The aim of this investigation is study on separation phenomenon inside a special vortex tube affected by structural and physical factors including; throttle diameter, nozzle number and injection pressure as well as the parametric optimization based on separation efficiency using experimental and 3D-CFD methods. The results show that convergent VT with D_th=5.5mm provides 30.01% and 20.04% higher cooling and heating effectiveness compared to basic model. As another result, the higher injection pressure, the higher cooling effectiveness. The cooling effectiveness improves(16.86%) with increase in slot number up to N=4, then decreases. The maximum disagreement between experimental and predicted values is 6.25%.