Insights into Humidification Measurement Methods: Resolving High Water Contents with an Optical Gas Diagnostics Tool

Braun K, Rüppel B, Weiß L, Wensing M (2025)

Publication Language: English

Publication Type: Conference contribution, Conference Contribution

Publication year: 2025

Event location: Luzern

Abstract

The humidification of feed gases, and water management in general, is crucial for the performance and durability of proton exchange membrane fuel cells (PEMFC). Research and development require precise and, for dynamic operation, time-resolved determination of the water content of the gas flows on the cathode and anode side. Available sensors show measured value deviations especially in the operating range of PEM fuel cells (temperatures around 80°C at high relative humidities close to saturation). Occurring condensations of liquid water lead to a flooding of the sensor with long recovery times. Via this study we sought to better understand the measurement of relative humidity. We investigate the influencing factors and accuracy of sensors based on electrical capacitance. Furthermore, we analyze the dynamics of the sensor to evaluate the temporal resolution of the operating conditions. As a reference measurement and alternative option for research and development, we use an optical measurement of gas humidity based on Raman scattering [1]; after directing a laser beam into the gas flow, this method analyzes backscattered light using a spectrometer and advanced processing techniques. The results show the molar composition of the gas mixture. For this study, we tailored the analysis and calibration procedures specifically to the assessment of water content. The incorporation of data on temperature and pressure enables us to determine relative humidity accurately and with temporal resolution. This method is a valuable addition to conventional humidity sensors, especially in measurement environments where gas flows with variable composition, state conditions and high water contents are present, such as in fuel cell research.

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How to cite

APA:

Braun, K., Rüppel, B., Weiß, L., & Wensing, M. (2025). Insights into Humidification Measurement Methods: Resolving High Water Contents with an Optical Gas Diagnostics Tool. In Proceedings of the EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing. Luzern, CH.

MLA:

Braun, Katharina, et al. "Insights into Humidification Measurement Methods: Resolving High Water Contents with an Optical Gas Diagnostics Tool." Proceedings of the EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing, Luzern 2025.

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