Tenth International Conference on Computational Fluid Dynamics (ICCFD10), Barcelona, Spain, July 9-13, 2018 ICCFD10-340 Numerical Analysis of Phase Separation in Curved Ranque– Hilsch Vortex tube Pouriya H. Niknam*, Saman Farhangdoust**, Mashallah Rezakazemi*** * Corresponding author: pniknam@ccerci.ac.ir * Chemistry & Chemical Engineering Research Center of Iran ** Louisiana Tech University, Materials & Infrastructure Systems Engineering Department *** Shahrood University of Technology, Faculty of Chemical and Materials Engineering Abstract The phase separation characteristic in a novel vortex tube using a turbulence model is discussed in the present research. The curved geometry of the introduced vortex tube contributes to an effective phase separation by liquid removal enhancement. The hydrodynamic behavior of the proposed vortex tube is investigated in different inlet boundary conditions by a 3D CFD model. The BSL − turbulence model is utilized which is suitable for the complex flow pattern through vortex tube. Meanwhile, the liquid phase is moved by the axial velocity and by swirling effect to the wall side. The curvature design helps the liquid layer to be removed physically by a ring and a specific drainage considered at the half of the length of the tube. The results show that the efficiency of curved vortex tube is predicted up to 60% for the extraction of the heavy fraction. This efficiency is found highly dependent on the mass fraction of the outlets. Therefore, a balance between the product flow and quality should be preserved. Keywords: phase separation, dehydration, Vortex tube, Computational Fluid Dynamics (CFD), NDT 1 Introduction/Background A common vortex tube produces hot and cold streams simultaneously from a source of compressed gas entering tangentially via nozzles. The pressure of the inlet is about 5 to 7 bar and the pressure of both outlets are about the atmospheric condition. One of the streams has a higher temperature than the inlet compressed gas, while the other one has a lower temperature; this phenomenon is called the Ranque-Hilsch effect, or the thermal separation effect [1,2]. Transferring kinetic energy from the axis to the wall region causes thermal separation. The pressure difference between the two areas, caused by acceleration and viscous resistance, controls the temperature variation. The complexity of this internal fluid flow has been studied experimentally and numerically [3,4]. Many pieces of research have been based on 3D CFD models. The optimum angle was found to be not less than 45° and not more than 60°. Bovand et al. [5] showed that both the straight and 150° curved vortex tubes have higher performances as refrigerators than the other curvature angles. Different turbulent models are evaluated for simulation of common vortex tube as the comparison reported by Niknam et al. [6] in which k-kl-w was found to an effective approach. It was found that energy separation and cold side temperature depend mainly on the ratio of cold and hot gas mass flow rates and the inlet conditions. In the present study, the cooling feature of the vortex tube is utilized for phase separation of the gas stream with condensate content. A novel modification is applied to the geometry to achieve the