Flow structure and mechanism of heat transfer in a Ranque–Hilsch vortex tube
TL;DR: In this paper, the authors constructed a pattern of streamlines in the whole volume of the Ranque-Hilsch vortex tube from the velocity distributions measured using laser Doppler anemometry.
About: This article is published in Experimental Thermal and Fluid Science.The article was published on 2020-05-01. It has received 10 citations till now. The article focuses on the topics: Vortex tube & Streamlines, streaklines, and pathlines.
Citations
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TL;DR: In this article, the authors presented a novel waste heat recovery (WHR) system consisting of a Vortex Tube heat booster coupled to the exhaust stream of a 2000kW natural gas engine that drives a Supercritical CO2 Brayton Cycle (SCBC).
13 citations
TL;DR: In this paper , the authors proposed a method for the estimation of the flow behavior inside a vortex tube and provide reliable predictions by dividing the vortex tube flow field into six regions, and corresponding simplifications were made in different regions according to the flow features.
Abstract: • Research idea of dividing the vortex tube flow field into six regions was proposed. • An expression for the axial velocity profile was developed. • The mathematical model for the flow field based on the axial velocity was established. • The flow fields under four different μ c were computed and analyzed. • The reliability of the calculation model was verified through experimental data. The flow pattern and energy transfer process in the vortex tube are extremely complex, resulting in the difficulty of the direct calculation and prediction of the flow structure and temperature separation performance of a vortex tube. In view of this, research idea of dividing the vortex tube flow field into six regions was proposed, corresponding simplifications were made in different regions according to the flow features, and fluid parameters were coupled at the boundaries. An equation for the axial velocity component in the hot tube region was developed based on the characteristic that the axial velocity profiles under different conditions present similar patterns, the calculation method of reverse flow boundary which separates the working fluid into hot and cold fluids was described, and a set of relatively simple calculation methods for the internal flow field of vortex tubes was established based on the partition model. Three-dimensional velocity distributions inside the vortex tube under different working conditions were computed and analyzed. Further, the model was evaluated and validated through experimental data. The results showed good agreements of calculated data and experimental velocity fields. This work proposed a convenient calculation method for the estimation of the flow behavior inside a vortex tube and provide reliable predictions.
7 citations
TL;DR: In this article , extensive three-dimensional CFD simulations of vortex tube (VT) are conducted with five inert gases, namely helium, neon, argon, nitrogen, and carbon dioxide, to understand the influence of different properties of these gases on the flow phenomena and thermal performance of VT at wide range of cold mass fractions and inlet pressures.
6 citations
TL;DR: In this paper , the relative impacts of different boundary conditions on the temperature separation prediction of 3D Computational Fluid Dynamics (CFD) models of the Ranque-Hilsch Vortex Tube (RHVT) are explored.
Abstract: In this work the relative impacts that different boundary conditions have on the temperature separation predictions of 3D Computational Fluid Dynamics (CFD) models of the Ranque-Hilsch Vortex Tube (RHVT) are explored. Concurrently, in the interest of comparing to experimental results, the impact of including the exit plenums and inlet shroud in the computational models of temperature separation are examined. Simulations of the 3D model using the k − ε , k − ω , k − ω SST and Scale-Adaptive-Simulation SST turbulence models are presented and their relative impacts on flow structure and energy separation are discussed. The results of this study show that imposition of the inlet mass flow combined with mass flow rate at one outlet and pressure at the other leads to reasonable predictions, whereas multiple pressure conditions at RHVT boundaries leads to errors in inlet flow or mass flow split. It is also shown that each turbulence model predicts a unique eddy viscosity distribution inside the vortex tube and that the length of the stagnation stream surface is negatively correlated to the (average) eddy viscosity. By this observation, it is noted that the integral results for energy separation are not sufficient to determine which turbulence model is best.
2 citations
TL;DR: In this paper , the authors analyzed the energy separation performance of five area ratios (AR) from 0.02-0.32 with the same inlet areas and numerical simulation.
1 citations
References
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Book•
01 Jan 1955
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
Abstract: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow.
17,321 citations
Book•
01 Jan 1978
TL;DR: This book presents those parts of the theory which are especially useful in calculations and stresses the representation of splines as linear combinations of B-splines as well as specific approximation methods, interpolation, smoothing and least-squares approximation, the solution of an ordinary differential equation by collocation, curve fitting, and surface fitting.
