Effects of variable thermophysical properties on flow and energy separation in a vortex tube

• Energy separation and flow within a vortex tube were studied numerically.
• A 3D computational domain was generated considering the quarter of the geometry.
• The flow predictions are based upon the RSM model.
• Air is selected as the working fluid with temperature-dependent thermophysical properties.
• The mean pressure and temperature of the cold and hot exits are used in the exergy analysis.

A numerical study has been conducted to investigate the effects of variable fluid properties on the prediction of a basic tube vortex design. Beforehand, a literature review is presented to highlight some of the recent advances in the enhancements of the device design and its efficiency. The three-dimensional computations with constant and variable properties revealed that the constant thermophysical assumption might not have a dramatic effect if the aim is to predict global values only, but extra caution should be taken for an in-depth flow assessment. The exergy analysis conducted suggests that the highest exergy efficiency, for the current device design, ranges from 38% to 46% depending on the inlet pressure value. Based on the current numerical analysis; rather large exergy losses are due to irreversibility occurring at either; the lowest or the highest cold mass fraction boundary conditions.