1. Thermotactic habit of gas hydrate growth enables a fast transformation of melting ice.
- Author
-
Yang, Lei, Guan, Dawei, Qu, Aoxing, Li, Qingping, Ge, Yang, Liang, Huiyong, Dong, Hongsheng, Leng, Shudong, Liu, Yanzhen, Zhang, Lunxiang, Zhao, Jiafei, and Song, Yongchen
- Subjects
- *
GAS hydrates , *PHASE transitions , *DISCONTINUOUS precipitation , *HEAT of reaction , *MELTING - Abstract
• An anisotropy of gas hydrate growth was in-situ characterized through X-ray technique. • Themotactic habit of hydrate growth towards a low temperature region was proposed. • The hydrate morphology can be controlled via regulating the heat transfer scheme. Promoting hydrate formation kinetics is considered a major challenge hindering the application of hydrate-based techniques. Surfactants are thus widely used for a better gas solution and water conversion. Yet significant issues involving an uncontrolled morphology and foaming are encountered. In this work, a unique anisotropic behavior of gas hydrate formation was identified through in-situ X-ray technique with the rate of vertical growth 5 times higher than the lateral. This was ascribed to the varying driving force of hydrate nucleation at the wall surface where the reaction heat could be more easily dissipated. Consequently, a thermotactic habit of gas hydrate growth was proposed: the nucleation and growth would preferentially proceed towards a low temperature region to release the reaction heat. Hence through regulating the temperature and thereby the heat transfer scheme one can design the behavior and morphology of hydrate formation. Specifically, a surprisingly fast hydrate formation was observed when freezing the surfactant-containing solution prior to warming-up and pressurization. The melting ice consuming large amount of heat enabled a sequential transformation of water into hydrate tracing the thawing front. This thermotactic behavior was also consolidated in a more macroscopic process. The findings could provide new insights into the kinetics of gas hydrate formation coupling the heat-associated phase transition; the results could also be of help in the up-scale of the hydrate-based techniques where a concentrated transformation is highly required. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF