Thermodiffusion of CO2 in Water by Nonequilibrium Molecular Dynamics Simulations

Autor(es)

Coelho, Felipe M. ; Franco, Luis F. M. ; Firoozabadi, Abbas

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry B; v. 127, n. 12, p. 12-pg., 2023-03-17.

Resumo

The components of a fluid mixture may segregate due to the Soret effect, a coupling phenomenon in which mass flux can be induced by a thermal gradient. In this work, we evaluate systematically the thermodiffusion of the CO2-H2O mixture, and the influence of the geothermal gradient on CO2 segregation in deep saline aquifers in CO2 storage. The eHeX method, a nonequilibrium molecular dynamics simulation approach, is judiciously selected to simulate the phenomenon. At 350 K, 400 bar, and CO2 mole fraction of 0.02 (aquifer conditions), CO2 accumulates on the cold side, and the thermal diffusion factor is close to 1 in a number of force fields. The lower the temperature, the higher is the separation and the thermal diffusion factor. In colder regions, water self-association is stronger, whereas the CO2-H2O cross-association and the CO2-CO2 interactions enhance at higher temperatures. Thermodiffusion and gravitational segregation have opposite effects on CO2 segregation. At typical subsurface conditions, the Soret effect is more pronounced than gravity segregation, and CO2 concentrates in the top (colder region). Our work sets the stage to model the effect of electrolytes on CO2 segregation in subsurface aquifers and other areas of interest. (AU)

• Processo FAPESP: 18/02713-8 - Dinâmica molecular de fluidos confinados: propriedades de equilíbrio e de transporte
• Beneficiário: Luís Fernando Mercier Franco
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 20/13300-6 - Simulações de dinâmica molecular para estudo de propriedades de equilíbrio de misturas de fluidos confinados
• Beneficiário: Felipe Mourão Coelho
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 21/13068-9 - Termodifusão de CO2 em água: o impacto do gradiente geotérmico no sequestro de carbono em aquíferos salinos profundos via simulação molecular
• Beneficiário: Felipe Mourão Coelho
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado Direto