Thermodynamic analysis of the energy separation in a counter-flow vortex tube (original) (raw)
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2014
The main objective of this paper is to study the effect of inlet gas temperature change on the fluid flow characteristics and energy separation phenomenon within a counter-flow vortex tube. The computational fluid dynamics (CFD) model is a three-dimensional steady compressible model that utilizes the k-ɛ turbulence model in order to analyse the high rotating flow. In this numerical research, different inlet gas temperatures have been used in the modeling in order to analyse the operation of the vortex tube. The results showed that increasing the inlet gas temperature leads to greater temperature separation, as well as greater hot and cold temperature separation. Moreover, it was found that increasing the inlet temperature does not have any significant effect on the stagnation point and maximum wall temperature position. Since this research concerns increased inlet gas temperatures, an implication of this study can be for vortex tubes to be used in procedures where heating or preheat...
Effects of variable thermophysical properties on flow and energy separation in a vortex tube
International Journal of Refrigeration, 2013
The present paper considers the numerical simulation and exergy analysis of a vortex tube with temperature-dependent thermophysical properties of air selected as the working fluid. A 3D computational domain has been generated considering the quarter of the geometry and assuming periodicity in the azimuthal direction which was found to exhibit correctly the general behaviour expected from a vortex tube. First, flow and heat transfer within the vortex tube have been determined by solving the conservation equations of continuity, momentum and energy using the second moment closure model (RSM) to model the turbulence effects. Results allow to obtain the flow and heat transfer behaviours within the tube and to compute mean pressures and temperatures at the cold and hot ends. These parameters are used in the exergy analysis to quantify the exergy losses produced within the vortex tube and its exergy efficiency. The models results are compared to experimental data obtained from the literature. Four cases have been considered by changing the inlet air pressure from 200 up to 380 kPa. It has been observed that RSM model is not only capable of predicting fairly well the general flow features but also it is capable of matching correctly the measured cold and hot outlet temperatures.
A critical review of temperature separation in a vortex tube
Experimental Thermal and Fluid Science, 2010
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Flow behavior and thermal separation mechanism on vortex tube
Journal of Thermal Engineering, 2021
Flow behaviour and thermal separation mechanism on vortex tubes have been studied numerically. Rapid expansion indicated by high-pressure gradient near the inlet and the exit ports contributes to energy separation on the parallel and the counter flow vortex tubes. It creates a cooling process at the core region and drives an internal and rotational energy transfer to the peripheral region, then increases the gas temperature at the periphery along with friction due to the presence of the confined wall. Static temperature is related to static pressure in such a way that low pressure leads to the low static temperature at the same region inside the vortex tube. On the other hand, the high total temperature is found in the region with the low dynamic velocity. For both vortex tubes, the flow fields are mainly governed by the tangential velocity at the periphery and by the axial velocity at the core region. The maximum Mach number values based on the maximum tangential velocities in the inlet area for the counter and the parallel flow vortex tubes are 0.689 and 0.726, respectively, so both are compressible and subsonic flows. For the same size of geometry and boundary conditions, the parallel flow vortex tube has higher COP than the counter flow vortex tube i.e. 0.26 and 0.25, respectively.
The Expansion Process in a Counter-flow Vortex Tube
Journal of Vortex Science and Technology, 2015
The process of temperature separation in a Ranque-Hilsch vortex tube is dependent on a multitude of factors, such as the pressure gradients, flow stagnation and mixture, energy transfer between different flow layers and heat transfer between the tube and the ambient air. The pressure gradient in an expansion process within a vortex tube has been proposed as the dominating reason for the temperature drop. However, at present, there is no general agreement within the research community for the expansion process itself, primarily due to the complexity of the internal flow conditions in the tube. Therefore, in the present article, a deeper insight into the separation mechanism within a vortex tube is presented, based on an analytical analysis using different expansion models, including isentropic expansion, free expansion and Joule-Thomson expansion. It was observed that the isentropic expansion is the only possible expansion process within a vortex tube. This was confirmed through comparison with experimental results obtained from different sources.
Experimental study of the thermal separation in a vortex tube
Experimental Thermal and Fluid Science, 2013
Ranque effect Ranque-Hilsch vortex tube Forced and free vortex Thermal separation Vortex flow a b s t r a c t A vortex tube, a simple mechanical device capable of generating separated cold and hot fluid streams from a single injection, has been used in many applications, such as heating, cooling, and mixture separation. To explain its working principle, both experimental and numerical investigations have been undertaken and several explanations for the temperature separation in have been proposed. However, due to the complexity of the physical process in the vortex tube, these explanations do not agree with each other well and there has not been a consensus.
