Molecular dynamics investigation on the composition separation of binary organic mixture in a double-walled T-shaped carbon nanotube separator

The composition separation of binary mixtures in a single-walled T-shaped carbon nanotube has aroused widespread interest. Practically, the double-walled carbon nanotube is widely utilized as well due to its advantageous thermal stability and mechanical properties. However, composition separation in a double-walled, T-shaped carbon nanotube is rarely reported in published literature, which presents a knowledge gap in the application of carbon nanotubes in designing nanodevices. Therefore, in this work, the transport and composition separation of a promising binary organic mixed working fluid in thermodynamic cycles, HFC32/HC600a, in a double-walled, T-shaped carbon nanotube are investigated through non-equilibrium molecular dynamics simulation. The transport and composition separation are driven by the temperature difference; the effects of these temperature differences and interlayer twist angles are carefully discussed. Moreover, the transport and composition separation performance in a double-walled, T-shaped carbon nanotube are compared to those in a single-walled one. The underlying mechanism is analyzed from the perspective of the interaction force and the potential of mean force point of view. The results indicate that satisfactory composition separation can be obtained in a double-walled T-shaped carbon nanotube, and the performance difference from the single-walled one contributes to a larger interaction force between the nanotube and the mixture molecules. © 2020 Elsevier B.V.