Synergistic electricity and freshwater cogeneration by integrating high-temperature proton exchange membrane fuel cells with humidifier–dehumidifiers

Abstract

Coastal and island regions face chronic freshwater shortages and fragile power supply. Integrating high-temperature proton exchange membrane fuel cells (HT-PEMFCs) with humidifier–dehumidifiers (HDHs) can address both needs, yet system-level performance remains insufficiently quantified. This work develops a coupled system-level model that captures key thermodynamic–electrochemical irreversibilities to predict the performance of an HT-PEMFC/HDH hybrid system, and the constituent subsystem models are validated against published data. Numerical results show that, at an operating temperature of 435 K, the hybrid system attains a maximum power density of 5.09 kW m⁻² and energy and exergy efficiencies of 24.53% and 26.06%, representing gains of 0.93% and 0.95% over a stand-alone HT-PEMFC. Parametric studies identify operating current density, membrane relative humidity, and phosphoric acid doping level as effective levers for performance enhancement, whereas larger humidifier area, thicker membranes, and higher HDH humidity impede it. Moreover, Local sensitivity analysis ranks membrane thickness as the dominant driver, followed by doping level and membrane humidity, with humidifier area exerting the weakest influence. The results provide quantitative guidance for the design and operation of high-efficiency HT-PEMFC/HDH cogeneration systems tailored to water- and power-constrained coastal and island applications.