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• FCREx dynamic & operation limits effect on performance & durability was evaluated. • Performance and durability for FCREx vehicles in driving cycle were correlated. • Maximum lifetime (+110%) was achieved with |di/dt| max = 0.01 A/cm2s i min = 0.15 A/cm2. • |di/dt| max = 0.001 A/cm2s or i min = 0.2 A/cm2 do not allow charge-sustained mode. • Recommendations for FCREx vehicle and FC stack manufacturers were elaborated. Aiming at increasing fuel cell (FC) stack durability in driving conditions, part of the scientific community has focused its efforts on developing energy management strategies (EMS) for fuel cell hybrid vehicles (FCV). Nonetheless, most of these studies do not explicitly explain the effect of constraining the EMS in both degradation and performance when acting on the FC system dynamics or operational space nor consider the FC range-extender (FCREx) architecture for passenger car application. This study evaluates the potential of FCREx architecture to maximize FC stack durability and performance through control strategy dynamic and operational space limitations. For that purpose, a FCV modeling platform was developed and integrated together with an EMS optimizer algorithm and a semi-empirical advanced FC stack degradation model for driving cycle conditions. The resulting modeling platform was then simulated in WLTC 3b driving cycle to predict FC degradation and H 2 consumption with different dynamic and operational restrictions. Practical limits for EMS constraining were identified as —di/dt— max = 0.001 A/cm2s or i min = 0.2 A/cm2 since they prevented the EMS from fulfilling the constant state-of-charge constraint in high-dynamic driving condition. In this sense, —di/dt— max = 0.01 A/cm2s and i min = 0.15 A/cm2 were recommended as the combination of constraints that maximizes FC stack durability (+110%) without affecting the FCV operability with only an increase in of 4.7% in H 2 consumption. From these results, a set of recommendations and guidelines for FCREx vehicle manufacturers and FC stack developers were elaborated based on the benefits of understanding the dynamics and operational constraints that the FC system is going to be subjected to under real operation. [ABSTRACT FROM AUTHOR]

In this study, durability and performance prediction were integrated in the sizing process of the FC stack of a fuel cell range-extender (FCREx) vehicle together with the design of a dynamics-limited control strategy. For that purpose, a FCREx vehicle model integrating a FC stack, balance of plant, battery, H 2 tank and vehicle body (C-class SUV) validated in previous studies was used. To predict FC stack degradation rate, a novel semi-empirical multi-layered degradation modeling framework for automotive application is proposed and developed. Degradation rates are calculated based on reference degradation rates measured at reference and known conditions (1st layer) and scaled with the electrochemical phenomena (2nd layer) and the operating conditions (3rd layer) through scaling functions based on physical tendencies. Results show how increasing the FC stack power decreases H 2 consumption but increases durability, while increasing the dynamic limitations on the control strategy increases both H 2 consumption and durability. The isolated effect of sizing implied a decrease in H 2 consumption of ∼ 3% and an increase in FC stack durability of ∼ 53% when comparing the 40 kW and 100 kW designs. In contrast, the effect of dynamic limitations was significantly perceived in the 40 kW design which implied an increase in H 2 consumption close to 8% and an increase in durability of 294% when comparing the infinite dynamics and the highest dynamically restricted cases. Nevertheless, the effect of sizing is neglected under high dynamic limitation and limiting the current density change rate to 0.001 A/cm2 s may prevent the control strategy from fulfilling the charge sustaining mode in aggressive driving. Based on these results, a set of recommendations were elaborated for FC stack and FCV manufacturers aiming to apply FCREx architecture to passenger car vehicles. • Higher FC stack power decreases H 2 consumption and increases durability. • Higher dynamic limitation increases H 2 consumption and durability. • FC stack sizing effect becomes negligible under high dynamic limitations • A novel semi-empirical degradation model for automotive applications was developed. • Degradation rates are scaled with electrochemical phenomena and physical conditions [ABSTRACT FROM AUTHOR]

Fuel cell (FC) technologies for mobility are gaining interest as promising options to decarbonize the transport sector in line with the current progress towards the H 2 economy. Previous studies show how the fuel cell range extender (FCREx) powertrain architecture can offer flexible and efficient operation along with the potentially low total cost of ownership (TCO) in passenger car applications. Cradle-to-grave emissions of these vehicles have not been estimated, nor their variation with the components sizing or the H 2 production pathway analyzed. In this study, the life cycle assessment (LCA) and sizing methodologies were combined to address these knowledge gaps. The design spaces were generated by varying the FC maximum power, the battery capacity and the H 2 tank capacity and by simulating the resulting designs with the WLTC 3b driving cycle. Then, the lifetime H 2 and energy consumption results and design parameters were calculated and used as inputs to estimate the greenhouse gases (GHG) and NO X emissions on the manufacturing and fuel production cycles. From the results, it was proven how considering steam methane reforming (SMR) with carbon capture and storage (CCS) as the H 2 production pathway could decrease by 60% and 38% GHG-100 and NO X emissions respectively, with respect to electrolysis where electricity is generated with the EU mix. The optimum design, in terms of emissions, was found to be with low-moderate battery capacity and moderate-high FC maximum power in contrast to the optimum design for performance, which had high battery capacity and high FC stack power. • A novel approach using sizing and LCA methodologies is used for passenger FCREx. • Design spaces for FCREx vehicles showing GHG-100, NO X and performance are generated. • Production pathways for H 2 were electrolysis with the EU mix, SMR and SMR with CCS. • GHG-100 & NO X emissions may vary up to 10% when comparing the worst and best designs. • Emissions-wise and performance-wise optimum FCREx designs are compared [ABSTRACT FROM AUTHOR]

Aiming to reduce global warming and emissions in general, cleaner technologies are the spotlight of research and industry development. Among them, fuel cell vehicles (FCV) are gaining interest to decarbonize the transport sector. Plug-in FCV or FCV in range-extender configuration (FCREx) is an interesting option to reduce the total cost of ownership (TCO) and the energy usage per km. The aim of this study was to generate design spaces of FCREx by varying the FC stack maximum power output, the battery capacity, and the H 2 tank capacity to understand the implications of this architecture in range, consumption, and cost (estimated with a WLTP driving cycle). Unlike other studies, the approach was focused on a novel architecture for passenger vehicles and was focused on the development of the validated FC system model and the energy management strategy (EMS) optimization for each design, based on the Pontryagin Minimum Principle (PMP). Consumption was found to decrease with increasing battery capacity and FC maximum power due to the higher efficiency of the systems. The design spaces showed how with 5 kg of H 2 and ≥ 50 kWh of battery capacity the maximum range of FCREx could be over 700 km. The results of this study showed how FCREx architecture could provide overall energy consumption saving up to 6.8% and H 2 consumption saving ranging from 16.8% to 25%, compared to current commercial FCVs. The optimum FCREx design, not only based on performance, should have ∼ 30 kWh of battery capacity and ≥ 80 kW of FC maximum power to minimize manufacturing costs while maximizing efficiency. • Passenger FCREx components sizing and evaluation was performed for the first time. • As a novelty, the optimization comprises both the EMS and the FC system operation. • Space designs for plug-in FCV (FCREx) were generated. • Equivalent-in-range FCREx designs were compared to commercial FCV. • FCREx architecture potentially increases FCV range and efficiency (16.8%–25%). [ABSTRACT FROM AUTHOR]