IJERT-Thermodynamic Analysis Of Counter Flow Vortex Tube
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/thermodynamic-analysis-of-counter-flow-vortex-tube https://www.ijert.org/research/thermodynamic-analysis-of-counter-flow-vortex-tube-IJERTV2IS2086.pdf The vortex tube also known as Ranque tube, with no moving parts and reliable device it produces hot and cold gas streams simultaneously from the source of the compressed gas, An experiment has been conducted to evaluate the thermodynamic analysis of the vortex tube. During the study the cold mass fraction was varied from 0.2-0.8 for a fix inlet pressure of 4 bar and the inlet pressure was varied between 2-7 bar for a fix opening of the cone valve. The maximum temperature drop was observed for cold mass fraction of 0.4 and the effective refrigerating effect was observed between the 0.35-0.65 of the cold mass fraction, as the refrigerating effect and heating effect is a function of mass of the cold air and the temperature drop. A thermodynamic model has been used to investigate vortex tube energy separation, the results indicated that as hot tube length or inlet pressure increases the temperature difference increases too,The second law analysis shows that the for air, it is middle tube which generates lowest entropy.
2017
A numerical analysis is carried out in this study in order to understand the flow field and the associated temperature separation in a Ranque-Hilsch vortex tube. A three dimensional computational fluid dynamics model, using ideal gas compressible flow assumptions, is employed to predict the performance of a vortex tube. The standard k-epsilon CFD turbulent model is adopted in this study. The study focuses on an insulated counter flow vortex tube with four tangential inlet streams, one axial hot outlet stream and one axial cold outlet stream. The study shows that one can numerically predict the behaviour of energy separation using ideal gas assumption. The numerical study shows that with an adapted vortex tube size a maximum temperature separation is achieved at optimum pressure value of 4 bar. For insulated tube, as tube length increases, the energy separation increases until it approaches an asymptote value. An optimum diameter exist where energy separation reach maximum value.
3D Numerical Investigating of Flow Field and Energy Separation in Counter-flow Vortex Tube
Proceedings of the 2nd World Congress on Momentum, Heat and Mass Transfer, 2017
A numerical analysis is carried out in this study in order to understand the flow field and the associated temperature separation in a Ranque-Hilsch vortex tube. A three dimensional computational fluid dynamics model, using ideal gas compressible flow assumptions, is employed to predict the performance of a vortex tube. The standard k-epsilon CFD turbulent model is adopted in this study. The study focuses on an insulated counter flow vortex tube with four tangential inlet streams, one axial hot outlet stream and one axial cold outlet stream. The study shows that one can numerically predict the behaviour of energy separation using ideal gas assumption. The numerical study shows that with an adapted vortex tube size a maximum temperature separation is achieved at optimum pressure value of 4 bar. For insulated tube, as tube length increases, the energy separation increases until it approaches an asymptote value. An optimum diameter exist where energy separation reach maximum value.
International Journal of Heat and Technology, 2013
Xue et al. [12] studied pressure gradient, viscosity and turbulence, secondary circulation, and acoustic streaming in the vortex tube. Using a three-dimensional CFD model, Shamsoddini and Hossein Nezhad [13] analyzed the flow and heat transfer mechanism in the vortex tube. In order to investigate the variation of velocity, pressure, and temperature ABSTRACT A mechanical device with no moving parts, a vortex tube can generate cold and hot gas flows from compressed gas. This paper investigates the effect of using a divergent hot tube on vortex tube refrigeration capacity. The computational fluid dynamics (CFD) model used is a three-dimensional steady compressible model utilizing the k-ɛ turbulence model. In this numerical research, different divergence angles of the hot tube (β=0°, 1°, 2°, 3°, 4°, and 6°) have been simulated to analyze the performance of the vortex tube. The results showed that as the angle diverges from β=0°, cold temperature separation improves at cold mass fractions greater than about 0.4, but increasing the angle to more than 4° impairs cold temperature separation compared with the cylindrical model because a secondary circulation develops in the vortex tube. Validation of a previous experimental study that used a cylindrical vortex tube has also been performed in this research.