More Like this

1. Mechanisms underlying rapid electronucleation and freezing of hydrates

   Acharya, P; Shahriari, A; Lin, D; Bahadur, V. (November 2017, Proceedings of ASME 2017 International Mechanical Engineering Congress & Exposition)

   Nucleation of hydrates is constrained by very long induction (wait) times, which can range from hours to days. Electronucleation (application of an electrical potential across the precursor solution) can significantly reduce the induction time for nucleation. This study shows that porous aluminum foams (open-cell) enable near-instantaneous electronucleation at very low voltages. Experiments with tetrahydrofuran hydrates reveal that aluminum foam electrodes enable voltage-dependent nucleation with induction times of only tens of seconds at voltages as low as 20 V. Foam-based electrodes can reduce the induction time by up to 150X when compared to non-foam electrodes. Furthermore, this study reveals that electronucleation can be attributed to two distinct phenomena, namely bubble generation (due to electrolysis), and the formation of metal-ion coordination compounds. These mechanisms affect the induction time to different extents and depend on electrode material and polarity. Overall, this work uncovers the benefits of using foams for formation of hydrates, with foams aiding nucleation as well as propagation of the hydrate formation front. 

   more » « less
2. Aluminum foam-based ultrafast electronucleation of hydrates

   Acharya, P; Shahriari, A; Carpenter, K; Bahadur, V (July 2017, Proceedings of the ASME Summer Heat Transfer Conference)

   Nucleation of hydrates requires very long induction (wait) times, often ranging from hours to days. Electronucleation, i.e. nucleation stimulated by the presence of an electric field in the precursor solution can reduce the induction time significantly. This work reveals that porous aluminum foams enable near-instantaneous electronucleation at very low voltages. Experiments with tetrahydrofuran hydrate nucleation reveal that open-cell aluminum foam electrodes can trigger nucleation in only tens of seconds. Foam-based electrodes reduce the induction time by as much as 150X, when compared to non-foam electrodes. This work also discusses two mechanisms underlying electronucleation. These include bubble generation (due to electrolysis), and the formation of metal-ion coordination compounds. These mechanisms depend on electrode material and polarity, and affect the induction time to different extents. This work also shows that foams result in more deterministic nucleation (compared to stochastic) when compared with non-foam electrodes. Overall, electronucleation can lead to a new class of technologies for active control of formation of hydrates. 

   more » « less
3. Aluminum foam-based ultrafast electronucleation of hydrates

   Acharya, P; Shahriari, A; Carpenter, K; Bahadur, V (July 2017, Proceedings of the 2017 ASME Summer Heat Transfer Conference)

   Nucleation of hydrates requires very long induction (wait) times, often ranging from hours to days. Electronucleation, i.e. nucleation stimulated by the presence of an electric field in the precursor solution can reduce the induction time significantly. This work reveals that porous aluminum foams enable near-instantaneous electronucleation at very low voltages. Experiments with tetrahydrofuran hydrate nucleation reveal that open-cell aluminum foam electrodes can trigger nucleation in only tens of seconds. Foam-based electrodes reduce the induction time by as much as 150X, when compared to non-foam electrodes. This work also discusses two mechanisms underlying electronucleation. These include bubble generation (due to electrolysis), and the formation of metal-ion coordination compounds. These mechanisms depend on electrode material and polarity, and affect the induction time to different extents. This work also shows that foams result in more deterministic nucleation (compared to stochastic) when compared with non-foam electrodes. Overall, electronucleation can lead to a new class of technologies for active control of formation of hydrates. 

   more » « less
4. Carbon Foam/CaCl ₂ ·6H ₂ O Composite as a Phase-Change Material for Thermal Energy Storage

   https://doi.org/10.1021/acs.energyfuels.3c01275  

   Jing, Yikang; Dixit, Kunal; Schiffres, Scott N; Liu, Hao (July 2023, Energy & Fuels)

   Inorganic salt hydrates are promising phase-change materials (PCMs) for thermal energy storage due to their high latent heat of fusion. However, their practical application is often limited by their unstable form, dehydration, large supercooling, and low thermal conductivity. Porous melamine foam and its carbonized derivatives are potential supporting porous materials to encapsulate inorganic salt hydrate PCMs to address these problems. This work investigates the effect of pyrolysis temperature on the morphology and structure of the carbonized foams and their thermal energy storage performance. Pyrolysis of melamine foam at 700−900 °C leads to the formation of crystalline sodium cyanate and sodium carbonate particles on the foam skeleton surface, which allows the spontaneous impregnation of the carbon foam with molten CaCl2·6H2O.The form-stable foam-CaCl2·6H2O composite effectively suppresses supercooling and dehydration, demonstrating the efficacy of carbon foam as a promising supporting material for inorganic salt hydrate PCMs. 

   more » « less
5. Analysis of Electrochemical Capture of CO2 From Oceanwater Coupled With Hydrates-Based Seabed Sequestration

   https://doi.org/10.1115/ES2024-132209  

   Hamalian, Mark; Bhati, Awan; Bahadur, Vaibhav (July 2024, American Society of Mechanical Engineers)

   Abstract Novel energy efficient and scalable carbon capture and sequestration technologies are critical to meeting the goals of the Paris Agreement. In this study, we present a first-order system-level assessment of an integrated carbon capture and carbon sequestration plant that couples electrochemical CO2 capture from oceanwater with co-located long-term carbon sequestration as CO2 hydrates (ice-like solids) on the seabed. Separate recent experimental results associated with electrochemical capture and hydrate formation form the basis for this energetics-focused analysis, which evaluates power consumption of all the key components associated with capture and sequestration. Hydrates can be formed from both pure water as well as seawater, and the implications of including a desalination plant to provide pure water for hydrate formation are studied. All analysis is conducted for a 1 plant which captures and sequesters 1 megaton CO2 annually. Our results indicate the carbon capture will consume significantly more energy than carbon sequestration despite the use of a low-energy consuming electrochemical technique. From a sequestration standpoint, there are clear benefits to forming hydrates at high pressures, since the elevated formation rates reduce the number of hydrate formation reactors significantly. It is also seen that the addition of a desalination plant to provide pure water for hydrate formation (which speeds up hydrate formation) will not affect the energetics of the overall process significantly; however the CAPEX and operational aspects of including a desalination plant need to be analyzed in greater detail. Overall, this study seeds a novel CCS concept which can be deployed via decommissioned oil-gas platforms to capture CO2 from surface oceanwater and store CO2 right below on the seabed after appropriate sealing (artificial or natural). 

   more » « less