Session: Raymond Viskanta Memorial Symposium-06: Thermal Management and Phase Change

Paper Number: 105986

105986 - Molecular Dynamics Simulations of Water Evaporation and Condensation in Membrane and Hydrogel 

Understanding the dynamics of water condensation–evaporation behavior on fibers and in hydrogels is important for improving the performance of fibrous membranes and hydrogels that are used in water purification applications. In this talk, I will present our recent work in understanding these dynamics using molecular dynamics simulations. We used molecular dynamics simulations as the conventional (experimental or computational) methods do not have the required atomistic resolution to reveal the dynamics of water condensation–evaporation on the surface of fibers and also inside the hydrogel.  I will first demonstrate a strategy to simulate the steady-state water condensation–evaporation process, i.e., simulation times >> 10 ns, in contrast to the quasi-steady-state simulations (simulation time <~2 ns) reported in most previous studies. I will then show a simulation platform to study the dynamics of the water condensation–evaporation on fibers and can be used to guide the design of direct contact distillation membranes, where the effects of surface wettability, temperature difference, and capillary condensation were explored. Moreover, I will show our recent work in the molecular-level understanding of the reduction of water evaporation enthalpy in the hydrogel, how this reduction correlates with the three states of water (“bound water”, “intermediate water”, and “free water”) in the hydrogel, and how the molecular structure and composition of polymer chains in hydrogel affect the evaporation.

Presenting Author: Jun Liu North Carolina State University