Entropy study of water in carbon nanotube surface with uneven hydrophobicity

The water flows in carbon nanotubes (CNTs) have extensive potential for use in applications such as water desalination, water purification and high efficiency of nanofluid energy absorption systems. Furthermore, the surface hydrophobicity of CNTs exhibits significant impact on the water transport and water phase which make the CNT a good candidate for a latent heat thermal storage system. The hydrophobicity of CNTs can be assessed by the values of interaction-energy-coefficient (IEC) - a key factor denoting the energy interaction strength between water molecules and carbon atoms. In this study, the water transport and phase in CNTs of different lengths and diameters and hydrophobicity were investigated using a combined two-phase thermodynamic (2PT) model and molecular dynamics (MD) simulation approach. The results show the existence of a solid phase of water in the CNTs of a long length and small radius. In addition, the distribution of hydrophobic and hydrophilic sections affects the water phase in CNTs significantly.