Amy Brunsvold

A review on wetting and water condensation - Perspectives for CO 2 condensation

Liquefaction of vapor is a necessary, but energy intensive step in several important process industries. This review identifies possible materials and surface structures for promoting dropwise condensation, known to increase efficiency of condensation heat transfer. Research on superhydrophobic and superomniphobic surfaces promoting dropwise condensation constitutes the basis of the review. In extension of this, knowledge is extrapolated to condensation of CO2. Global emissions of CO2 need to be minimized in order to reduce global warming, and liquefaction of CO2 is a necessary step in some carbon capture, transport and storage (CCS) technologies. The review is divided into three main parts: 1) An overview of recent research on superhydrophobicity and promotion of dropwise condensation of water, 2) An overview of recent research on superomniphobicity and dropwise condensation of low surface tension substances, and 3) Suggested materials and surface structures for dropwise CO2 condensation based on the two first parts.

EXPERIMENTAL METHODS FOR INVESTIGATING THE DISCRETE DROPLET IMPACT PHENOMENA OF A MODEL FLUID RELEVANT FOR LNG HEAT EXCHANGERS

To improve knowledge on the design and operational issues of heat exchangers used in the liquefaction process of liquefied natural gas (LNG), experiments were conducted to investigate the complex two-phase flow phenomena in an n-pentane environment. Special focus was placed on characterizing the impact thresholds (bouncing, coalescence, splashing, etc.) of n-pentane droplets impinging on a flowing liquid film of various angles. In the phase diagram of velocity and diameter, the threshold of splashing for n-pentane was found to be below that for water (i.e. lower translational energies lead to splashing). The splashing threshold was well-characterized by a model reported previously for water droplets on stationary surfaces, adjusted slightly for non-normal impacts, which is influenced greatly by the thickness of the liquid film. In addition, the bouncing threshold of n-pentane was found to decrease with higher liquid film velocities with a threshold generally lower than that of water.Copyright