Growth Pattern Dependence of Tetrahydrofuran Hydrates in Glass Beads of Two Sizes on Growth Rate and Glass Bead Mixing Ratio

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• 作者：Michihiro Muraoka ; Kazushige Nagashima
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：August 6, 2014
• 年：2014
• 卷：14
• 期：8
• 页码：3813-3824
• 全文大小：800K
• ISSN：1528-7505

文摘

We observed the pattern formation of tetrahydrofuran (THF) clathrate hydrates in a mixture comprising a THF鈥?7H₂O solution and glass beads of two sizes (2 and 50 渭m diameter) as functions of growth rate and glass bead mixing ratios (by weight). The overall hydrate growth rate, V, was controlled using a directional growth apparatus. The results showed that the growth interface of the initial hydrate layer destabilized with growth. The wavelength, 位, of the destabilized initial hydrate layer demonstrated a power law decrease as the growth rate V increased. We successfully formed various hydrate patterns and classified them into a pattern diagram according to the glass bead mixing ratio and the growth rate V. In addition, we are the first to successfully obtain a needle pattern. Image analysis showed that the segregated growth area of the hydrates and the average hydrate area increased, whereas the number density of hydrate grains decreased with decreasing V. These results are qualitatively consistent with the frost heave model. Finally, we proposed needle, nodular, and massive pattern hydrate formation models by summarizing the discussions from the frost heave model and the morphological instability model of crystal growth.