Numerical Simulations of Cryogenic Hydrogen Cooling in Vortex Tubes with Smooth Transitions

Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work, novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically, a smooth transition is arranged between a vortex chamber, where compressed gas is injected, and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection.

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Performance Assessment of Parallel Connected Ranque–Hilsch Vortex Tubes Using Nitrogen, Oxygen, and Air With Brass and Polyamide Nozzles: An Experimental Analysis

Journal of Heat Transfer ◽

10.1115/1.4045645 ◽

2020 ◽

Vol 142 (3) ◽

Cited By ~ 1

Author(s):

Volkan Kirmaci

Keyword(s):

Vortex Tube ◽

Experimental Studies ◽

Working Fluid ◽

Tube System ◽

Working Fluids ◽

Heating And Cooling ◽

Thermodynamic Performance ◽

Outlet Valve ◽

And Performance ◽

Vortex Tubes

Abstract In this study, heating and cooling performances of two vortex tubes connected in parallel using different working fluids were compared. In experimental studies, oxygen, nitrogen, and air were used as working fluids in counterflow Ranque–Hilsch vortex tube (RHVT) and performance evaluation was performed. Nozzles made of polyamide and brass are used, and the number of these nozzles is 2, 4, and 6. Compressed working fluids were used to operate the vortex tube system at different inlet pressure values varying from 150 kPa to 600 kPa with 50 kPa increment. The geometric characteristics of the vortex tube are the length of the hot tube and the diameter of the orifice, which are 100 mm and 7 mm, respectively. Experiments were performed with the hot flow outlet valve fully open. The thermodynamic performance of the parallel connected vortex tube system was determined by performing exergy analysis. As a result of experimental studies, the highest performance of parallel connected RHVT system was obtained when nitrogen was used as a working fluid with brass-six-nozzle at 600 kPa.

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Computational Fluid Dynamic Prediction and Physical Mechanisms Consideration of Thermal Separation and Heat Transfer Processes Inside Divergent, Straight, and Convergent Ranque–Hilsch Vortex Tubes

Journal of Heat Transfer ◽

10.1115/1.4043728 ◽

2019 ◽

Vol 141 (10) ◽

Cited By ~ 1

Author(s):

Adib Bazgir ◽

Nader Nabhani ◽

Bahamin Bazooyar ◽

Ali Heydari

Keyword(s):

Vortex Tube ◽

Fluid Dynamic ◽

Three Dimensional ◽

Numerical Data ◽

Dynamic Prediction ◽

Temperature Separation ◽

Flow Phenomena ◽

Stream Lines ◽

Physical Phenomena ◽

Vortex Tubes

AbstractThe design of Ranque–Hilsch vortex tube (RHVT) seems to be interesting for refrigeration and air conditioning purposes in industry. Improving thermal efficiency of the vortex tubes could increase the operability of these innovative facilities for a wider heat and cooling demand to this end; it is of an interest to understand the physical phenomena of thermal and flow patterns inside a vortex tube. In this work, the flow phenomena and the thermal energy transfer in RHVT are studied for three RHVT: straight, divergent, and convergent vortex tubes. A three-dimensional numerical analysis of swirling or vortex flow is performed, verified, and validated against previous experimental and numerical data reported in literature. The flow field and the temperature separation inside an RHVT for different configuration of straight, five angles of divergent hot tube (1 deg, 2 deg, 3 deg, 4 deg, and 6 deg) and five angle of convergent hot tube (0.5 deg, 0.8 deg, 1 deg, 1.5 deg, and 2 deg) are investigated. The thermal performance for all investigated RHVTs configuration is determined and quantitatively assessed via visualizing the stream lines for all three scenarios.

