%0 Journal Article
%T CFD Analysis of Energy Separation in Ranque-Hilsch Vortex Tube at Cryogenic Temperature
%A T. Dutta
%A K. P. Sinhamahapatra
%A S. S. Bandyopadhyay
%J Journal of Fluids
%D 2013
%R 10.1155/2013/562027
%X Study of the energy separation phenomenon in vortex tube (VT) at cryogenic temperature (temperature range below 123£¿K) has become important because of the potential application of VT as in-flight air separator in air breathing propulsion. In the present study, a CFD model is used to simulate the energy separation phenomenon in VT with gaseous air at cryogenic temperature as working fluid. Energy separation at cryogenic temperature is found to be considerably less than that obtained at normal atmospheric temperature due to lower values of inlet enthalpy and velocity. Transfer of tangential shear work from inner to outer fluid layers is found to be the cause of energy separation. A parametric sensitivity analysis is carried out in order to optimize the energy separation at cryogenic temperature. Also, rates of energy transfer in the form of sensible heat and shear work in radial and axial directions are calculated to investigate the possible explanation of the variation of the hot and cold outlet temperatures with respect to various geometric and physical input parameters. 1. Introduction The Ranque-Hilsch vortex tube (VT) separates a compressed gas stream into two lower pressure streams with one stream having higher temperature and the other having lower temperature than the inlet stream. This phenomenon is referred to as energy (temperature) separation. VT consists of one or more tangential inlet nozzles (vortex generator/generator), a tube, an orifice at the cold gas outlet, and a conical control valve at the hot gas outlet. When compressed gas is tangentially injected into the VT through the inlet nozzles, intense swirling flow is generated and the gas proceeds towards the hot outlet. A portion of the gas moving towards the hot outlet reverses its direction near the hot outlet and moves towards the cold outlet along the axial region (also called the core region) of the tube. The peripheral region of the flow is found to be warmer than the inlet gas, while the flow near the core region becomes colder than the inlet gas. The warm peripheral flow comes out through the annular space between the tube wall and the conical valve at the hot outlet. The colder core flow in the opposite direction comes out through the central orifice of the cold outlet. The conical valve placed at the hot outlet controls the relative mass flow rate of hot and cold gases. The airflow in a VT is shown in Figure 1(a) with representative values of pressures and temperatures at inlet and outlets for VT working with room temperature air. Due to its advantages, such as no moving
%U http://www.hindawi.com/journals/fluids/2013/562027/