Hydrate Growth over a Sessile Drop of Water in Cyclopentane

Abstract

Liquid cyclopentane is frequently used in hydrate formation studies as an analogue of natural gas because cyclopentane hydrates are stable above the ice melting point at ambient pressure. In this study, hydrate growth was established on a sessile water drop of 11 mm in diameter and 4.5 mm in height (volume of 0.25 mL) immersed in liquid cyclopentane. The hydrate formation mechanism and growth processes were observed optically over an extended range of subcooling temperatures from 5.1 to 15.2 °C, with the cyclopentane bulk temperature maintained in different experimental runs between 2.6 and −7.5 °C. Qualitative and quantitative comparisons were performed to confirm the absence of ice freezing during hydrate formation, and thus, the lack of contamination of the latter from the former in the experiments. Different transformations in the hydrate film morphology were registered from macroscopic observation over the considered range of subcooling temperatures, with the hydrate crystals composing the film taking the form of polyhedral, dendritic, or spherulitic structures. It was also found that the hydrate growth rate varied depending on the subcooling temperature, with the variation of the growth rate as a function of this temperature changing from a power to an (approximately) linear law with an increase in the degree of subcooling. We postulate that hydrate film growth can be governed by different mechanisms, whose roles change over the range of explored subcooling temperatures.

A Peptoid-like Approach Led to Lactam–Lactam Dimer Formation in 2-Hydroxy-N-alkyl-N-phenyl-nicotinamides and Their Polymorphism and Solvatomorphism

“…To answer these questions, crystals were grown in a variety of apolar, polar aprotic, and polar protic solvents. Solvatomorphism − was observed in compounds 1 and 2 , and polymorphism was revealed in compounds 3 and 4 . The dominant synthon observed in all four molecules is the LLD.…”

Amorphous-like thermal conductivity and high mechanical stability of cyclopentane clathrate hydrate

“…The clathrate formation and phase behavior of cyclopentane (CP) clathrate hydrate have been studied both in mixtures and pure state, 8–18 and its properties have been studied by calorimetry, 19 nuclear magnetic resonance, 21–23 infrared, 24 Raman 25 and dielectric spectroscopy. 26 In this study, we have measured the thermal conductivity of CP CH, which has not been investigated before.…”