70 °C within 30 min at load currents ranging from 5 A to 25 A, leading to significant voltage losses and performance degradation, thereby highlighting the necessity of effective cooling. Under active cooling, the stack was operated at higher loads of 20 A to 30 A, maintaining a stable temperature of approximately 55 °C as the coolant removed the heat generated by the stack. Thermal equilibrium between the stack and coolant was achieved, ensuring stable voltage throughout operation. Additionally, a thermal management system model was developed to predict coolant temperature variations across components over time. The model results indicated a predicted heat removal ratio between 1 and 2, and the heat exchanger demonstrated effective heat rejection. These thermal management improvements contributed to enhanced stack performance and greater operational durability.