Abstract: This book is based on the author's experience with calculations involving polynomial splines. It presents those parts of the theory which are especially useful in calculations and stresses the representation of splines as linear combinations of B-splines. After two chapters summarizing polynomial approximation, a rigorous discussion of elementary spline theory is given involving linear, cubic and parabolic splines. The computational handling of piecewise polynomial functions (of one variable) of arbitrary order is the subject of chapters VII and VIII, while chapters IX, X, and XI are devoted to B-splines. The distances from splines with fixed and with variable knots is discussed in chapter XII. The remaining five chapters concern specific approximation methods, interpolation, smoothing and least-squares approximation, the solution of an ordinary differential equation by collocation, curve fitting, and surface fitting. The present text version differs from the original in several respects. The book is now typeset (in plain TeX), the Fortran programs now make use of Fortran 77 features. The figures have been redrawn with the aid of Matlab, various errors have been corrected, and many more formal statements have been provided with proofs. Further, all formal statements and equations have been numbered by the same numbering system, to make it easier to find any particular item. A major change has occured in Chapters IX-XI where the B-spline theory is now developed directly from the recurrence relations without recourse to divided differences. This has brought in knot insertion as a powerful tool for providing simple proofs concerning the shape-preserving properties of the B-spline series.
10,258 citations
TL;DR: The design of a vortex tube of good efficiency in which the expansion of a gas in a centrifugal field produces cold is described and the important variables in construction and operation are discussed and data for several tubes under various operating conditions are given.
Abstract: The design of a vortex tube of good efficiency in which the expansion of a gas in a centrifugal field produces cold is described. The important variables in construction and operation are discussed and data for several tubes under various operating conditions are given. Low pressure gas, 2 to 11 atmospheres, enters the tube and two streams of air, one hot and the other cold, emerge at nearly atmospheric pressure. The cold stream may be as much as 68°C below inlet temperatures. Efficiencies and applications are discussed.
447 citations
TL;DR: In this article, the authors present an overview of the phenomena occurring inside the vortex tube during the temperature/energy separation on both the counter flow and parallel flow types, and present several different hypotheses based on experimental, analytical, and numerical studies.
Abstract: The vortex tube or Ranque–Hilsch vortex tube is a device that enables the separation of hot and cold air as compressed air flows tangentially into the vortex chamber through inlet nozzles. Separating cold and hot airs by using the principles of the vortex tube can be applied to industrial applications such as cooling equipment in CNC machines, refrigerators, cooling suits, heating processes, etc. The vortex tube is well-suited for these applications because it is simple, compact, light, quiet, and does not use Freon or other refrigerants (CFCs/HCFCs). It has no moving parts and does not break or wear and therefore requires little maintenance. Thus, this paper presents an overview of the phenomena occurring inside the vortex tube during the temperature/energy separation on both the counter flow and parallel flow types. The paper also reviews the experiments and the calculations presented in previous studies on temperature separation in the vortex tube. The experiment consisted of two important parameters, the first is the geometrical characteristics of the vortex tube (for example, the diameter and length of the hot and cold tubes, the diameter of the cold orifice, shape of the hot (divergent) tube, number of inlet nozzles, shape of the inlet nozzles, and shape of the cone valve. The second is focused on the thermo-physical parameters such as inlet gas pressure, cold mass fraction, moisture of inlet gas, and type of gas (air, oxygen, helium, and methane). For each parameter, the temperature separation mechanism and the flow-field inside the vortex tubes is explored by measuring the pressure, velocity, and temperature fields. The computation review is concentrated on the quantitative, theoretical, analytical, and numerical (finite volume method) aspects of the study. Although many experimental and numerical studies on the vortex tubes have been made, the physical behaviour of the flow is not fully understood due to its complexity and the lack of consistency in the experimental findings. Furthermore, several different hypotheses based on experimental, analytical, and numerical studies have been put forward to describe the thermal separation phenomenon.
226 citations
TL;DR: In this article, an account is given of the findings contained in a concensus document compiled by a group of experts on laser anemometry concerning statistical particle bias and its possible remedies.
Abstract: An account is given of the findings contained in a concensus document compiled by a group of experts on laser anemometry concerning statistical particle bias and its possible remedies. Emphasis is placed on the systematic character of this bias, rather than its magnitude. Since bias errors are a function of flow velocity and turbulence intensity, the measured results may contain apparent trends due solely to the measurement process. Attention is given to the panel's attempt to clear up terminological confusions in the matter of rates, scales, and magnitudes, as well as to its suggested processing methods for the elimination of velocity bias and the remedy of angle bias.
173 citations