Counter-flow Vortex Tube Research Articles

Parametric and internal study of the vortex tube using a CFD model

A computational fluid dynamics (CFD) model is used to investigate the energy separation mechanism and flow phenomena within a counter-flow vortex tube. A two-dimensional axi-symmetric CFD model has been developed that exhibits the general behavior expected from a vortex tube. The model results are compared to experimental data obtained from a laboratory vortex tube operated with room temperature compressed air. The CFD model is subsequently used to investigate the internal thermal-fluid processes that are responsible for the vortex tube's temperature separation behavior. The model shows that the vortex tube flow field can be divided into three regions that correspond to: flow that will eventually leave through the hot exit (hot flow region), flow that will eventually leave through the cold exit (cold flow region), and flow that is entrained within the device (re-circulating region). The underlying physical processes are studied by calculating the heat and work transfers through control surfaces defined by the streamlines that separate these regions. It was found that the energy separation exhibited by the vortex tube can be primarily explained by a work transfer caused by a torque produced by viscous shear acting on a rotating control surface that separates the cold flow region and the hot flow region. This work transfer is from the cold region to the hot region whereas the net heat transfer flows in the opposite direction and therefore tends to reduce the temperature separation effect. A parametric study of the effect of varying the diameter and length of the vortex tube is also presented.

Experimental Investigation on Dust Separation Characteristics of a Vortex Tube

Dust separation characteristics of a counter-flow vortex tube were investigated with lime powders whose mean particle sizes were 5 and 14.6µm. The experiment showed that a vortex tube can be used as an efficient pre-skimmer to separate particles from the waste gas in industry. In case of fine particles, a trend of increasing separation efficiency was observed with inlet pressure up to 160kPa at which the flow rate was 9.5m3/hr, but there was a tendency of reduction in the coarse particles. For both powder sizes, the efficiency and the effective nozzle inlet velocity were 93% and 14.52m/s respectively, while the tested vortex tube had a small diameter of 16mm and the ratio of the nozzle hole area to the tube cross-sectional area was 0.15. Additionally, the geometric ratios of the vortex tube could be proposed as 0.44 for the ratio of the orifice diameter at clean gas exit to the tube diameter and 14.0 for the ratio of the tube length to the diameter.

Experimental Investigation of the Energy Separation in Vortex Tubes

Measurements of the state and the velocity distribution of air in a counterflow vortex tube have been undertaken. In order to determine the axial variation of the flow quantities, measurements were carried out in several cross-sections.The experimental results show that the velocity is predominantly tangential. A comparison of the order of magnitude of the radial and axial convection terms in the equations of motion and energy shows that these terms are of equal importance.The energy equation in terms of the total temperature is used as a basis for discussing the influence of turbulence in the flow on the separation of energy in the vortex tube.