The vortex tube (VT) cyclone separators are widely used in separation processes such as purification of the hydrocarbon mixtures. An experimental setup has been designed to study both the cooling and heating separations in VT for two main cases: a) structural parameters of the control valve and b) geometrical parameters of the hot tube. In each case, the optimized values of structural parameters have been determined and the effects of the above-mentioned factors on the separation quality have been evaluated. The relation between the positions of both the secondary circulations and the stagnation points and the separation quality has been explained for different throttle diameters. The shape of flow domain inside the separator has been explained using three-dimensional computational fluid dynamics (CFD) models. Finally, the comparison between the computed and laboratory outputs presents a favorable agreement.