Understanding transport and separation of organic mixed working fluids in T-junction from multi-scale insights: Literature review and case study

The separator has been proven to be an important component to improve the energy-efficient performance of thermodynamic cycles. Moreover, the T-junction, as a typical separator for the phase and the composition separation, has been widely applied in energy and chemical systems. However, at the present stage, the clarification on mechanisms of the composition separation in T-junctions is still missing, as the related study on the macroscale is encountering a bottleneck. This poses a critical challenge to its further applications in thermodynamic cycles. Alternatively, composition separation on the nanoscale via T-junctions would guide a new direction. Furthermore, with the help of the multi-scale coupling scheme, the mechanism could be understood from the molecular insights due to the unity of macroscopic phenomena and microscopic molecular motions. Therefore, in this study, a comprehensive review of the transport and the separation of mixtures in T-junctions from multi-scale insights is presented. The review firstly covers the basic knowledge, applications and recent advances of T-junctions on both macroscale and nanoscale. The pros and cons of existing studies are analyzed as well. Moreover, knowledge gaps and development prospects are proposed. Because there is a lack of study on the nanoscale separation, a case study was conducted. Finally, with the state-of-the-art of macroscale and nanoscale studies comprehensively presented, the multi-scale coupling scheme is introduced to provide a bridge between the macroscale and the nanoscale. This work endeavors to provide a whole picture of multi-scale studies on the transport and the separation of mixtures in T-junctions, and provide a new idea to clarify the separation mechanism. © 2020