Diagnosing Stagnant Gas Bubbles in a Polymer Electrolyte Membrane Water Electrolyser Using Acoustic Emission

Abstract

The use of acoustic emission as a low-cost, non-destructive, and operando diagnostic tool has been demonstrated for a range of electrochemical energy conversion and storage devices, including polymer electrolyte membrane water electrolysers (PEMWEs) and fuel cells. In this work, an abrupt change in acoustic regime is observed during operation of a PEMWE as the current density is increased from 0.5 to 1.0 A cm −2. This regime change is marked by a sudden drop in the number of acoustic hits, while hit duration, amplitude, and energy increase significantly. It is found that the change in acoustic regime coincides with a significant extension of the stagnant bubble region in the flow channels of the PEMWE, observed with high-speed optical imaging. These results demonstrate that acoustic emission can be used effectively as an operando diagnostic tool to monitor bubble formation (two-phase flow conditions) in PEMWEs, facilitating rapid testing or prototyping, and contributing to operational safety.

Bubble detection on the cathode and anode of a high-performing capillary-fed water electrolysis cell

“…17 This technique has been gaining attention for its potential applications in electrochemical devices 18 and has been applied to the detection of bubble formation in PEMWE by monitoring and analyzing sound waves generated when bubbles form and burst. [19][20][21] However, its use and technical capabilities in 'bubblefree' or 'bubble-scarce' electrolysers have not been studied.…”

Deep learning-enhanced characterization of bubble dynamics in proton exchange membrane water electrolyzers

“…AE serves as a non-destructive, operando diagnostic tool utilizing a piezoelectric sensor to capture mechanical disturbances emanating from an object. 8 This methodology facilitates the determination of bubble size distribution and the elucidation of diverse gas-flow patterns through the analysis of acoustic waves generated by bubbles. 9,10 However, AE has limited spatial resolution and susceptibility to background noise, which can impede the accurate localization and size determination of bubbles.…”

Mass transport in PEM water electrolysers: A review

“…• Electrochemical impedance spectroscopy (EIS) [166,167] • Neutron imaging [65][66][67][68][69][168][169][170] • X-ray imaging [63,[171][172][173][174] • Optical imaging [50,56,[59][60][61] • Porous transport layer (PTL)-on-a-chip [175,176] • Acoustic techniques [71,177,178] widely [55,57,120,167,[179][180][181][182] or is not reported at all. A more systematic approach to the analysis of EIS spectra, comparable to established work for fuel cells [183][184][185][186],…”