arXiv subjects

David Weik

Publications and source records attributed to David Weik.

3 recordsLinked to original sources

arXiv2025

Monitoring of Fluid Transport in Low Temperature Water Electrolyzers and Fuel Cells: Emerging Technologies and Future Prospects

Low temperature water electrolyzers (LTWEs) and low temperature hydrogen fuel cells (LTFCs) present a promising technological strategy for the productions and usages of green hydrogen energy towards a net-zero world. However, the interactions of gas/liquid (fluid) transport and the intrinsic reaction kinetics in LTWEs/LTFCs present one of the key hurdles hindering high production rate and high energy conversion efficiency. Addressing these limitations requires analytical tools that are capable of resolving fluid transport across the heterogeneous, multiscale structures of operating LTWE and LTFC systems. This review provides a comprehensive overview of recent advancements in measurement technologies for investigating fluid transport. We first outline the technical requirements of such analytical systems, and assess the capabilities and limitations of established optical, X-rays and neutrons based imaging systems. We emphasis on emerging strategies that utilize integrated miniaturized sensors, ultrasound, and other alternative physical principles to achieve operando, high-resolution, and scalable measurements towards applications at device and system levels. Finally, we outline future directions in this highly interdisciplinary field, emphasizing the importance of next-generation sensing concepts to overcome the fluid transport hurdle, towards accelerating the deployment of green hydrogen technologies.

physics.app-ph↗

arXiv2024

Scanning Acoustic Microscopy for Quantifying Bubble Evolution in Alkaline Water Electrolyzers

Improved understanding of gas/liquid transport in electrochemical gas-evolving systems is increasingly demanded for optimizing device performance. However, high-resolution measurement techniques for in-situ imaging remain limited. This work demonstrates the use of volumetric scanning acoustic microscopy (SAM) for quantifying hydrogen bubble evolution in porous nickel electrodes in a customized alkaline water electrolysis cell. By using high-frequency focused ultrasound, SAM enables volumetric imaging with high spatial resolution in the range of tens of micrometers. This allows the distribution of gas bubbles within the complex 3D architecture of porous electrodes to be resolved. Digital image processing methods are used to segment and quantify the gas content in the electrode. Thus, non-destructive SAM imaging is demonstrated to be an accessible and scalable analytical tool for the quantitative investigation of bubble evolution in operando electrochemical environments. Here, a solid foundation is established for future studies aimed at optimizing bubble dynamics and cell design under practically relevant operating conditions, ultimately contributing to higher electrolysis efficiencies.

physics.app-ph↗

arXiv2024

Uncertainty Quantification of Super-Resolution Flow Mapping in Liquid Metals using Ultrasound Localization Microscopy

Convection of liquid metals drives large natural processes and is important in technical processes. Model experiments are conducted for research purposes where simulations are expensive and the clarification of open questions requires novel flow mapping methods with an increased spatial resolution. In this work, the method of Ultrasound Localization Microscopy (ULM) is investigated for this purpose. Known from microvasculature imaging, this method provides an increased spatial resolution beyond the diffraction limit. Its applicability in liquid metal flows is promising, however the realization and reliability is challenging, as artificial scattering particles or microbubbles cannot be utilized. To solve this issue an approach using nonlinear adaptive beamforming is proposed. This allowed the reliable tracking of particles of which super-resolved flow maps can be deduced. Furthermore, the application in fluid physics requires quantified results. Therefore, an uncertainty quantification model based on the spatial resolution, velocity gradient and measurement parameters is proposed, which allows to estimate the flow maps validity under experimental conditions. The proposed method is demonstrated in magnetohydrodynamic convection experiments. In some occasions, ULM was able to measure velocity vectors within the boundary layer of the flow, which will help for future in-depth flow studies. Furthermore, the proposed uncertainty model of ULM is of generic use in other applications.

physics.flu-dyn↗