Variation features of unfrozen water content of water-saturated coal under low freezing temperature

Abstract To determine the unfrozen water content variation characteristics of coal from the low temperature freezing based on the good linear relationship between the amplitude of the nuclear magnetic resonance (NMR) signal and movable water, pulsed NMR technology was used to test water-saturated co...

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Autores principales:	Bo Li, Laisheng Huang, Xiaoquan Lv, Yongjie Ren
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/d6e986291e0146069e428f08d8bfcc0c
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spelling	oai:doaj.org-article:d6e986291e0146069e428f08d8bfcc0c2021-12-02T16:14:23ZVariation features of unfrozen water content of water-saturated coal under low freezing temperature10.1038/s41598-021-94943-62045-2322https://doaj.org/article/d6e986291e0146069e428f08d8bfcc0c2021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-94943-6https://doaj.org/toc/2045-2322Abstract To determine the unfrozen water content variation characteristics of coal from the low temperature freezing based on the good linear relationship between the amplitude of the nuclear magnetic resonance (NMR) signal and movable water, pulsed NMR technology was used to test water-saturated coal samples and analyze the relationship between the unfrozen water content, the temperature and pore pressure during freeze–thaw from a microscopic perspective. Experimental results show that the swelling stress of the ice destroys the original pore structure during the freezing process, causing the melting point of the pore ice to change, so the unfrozen water content during the melting process presents a hysteresis phenomenon. When phase equilibrium has been established in the freezing process, the unfrozen water is mainly the film water on the pore surface and pore water in pores with pore radius below 10 nm. At this time, the freezing point of the water in the system decreases exponentially as the temperature increases. The micropores of the coal samples from the Jiulishan Coalmine are well-developed, and the macropores and fractures are relatively small, with most pores having a pore radius between 0.1 and 10 nm. The pore water freezing point gradually decreases with the pore radius. When the pore radius decreases to 10 nm, the freezing point of pore water starts to decrease sharply with the decreasing pore radius. When the pore radius reaches 1.54 nm, the pore water freezing point changes as fast as 600 ℃/nm.Bo LiLaisheng HuangXiaoquan LvYongjie RenNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Bo Li Laisheng Huang Xiaoquan Lv Yongjie Ren Variation features of unfrozen water content of water-saturated coal under low freezing temperature
description	Abstract To determine the unfrozen water content variation characteristics of coal from the low temperature freezing based on the good linear relationship between the amplitude of the nuclear magnetic resonance (NMR) signal and movable water, pulsed NMR technology was used to test water-saturated coal samples and analyze the relationship between the unfrozen water content, the temperature and pore pressure during freeze–thaw from a microscopic perspective. Experimental results show that the swelling stress of the ice destroys the original pore structure during the freezing process, causing the melting point of the pore ice to change, so the unfrozen water content during the melting process presents a hysteresis phenomenon. When phase equilibrium has been established in the freezing process, the unfrozen water is mainly the film water on the pore surface and pore water in pores with pore radius below 10 nm. At this time, the freezing point of the water in the system decreases exponentially as the temperature increases. The micropores of the coal samples from the Jiulishan Coalmine are well-developed, and the macropores and fractures are relatively small, with most pores having a pore radius between 0.1 and 10 nm. The pore water freezing point gradually decreases with the pore radius. When the pore radius decreases to 10 nm, the freezing point of pore water starts to decrease sharply with the decreasing pore radius. When the pore radius reaches 1.54 nm, the pore water freezing point changes as fast as 600 ℃/nm.
format	article
author	Bo Li Laisheng Huang Xiaoquan Lv Yongjie Ren
author_facet	Bo Li Laisheng Huang Xiaoquan Lv Yongjie Ren
author_sort	Bo Li
title	Variation features of unfrozen water content of water-saturated coal under low freezing temperature
title_short	Variation features of unfrozen water content of water-saturated coal under low freezing temperature
title_full	Variation features of unfrozen water content of water-saturated coal under low freezing temperature
title_fullStr	Variation features of unfrozen water content of water-saturated coal under low freezing temperature
title_full_unstemmed	Variation features of unfrozen water content of water-saturated coal under low freezing temperature
title_sort	variation features of unfrozen water content of water-saturated coal under low freezing temperature
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/d6e986291e0146069e428f08d8bfcc0c
work_keys_str_mv	AT boli variationfeaturesofunfrozenwatercontentofwatersaturatedcoalunderlowfreezingtemperature AT laishenghuang variationfeaturesofunfrozenwatercontentofwatersaturatedcoalunderlowfreezingtemperature AT xiaoquanlv variationfeaturesofunfrozenwatercontentofwatersaturatedcoalunderlowfreezingtemperature AT yongjieren variationfeaturesofunfrozenwatercontentofwatersaturatedcoalunderlowfreezingtemperature
_version_	1718384321577877504

Variation features of unfrozen water content of water-saturated coal under low freezing temperature

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