Observation and kinetic modeling of carbon dioxide deposition under reduced pressures at cryogenic temperatures

Abstract

Liquefied natural gas (LNG) is typically vaporized through heat exchange with seawater or other sources and used as city gas or power generation fuel, but its cold energy remains underutilized. This study proposes a new CO₂ capture process leveraging LNG’s cryogenic temperatures to create a vacuum environment, recovering CO₂ from amine-based solutions as dry ice. CO₂ deposition under cryogenic and vacuum conditions was observed, and a deposition rate model was developed. In the experiment, liquid nitrogen circulated through the tube side of a glass vertical single-tube shell-and-tube heat exchanger (230 mm long), while CO₂ was supplied to the shell side. CO₂ was deposited on the outer surface of a 5-mm diameter tube, with its growth rate measured by a laser displacement sensor. At 293 K and pressures of 140–1000 Pa, experimental results matched a rate model based on energy balance and mass transfer.