In this equation m_ c is the mass flow rate at the cold exit and m_ i is
the inlet flow rate. Vortex tube performance was first discovered by
Ranque [1] when he was investigating processes in a dust separation cyclone. The German physicist Rudolf Hilsch [2] improved the
design of this mechanism. Some of investigations on various aspects of vortex tubes are briefly mentioned below: Dutta et al. [3]
performed a numerical study on energy separation inside a simple vortex tube. In their work a three dimensional Computational
Fluid Dynamics (CFD) model is applied to study the phenomena of
energy separation in a vortex tube with compressed air at normal
atmospheric temperature and cryogenic temperature as the
working fluid. Also in this work the NIST real gas model is employed
for the first time to accurately compute the thermodynamic and
transport properties of working fluid inside the vortex tube.
Baghdad et al. [4] analyzed the prediction capability of different
turbulence models including: the ke 3, keu and SST keu. Four cases
have been assumed by changing the pressure inlet in the range of
200e380 kPa. In their work, this is clearly observable that all the
above mentioned turbulence models are capable of predicting fairly
well the general flow characteristic. Valipour et al. [5] studied the
effect of curved working tube on vortex tube performance. They
found that the curvature in the main tube has different effects on
the vortex tube performance depending on inlet pressure and cold
mass fraction. Also their work presents that the maximum cold
temperature difference is created by straight one. Dincer [6] performed an experimental study on vortex tube systems. In his study,
performances of vortex tubes were experimentally investigated
under three different situations on basis of inlet pressure and the
cold mass fraction. 1st situation is the conventional vortex tube.