Homogeneous nucleation of water droplets in mixtures of carbon dioxide and nitrogen

0573293 - ÚT 2024 eng C - Konferenční příspěvek (zahraniční konf.)
Lukianova, Tetiana - Lukianov, Mykola - Hrubý, Jan
Homogeneous nucleation of water droplets in mixtures of carbon dioxide and nitrogen.
[Trondheim Conference on CO2 Capture, Transport and Storage /12./. Trondheim (NO), 19.06.2023-21.06.2023]
Grant CEP: GA MŠMT(CZ) EF16_019/0000753
Institucionální podpora: RVO:61388998
Klíčová slova: CO2 Transport * CO2 utilization * homogeneous nucleation * water * nitrogen
Obor OECD: Thermodynamics
https://www.sintef.no/projectweb/tccs-12/

Being a combustion product, carbon dioxide is mainly found in mixtures with nitrogen and water vapor. For the purposes of carbon transport, storage, and utilization, it is desirable to reduce the contents of other components. The degree of purity is a tradeoff between costs of separation and requirements for downstream technology. Therefore, impurities will always be present at considerable levels. Condensation of moisture can be an undesirable effect when occurring in a transport pipeline. On the other hand, condensation processes can be utilized as a part of separation technologies. Homogeneous nucleation of water droplets was studied by numerous investigators. Water nucleation was studied in argon [1] and other monatomic gases [2], and in nitrogen [3]. Recently, Campagna et al. [4] measured nucleation rates of water in mixtures of carbon dioxide and nitrogen at pressures up to 2 MPa at 240 K with CO2 molar fraction up to 0.25. By analysis of nucleation rate data using the nucleation theorem, they obtained information on the composition of critical clusters [5]. In the present study, we present measurements of nucleation rate in 5 carrier gas mixtures spanning from pure N2 to pure CO2 at 5 isotherms from 220 K to 260 K. All measurements were performed at subatmospheric pressure, typically 50 kPa. The expansion chamber used in this study was developed by Wagner and Strey [6] and it was used for numerous studies of homogeneous nucleation by the group of Prof. R. Strey at Max-Planck-Institut für Biophysikalische Chemie, Göttingen [2], and at Universität zu Köln [1]. The chamber was rebuilt several times. At the Institute of Thermomechanics, several upgrades were made, including a completely oil-free vacuum setup preventing a danger of back-leakage of oil vapors. The experimental results – nucleation rates for various temperatures, supersaturations, and compositions of the carrier gas – are shown in Fig. 1. On the contrary to previous studies performed with this apparatus [1,2], we evaluated the temperatures and supersaturations using real-gas computations. The real-gas effects are quite strong for these carrier gases. The difference in nucleation rates for the various carrier gas mixtures is not large, although it can be seen that CO2 somewhat promotes nucleation even at low pressure. This effect is primarily attributed to gas adsorption which diminishes the surface tension. Also, it can be seen that the slope of the isotherms in Fig. 1 gets smaller with increasing CO2 contents, which can be interpreted as a decreasing number of water molecules forming the critical cluster.
Trvalý link: https://hdl.handle.net/11104/0351464