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Effect of secondary swirl in supersonic gas and plasma flows in the self-vacuuming vortex tube

MATEC Web of Conferences ◽

10.1051/matecconf/201820900020 ◽

2018 ◽

Vol 209 ◽

pp. 00020 ◽

Cited By ~ 1

Author(s):

Vyacheslav Volov ◽

Anton Lyaskin

Keyword(s):

Pressure Drop ◽

Shock Waves ◽

Energy Loss ◽

Flow Structure ◽

Vortex Tube ◽

Extreme Values ◽

The Self ◽

Temperature Separation ◽

Loss Estimations ◽

Vortex Tubes

This article presents the results of simulation for a special type of vortex tubes – self-vacuuming vortex tube (SVT), for which extreme values of temperature separation and pressure drop are realized. The main results of this study are the flow structure in the SVT and energy loss estimations on oblique shock waves, gas friction, instant expansion and organization of vortex bundles in SVT.

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Experimental Study About Performance Analysis of Parallel Connected Ranque–Hilsch Counter Flow Vortex Tubes With Different Nozzle Numbers and Materials

Journal of Heat Transfer ◽

10.1115/1.4040707 ◽

2018 ◽

Vol 140 (11) ◽

Cited By ~ 10

Author(s):

Hüseyin Kaya ◽

Fahrettin Günver ◽

Onuralp Uluer ◽

Volkan Kırmacı

Keyword(s):

Exergy Analysis ◽

Vortex Tube ◽

Cooling Capacity ◽

Coefficient Of Performance ◽

Inlet Pressure ◽

Working Fluid ◽

Counter Flow ◽

Heating And Cooling ◽

Flow Vortex ◽

Vortex Tubes

An experimental analysis for parallel connected two identical counter flow Ranque–Hilsch vortex tubes (RHVT) with different nozzle materials and numbers was conducted by using compressed air as a working fluid in this paper. Heating and cooling performance of vortex tube system (circuit) and the results of exergy analysis are researched comprehensively according to different inlet pressure, nozzle numbers, and materials. Nozzles made of polyamide plastic, aluminum, and brass were mounted into the vortex tubes individually for each case of experimental investigation with the numbers of nozzles 2, 3, 4, 5, and 6. The range of operated inlet pressure 150–550 kPa with 50 kPa variation. The ratio of length–diameter (L/D) of each vortex tube in the circuit is 14 and the cold mass fraction is 0.36. Coefficient of performance (COP) values, heating, and cooling capacity of the parallel connected RHVT system were evaluated. Further, an exergy analysis was carried out to evaluate the energy losses and second law efficiency of the vortex tube circuit. The greatest thermal performance was obtained with aluminum-six-nozzle when taking into account all parameters such as temperature difference, COP values, heating and cooling capacity, and exergy analysis.

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Numerical investigation of operating pressure effects on the performance of a vortex tube

Thermal Science ◽

10.2298/tsci110907030p ◽

2014 ◽

Vol 18 (2) ◽

pp. 507-520 ◽

Cited By ~ 2

Author(s):

Nader Pourmahmoud ◽

Hassan Zadeh ◽

Omid Moutaby ◽

Abdolreza Bramo

Keyword(s):

Turbulent Flows ◽

Vortex Tube ◽

Swirling Flow ◽

Vortex Chamber ◽

Pressure Effects ◽

Dynamics Simulation ◽

Working Fluid ◽

Axial Distance ◽

Computational Domain ◽

Operating Pressure

A three-dimensional computational fluid dynamics simulation of a vortex tube has been carried out to realize the effects of operating pressure. The highly rotating flow field structure and its characteristic are simulated and analyzed with respect to various operating inlet pressure ranges. Numerical results of compressible and turbulent flows are derived by using of the standard k-? turbulence model, where throughout the vortex tube was taken as a computational domain. The main object of the present research is to focus on the importance of identifying the suitable inlet gas pressure corresponds to used vortex tube geometry. Achieving a highly swirling flow and consequently maximum cold temperature difference were the key parameters of judgment. The results revealed that these acceptable conditions of machine performance can be provided when the inlet operating pressure is appropriate both to mechanical structure of machine and physical properties of working fluid. The stagnation point location in the axial distance of vortex tube and Mach number contours in the vortex chamber as additional information are extracted from flow filed; such that interpretation of shock wave formation regions may be accounted as significant features of investigation. Finally, some results of the CFD models are validated by the available experimental data and shown reasonable agreement, and other ones are compared qualitatively.

