Experimental and numerical investigation of energy separation in counterflow and uniflow vortex tubes

There are mainly two types of vortex tube - counterflow and uniflow. Many papers mention that energy separation in uniflow configuration is inferior to that in counterflow configuration. However, an in-depth analysis to find the reason behind this phenomenon is not found in the literature. In this paper experimental investigation is conducted for comparing energy separation in counterflow and uniflow vortex tubes for same geometrical and operating parameters. Also, 3-D CFD analysis is conducted to find the cause of difference in energy separation in these types of vortex tube. Flow field inside both tubes are analyzed and the rates of work and heat transferred between core region and peripheral region are calculated. Tangential shear work transfer from the core region to the peripheral region is identified as the reason of energy separation, while heat transfer from peripheral zone to axial zone reduces energy separation in both counterflow and uniflow vortex tubes. However, transfer of significantly greater sensible heat from peripheral region to core region in uniflow vortex tube causes more reduction of energy separation by decreasing the hot exit temperature and increasing the cold exit temperature. (C) 2020 Elsevier Ltd and IIR. All rights reserved.