Three dimensional numerical analysis of the performance of different working fluids in vortex tubes

Improving efficiency of energy systems has become significantly crucial to address climate change. One way to achieve this is by incorporating new devices, such as vortex tubes, but their use is limited due to limited development and inadequate efficiency. A key factor in improving their performance is the choice of the suitable working fluid. This research study aims to numerically investigate the performance of different working fluids and their properties. A three dimensional computational model is developed by using the standard k- ϵ turbulence model and by considering a mesh independence study and a y + study. This study comprises two main investigations. The first investigation examines the performance of different working fluids, including nitrogen, carbon dioxide, oxygen, air, helium, and argon, at different inlet pressures. The second investigation evaluates four different working fluid properties — thermal conductivity, dynamic viscosity, molecular weight, and heat capacity ratio — to determine which one has more significant influence on the temperature separation than others. Additionally, the effect of turbulence on temperature separation is also investigated. As a result, Argon is the best performing fluid, followed by Helium. Nitrogen, oxygen, and air have almost similar performance, whereas CO 2 exhibits the lowest performance. Furthermore, the working fluid having lower molecular weight and heat capacity ratio results in higher temperature separation. It is found that turbulent eddy viscosity has a significant effect on temperature separation. These findings contribute to the selection of the appropriate working fluid for specific applications and improve the understanding of the vortex tube temperature separation. • Numerical investigation of temperature separation of six different working fluids. • Evaluation of the effect of working fluid properties on the temperature separation. • Results can be used to select a suitable working fluid for a specific application. • Experimental investigation is necessary to validate the current numerical results.