No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
An experimental investigation of the optimum geometry for the cold end orifice of a vortex tube
Abstract
A vortex tube is a simple mechanical device, which splits a compressed gas stream into a cold and hot stream without any chemical reactions or external energy supply. This paper presents the results of a series of experiments focusing on various geometries of the “cold end side” for different inlet pressures and cold fractions. Specifically, the tests were conducted using different cold end orifice diameters.Energy separation and energy flux separation efficiencies are defined and used to recover characteristic properties of the vortex tube. These are used to show an appropriate scale to non-dimensionalize the energy separation effect. The experimental results indicate that there is an optimum diameter of cold end orifice for achieving maximum energy separation. The results also show that the maximum value of energy separation was always reachable at a 60% cold fraction irrespective of the orifice diameter and the inlet pressure. The results are compared with the previous studies on internal flow structure, and optimal operating parameters are shown to be consistent with a matching of orifice size with the secondary circulation being observed.
... Additionally, while energy separation initially increased with inlet pressure, a pressure surge led to smothering effects and a downward trend in separation efficiency. Muller (2009) [22] conducted an experimental study on the impact of the cold outlet diameter on separation efficiency, while Markal et al. [23] examined valve angles of 30°, 45°, 60°, and 75°, finding higher efficiency at 30° and 60°. Vortex tubes are compact, lightweight, and easy to install in various applications. ...
... Additionally, while energy separation initially increased with inlet pressure, a pressure surge led to smothering effects and a downward trend in separation efficiency. Muller (2009) [22] conducted an experimental study on the impact of the cold outlet diameter on separation efficiency, while Markal et al. [23] examined valve angles of 30°, 45°, 60°, and 75°, finding higher efficiency at 30° and 60°. Vortex tubes are compact, lightweight, and easy to install in various applications. ...
... Additionally, while energy separation initially increased with inlet pressure, a pressure surge led to smothering effects and a downward trend in separation efficiency. Muller (2009) [22] conducted an experimental study on the impact of the cold outlet diameter on separation efficiency, while Markal et al. [23] examined valve angles of 30 • , 45 • , 60 • , and 75 • , finding higher efficiency at 30 • and 60 • . ...
The vortex tube, also known as the Ranque–Hilsch vortex tube, is a mechanical device that separates compressed gas into hot and cold streams. It offers a reliable and cost-effective solution to a wide range of cooling applications, as it operates without moving parts, electricity, or refrigerants. Research on vortex tubes has primarily focused on understanding the mechanisms of energy separation and optimizing cooling performance by altering geometric operational parameters. In this study, a Computation Fluid Dynamics (CFD) analysis was conducted to enhance the prediction of energy separation performance and improve the overall energy efficiency of the vortex tube. First, the geometry of the experimental device was modeled to closely match its actual shape, unlike the simplified geometries commonly used in previous CFD studies. Simulations were then carried out with variation in grid systems and turbulence models, and the results demonstrated improved agreement with experimental data compared to those reported in previous studies. Finally, simulations with a modified shape of the inlet nozzle shape were performed, revealing that the energy separation effect of the vortex tube could be enhanced by approximately 15% with an increased inlet expansion ratio (ϵ) while maintaining a constant nozzle length.
... With their ability to harvest low-temperature-gradient energy, the main disadvantage is the need for heat removal from the cold side. There is no temperature gradient in gas flows, but it can be created artificially using the Ranque-Hilsch effect [14]. ...
... A Ranque-Hilsch vortex tube is a device in which two gas flows with different temperatures can be generated using compressed gas ( Figure 1). Vortex tubes vary widely in geometry, particularly in their diameter/length ratio [14,15]. The efficiency of the tube depends on its geometrical dimensions, the setting of the constriction angle, and is directly proportional to the gas pressure at the inlet [13]. ...
... These data were calculated for the case when the efficiency of the voltage step-up converter is 60%. According to Formula (14), in the indicated vortex tube inlet pressure range, the output current limit of the DC/DC boost converter will be limited in values of 0.1 to 0.3 mA. It is assumed that the average value of voltage on the supercapacitor is about 5 V. ...
This article deals with the creation of a power supply system of wireless sensors which take measurements and transmit data at time intervals, the duration of which is considerably less than the activation period of sensors. The specific feature of the power supply system is the combined use of devices based on various physical phenomena. Electrical energy is generated by thermoelectrochemical cells. The temperature gradient on the sides of these cells is created by a vortex tube. A special boost DC/DC converter provides an increase in the output voltage of thermoelectrochemical cells up to the voltage that is necessary to power electronic devices. A supercapacitor is used to store energy in the time intervals between sensor activation. A study of an experimental sample of the power supply system for wireless sensors was conducted. Using the model in MATLAB + Simulink program, the possibility and conditions for creating the considered system for a particular type of wireless sensor were shown.
... Rafiee and Rahimi According to the study of Saida et al. [9], when the length-diameter ratio of the cold/heat separation pipe is 22-55 times, the cold/heat separation effect is the best. Saida Nimbalkar et al. [10] found that too small cold outlet would cause secondary flow phenomenon in the vortex tube, and the mixing of cold and hot gas caused by it would reduce the ratio of energy separation. Nimbalkar Through the experimental study on the influence of different geometric parameters on RHVTperformance.Westley [11] believed that the energy separation effect was related to the injecting area of injecting hole, length of energy separation pipel, cross-sectional area of generating chamber, area of cold outlet and 2 flow pressure, and the optimized proportion relationship was given as follows: Aiming to achieve the maximum temperature difference between hot and cold outlet,. ...
... The table indicates that there are significant and discrete differences among the parameters. Therefore, for performance comparison of vortex tubes, a unified energy separation model based on structural parameters is needed, and regression analysis can be carried out through intelligent algorithms to obtain the optimal structural parameters that achieve the maximum cold-to-hot separation [10,22,23,25,27]. ...
In this paper, in order to establish the energy separation mechanism of the vortex tube, the hydrodynamic behavior of the compressible fluid in the asymmetric cavity space is investigated, and a numerical model of the trajectory deflection behavior is deduced and established; in order to form the optimal design method of the structural parameters of the vortex tube, the force situation of the fluid microelements entering different regions of the vortex chamber of the vortex tube is analyzed, and the trajectory deflection equations are corrected by combining with the expansion behavior of the fluid and the characterizing equations of vortex strength, transportability, and vortex initiation characteristics are given. The characterization equations of vortex strength, transportability and vortex initiation characteristics are given, and the numerical simulation of their influence parameters is carried out; in order to realize the prediction of the vortex tube performance of a given structure, the multifactor Pearson thermodynamic map is used to correlate and analyze the experimental data of vortex tubes reported publicly in the past years, and the polynomial regression equations are designed and established for the prediction of the vortex tube's energy separation effect and the confidence level and the degree of coincidence of the prediction results are examined. The confidence level and degree of agreement of the prediction results were examined. It is found that: the trajectory deflection motion of the compressible fluid in the asymmetric cavity space is the result of the combined effect of structural air pressure bias and the expansion behavior of the incident fluid; in order to improve the vortex strength in the vortex tube, the vortex initiation chamber space should be as small as possible; the increase of the diameters of the hot-end pipe and the cold-end pipe is conducive to the enhancement of vortex strength, but at the same time, it weakens the vortex transport in the heat pipe; the vortex initiation chamber size has a negative correlation with the hot-end temperature rise, and the inlet fluid pressure has a The negative correlation between the size of the vortex chamber and the temperature rise at the hot end, the positive correlation between the increase of inlet fluid pressure and the resulting temperature rise, and the strong correlation between the inlet fluid pressure and the friction coefficient on the effect of energy separation; the predictive equations for the effect of energy separation obtained by the fitting are in good agreement with the real situation.
... Vortex tube is covered extensively in literatures through experimental and numerical analysis. The experimental work of Nimbalkar and Muller [12] indicated that there is an optimum diameter of the cold end orifice for achieving maximum energy separation. Also, the results [12] have showed that the maximum value of energy separation is always reachable at a 60% of the cold mass fraction regardless of the orifice diameter and the inlet pressure. ...
... The experimental work of Nimbalkar and Muller [12] indicated that there is an optimum diameter of the cold end orifice for achieving maximum energy separation. Also, the results [12] have showed that the maximum value of energy separation is always reachable at a 60% of the cold mass fraction regardless of the orifice diameter and the inlet pressure. The optimum diameter to the length ratio of the hot side has been investigated by Dincer et al. [13,14]. ...
... This rounded-off entrance of the hot tube elongates the circulation near the vortex chamber and thus improves the cooling performance. Nimbalkar and Muller (2009) experimentally worked with a different cold end diameter of the vortex tube and compared their results with the previous literature. They found that RHVT performs to its best level at an optimum cold diameter size. ...
