Open Access Publications
Permanent URI for this collection
Open access publications by faculty, postdocs, and graduate students in the Department of Mechanical Engineering.
Browse
Browsing Open Access Publications by Author "Advani, Suresh G."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Biosourced Antioxidants for Chemical Durability Enhancement of Perfluorosulfonic Acid Membrane(Advanced Functional Materials, 2024-01-02) Agarwal, Tanya; Adhikari, Santosh; Babu, Siddharth Komini; Prasad, Ajay K.; Advani, Suresh G.; Borup, Rodney L.The chemical durability of perfluorosulfonic acid (PFSA) membranes is a topic of growing interest to meet Department of Energy (DOE) durability targets for heavy-duty vehicle (HDV) applications. State-of-the-art membranes like Nafion, rely on the use of cerium, heteropolyacids, and other inorganic additives to increase PFSA chemical durability. A less explored avenue for the oxidative stabilization of PFSA and hydrocarbon membranes is the use of organic antioxidants. No reversible organic antioxidant has been demonstrated to date which can enhance membrane lifetime by factors comparable to cerium. Here, ellagic acid (EA) is demonstrated as a promising radical scavenger for PFSA's. It is found that the incorporation of EA enhances the chemical durability of Nafion by 160%. EA, when incorporated with cerium as an electron donorenhances Nafion durability by at least 80% compared to a membrane incorporated with just cerium in DOE-defined durability tests. EA is found to be reversible in acidic conditions like those of fuel cells and its reversibility could be further enhanced by the use of suitable co-antioxidants.Item Composite Membrane Based on Graphene Oxide Sheets and Nafion for Polymer Electrolyte Membrane Fuel Cells(Electrochemical Society, 2014-10-29) Wang, Liang; Kang, Junmo; Nam, Jae-Do; Suhr, Jonghwan; Prasad, Ajay K.; Advani, Suresh G.; Liang Wang, Junmo Kang, Jae-Do Nam, Jonghwan Suhr, Ajay K. Prasad and Suresh G. Advani; Wang, Liang; Prasad, Ajay K.; Advani, Suresh G.A composite membrane for fuel cell applications was prepared by incorporating custom-made graphene oxide (GO) in Nafion resin. The GO was used to provide mechanical reinforcement to Nafion. Transmission electron microscopy confirmed the formation of highly crystalline and individually-dispersed graphene oxide sheets. Tensile strength, water uptake, swelling, proton conductivity and electrical conductivity of the composite membranes were measured and compared with pure Nafion. The polarization curves indicated that the fuel cell performance of the 3wt% GO/Nafion composite membrane was similar to that of the pure Nafion membrane, but the composite membrane was superior to Nafion in terms of mechanical properties.Item Fluoroalkyl phosphonic acid radical scavengers for proton exchange membrane fuel cells(Journal of Materials Chemistry A, 2023-04-06) Agarwal, Tanya; Adhikari, Santosh; Kim, Yu Seung; Babu, Siddharth Komini; Tian, Ding; Bae, Chulsung; Pham, Nguyet N. T.; Lee, Seung Geol; Prasad, Ajay K.; Advani, Suresh G.; Sievert, Allen; Rasika, Wipula Priya Liyanage; Hopkins, Timothy E.; Park, Andrew; Borup, RodRadical-induced degradation of proton exchange membranes limits the durability of proton-exchange membrane fuel cells. Cerium is widely used as a radical scavenger, but the migration of cerium ions to the catalyst layer has been an unresolved issue, reducing its effectiveness over time. Here, we report phosphonic acids as a promising class of radical scavengers, showing competent radical scavenging activity compared to cerium without the migration issue. The ex situ Fenton test shows that the fluoride emission rate for Nafion membrane incorporated with fluoroalkyl phosphonic acid ranged from 0.22 to 0.37 μg F cm−2 h−1, lower than that of the cerium-incorporated Nafion™ membrane (0.39 μg F cm−2 h−1). The in situ open circuit voltage hold test confirmed that a phosphonic acid-incorporated Nafion™ membrane has a 58% lower fluoride emission rate compared to the baseline. Density functional theory calculations indicate that the activation energy of the hydroxyl radical scavenging reaction of an alkyl phosphonic acid is only 0.68 eV, suggesting an effective radical scavenging pathway.Item Theory-guided machine learning for optimal autoclave co-curing of sandwich composite structures(Polymer Composites, 2022-07-06) Lavaggi, Tania; Samizadeh, Mina; Niknafs Kermani, Navid; Khalili, Mohammad Mahdi; Advani, Suresh G.The bonding of a honeycomb core to the thermoset prepreg facesheets by co-curing them allows one to manufacture composite sandwich structures in a single operation. However, the process is strongly dependent on the prescribed autoclave cure cycle. A previously developed physics-based simulation can predict the bond quality as a function of the process parameters. The disadvantage of physics-based simulations is the high computational effort needed to identify the optimal cure cycle to fabricate sandwich structures with desired bond-line properties. Theory guided machine learning (TGML) methods have demonstrated their capabilities to reduce the computational effort for different applications. In this work, three TGML models are trained on a data set produced from physics-based simulations to predict the co-cure process of honeycomb sandwich structures. The accuracy of the TGML models were compared to select the best performing predictive tool. In addition to reduction of computational time by orders of magnitude, we demonstrate how the TGML tools can also quantify the contribution of each process parameter on the properties of the fabricated part. The most accurate model was implemented in an optimization routine to tune the input process parameters to obtain the desired properties such as the bond-line porosity and facesheet consolidation level. This methodology could be extended to any process simulation of composites manufacturing processes.