Effect of surface curvature and wettability on nucleation of methane hydrate

Abstract

Natural gas hydrate nucleation is a complex physical and chemical process that is not well understood presently. In this article, an improved thermodynamic model is proposed to analyze the effects of surface curvature and wettability on methane hydrate nucleation for the first time. The results indicate that methane hydrate nucleation is more difficult on hydrophilic curvature surfaces under the same conditions, with a larger critical nucleation radius and required energy barrier than on hydrophobic surfaces. Furthermore, a convex surface is more favorable for forming methane hydrate under the same conditions than a concave surface. The model's results are critical in elucidating the microscopic mechanism of methane hydrate nucleation and providing a theoretical foundation for developing technologies for strengthening and inhibiting hydrate formation.

Effect of surface roughness on methane hydrate formation and its implications in nucleation design

“…However, when D > 2, that is, when the wall is rough, the nucleation barrier on hydrophilic walls significantly increases. This indicates that the rough wall with curvature inhibits hydrate nucleation significantly, which is consistent with our previous findings 23 and can explain the experimental phenomenon in which hydrophilic nanoparticles inhibit hydrate formation. [50][51][52] In the hydrophobic region, the curves with varying degrees of roughness are extremely close (almost coincide), but ΔG*(D > 2) < ΔG*(D = 2), which is favorable for nucleation.…”

“…These technologies cannot be developed without an in‐depth comprehension of the mechanism of hydrate nucleation and mastery of the regulation technology of hydrate nucleation 21,22 . In contrast to conventional crystal nucleation, however, the current understanding of hydrate nucleation is insufficient, 23 particularly the theoretical description of hydrate nucleation by the corresponding wall roughness. Notably, the characteristics of other crystal nucleation controls, such as the regulation of (super) hydrophobic surfaces, 24–27 the control of ice formation in clouds, 28–31 the selection and control of protein crystals, 32,33 and the prevention of material damage due to surface freezing and adhesion, 34–36 are well understood in many fields.…”

Multifunctional Amphiphobic Coating toward Ultralow Interfacial Adhesion of Hydrates

“…A similar trend also has been reported for the critical nucleation energy of ice and gas hydrate as a function of the contact angle of the substrate surface. 38,39 It can be seen from Figure 4a that the contact angle of the TBAB droplet on the hydrophobic surface is greater than that on the bare substrate surface. Therefore, the superhydrophobic surface must overcome a higher energy barrier to nucleate, which delayed the nucleation time of TBAB hydrate by 42− 43%.…”