... In an experimental study, Nurhasanah et al. (2014) found similar results regarding cold end diameter. However, their results in respect of cold mass fraction were contradictory to (Nimbalkar and Muller, 2009). Kandil and Abdelghany (2015) performed a computational investigation using Ansys fluent software to show the effect of cold orifice diameter to hot tube diameter ratio, length-to-diameter ratio, and the effect of circular fins. ...
... One of the places (or pieces) that can be effective in directing the flow stream and shaping the separation process inside the vortex tube is the cold orifice (the cold outlet). Nimbalkar and Muller [7] concluded that this parameter (the cold outlet diameter: D c /D) has an optimum value and has a small effect on the separation quality for the cold mass fractions <0. 6. In the case of "Energy Flux Separation", the configuration with D c /D = 0.5 presents the maximum value. ...
... Eiamsa-ard [8] tested two structural parameters (for directing the fluid flow) including; the multiple inlet snail injectors (compared with the conventional type) and D c /D. As the results: a) the snail injectors produced better separation than the conventional type, b) the higher snail injector number, the higher efficiency, c) D c /D = 0.5 was the optimum value which is the same as the results of Nimbalkar and Muller [7] (testing the cold diameter). Rafiee and Rahimi [9] increased the thermal efficiency (cold temperature) of the vortex tube by reducing the output area of the nozzle relative to its input (convergent nozzles). ...
In the industries related to the separation of suspended particles, gases, liquids and especially thermal usages, precise and effective separation systems such as vortex tubes are used. The vortex tube is a system without moving parts or applying chemical agents that can divide the inlet fluid (as the system operator) into two parts. The whole process of the separation occurs due to the kinematic properties of the fluid inside the system. For this reason, all the components that are effective in determining the direction of the fluid inside the system can affect the efficiency of the VT. This experimental study wants to present a comprehensive report on the effect of the ratio of the rounded radius to the main tube radius (R⁎/R: as a dimensionless parameter) on the temperature separation (ΔTc, ΔTh and ΔT), the power separation (cooling Qc, heating Qh and total Qtotal), the isentropic efficiency (η), the coefficient of performance (COPCM and COPHP) and the internal velocity patterns (axial and swirl). Based on the results, the changes in the radius have extensive effects on all of the mentioned efficiency factors. The results show that there is an optimum value that has the best performance in all the criteria.
... perature separation. Earlier studies by B. Upendra et al. [10] and S. Nimbalkar and Michael Mueller [11] also suggest the requirement of optimum cold end orifice diameter in their experimental and computational studies. Genetic algorithm based optimization of the cold end orifice diameter is found using a back propagation neural network technique by H. Pourier et al. [12]. ...
... The optimum ratio of cold end orifice diameter to vortex tube diameter is found by varying the orifice diameter ( [9], [10] and [11]) in a given range. The results from these studies indicate the ratio to be maintained as 0.5. ...
Separating the cold and hot air by using the principles of the vortex tube can be applied to industrial applications such as cooling equipment in CNC machines, heating processes, cooling suits, refrigerators etc. The vortex tube is well-suited for these applications because it is simple with no moving parts, quiet, compact, and does not use refrigerants. This study is devoted to the development and testing of an automated vortex tube that can meet the demands of time variant applications such as spot cooling during welding. This is achieved with the help of a moving blockage cone at hot end and orifice area controller at cold end. The performance of a counter-flow vortex tube is validated by comparing the results obtained from the present work with the literature .
... Sachin U Nimbalkar and Michael R Muller [5] investigated that the Energy separation and Energy flux separation efficiencies help recover the parametric characteristics of a Vortex tube. Their study found out that for maximum energy separation there is an optimum orifice end diameter. ...
... The effect of orifice diameter on the energy flux separation efficiency (mi = 0.45 kg/min). Error bars in the graph indicate 5% of experimental error [5]. ...
A vortex tube is a simple device which splits a high pressure gas stream into a cold and hot stream without any chemical reactions or external energy supply. It is a mechanical device without any moving parts. The splitting of flow into regions of low and high temperature range is referred to as the temperature separation effect. The performance of vortex tube depends on two basic parameters, first is the working parameter such as inlet pressure of compressed air, and the other one is geometric parameters such as number of nozzles , diameter of nozzle, cone valve angle, length of hot side tube, cold orifice diameter, and as well as material of vortex tube. Vortex tube has interesting functions and several industrial applications, and, as a refrigerator, it is used as a spot cooling device in industry.
... Fig.4 shows the comparison between three different gases: air, oxygen and nitrogen which concludes that higher temperature difference is obtained by using nitrogen due to its smaller molecular weight. Sachin U Nimbalkar and Michael R Muller [5] investigated that the Energy separation and Energy flux separation efficiencies help recover the parametric characteristics of a Vortex tube. Their study found out that for maximum energy separation there is an optimum orifice end diameter. ...
... The effect of orifice diameter on the energy flux separation efficiency (mi = 0.45 kg/min). Error bars in the graph indicate 5% of experimental error [5]. ...
A vortex tube is a simple device which splits a high pressure gas stream into a cold and hot stream without any chemical reactions or external energy supply. It is a mechanical device without any moving parts. The splitting of flow into regions of low and high temperature range is referred to as the temperature separation effect. The performance of vortex tube depends on two basic parameters, first is the working parameter such as inlet pressure of compressed air, and the other one is geometric parameters such as number of nozzles , diameter of nozzle, cone valve angle, length of hot side tube, cold orifice diameter, and as well as material of vortex tube. Vortex tube has interesting functions and several industrial applications, and, as a refrigerator, it is used as a spot cooling device in industry.
... Also, this result may be due to that behind N = 3, the flow at nozzle level becoming more turbulent causing the hot and cold flows mix together in turn of enhancing the cold temperature difference [36,38]. But in the case of nozzle, N = 6, increase in the number of nozzles may cause an increase in the outlet temperature of cold air side temperature. ...
... Hence, the highest value of coefficient of performance for mass cold fraction is 0.4, L/D = 15 and inlet pressure 6 bar is equal to 0.21 as shown in Fig. 9(b). This is due to the fact that at the exit of nozzles, some free vortices are formed and such forced vortices decrease with the increase of the nozzle [38,39]. The vortices play a major role in confining and mixing cold and hot flow inside the vortex tube and the reduction in the number of vortices causes less mixing of central cold flow with peripheral hot flow [12]. ...
... Also, this result may be due to that behind N = 3, the flow at nozzle level becoming more turbulent causing the hot and cold flows mix together in turn of enhancing the cold temperature difference [36,38]. But in the case of nozzle, N = 6, increase in the number of nozzles may cause an increase in the outlet temperature of cold air side temperature. ...
... Hence, the highest value of coefficient of performance for mass cold fraction is 0.4, L/D = 15 and inlet pressure 6 bar is equal to 0.21 as shown in Fig. 9(b). This is due to the fact that at the exit of nozzles, some free vortices are formed and such forced vortices decrease with the increase of the nozzle [38,39]. The vortices play a major role in confining and mixing cold and hot flow inside the vortex tube and the reduction in the number of vortices causes less mixing of central cold flow with peripheral hot flow [12]. ...
... For example, it was observed that the greatest cold temperature diminution (ΔT c ) will be obtained if the inlet is near the cold flow outlet and inflow pressure, thus the mass flow and swirl strength will become greater than the other cases; therefore, the greatest cold temperature diminution (ΔT c ) at the cold outlet can be achieved. Nimbalker and Muller [10] reported on the optimum cold orifice geometry of vortex tube for various fs (ξ) and pressures at inlet. It was observed that the optimum diameter of the tube, which is same as Saidi et al. [11] but 8% less than the Manimaran 2016 Computational analysis of energy separation [60] outcome of Behera et al. [12]. ...
... The results indicate that the influence of nozzle inlet number on the cooling capability firmly relies on the cold mass fraction. Based on the analysis of the secondary circulation flow in the vortex tubes reported by [10], the inner layer backflow from hot end can discharge freely out of cold end at lower cold mass fraction, but the backflow will be chocked at the cold end exit zone and cause the secondary circulation flow at higher cold mass fraction. It results in the impaired performance of vortex tubes due to the mixing of the hot and cold stream. ...
