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The application of bulk acoustic wave (BAW) resonators for the in-situ investigation of polymer electrolytes and high temperature media

Bharath, VJ; (2018) The application of bulk acoustic wave (BAW) resonators for the in-situ investigation of polymer electrolytes and high temperature media. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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With the realities of the energy and environmental crises drawing ever closer, the need to fast-track the development of promising future renew-able energy technologies such as fuel cells is of paramount importance. However, with significant technical barriers to overcome before transition to a fully renewable energy based low carbon economy, the world must, in the short term, continue to rely on existing electricity generation meth-ods such as crude oil refining. It is therefore critical that there remains a focus on advancing and maximising both future and existing technologies’ power conversion efficiencies. Electricity generation technologies represent complex systems; advanced non-intrusive in-situ investigations can significantly aid with technological advancements through fundamental understanding of the processes oc-curring at the interfacial level. Intimate knowledge of the morphological and structural phenomena occurring at the interface can be gathered us-ing techniques such as bulk acoustic wave (BAW) resonators and provide new insight into factors such as operating conditions to guide future technological developments of complex systems. This thesis outlines the establishment of surface developed, BAW resona-tors for non-intrusive, in-situ application within bespoke, calibrated ex-perimental set ups to elucidate the interfacial phenomena in the viscoelas-tic phase, and specifically within both the fuel cell industry and the re-finement of heavy crude oil as indicated below. Low-temperature fuel cells (specifically proton exchange membranes (PEMs)) represent a promising constituent in the low carbon economy for portable and automotive power. Yet, issues pertaining to durability and cost hinder the technology’s commercialisation. Recent reaction kinetics development in the less well established alkaline anion-exchange mem-brane (AAEM) fuel cell however, has shown avenues for significant cost reductions. However, the AAEM is not without challenges; linked pri-marily to hydration states, many reports have shown the technology’s susceptibility to chemical degradation when operated at temperatures ≥ 65 OC; carbon dioxide poisoning when operating in air; and general sys-tem integration issues due to a lack of understanding of the AAEM’s swelling and water loading mechanisms. A commercially available thin-film AAEM is investigated here using a novel composite (ionomer-cast) quartz crystal microbalance (QCM) and crystal admittance spectroscopy (CAS) for interfacial characterisation. The study focuses on operation in the presence of hydration and how this affects the ionomer’s water uptake, loading and swelling mechanisms as well as the susceptibility of the cationic groups to resist cleavage in the presence of hydroxide ions, leading to E2-(Hofmann) elimination. Opera-tion in conditions that can induce carbonate formation and interaction within the membrane are also investigated. The world’s ever-increasing energy demand has however not just pro-gressed the development of future renewables such as fuel cells, but also required the innovative use of traditional and non-traditional resources such as ‘heavy’ crude oil. However, with significantly more variable com-positions of saturates, aromatics, resins and asphaltenes (SARAs) be-tween wells compared to traditional crude oil supplies, refining and transportation of heavy crude oil using existing infrastructure has become subject to spurious effects of fouling. Fouling from heavy crude oil in pipelines and refinery equipment is un-predictable, causes major flow assurance issues and occurs primarily as a result of asphaltene destabilisation. Current monitoring and mitigation techniques require time-intensive, large-volume analysis that is not able to react quickly enough to changing oil grades. As such, this study outlines the development of a novel high temperature, high pressure, rapid, low-volume on-site feedback system for fouling de-tection and characterisation using an iron-electrodeposited gallium ortho-phosphate microbalance (iGCM). The iGCM coupled with X-ray comput-er tomography is used here to offer new insight into the phenomena oc-curring at the iron–oil interface and thus providing the necessary flow assurance information required to implement fouling rejection or conver-sion techniques.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The application of bulk acoustic wave (BAW) resonators for the in-situ investigation of polymer electrolytes and high temperature media
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10043712
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