Chuanhua Duan

Exploring the Effect of Surface Active Contaminant on Water Capillary Evaporation in Nanoscale Confined Spaces

PROJECT DESCRIPTION
The goal of this project is to quantify and elucidate the effect of surface active contaminants on water capillary evaporation in nanoscale confined spaces. Capillary evaporation is one of the most efficient approaches for heat and mass transfer and has shown many promising applications in thermal management, membrane distillation and microfluidic pumping. This thin-film-evaporation based heat/mass transfer strategy utilizes capillary action of micro/nanoscale channels/tubes to drive the liquid and maintain a steady thin liquid film around the meniscus at the channel/tube entrance for fast evaporation. Consequently, high heat/mass fluxes and heat transfer coefficients could be simultaneously achieved by this strategy at relatively low operating temperatures. However, in reality, this evaporation process could be significantly affected by the presence of surface active contaminants, including fatty acids, alcohols, mono-glycerides and surface active ions, which could change liquid-solid interaction and liquid-vapor interaction, leading to a dramatic decreasing of evaporation performance.

Herein we propose to conduct a thorough study on the effect of surface active contaminants on capillary evaporation in various nanoscale confinements using single nanochannel/nanopore devices. We will prepare aqueous solutions with different concentrations of surface active salts and/or fatty acids with varied molecular lengths as contaminated working and measure capillary evaporation of these solutions in in single nanochannels/nanopores with a feature size ranging from 10 nm to 200 nm.  We will investigate the effect of contaminants size and concentration on capillary evaporation. We will also study the dependence of contaminant accumulation on geometrical confinements and the resulting evaporation rate changes. Success of this study will clarify the effect of contaminants on capillary evaporation in nanoscale confined spaces for the first time, which will pave the road for optimization of nanoporous membranes to achieve the maximum evaporation performance in reality.

LEARNING GOALS
• Achieve a basic understanding of capillary evaporation
• Learn how to use microscope and camera to do single nanochannel/nanopore evaporation measurements
• Understand the effect of surface active contaminant on liquid/air interface properties
• Understand the effect of surface active contaminant on capillary evaporation in nanoscale confined spaces

Learn more about Professor Duan’s work at his lab website.