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This study performed a comprehensive experimental and theoretical analysis of a shell-and-tube type gas-to-gas humidifier module in a 95 kW class hydrogen fuel cell vehicle. The humidifier module features a polysulfone hollow fiber membrane characterized by its hydrophilic and non-fluorinated properties. Experimental investigations were conducted to understand the impacts of the inlet temperature, relative humidity, and temperature differences on heat and mass transfer rates, and the approach dew point temperature (ADT). The results showed that the ADT increased from 12.42 to 15.89 °C with a temperature difference of 15 °C between the shell and tube inlet sides, as the flow rate increased from 1000 to 3400 L/min, with the highest performance observed at lower flow rates. Simultaneously, a detailed theoretical model was developed, incorporating a new dual-mode sorption approach that accounts for temperature dependency within the solution-diffusion mechanism across the membrane. The developed model was in good agreement with the experimental results, with a relative error of less than 5 %. Furthermore, the dynamic model accurately predicts the response of the humidifier module to step changes in feed flow rates, simulating load variations in the fuel cell vehicle. This provides valuable insights into the humidifier's adaptability and responsiveness, which are crucial for optimizing its performance under various operating conditions. [Display omitted] • Applied a membrane humidifier in a 95 kW class hydrogen fuel cell vehicle. • Demonstrated the effects of operating conditions on membrane humidifier performance. • Developed a detailed model with a temperature-dependent new dual-mode sorption model. • Evaluated spatial variation to capture the distribution of humidification. • Investigated the humidifier's dynamic behavior during PEMFC load variations. [ABSTRACT FROM AUTHOR]

In this study, to maximize the electrical efficiency of the direct ammonia solid oxide fuel cell (SOFC) system, anode-off gas is recirculated for enhancing the system fuel utility and the system exhaust heat is utilized for the organic Rankine cycle (ORC) generating additional electricity. To confirm the superiority of the anode-off gas recirculation (AOGR) SOFC–ORC hybrid system, its electrical efficiency has been compared with two reference systems such as the stand-alone SOFC system without AOGR and the stand-alone AOGR SOFC system. A numerical model on three systems has been developed using Aspen Plus® and validated. Parametric analysis of the three systems has been conducted by varying the operating parameters such as the pump pressure, current density, AOGR ratio, condensation ratio, and fuel utilization. The AOGR SOFC-ORC hybrid system has the highest electrical efficiency among the three types of systems, 70.92 % under nominal conditions. The optimal operational range for the AOGR SOFC-ORC hybrid system has been revealed. As an ammonia-fueled distributed power generation, the proposed system can contribute to achieving net zero in countries where renewable energy is not abundant. This study can provide fundamental insights for establishing an optimization of direct ammonia SOFC systems. [Display omitted] • Direct ammonia AOGR SOFC system was integrated with ORC to maximize efficiency. • Numerical analysis is conducted on stand alone SOFC, AOGR SOFC, and AOGR SOFC-ORC. • Parametric study confirmed the superiority of the AOGR SOFC-ORC hybrid system. • Hybrid system can maintain high efficiency at low AOGR and low fuel utilization. • Hybrid system has the maximum efficiency of 71.35 % under fuel utilization of 60 %. [ABSTRACT FROM AUTHOR]

Proton-exchange membrane fuel cells (PEMFCs) operate at low temperatures and are used in household appliances and vehicles because of their high power density and fast start-up/shut-down capabilities. Previous research has focused on improving the performance of PEMFCs by enhancing their structures and constituent materials of their components. However, as PEMFCs are being commercialized, their durability remains a critical challenge that needs to be addressed. Although numerous studies have evaluated the durability of membrane electrode assemblies (MEA), limited research has been conducted on the durability of gas diffusion layers (GDL). The GDL, with its nanometer-to micrometer-sized pores and thickness of hundreds of microns, is prone to mechanical degradation during long-term operation. Moreover, the GDL is susceptible to carbon corrosion because it primarily consists of carbon materials, similar to the catalyst layer. Therefore, to ensure the performance and longevity of PEMFCs, it is of utmost importance to investigate the durability of the GDL. This study quantitatively investigates the variations in the performance and mechanical and chemical characteristics of GDLs during an extended period of operation in a fuel cell electric vehicle (FCEV), and two types of GDLs are analyzed. • Evolution in the performance of gas diffusion layer with operation time. • Evolution in the mechanical properties of gas diffusion layer with operation time. • Evolution in the chemical properties of gas diffusion layer with operation time. • Change in oxygen transport resistance within gas diffusion layer with operation time. [ABSTRACT FROM AUTHOR]

The gas diffusion layer (GDL) is an essential component of a proton-exchange membrane fuel cell (PEMFC) that supplies reactant gases to catalysts by facilitating the discharge of water generated via electrochemical reaction. The GDL is primarily composed of a substrate and a microporous layer (MPL), of which the latter increases the specific contact area for electrochemical reactions with catalysts and forms a capillary pressure gradient within the GDL. The MPL primarily comprises carbon black and polytetrafluoroethylene. Carbon black is categorized into the main and additive carbon blacks. Additive carbon black is utilized to augment the specific surface area of the MPL. This study examines the effects of four GDLs with varying additive carbon black contents constituting 20%–30 % of the total carbon black content on the performance of PEMFCs. In addition, the effects of the MPL characteristics on the durability of the GDL is investigated systematically, particularly in relation to carbon corrosion and freeze/thaw conditions. Furthermore, the deterioration in the performance and properties of the GDL are investigated via an acidic solution immersion accelerated stress test. • Effects of additive carbon black on the performance of gas diffusion layer. • Effects of additive carbon black on the durability of gas diffusion layer. • Effects of newly developed carbon corrosion accelerated stress test. • Effects of newly developed freeze/thaw accelerated stress test. • Effects of newly developed acidic solution immersion accelerated stress test. [ABSTRACT FROM AUTHOR]