This research article demonstrates how using different turbulence models may affect the temperature detachment (the temperature diminution of cold air (∆Tc = Ti − Tc)) inside straight counter-flow Ranque-Hilsch Vortex Tube (RHVT). The code is utilized to find the optimized turbulence model for energy separation by comparison with the experimental data of the setup. To obtain the results with a minimum error, various turbulence models have been investigated in steady state and transient time-dependence modes. Results show that RNG k-ε turbulence model has the best correspondence with the obtained experimental data from the setup; therefore, by using a RNG k-ε turbulence model with respect to Finite Volume Method (FVM), all the computations have been carried out. Moreover, some geometric parameters are focused on the length of hot tube and number of nozzle intakes within divergent and convergent hot-tube. Numerical results present that there is an optimum angle for obtaining the highest refrigeration performance, and 2ο divergence is the optimal candidate under our numerical analysis conditions. Length of hot tube which exceeds a critical length has slight effect on the refrigeration capacity. The critical length is L = 166 mm in our study. Temperature reduction sensitivity can be reduced by increasing number of nozzles and maximum temperature reduction can be obtained.
... The existence of secondary flows in vortex tube has been discovered by Ahlborn and Groves (1997) and supported experimentally and numerically by others researchers (Gao et al. 2005;Gutsol and Bakken 1998;Cockerill 1995;Aljuwayhel, Nellis, and Klein 2005). Some researchers demonstrated that the apparition of a secondary flow in vortex tubes depends on the cold nozzle diameter (Behera et al. 2008;Nimbalkar and Muller 2009) and that there is a critical diameter beyond which the secondary flow disappears. Since this theory is only valid for specific vortex tubes sizes, its responsibility in the energy separation is not completely accepted. ...
... A number of investigations have been specifically carried out, using geometrical modifications, in order to improve the performance of vortex tubes. These include different inlet nozzle numbers (Behera et al. 2005;Kirmaci 2009;Dincer et al. 2009; among others), helical nozzles (Pourmahmoud, Hassanzadeh, and Moutaby 2012;Bovand et al. 2014), nozzle aspect ratio (Avci 2013), nozzle diameter (Mohammadi and Farhadi 2013), helical swirl flow generator Farzaneh-Gord and Sadi 2014), the tube length to the tube inner diameter (Dincer et al. 2008;Markal, Aydin, and Avci 2010;Aydin, Markal, and Avci 2010;among others), the cold end diameter (Behera et al. 2005;Nimbalkar and Muller 2009;Im and Yu 2012;Kandil and Abdelghany 2015), conical valve angle (Dincer et al. 2009;Markal, Aydin, and Avci 2010;Rafiee and Sadeghiazad 2014), multiple snail entries (Eiamsaard 2010). Further two-stage vortex tubes (Guillaume and Jolly III 2001;Bej and Sinhamahapatra 2014) and annular vortex tube have been also studied. ...
A numerical assessment is carried out to examine the effects of the commonly assumed adiabatic wall boundary conditions via non-adiabatic ones on the predicted temperature differences. Interestingly, the influence of the boundary type is found rather small at low cold fraction values but becomes significant at the high values. This finding completes the current knowledge which is to date somewhat lacking or even contradicting. Coverage of the studies on vortex tube has enabled the authors to identify the dominant dimensionless numbers affecting the flow physics within the device. Hence, a generic correlation which can be easily adapted for a given vortex tube design is proposed. The numerical predictions obtained reveals that the model is capable of mimicking the flow physics in a reasonably good agreement with experimental results provided that sufficiently fine grids are used. The numerical tests also reveal that the global discretization error for the commercial code is approaching the numerical schemes order. Last but not least, thanks to the control volume thermodynamic analysis carried out in the present study, the authors were able to demonstrate and for the first time, the existing implicit link between the kinetic energy variation within the device and its resulting isentropic efficiency.
... Dcold determines how efficiently the cooled air is expelled from the VT, affecting the system's pressure balance and the temperature distribution within the tube [50,51]. Dnozzle controls the volume and initial speed of air entering the system, directly affecting the VT's thermal separation performance [52,53]. ...
In this study, the optimization of a vortex tube (VT) with a fixed tube diameter and boundary conditions was attempted by determining four different design factors: the value of the conical valve degree (α), the number of nozzles (N), the cold flow exit diameter (Dcold exit), and the nozzle inlet diameter (Dnozzle), to improve the Cooling Coefficient of Performance (COPcooling). For each identified factor, five different levels were assigned, and an L25 orthogonal series was constructed using the Taguchi approach. The 3D-designed cases were subjected to numerical analysis in the ANSYS Fluent software program using the standard k-epsilon turbulence model. The effect levels of the design parameters were determined using the Analysis of variance (ANOVA) approach. Furthermore, after obtaining an empirical equation with COPcooling as the independent variable through Regression analysis, a confirmation test was conducted. The results indicated that the order of influence of the five parameters on COPcooling was N> Dnozzle> Dcold > α, with the N parameter having the strongest impact on the COPcooling in the VT, while the α parameter had the least effect. Additionally, the optimal VT showed a 40.3% improvement in COPcooling, when compared to a VT with initial geometric parameters. It has been identified that using the Taguchi approach for VT geometry optimization significantly enhanced performance
... Furthermore, advanced computer-aided techniques can establish relationships between hole structural parameters and purging plug thermomechanical behavior, offering a more precise understanding of plug performance characteristics and service behaviors. Analogously, in fields like oil and gas transportation and HVAC systems, optimizing flow and temperature fields through structural design enhancements can reduce energy consumption and operational costs [24][25][26][27][28][29][30]. Jiang et al. explored the relationship between the size of the reducing pipe and the flow characteristics [31]. ...
The purging plug is essential for enhancing production efficiency in molten steel refining, yet it faces challenges related to structural integrity due to its lifespan often not aligning with the ladle's repair cycle. This study introduces a novel corundum-calcium hexaluminate purging plug with gradual holes designed to alleviate internal stress concentration. Utilizing a multi-objective optimization model and fluid-solid coupling heat transfer method, the impact of structural parameters on thermal and mechanical properties was systematically investigated. The numerical simulation results indicate that increasing the number of gradient layers positively impacts temperature distribution. Notably, the D-210 (1.0 mm diameter) aperture reduces the stress gradient Δσ max by 648.06 MPa compared to D-212 (1.2 mm diameter) at the Y = 0.313 m section. Additionally, variation in inclination angle impacts tensile stress σ t and shear stress τ, an inclination angle of 6 • (α6) reduces maximum tensile stress by 211.41 MPa compared to an angle of 0 • (α0).
... Apart from the research on operating conditions and different working fluids, the investigations on the effect of geometrical parameters also helped in the optimization of energy separation phenomena with necessary modifications in design. Various noticeable improvements in the geometrical designs have been made in the previous literature presenting a detailed investigation of the effects of parametric changes in nozzle geometry (Pourmahmoud et al., 2015), (Attalla et al., 2014), (Avci, 2013), nozzle numbers (Cebeci et al., 2016b;Shamsoddini and Nezhad, 2010;Mohammadi and Farhadi, 2013;Attalla et al., 2017b), nozzle material , control valve geometry (Markal et al., 2010;Sadeghiazad, 2017d, 2014a;Sadi and Farzaneh-Gord, 2014), cone length of control valve (Rafiee and Sadeghiazad, 2014b) hot tube taper angle (Takahama and Yokosawa, 1981), (Hamdan et al., 2018;Chang et al., 2011;Pouraria and Zangooee, 2012), navigator's angle (Rafiee and Sadeghiazad, 2020;Rafiee, , 2023 and the rounding off the edge at the junction of the vortex chamber and hot tube (Rafiee and Rahimi, 2014), , length to diameter (L/D) ratio (Dincer et al., 2008;Bramo and Pourmahmoud, 2011;Behera et al., 2005), cold mass fractions and cold orifice diameter (Nurhasanah et al., 2014;Nimbalkar and Muller, 2009;Im and Yu, 2012;Saidi and Valipour, 2003). Geometry has also been modified by introducing a new diffuser design at the hot end of a classical VT to reduce air friction loss and improve performance (Wu et al., 2007). ...
... Nimbalkar and Muller [8] conducted numerous experiments to determine the effects of the cold exit geometry, inlet pressure, and cold mass fraction on the RHVT performance. They found that the cold exit diameter and cold mass fraction significantly affected the heating and cooling efficiency, especially when the cold mass fraction was greater than 60 %. ...
... Based on this phenomenon, he described the vortex tube as a classic thermodynamic refrigeration cycle. However, experiments and numerical simulation studies by other scholars indicate that the occurrence of secondary circulations is caused by the mismatch between the cold orifice diameter and the reverse flow radius [47][48][49]. When the radius of the reverse flow radius R ε is larger than that of the cold orifice, due to the limitation of the size of the cold orifice plate, part of the fluid turns back again to the hot end, that is, secondary circulation phenomenon occurs. ...
