Surface wettability effect on heat transfer across solid-water interfaces

Abstract

• Mechanisms of surface wettability effect on interfacial heat transfer are unraveled. • Hydrophilic surface promotes heat transfer through enhanced hydrogen-bonded network. • Molecular roughness with high biphasic contact area is beneficial to heat transfer. • Multiple and shallow vacancies are better than the deep but fewer ones on substrate. Although it has been found that the heat transfer across solid–liquid interface can be affected by the surface wettability, the underlying mechanism remains ambiguous. Herein non-equilibrium molecular dynamics simulations are conducted to unravel the microscopic mechanisms of heat transfer across solid-water interfaces. Specifically, two aspects of the solid surface wettability are investigated including modifying surface chemistry and introducing molecular roughness. We find that enlarging the solid-water interaction strength facilitates the formation of hydrogen-bonded network of water, hence enhancing the interfacial heat transfer. In addition, introducing molecular roughness can promote heat transfer by increasing the solid-water contact area. When the contact area remains the same, the substrates with multiple and shallow vacancies are more beneficial to heat transfer than those with deep but fewer vacancies. This work sheds insights into the mechanistic understanding of the heat transfer process and provides theoretical guidance for the development of efficient heat transfer devices.