A Hydrogen-fueled hybrid system based on HT-PEMFCs for simultaneous electrical power generation and high-value heat storage

Abstract

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) inherently produce waste heat, leading to component degradation, increased cooling demands, and reduced efficiency and longevity. To mitigate these challenges, this study introduces isopropanol-acetone-hydrogen chemical heat pumps (IAH-CHPs), selected for their proven ability to efficiently upgrade and store the waste heat from HT-PEMFCs in a high-value form. Grounded in thermodynamic and electrochemical principles, a comprehensive mathematical model, incorporating key irreversible losses, is developed to evaluate the potential. Numerical calculations predict a 29 % increase in the hybrid system’s maximum power density compared to a standalone HT-PEMFC operating at 443 K, along with corresponding enhancements of 14.17 % in energy efficiency and 14.16 % in exergy efficiency. Preliminary predictions confirm the feasibility of this approach, and the optimal operating ranges for maximizing power density are identified. Additionally, exhaustive parametric studies reveal the impacts of various structural and operational parameters – such as leakage current density, phosphoric acid doping, relative humidity, operating temperatures, and critical factors within the heat pump cycle – on the system’s thermodynamic performance and key current density indicators. Local sensitivity analyses highlight effective performance regulation strategies. These results provide essential insights for mitigating waste heat challenges, enhancing system efficiency, and extending the operational lifespan for HT-PEMFCs.