Optimization of vortex tube performance based on the internal flow field structure is considered as an effective optimization strategy, yet limited by the complex flow process inside the vortex tube, and the unknown mutual influence mechanism of different geometrical and operational parameters on the performance, there still has few quantitative flow field calculation model and corresponding optimization method. Herein, the direct mapping relationship between different parameters and the dimensionless reverse flow radius, an important indicator of the internal flow field structure was dug out by constructing an artificial neural network (ANN) in this work. Eight variables, cold mass fraction (μc), dimensionless axial position (Z), length to tube diameter ratio (Lvt/Dvt), inlet to cold outlet pressure ratio (pin/pc), cold orifice to tube diameter ratio (Dc/Dvt), Reynolds number (Re), geometrical swirl number (Sgeo) as well as vortex tube diameter (Dvt) were selected as the inputs. The MSE and the correlation coefficient of this ANN model were 0.00132 and 0.981, respectively. By comparing and correlating the flow structure calculated by this ANN model with the optimization work in the literature, it was showed that the boundary conditions where secondary circulation and stagnation point occur were in good agreement with the optimal parameters for maximum energy separation performance, then a multi-parameter co-optimization strategy of the vortex tubes was proposed. Further, mutual impact of different parameters to the flow structure was investigated, and the synergy of factors' effects was analyzed. This research provided an effective model and a new method for exploring the flow structure and improving the performance of vortex tubes.
... They also report that helium is better than oxygen or air as the working gas for a higher performance of VT. Nimbalkar et al. [91] performed a CFD analysis and experimental investigation to optimize the geometry of VT. ...
Ranque-Hilsch vortex tube (RHVT) is an equipment that sequestrated a single stream flow of fluid (gas) into two different flows simultaneously, one hotter than the inlet and one cooler. Traditionally vortex tubes are mostly operated at high entrance pressures (>10 psig) and always used for cooling operations. There are semi-industrial and industrial usages which can lead to unused pressurized gases. Vortex tube energy separation can be used as a waste pressure energy recovery method from high and low pressure references (sources). In various industrial systems, magnitudes of waste pressure may be lower but may have significant mass flow rates. Hence it is important to make sure that vortex tube provides the required energy separation while harnessing the low pressure but
high mass flow rate waste energy and utilizes it for not only cooling but also for heating
purposes. Our recent experimental observations show that in the low inlet pressure regime (<10 psig); vortex tubes behave differently and produce multiple flow structures rather than expected re- circulating cold stream and the columnar hot stream type of flow (simply “Vortex Tube flow” or VT-flow). This paper characterizes industrial waste pressure as a reclaimable form of energy, analyzes the effectiveness of ‘vortex tube energy separation’ in recovering waste energy from low pressure sources, and explores experimentally the possibility of multiple flow structures (like Reverse, Elbow, T-flow or VT-flow) inside vortex tube in a low inlet pressure regime. First time, a study of flow modes in low pressure vortex tubes with small cold fractions has been presented which yielded quantitative confirmation of simple one dimensional model for these flows allowing both predictive capabilities and guidance in design.
... Various experiments are conducted to check some factors such as the inlet conditions, geometry and mass flow distribution from warm outlet to cold outlet on the exit temperatures in VTs [7][8][9].For example, it was observed that the greatest cold temperature diminution (ΔTc) will be obtained if the inlet is near the cold flow outlet and inflow pressure, thus the mass flow and swirl strength will become greater than the other cases; therefore, the greatest cold temperature diminution (ΔTc) at the cold outlet can be achieved. Nimbalker and Muller [10] reported on the optimum cold orifice geometry of vortex tube for various cold mass fractions ( ) and pressures at inlet. It was observed that the optimum diameter of the tube, which is same as Saidi et al. [11] but 8% less than the outcome of Behera et al. [12]. ...
The design of innovative Ranque-Hilsch vortex tube (RHVT) for the development of green and low cost refrigeration and air conditioning systems has become increasingly important in cooling (and heating) process industries. In this light improving the heat transfer mechanism and thermal efficiency (cooling optimization) of the RHVT has been an ongoing concern. This research demonstrates how using different turbulence models may affect the temperature detachment (the temperature diminution of cold air (ΔTc = Ti - Tc)) inside straight counter- flow Ranque-Hilsch Vortex Tube (RHVT). The code is utilized to find the optimized turbulence model for energy separation by comparison with the experimental data of the setup. To obtain the results with a minimum error, ten turbulence models have been investigated in steady state and transient time-dependence modes. Results show that RNG k-ε turbulence model has the best correspondence with the previous experimental data; therefore, by using a RNG k-ε turbulence model with respect to Finite Volume Method (FVM) and based on the Computational Fluid Dynamic (CFD), all the computations have been carried out.
... The vortex tube was sectioned at the center where the mass flow rate was observed to be larger than the outlet. Nimbalkar et al. [22] studied straight vortex tubes with different cold orifice diameters and found that secondary circulation was a major performance degrading factor in the analysis of these tubes. ...
Vortex tube that splits a single compressed gas stream into two separate hot and cold streams had been successfully used for spot cooling, and refrigeration. Significant temperature gradient exists between hot and cold stream ends that could be utilized for power generation using thermo-electric generators. Distance between hot and cold ends could be vital for small inaccessible down-hole well locations which may require the use of curved vortex tubes. Efficiency of vortex tube depends on temperature difference between hot and cold ends. In this work, effects of tube curvature on temperature separation efficiency are investigated through numerical simulations. Numerical models of straight and curved vortex tubes are developed in a commercial computational fluid dynamics package Ansys-fluent®. For the curved tube, multiple curvature angles are used to analyze the effects of curvature on velocity and temperature fields inside the vortex tube. The standard κ − ε turbulence model is used to model three-dimensional turbulence. The cold stream mass fraction is varied by controlling hot exit pressure. The numerical results for 110° curved vortex tube are validated through published experimental data and are found to be in good agreement. It is found that the curvature has affirmative results on temperature separation efficiency as compared to straight tube. This is mainly due to the energy separation phenomenon governed by the multi-circulation loop extension and multiple vortex formation in curved vortex tubes. Curvature angles of 180° and 270° have similar effects on the vortex tube where the maximum ΔTc obtained is 15.7 K which is about 5.3% higher than the straight vortex tube. The temperature separation ΔThc values for curved tubes are comparable with straight tube, the maximum being 25.2 K for the 150° curved vortex tube which is about 0.8 per higher than the straight tube. The temperature separation efficiency for curved vortex tubes with curvature angles larger than 150° is found to be higher than straigt tube, the maximum value being 8.7% for the 270° curved tube. A profound investigation of the effects of curvature on energy separation phenomenon in a vortex tube had been lacking and this research attempts to fill that gap. This novel work is expected to provide insight into the energy separation mechanisms in vortex tubes and lead the way to their use in thermo-electric power generation.
... Distinctive feature of VT to generate spontaneous temperature variation unlike conventional refrigeration systems has motivated several researchers to study and improve its performance. The change in performance of VT due to pressure at the inlet and number of nozzles was experimentally studied by Dincer et al. [5], Nimbalkar and Muller [6], Eiamsa-ard [7] and Markal et al. [8]. The research of Xue et al. [9] was focused towards flow characteristics https://doi.org/10.1016/j.matpr.2021. ...
A Vortex Tube (VT) creates instant separate hot and cold streams from an input stream of compressed air. However, the output of VT depends on numerous operating and geometric characteristics. Further, experimentation using all combinations of conditions is rather unrealistic, both physically and financially. Hence, a primary evaluation of VT becomes important using principles of Design of Experiments.
This research work presents methodology and results of a statistical assessment of VT’s temperature separation effect through Taguchi method. This method is beneficial because it requires lesser number of trials. Present study uses L16 orthogonal array to perform the experiments for different conditions of pressure at entry to VT, cold mass fraction (µc) and insulation. Distinctiveness of this analysis is that statistical analysis of VT has been presented using Mixed Taguchi Design. This method represents different number of levels for control factors, unlike other designs. Lastly, confirmation experiment authenticates the usefulness of Taguchi method to predict VT’s performance with adequate accuracy. Results specify that experimental efforts are reduced by 62.96% using Taguchi method.
... Dincer et al [4] determined experimentally the effects of position, diameter (5, 6, 7, 8 mm) and angle (30°-180°) of the movable plug, located at the hot outlet side in a Ranque-Hilsch Vortex Tube (RHVT), for best performance. Nimbalkar et al [5] presented the results of a series of experiments focusing on various geometries of the "cold end side" for different inlet pressures and cold fractions. ...
... It is observed that as the number of nozzles is increased, power of cooling increases significantly while cold outlet temperature decreases moderately. Nimbalkar et al [28] and Muller presented the results of a series of experiments focusing on various geometries of the ''cold end side" for different inlet pressures and cold fractions. K. Kiran Kumar Rao1 et al [29] presented the results by using homogenous wood like rose wood and sapota wood with Length of the Hot pipe = 290mm Diameter of the hot Pipe = 12mm with L/D ratio=24. ...
