Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation

When gas hydrates dissociate into gas and liquid water, many gas bubbles form in the water. The large bubbles disappear after several minutes due to their buoyancy, while a large number of small bubbles (particularly sub-micron-order bubbles known as ultra-fine bubbles (UFBs)) remain in the water fo...

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Main Authors: Tsutomu Uchida, Hiroshi Miyoshi, Kenji Yamazaki, Kazutoshi Gohara
Format: Article
Language:English
Published: MDPI AG 2021-06-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/14/12/3386
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spelling doaj-96ca88a2df20427bb74a7544315863292021-06-30T23:39:35ZengMDPI AGEnergies1996-10732021-06-01143386338610.3390/en14123386Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate FormationTsutomu Uchida0Hiroshi Miyoshi1Kenji Yamazaki2Kazutoshi Gohara3Faculty of Engineering, Hokkaido University, Sapporo 060-8628, JapanGraduate School of Engineering, Hokkaido University, Sapporo 060-8628, JapanFaculty of Engineering, Hokkaido University, Sapporo 060-8628, JapanFaculty of Engineering, Hokkaido University, Sapporo 060-8628, JapanWhen gas hydrates dissociate into gas and liquid water, many gas bubbles form in the water. The large bubbles disappear after several minutes due to their buoyancy, while a large number of small bubbles (particularly sub-micron-order bubbles known as ultra-fine bubbles (UFBs)) remain in the water for a long time. In our previous studies, we demonstrated that the existence of UFBs is a major factor promoting gas hydrate formation. We then extended our research on this issue to carbon dioxide (CO<sub>2</sub>) as it forms structure-I hydrates, similar to methane and ethane hydrates explored in previous studies; however, CO<sub>2</sub> saturated solutions present severe conditions for the survival of UFBs. The distribution measurements of CO<sub>2</sub> UFBs revealed that their average size was larger and number density was smaller than those of other hydrocarbon UFBs. Despite these conditions, the CO<sub>2</sub> hydrate formation tests confirmed that CO<sub>2</sub> UFBs played important roles in the expression of the promoting effect. The analysis showed that different UFB preparation processes resulted in different promoting effects. These findings can aid in better understanding the mechanism of the promoting (or memory) effect of gas hydrate formation.https://www.mdpi.com/1996-1073/14/12/3386nanobubblememory effectcarbon dioxideinduction time
collection DOAJ
language English
format Article
sources DOAJ
author Tsutomu Uchida
Hiroshi Miyoshi
Kenji Yamazaki
Kazutoshi Gohara
spellingShingle Tsutomu Uchida
Hiroshi Miyoshi
Kenji Yamazaki
Kazutoshi Gohara
Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
Energies
nanobubble
memory effect
carbon dioxide
induction time
author_facet Tsutomu Uchida
Hiroshi Miyoshi
Kenji Yamazaki
Kazutoshi Gohara
author_sort Tsutomu Uchida
title Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
title_short Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
title_full Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
title_fullStr Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
title_full_unstemmed Promoting Effect of Ultra-Fine Bubbles on CO<sub>2</sub> Hydrate Formation
title_sort promoting effect of ultra-fine bubbles on co<sub>2</sub> hydrate formation
publisher MDPI AG
series Energies
issn 1996-1073
publishDate 2021-06-01
description When gas hydrates dissociate into gas and liquid water, many gas bubbles form in the water. The large bubbles disappear after several minutes due to their buoyancy, while a large number of small bubbles (particularly sub-micron-order bubbles known as ultra-fine bubbles (UFBs)) remain in the water for a long time. In our previous studies, we demonstrated that the existence of UFBs is a major factor promoting gas hydrate formation. We then extended our research on this issue to carbon dioxide (CO<sub>2</sub>) as it forms structure-I hydrates, similar to methane and ethane hydrates explored in previous studies; however, CO<sub>2</sub> saturated solutions present severe conditions for the survival of UFBs. The distribution measurements of CO<sub>2</sub> UFBs revealed that their average size was larger and number density was smaller than those of other hydrocarbon UFBs. Despite these conditions, the CO<sub>2</sub> hydrate formation tests confirmed that CO<sub>2</sub> UFBs played important roles in the expression of the promoting effect. The analysis showed that different UFB preparation processes resulted in different promoting effects. These findings can aid in better understanding the mechanism of the promoting (or memory) effect of gas hydrate formation.
topic nanobubble
memory effect
carbon dioxide
induction time
url https://www.mdpi.com/1996-1073/14/12/3386
work_keys_str_mv AT tsutomuuchida promotingeffectofultrafinebubblesoncosub2subhydrateformation
AT hiroshimiyoshi promotingeffectofultrafinebubblesoncosub2subhydrateformation
AT kenjiyamazaki promotingeffectofultrafinebubblesoncosub2subhydrateformation
AT kazutoshigohara promotingeffectofultrafinebubblesoncosub2subhydrateformation
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