Fiber optic sensors integrated into fuel cell stacks have the potential to significantly enhance the temperature control and health monitoring of fuel cells. Inhomogeneous loading, both within individual cells and across different cells in a stack, leads to the formation of local hotspots that accelerate aging and degrade performance. This study investigates the behavior and feasibility of incorporating polyimide-coated optical fiber sensors into bipolar plates for precise and spatially resolved temperature monitoring. The sensor is successfully integrated into a single cell of a fuel cell stack and positioned on the bipolar plate in direct contact with the membrane electrode assembly. Pre-tests are conducted to thoroughly evaluate the technical properties of the fiber in relation to specific cell requirements. Additionally, a physical prototype featuring the sensor is developed and employed to validate its effectiveness under realistic operating conditions. The temperature measurement obtained via the fiber exhibits a continuous profile throughout the entire length, covering both the active area and distributor region of the cell. Throughout the entire 60 min test period, the measuring system provides continuous and uninterrupted temperature measurements, encompassing the start of the stack, the heating phase, the subsequent stable operating point, and the cooling phase. However, some technical challenges have been identified, as mechanical pressure exerted on the fiber influences the measured temperature. While this work demonstrates promising results, further advancements are necessary to address inhomogeneous loading within fuel cells and hotspot mitigation. The precise monitoring of temperature distribution enables early detection of potential damage, facilitating timely interventions to improve the service life and overall performance of fuel cells.

This article investigates the potential of the energetic utilization of hydrogen expansion in a fuel cell electric vehicle (FCEV) as pressure decreases from 700 bar in the H2 storage to approximately 5 bar in the fuel cell stack. The article focuses on the boundary conditions of passenger and heavy-duty vehicles, which are analyzed and evaluated by means of simulations. The expansion process is evaluated from the thermodynamic side with assumptions of an isothermal and isentropic process.

This paper presents an innovative approach to modified electrochemical impedance spectroscopy (EIS) for real-time health monitoring of galvanic cells, particularly batteries and fuel cells in high-dynamic applications such as vehicles. Traditional methodologies, including cell voltage monitoring, offer limited diagnostic value. In contrast, conventional EIS provides comprehensive system insights; however, its applicability is constrained by prolonged measurement durations, rendering it impractical for dynamic conditions. This article presents a method that iteratively selects specific frequency bands and key points, thereby substantially reducing measurement time without compromising critical system information. This approach was initially validated using battery systems, which exhibit well-regulated operational behavior, thus facilitating a rigorous evaluation of the concept. Experimental results demonstrated that the modified EIS method achieves performance comparable to conventional EIS but with measurement times reduced by up to 92%. This validation underscores its reliability and precision, thereby supporting proactive maintenance strategies and extending system longevity. The reduction in measurement time enables more precise analyses across diverse dynamic operational spectra. Consequently, this approach constitutes a robust solution for health monitoring of fuel cells and batteries in dynamic environments, capitalizing on the advantages of EIS while addressing its inherent limitations.

The authors would like to make the following changes to their paper published in Energies