Refrigeration plays an important role in developing countries, primarily for the preservation of food, medicine, and for air conditioning Conventional refrigeration systems are using Freon as refrigerant. As they are the main cause for depleting ozone layer, extensive research work is going on alternate refrigeration systems. Vortex tube (VT) is a non-conventional cooling device, having no moving parts which are capable of separating hot and cold gas stream form an inlet gas stream with a proper pressure without affecting the environment. This device suits for vital applications because of its light weight, simple and more importantly it is compact. This paper presents experimental results by the different investigators on the effect of various geometrical parameters, like nozzles, orifice, conical needle modifications, and different material like metallic and non metallic and experiment, to improve cop, cooling performance of vortex tube under these conditions listed below. 1. Tangential nozzle orientation with Symmetry/ asymmetry of around 4 nozzles with stopper. 2. Cold orifice diameter to the inlet diameter (d/D) and the length to its inlet diameter (L/D) 3. Cylindrical and conical hot tubes with conical angle of about 2.5˚ surpassed. 4. The effect of varying the cone valve diameter (dc= 14, 12,10,8, and 6mm), with constant nozzle diameter of 6.5 mm by varying the pressure of the inlet air 2-6 bar 5. The effects of cooling of a hot tube directly cooled by cooling water jacket. 6. The effect of cold end side which has the form of convergent helical nozzles with 7 mm orifice diameter and 6 no. of nozzles by inlet pressure (2 to 5 bar in step of 1bar),conical valves with an angle (30°,45°,60°90°). 7. The effect of Ranque-Hilsch vortex tube (RHVT) with threads cut (pitch is 1 and 2 mm) on its inner surface of hot tube. 8. Different materials of hot tubes with adiabatic like Mild steel, Aluminium and Copper with same L/D ratio 9. By influence of uniform curvature of main tube of VT Also by the literature review it is clear that there is no theory so perfect, which gives the satisfactory explanation of the vortex tube phenomenon. Due to this reason researcher conduct the series of experimentation to understand the effect of various parameters mentioned above to improve the performance of vortex tube.
... Kirmaci and Kaya 7 provided an extensive review on effect of different parameters such as working fluid, nozzle number, and nozzle material investigated by both experiments and simulation. The influence of divergent angle for energy separation by Chang et al 8 and Takahama et al, 9 optimum cold orifice geometry of VT for various cold mass fractions (ξ ) and different pressures at inlet by Nimbalker and Muller 10 and Saidi et al, 11 and the influence of hot-tube configuration on the operating condition of the VT by Valipour and Niazi 12 have been experimentally obtained, analyzed, and reported so as to provide a better design and operation of this separation device. These experimental studies were also numerically tracked and discussed in more detail using mathematical techniques. ...
This study provides analysis of a cooled Ranque–Hilsch vortex tube (RHVT) with various specifications. It shows how cooling influences energy conversion inside the RHVT and improves performance of the device in separation of hot gas from the cold stream within the fluid by presenting the temperature detachment (the temperature diminution of cold air (ΔTc = Ti − Tc), isentropic efficiency (ηis), and coefficient of performance (COP) of divergent, convergent, and straight VTs. Two key parameters including hot tube length and number of nozzles for cooling and insulated cases are investigated to find out how the performance of the VT is affected by different geometry configurations under cooling conditions. These influences were researched for straight, convergent, and divergent VT separators under different flow characteristics. The optimum geometrical conditions for the cooling cases were identified. Results are indicative of positive influence of cooling for energy separation inside a VT. The quantities of ΔTc, ηis, and COP for the cooled RHVT are greater than uncooled RHVT for various types of VTs. Cooling the VTs leads to an increase of 12.5% in ΔTc, 14.4% in ηis, and 15.1% in COP when the base case was an uncooled VT.
... They also report that helium is better than oxygen or air as the working gas for a higher performance of VT. Nimbalkar et al. [58] performed a CFD analysis and experimental investigation to optimize the geometry of VT. They reported that the optimum size of the cold exit is 58% of the diameter of tube, which is same as Saidi et al. [57] but 8% smaller than the result of Behera et al. [31]. ...
Ranque-Hilsch vortex tube (RHVT) is an equipment that sequestrated a single stream flow of fluid (gas) into two different flows simultaneously, one hotter than the inlet and one cooler. Traditionally vortex tubes are mostly operated at high entrance pressures
(>10 psig) and always used for cooling operations. There are semi-industrial and industrial usages which can lead to unused pressurized gases. Vortex tube energy separation can be used as a waste pressure energy recovery method from high and low pressure references (sources). In various industrial systems, magnitudes of waste pressure may be lower but may have significant mass flow rates. Hence it is important to make sure that vortex tube provides the required energy separation while harnessing the low pressure but high mass flow rate waste energy and utilizes it for not only cooling but also for heating purposes. Our recent experimental observations show that in the low inlet pressure regime (<10 psig); vortex tubes behave differently and produce multiple flow structures rather than expected recirculating cold stream and the columnar hot stream type of flow (simply “Vortex Tube flow” or VT-flow). This paper characterizes industrial waste pressure as a reclaimable form of energy, analyzes the effectiveness of ‘vortex tube energy separation’ in recovering waste energy from low pressure sources, and explores experimentally the possibility of multiple flow structures (like Reverse, Elbow, T-flow or VT-flow) inside vortex tube in a low inlet pressure regime. First time, a study of flow modes in low pressure vortex tubes with small cold fractions has been presented which yielded quantitative confirmation of simple one dimensional model for these flows allowing both predictive capabilities and guidance in design.
... For instance it was observed that the energy separation improves when inlet is closer to cold outlet and increasing the inlet pressure and in consequence the inlet mass flow and swirl strength, decreases the cold outlet temperature as increasing the hot outlet temperature. Nimbalker and Muller [6] determined the optimized condition for cold mass ratio, cold end design and various inlet pressure. The reported diameter for optimization was the same as reported by Saidi et al. [7] it was smaller by 8% than Behera et al. [8]. ...
... They also report that helium is better than oxygen or air as the working gas for a higher performance of VT. Nimbalkar et al. [54] performed a computational fluid dynamic (CFD) analysis and experimental investigation to optimize the geometry of VT. They reported that the optimum size of the cold exit is 58% of the diameter of tube, which is same as Saidi and Valipour [53] but 8% smaller than the result of Behera et al. [27]. ...
The 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 the present work, the flow phenomena and the thermal energy transfer in Ranque-Hilsch vortex tube 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 a RHVT for different configuration of straight, five angles of divergent hot-tube (1, 2, 3, 4 and 6 degree) and five angle of convergent hot-tube (0.5, 0.8, 1, 1.5 and 2 degree) are investigated. The thermal performance for all investigated RHVTs configuration is determined and quantitatively assessed via visualizing the stream lines for all three scenarios.
... For example, it was observed that the greatest cold temperature diminution (¿ Ö ) will be obtained if the inlet is near the cold flow outlet and inflow pressure, thus the mass flow and swirl strength will become greater than the other cases; therefore, the greatest cold temperature diminution (¿ Ö ) at the cold outlet can be achieved. Nimbalker and Muller [10] reported on the optimum cold orifice geometry of vortex tube for various cold mass fractions (ae) and pressures at inlet. It was observed that the optimum diameter of the tube, which is same as Saidi et al. [11] but 8% less than the outcome of Behera et al. [12]. ...
The design of innovative Ranque-Hilsch vortex tube (RHVT) for the development of green and low cost refrigeration and air conditioning systems has become increasingly important in cooling (and heating) process industries. In this light improving the heat transfer mechanism and thermal efficiency (cooling optimization) of the RHVT has been an ongoing concern. This research demonstrates how using different turbulence models may affect the temperature detachment (the temperature diminution of cold air (∆T𝑐 = T𝑖 − T𝑐)) inside straight counter- flow Ranque-Hilsch Vortex Tube (RHVT). The code is utilized to find the optimized turbulence model for energy separation by comparison with the experimental data of the setup. To obtain the results with a minimum error, ten turbulence models have been investigated in steady state and transient time-dependence modes. Results show that RNG k-ԑ turbulence model has the best correspondence with the obtained experimental data from the setup; therefore, by using a RNG k-ԑ turbulence model with respect to Finite Volume Method (FVM) and based on the Computational Fluid Dynamic (CFD), all the computations have been carried out.
... They concluded that optimum values of the angle of the control valve, the length of the pipe, and the diameter of the inlet nozzle are obtained to occur approximately in the ranges of = 0.5, #/ = 20, %/ = 1/3, which are expected to be useful for vortex tube applications. Nimbalkar and Muller [7] used in their experiments an internal diameter D=1.905cm and a length L = 25.4 cm (L/D ratio equal to 13.33). The tube was made of stainless steel and thermally insulated from the atmosphere to avoid errors due to heat conduction and to maintain repeatable steady-state. ...
