A new thermodynamic model for the prediction of air vortex tube performances.

A new thermodynamic model is proposed to predict the vortex tube performances. Static temperature drops while high pressure air is accelerated adiabatically through the nozzle. At the inlet, forced vortex, flat axial velocity's profile and constant static temperature are assumed, allowing the calculation of the mean total cold outlet temperature. It has been favourably compared to experimental data from the literature and to a new artificial neural network model. Results show that most important parameters for design purpose are the inlet to cold outlet pressure ratio to maximize the inlet velocity. The importance of the cold mass fraction is related to its impact on the cold side back pressure and axial velocity. The model shows that the influence of friction and boundary layer flow on the temperature separation is important. Finally, this model is used to identify the optimum cold outlet diameter.