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Energy Separation in Vortex Tubes with a Divergent Chamber

Journal of Heat Transfer ◽

10.1115/1.3244441 ◽

1981 ◽

Vol 103 (2) ◽

pp. 196-203 ◽

Cited By ~ 33

Author(s):

Heishichiro Takahama ◽

Hajime Yokosawa

Keyword(s):

Standard Procedure ◽

Vortex Chamber ◽

Installation Space ◽

Energy Separation ◽

Separation Effect ◽

Chamber Length ◽

Temperature Separation ◽

Higher Temperature ◽

Large Installation ◽

Vortex Tubes

The vortex tube is a simple device for separating a compressed gaseous fluid stream into two flows of high and low temperature. In order to produce a high temperature separation effect, the use of a sufficiently long tube with a smooth inner surface has been standard procedure up until now. However, since such a device requires a large installation space, an attempt was made to shorten the length of the vortex chamber without any fall in the temperature separation effect by using some divergent tubes as the vortex chamber. Experimental data obtained in these vortex chambers were compared with those in the commonly used straight vortex chambers. Observation indicates that a divergent tube with a small angle of divergence is effective in obtaining a higher temperature separation and makes possible a shortening of the chamber length.

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Experimental Investigation on the Performance of Vortex Tube With Non-Freeze Enhancement

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-37403 ◽

2014 ◽

Author(s):

Ran Duan ◽

Qitai Eri ◽

Kexin Li

Keyword(s):

Vortex Tube ◽

Reverse Flow ◽

Experimental System ◽

Working Fluid ◽

Pressure Reduction ◽

Mixing Process ◽

Performance Parameters ◽

Gas Temperature ◽

Moist Air ◽

Vortex Tubes

The vortex tube is a temperature separating device. In some of its applications (e.g., pressure reduction of natural gas), low gas temperature in the cold end is required, which may freeze the impure gas. To solve this problem, a vortex tube with non-freeze enhancement was designed and an experimental system was built. The non-freeze design enabled a reverse flow ejection in the pipe of the cold end. Moist air was used as the working fluid and the performance parameters of five similar vortex tubes were compared in this experiment. The characteristics of freeze based on the experiment were presented. The results indicated that thermal conductivity and mixing process played the most important role to avoid freeze when this vortex tube worked in low level of cold fraction. A feasible way to extend the range of working cold fraction for vortex tube is proposed accordingly.

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AN EXPERIMENTAL INVESTIGATION OF THE GOVERNING PROPERTIES IN A VORTEX TUBE

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4051510 ◽

2021 ◽

pp. 1-28

Author(s):

Matthew Fuqua ◽

James L. Rutledge

Keyword(s):

Heat Capacity ◽

Vortex Tube ◽

Flow Characteristics ◽

Reynolds Numbers ◽

Volumetric Heat Capacity ◽

Incoming Stream ◽

Temperature Separation ◽

External Sources ◽

Total Temperature ◽

Vortex Tubes

Abstract Although awareness of the phenomenon of temperature separation in Ranque-Hilsch vortex tubes dates back at least nine decades, some mystery surrounding the phenomenon remains to this day. These devices split an incoming stream of fluid into two streams—one with a greater total temperature than the incoming fluid and the other with a lower total temperature. This temperature separation is accomplished with no moving parts and no external sources of energy including heat transfer to or from the device. In attempts to understand the physics of the temperature separation, previous researchers have characterized the effect through various inlet temperatures and pressures as well as various gases with different properties. Unfortunately, the findings documented in the literature are sometimes inconsistent indicating the possibility that previously uncontrolled properties and flow conditions govern temperature separation to an unappreciated degree. In the present research, two new flow characteristics are examined for their role in temperature separation—volumetric heat capacity, ρC_p, and nozzle velocity. In the present experiments with air, it was found that by matching nozzle velocity and ρC_p—even with disparate pressures, temperatures, Reynolds numbers, and Mach numbers—the resulting temperature separation curves are identical. This is the first known documentation of such a finding. The results suggest that nozzle velocity is fundamental to scaling the performance of a vortex tube, while the nozzle volumetric heat capacity is also relevant to its behavior.

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