This paper presents effect of cold mass friction, the rates of air flow, the inlet pressure, and the time on hot and cold air temperatures that are generated in the vortex tube. The vortex tube is manufactured by simple equip-ments within low prices. That proves the simplification of the vortex tube. Although the efficiency of vortex tube is low, but it produces low temperatures without using expensive cooling machines.
... The energy separation within vortex tube (also famed as Ranque-Hilsch Effect) is widely argued in this presentation and is currently a controversial subject of researchTable 1 shows a brief overview of performed researches on vortex tubeMany researchers performed experiments in order to determine the dependence of exit temperature on geometric design, cold mass ratio and air inlet characteristics [3][4][5]For instance it was observed that the energy separation improves when inlet is closer to cold outlet and increasing the inlet pressure and in consequence the inlet mass flow and swirl strength, decreases the cold outlet temperature as increasing the hot outlet temperature Nimbalker and Muller [6] determined the optimized condition for cold mass ratio, cold end design and various inlet pressureThe reported diameter for optimization was the same as reported by Saidi et al [7] it was smaller by 8% than Behera et al [8]&RROLQJRIKRWWXEHZDVIRXQGWRHQKDQFHWKH ...
A Ranque-Hilsch vortex tube is a mechanical device in absence of any portable part or work input and significantly separates the inlet gas stream into hot and cold gas which provides a variety of applications. Current research consists a three-dimensional numerical model at steady state condition using installed fins on cold tube. Six different geometry were chosen for fins including triangle, square, rectangle, circle, parallelogram and trapezium. The outcome data of the research then is verified with compare to prior experiment results brought in literature. This chapter surveys the influence of different fin shapes on critical performance parameters of cold temperature difference (〖∆T〗_c), hot temperature difference (〖∆T〗_h), isentropic efficiency and COP numerically. The modeling results indicate that the parallelogram and rectangular fins have the highest and lowest cold temperature difference (〖∆T〗_c), isentropic efficiency and COP, respectively.
... The maximum difference in the temperatures of hot and cold streams was obtained for the plug diameter of 5 mm, tip angles of 30º and 60 º, 4 nozzles and by keeping the plug located at the far extreme end. Nimbalkar and Muller [16] investigated for the optimum geometry for cold end orifice of the tube, for different inlet pressures and cold fractions. The experimental results indicate that there is an optimum diameter of cold end orifice for achieving maximum energy separation. ...
The vortex tube is a device used for generation of cold and hot air streams from compressed air. This simple device is very efficient in theseparation of air streams into two different temperatures streams. Cold air coming out of vortex tube can be used for air conditioning and refrigeration purpose. The coefficient of performance (COP) and outlet cold air temperature difference (∆TC) of vortex tube are considerably influenced by its thermophysical and geometrical parameters. The present study deals with the experimental investigation on the effect of 2, 4 and 6nozzle number on COP and ∆TC of thevortex tube. Vortex tube with length to diameter ratio (L/D) 15'0°, 15'4°, 16'4°, 17'4° and 18'4° where 0° and 4° are diverging angles, cold end orifice diameter(do) 5, 6 and 7mm and valve angle (Ɵ) 30°, 45°, 60°, 75° and 90° have been experimented with inlet pressure (Pi) 2, 3, 4, 5 and 6 bar. The effect of nozzle number on COP and ∆TC for acold mass fraction (CMF) varying from 0 to 1 was studied and the validation of experimented and simulated value of COP and ∆TC for pressure varying from 2 bar to 6 bar was done.The experimental results are validated with simulation results. Experimental result indicates that COP increases with increase in inlet pressure but decreases as a number of nozzle increases.The simulation result holds true with anexperimental result where the value of COP decreases with increase in CMF value and ∆TCdecreases with increase in CMF. The best result was achieved for2 nozzle numberwhere it produces maximum 0.1237 COP for CMF = 1 and maximum ΔTC about 20.3794 at CMF = 1. The best COP experimentaland COPsimulation were achieved for 2 nozzle number as0.136668811 and 0.062378066 respectively at 6 bar inlet pressure.Also, the best ∆TCvalue of experimental and simulation was achieved at 6 bar pressure as 7.2 and 11.80075 respectively.
... It can be explained that larger orifice draws back hot gases towards cold end causing its mixing with cold gas giving rise to reduces temperature drops. Sachin et al. [9] studied four different diameters of the cold orifice. 3.454mm, 6.985mm, 9.576mm and 12.636mm, experimentally. ...
Vortex tube has been using widely in industry for the cooling process. It is working as a refrigerator which split compressed gas into the hot and cold stream without using any electrical or chemical process. In term of application, the effect of geometrical parameters on the cold flow temperature of vortex tube by using high temperature compressed gas is obscure, and effect of certain working gas has yet to be vigorously researched. Thus, the objective of this analysis is to determine the effect of length of the vortex tube, cold exit diameter and different high temperature working gas. There are 3 different tube length, 3 different cold diameter, and 7 different types of gas are used. The models are designed from SolidWork with several parameters. Simflow, which is free software, is selected to analyse the effect on model numerically. From the results, it is clear that the optimum tube length, cold exit diameter, and working gas are L = 175 mm, d = 4 mm and helium, respectively.
This investigation is to analyze experimentally the effect of different hot tubes on the energy separation performance of a counter-flow Ranque–Hilsch vortex tube and to study their influence on nozzle numbers. To examine the influence of different materials, interchangeable hot tubes made with plexiglass, teflon, steel, and aluminum were used in experimental vortex tube. To understand how the optimum number of nozzles is influenced by the change of hot tube material, vortex generators made of brass with nozzles numbers 2, 3, 4, 5, and 6 were used in the vortex tube. Experimental results indicate that hot tubes with different materials influence the heating and cooling performance of Ranque–Hilsch vortex tubes with an increasing inlet pressure and higher nozzle numbers (N > 3). Specifically, plastic tubes exhibited decreased cooling performance with increasing nozzle numbers, while metal tubes exhibited increased cooling performance. Plexiglass hot tubes have a higher COPcooling 55% than aluminum hot tubes at an input pressure of 2 bar.
In this paper, the deflection characteristics of incompressible fluid trajectories in nonuniform vertical perforations are investigated. The hydrodynamic equations of the model are established based on the basic equations of fluid mechanics and finite element analysis methods. The effect of the difference in diameter between the two sides of the hole and the control of the incident fluid parameters on the trajectory deflection produced by the fluid is shown. The results show that: 1. The aqueous fluid is deflected towards the side of the hole with the larger diameter by the nonequivalent vertical throughhole structure. The deflection angle increases with increasing nonequivalent ratio and decreases with increasing incident fluid pressure.2 In order to achieve directional deflection of vertically incident aqueous fluids, the nonlinear coupling between incident fluid pressure and vertical span is investigated in this paper and suitable equations are developed.3. From the results, the incompressible aqueous fluid cannot achieve natural vortex initiation in a vortex tube where the inlet axis is the same as the vortex chamber axis, with a maximum deflection of 0.12 mm in the vortex chamber.4. If | λ 2 -λ 3 | is increased to 2.45 without considering the constraint that the diameter of the model vortex chamber is larger than the height of the vortex chamber, the water body can shoot out of the vortex chamber while its tangential velocity can reach 22.07 m/s, which can produce the spiral effect.
The influence of tube curvature, conical valve geometry, and initial swirl on the thermal performance of vortex tubes is numerically investigated. Multiple models of straight and curved vortex tubes are developed in Ansys-fluent®. The effect of each parameter on flow and temperature fields is analyzed using 3d simulations with standard κ-ε turbulence model. The cold stream mass fraction is varied by controlling hot exit pressure. Truncated cone hot control valves are found to perform better than non-truncated valves, but the optimum truncation length depends on the application for which the vortex tube is to be used. The tube curvature too has a positive effect in raising the temperature separation between the two streams specifically for curvature angles larger than 150° with cold mass fractions ranging between 0.3 and 0.7. The performance of curved tubes can be improved further by combining curvature effect with other design changes such as the use of truncated cone hot flow valve and an optimum number of inlet nozzles. Three inlet nozzles have been found to produce an initial swirl that gives maximum cold stream temperature difference and maximum end-to-end temperature separation for the 110 curved vortex tube. The combined effect of the three parameters is studied for the 180° curved vortex tube with three nozzles and a truncated hot conical control valve. It is found that using this combination the cold stream temperature difference increased by about 23.4 percent while the end-to-end temperature separation improved by about 37.3 percent when compared with the straight vortex tube.
