Resumen de Analysis of hydrogen fuel cell powerplant architectures for future transport applications
In light of the environmental crisis and the growing interest in the use of H2 to advance toward the Hydrogen Economy, this thesis aims at analyzing and optimizing novel FCV powerplant architectures for passenger car and heavy-duty vehicle applications in terms of performance, durability, and environmental impact. For that purpose, a multi-physics flexible FCV modeling platform was developed integrating a validated FC stack model together with the BoP components, the mechanical and electrical components of the vehicle and powertrain, a semi-empirical physics-informed FC degradation model designed to be used in driving conditions and a real-time EMS optimizer that offers the best performance given a powerplant design and driving cycle so that all the proposed architectures for a given application are comparable.
The discussion of the results can be divided into 3 different parts. The first one is oriented towards the FCS performance optimization. The results in this part helped to identify the air management strategy that, given a set of constraints imposed in the BoP components, maximized the FCS net power output (efficiency) for each value of current density. The resulting energy balance comprising the FC stack power produced, the electrochemical losses, and the consumption of the BoP components was analyzed and used to determine and design the control strategy of the BoP actuators for driving cycle conditions.
The second part is focused on the evaluation and optimization, when possible, of the FCREx architecture for passenger car applications and the multi-FCS configuration for heavy-duty vehicle applications. Performance-wise the FCREx architecture offered minimum H2 consumption with high FC stack power and high battery capacity, but this design could be prohibitive in terms of costs. It could offer up to 16.8-25% lower H2 consumption and 6.8% lower energy consumption. Limiting the dynamics of this architecture increased the FC durability by 110% with a penalty in H2 consumption of 4.7%. The multi-FCS architecture for heavy-duty applications could operate with even lower dynamics, with an increase in the FC durability of 471% with a penalty in H2 consumption of 3.8%, since the driving profile of heavy-duty vehicles is usually more steady. Differential control and sizing could only provide benefits in terms of environmental impact or cost, not performance.
The last part considers the results obtained in terms of performance and durability to analyze the environmental impact of each architecture. The H2 production pathway affected significantly the life cycle emissions of both applications over any other design choice. The optimum design for FCREx architecture that minimized emissions had high FC stack power and moderate battery capacity. In the case of heavy-duty application, the optimum control dynamics for each design and H2 production pathway were identified, and the differential sizing design strategy was determined to only provide benefits if different FC stack technology was considered for the various stacks in the powerplant.