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.
An experimental investigation of a Ranque-Hilsch vortex tube has been performed. The investigation focuses on the effects that pressure magnitude, pressure drop and pressure ratio have on the temperature drop between the inlet and the cold outlet. The Ranque-Hilsch vortex tube used in the experiments was designed through consideration of a large body of experimental data consolidated from existing literature. Experiments are conducted for cases of constant cold exit pressure (0.31 [MPa]), constant pressure drop between the inlet and cold exit (0.31 [MPa]), and constant pressure ratio between the inlet and cold outlet (2.0). From the experimental data collected, the temperature drop was found to be best correlated to the ratio of the inlet and cold outlet pressures, suggesting that the process could be characterized as polytropic. Results for each case were reported in terms of recovery temperature and static temperature to illustrate the importance of interpreting the dynamic component of temperature in the results. The reported results show that for a pressure ratio of 2.0, the maximum recovery temperature drop is 13.96 [K], whereas the corresponding static temperature drop is 12.25 [K].
Abstrak Penelitian ini membahas mengenai fenomena pemisahan aliran dingin dan panas di dalam Ranque-Hilsch Vortex Tube (RHVT) jenis counter flow, dengan jumlah nosel 2, 3 dan 4 buah, pada tekanan udara masuk ke nosel sebesar 2 atm. Kajian dilakukan secara numeric menggunakan perangkat lunak komputasi dinamika fluida Fluent versi 14 dengan menggunakan model aliran viscous Kappa Epsilon (k-e) dengan domain komputasi 3D. Penelitian ini juga membahas mengenai phenomenaaliran swirl pemisahan aliran dingindan panas di dalam RHVT jenis counter flow pada tekanan udara masuk ke noselsebesar 2 atm dengan jumlah nosel 2 buah pada kondisi fraksi dingin yang bervariasi 23,93%, 23,95%, 24,02%, 26,63%, 33,50% dan 35,30% akibat perubahan tekanan udara keluar. Hasil simulasi numerik properties fluida ditampilkan dalam bentuk visualisasi kontur dan vektor dan garis alir kecepatan axial, kecepatan radial dan juga aliran sirkulasi balik beserta distribusi tekanan dan temperatur serta visualisasialiran swirlyang terjadi didalam RHVT. Pada fraksi dingin 23,93%temperatur minimum 13 o C dan maksimum 56 o C, pada fraksi dingin 23,95%, temperatur minimum 13 o C dan maksimum 50 o C,pada fraksi dingin 24,02%, temperatur minimum 12 o C dan maksimum 57 o C, pada fraksi dingin 26,63%, temperatur minimum 13 o C dan maksimum 66 o C, pada fraksi dingin 33,50%, temperatur minimum 14 o C dan maksimum 69 o C dan pada fraksi dingin 35,30%, temperatur minimum 13 o C dan maksimum 65 o C. Hasil simulasi yang menunjukan kinerja RHVT terbaik adalah yang mempunyai nosel 4 buah pada kondisi tekanan masuk 2 bar yang ditunjukan oleh kurva selisih temperatur udara masuk dengan temperatur udara keluar dingin ΔT c terhadap fraksi massa udara dingin terhadap massa udara masuk dua nosel. Abstract This study discusses the phenomenon of cold and heat flow separation in the ranque-Hilsch Vortex Tube (RHVT) counter flow type, which its nozzles number used varies from 2, 3 and 4 at 2 atm of inlet air pressure. Studies carried out using the computational numeric fluid dynamics software FLUENT version 14 by methode the viscous flow model Kappa Epsilon and 3D computational domain This study also discusses the phenomenon of swirl flow separation of cold and heat flow in the this tube which using 2 nozzle at cold fraction varied in range of 23.93%, 23.95%, 24.02%, 26.63%, 33.50% and 35.30% due to the changes in air pressure out. The results of numerical simulations of fluid properties displayed in the form of contour visualization and flow vector velocity in the line of axial, radial velocity and flow recirculation flow associated with distribution of pressure and temperature and visualization of swirl flow that occurs in RHVT. In the conditions in cold fraction of 23.93% resulting of decreasing temperature until 13 o C in cold end section and increasing of temperatur up to 56 o C in hot end section. In the cold fraction of 23.95%, the minimum temperature 13 o C and 50 o C maximum. and the cold fraction of 24.02%, the minimum temperature 12 o C and 57 o C maximum, the cold fraction of 26.63%, the minimum temperature 13 o C and 66 o C maximum, the cold fraction of 33.50%, the minimum temperature 14 o C and 69 o C maximum and the cold fraction 35.30%, the minimum temperature of 13 o C and 65 o C maximum. The simulation results show that best performance is RHVT which using 4 nozzles on condition 2 bar inlet pressure, shown by the curve of difference temperature between temperatures cold air out and air inlet temperature (ΔT c) against cold air mass fraction.
In this paper, the relationship between the flow structures in the vortex tube and its coordinated variation of the performance is numerically investigated. It is shown that the poor performance of vortex tubes is possibly due to the morbid flow structure controlling in it. A new method of managing the flow structures inside the vortex tube to achieve best suitable to the operation condition with a variable cold orifice ratio is proposed. Different cold orifice ratios, ranging from 0.3<Dc/D<0.8, were adopted to study how the cold orifice ratio affects the performance, especially the cooling performance. An interesting and important characteristic of the operating performance of a vortex tube can be realized by continuously changing the cold orifice ratios, that is, when the cold mass fraction increasing from 0.1 to 0.9, the total temperature difference can be “monotonically decreasing” (for Dc/D≤0.36), “firstly increasing then decreasing” (for 0.36<Dc/D<0.72) or “monotonically increasing” (for Dc/D=0.72), which provides a useful method to control the temperature of cold/hot stream and also boosts the cooling capacity. This feature results from the better synergy between the flow structure and the operation conditions, which is also simple and easy to be realized. Besides, a fast and preliminary diagnosis method on the flow field of the main tube with the distribution of the reverse flow boundary is presented, and it is helpful to the optimization design of vortex tube.
Le travail traité dans le cadre de cette thèse porte sur une simulation numérique de
l’écoulement compressible, tridimensionnel et turbulent dans un tube vortex. D’abord,
une étude bibliographique détaillée a permis de mettre en évidence les différentes
tentatives visant la compréhension du phénomène de séparation de l’énergie, d’une part,
et l’amélioration de ses performances d’autre part. Ensuite, les résultats des simulations
numériques ont été analysés.
Les résultats ont été obtenus par la résolution des équations qui régissent l’écoulement et
le transfert de chaleur dans le tube vortex à l’aide du code de calcul Fluent. Les résultats
reportés dans cette thèse sont basés sur quatre modèle de turbulence, à savoir le modèle k-
ε standard, le modèle k-ω, le modèle SST k-ω et le modèle des tensions de Reynolds
(RSM). Les résultats en termes d’écart de température entre les sorties chaude et froide
ont été comparés aux mesures expérimentales publiés. D’autres résultats relatifs aux
champs d’écoulement, des températures et de la turbulence ont été présentés et analysés.
Des simulations ont été également conduites en tenant en compte de la variation des
propriétés thermophysiques en fonction de la température. Ainsi, des expressions de la
chaleur spécifique à pression constante, de la viscosité et de la conductivité thermique de
l’air ont été développées et introduites dans le code.
Finalement, les résultats numériques obtenus ont été complétés par une analyse
exergétique visant à quantifier les pertes par irréversibilités et le rendement de ce
dispositif.
Vortex Tube (VT) is simplistic, yet attractive device for spot cooling applications due to its ability of spontaneous generation of cold and hot flows of air. This also aids in reducing production cycle time. Present experimentation reports VT’s performance enhancement by use of various materials. Subsequently, a novel association between temperature gradient magnitude with thermo-physical properties of VT material has been proposed. Results indicate performance improvement with increase in entry pressure for all materials tested. VT made from PA6 has higher performance than VTs of other materials. Cooling energy is higher by 6.55% for VT made from PA6 than mild steel VT at 3 bar pressure, while it’s higher by 10.47% at 4 bar pressure. Thermal conductivity and diffusivity of VT material are key factors for performance enhancement. Results are consistent with other works when compared on non-dimensional basis. Techno-economical evaluation of VT’s industrial application carried out in weld cooling clearly indicates substantial reduction in cycle time due to VT’s use. This consequently increases profits for a nominal investment, which gives payback period of 15 days only.
The vortex tube or Ranque–Hilsch vortex tube is a device that allows hot and cold air to be separated by the tangential flow of compressed air into the vortex chamber through the inlet nozzles and energy separation effects in a vortex tube have been investigated using a computational fluid dynamics model. The governing equations have been solved in an ANSYS Fluent code in a 3D compressible and turbulent model when Standard k-epsilon was used. The effects of geometrical parameters have been investigated. The results showed that the cold end diameter to tube diameter ratio (dc/D) affects the performance of the tube, and this effect changes when operating the tube at different cold mass fraction. The results showed that computational data were in good agreement with the experimental values.
A large number of operational and geometrical parameters are involved in the optimization of counterflow vortex tubes. The number of parameters is so important that most researchers relied on a one factor at a time approach which cannot capture the possible interactions between the relevant parameters. Additionally, literature contains very few information on how to design properly a vortex tube for given inlet conditions.
To identify the most important features, two approaches are used: artificial neural networks (ANNs) and thermodynamic modeling. Both methods could reproduce accurately the cold outlet temperature of vortex tubes from the literature. To achieve this, the ANN uses only the inlet pressure, the cold mass fraction, the length to the diameter ratio and the cold outlet diameter to the vortex diameter ratio. The output from another ANN is the inlet mass flow rate. This second ANN uses only the inlet pressure, the length to diameter ratio, the total inlet nozzles’ area and the vortex tube diameter as inputs to do the calculation. The most important parameter in the thermodynamic model is the inlet pressure to cold outlet pressure ratio. It is shown that the variations of this ratio by friction in the inlet nozzles are not negligible and should be considered in future vortex tubes’ design. The Bodewadt boundary layer flow between the inlet and the cold outlet affects also significantly the vortex tube performance.
The fundamental objective of this preliminary investigation was to simulate the desired separation in a commercially available vortex tube, using a system of hydrocarbons as a surrogate for air. A bench-scale system was constructed, a mixture of 21% cyclohexane and 79% n-pentane was selected, and a parametric study was devised to evaluate the effect of feed conditions on vortex tube separation performance. The desired separation was not achieved using the commercial vortex tube, a unit which was designed for air flow rates much higher than we were using in the bench scale environment. Modifications were made to the equipment in an effort to compensate for the lower flow rates; however, these modifications did not improve attempts to achieve the desired separation. All of the data seem to indicate that the best separations achieved in this study were only equivalent to one equilibrium flash stage. Many of the separations did not even match the equilibrium flash case, which suggests that the action of the commercial vortex tube used in this study produced mixing, entrainment, of other processes which serve to reduce the separation when compared to that of an equilibrium flash.
Various methods had been taken for the flow field studies, among them, qualitative visualizations and probe intrusive measurements have a long history and had been adopted since last 50s, while laser non-intrusive measurements and numerical simulations are the emerging methods, especially the former. Nowadays, more and more researchers have realized there are specific and regular flow structures in the strong turbulence of vortex tube, and the flow structures have great significance on understanding the energy separation process and performance. However, there still did not exist a review on the flow structure studies. The aim of this paper is to offer a critical review and discussion on the current studying methods, findings and differences on the flow structures in vortex tube. In addition, future scopes were proposed on the experimentally and theoretically verification of these flow structures and their effects on the energy separation process and performance.
This study is experimentally targeting to develop an effective novel system to produce fresh water, by sea water desalination using vortex tube. The vortex tube used compressed air as a power source, and produced hot air stream from one end and cold air stream from the other, taking that advantage in water desalination technology, with low consumption of heating energy under vacuum condition. Using four modes of compressor operation, mode I of continuous operation, mode II of five minutes on then ten minutes off, mode III of ten minutes on then five minutes off and mode IV of ten minutes on then ten minutes off. The following results are obtained: the quantity of the desalinated water was, 26% of the initial sea water quantity for mode II, while for mode IV, it was about 34%, for mode III, it was about 51%, while the maximum desalinated water quantity of 68% is obtained at mode I. Finally, the total dissolved solids in the produced desalinated water were about 480 mg/l. Therefore, using Ranque-Hilsch vortex tube in sea water desalination is highly recommended to be used as an effective agent to initiate sea water evaporation and desalinated water condensation.
The region in swirl/Reynolds number space where hysteresis is evident in the open pipe flow has been investigated, with the aim of determining whether it is possible to cause a jump from one state (without vortex breakdown) to another (with vortex breakdown) at the same swirl and Reynolds number. This initial study has showed that by introducing a large perturbation in the form of a transient swirl increase it is possible to generate a breakdown bubble, but this bubble disappears once the perturbation has propagated through the pipe.
The vortex tube represents a simple device in which a particular type of vortex motion may be studied in the laboratory in an attempt to obtain a better understanding of such flows. Such an investigation has been pursued in the Heat Transfer Laboratory of the University of Minnesota. The present paper summarizes the major results of this vortex-tube investigation.
The authors tried to explain the effects of the dimensions of a vortex tube (especially the rate of partial admission of nozzle) on the energy separation of gas flowing through it. They tried also to explain the influence of the cold air rate on the flow and thermal fields in a vortex tube with the optimum proportion of the total area of nozzle openings (Fn) to the cross-sectional area of main tube (Ft). From these researches the following results have been obtained : (1) The maximum efficiency of energy separation is obtained when Fn≒0.17Ft. (2) The values of turbulent diffusivity calculated from the tangential velocity profiles nearly coincide with the values computed from Keyes'empirical formula. Reynolds number of jet from the nozzle, Ret=(0.5∼3.0)×106. (3) For the case of large axial velocity, the modified formulae including the axial velocity terms (36) and (37) should be used to predict the stagnation temperature profile in the cross-section at the cold end of the tube.
A simple flow model was developed for the purpose of estimating the pressure drop along a tube supplied wih swirling flow. The model indicates that the energy losses observed for swirling flow can be orders of magnitude greater than that computed for comparable nonswirling flow. The losses are explained as due not only to the decay of the swirl, but also as a function of the axial flow area restriction caused by the swirl induced recirculating core. The results of analysis with the proposed model compared favorably with experimental data.
Linderstrom-Lang has reported that partial separation of the components of a gas mixture occurs when it is passed through a particular type of vortex tube. The present work confirms this effect and, using several different gas mixtures and several different sizes of tube, shows that there is a critical inlet Reynolds number for maximum separation by this device. A correlation is derived which satisfactorily predicts the performance over a wide range of gas parameters and applied pressures.RésuméLinderstrom-Lang a montré qu'une séparation partielle des composants d'un mélange gazeux se produit lorsqu'il s'écoule dans un tube à tourbillon de type particulier. Le présent travail confirme cet effet. Ayant expérimenté plusieurs mélanges gazeux et plusieurs tubes de dimensions différentes, on a montré qu'il existe un nombre de Reynolds critique d'admission donnant une séparation maximale par ce procédé. Une relation empirique a été obtenue qui permet de prédire de façon satisfaisante les performances dans un domaine étendu des paramètres du gaz et des pressions appliquées.ZusammenfassungLinderstrøm-Lang berichtete, daß beim Durchströmen einer besonderen Wirbelrohn-Bauart eine partielle Trennung der Komponenten eines Gasgemisches auftritt. Die vorliegende Arbeit bestätigt diesen Effekt und zeigt anhand verschiedener Gasgemische und mehrerer verschiedener Rohrgrößen, daß eine kritische Einlauf-Reynolds-Zahl existiert, bei der die Einrichtung eine maximale Trennwirkung aufweist. Es wird eine Korrelation abgeleitet, mit der in einem großen Bereich von Gasparametern und Drücken die Leistung befriedigend berechnet werden kann.РефератПo дaнным Линдecтpoмa-Лoнгa чacтичнoe paздeлeниe кoмпoнeнтoв гaзoвoй cмecи пpoиcчoдит пpи пpoчoждeнии ee пo вичpeвoй тpyбкe oпpeдeлeннoгo типa. Hacтoящaя paбoтa пoдтвepждaeт этo и c пoмoщью paзличныч гaзoвыч cмeceй и paзныч paзмepoв тpyбки пoкaзывaeт, чтo имeeтcя кpитичecкoe чиcлo Peйнoльдca нa вчoдe для мaкcимaльнoгo paздeлeния c пoмoщью вичpeвoй тpyбки. Пoлyчeнo cooтнoшeниe, yдoвлeтвopитeльнo oпиcывaющee кoэффициeнт пoлeзнoгo дeйcтвия в шиpoкoм диaпaзoнe измeнeния пapaмeтpoв гaзa и внeшнeгo дaвлeния.
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.
The temperature separation phenomenon of the Ranque-Hilsch (vortex) tube is not limited to compressible gases and vapors. Theoretical analysis using the Second Law of Thermodynamics establishes that a net entropy producing temperature separation effect is possible when incompressible liquids are used in these devices. Experiments with liquid water in a commercial counterflow Ranque-Hilsch tube designed for use with air verify that significant temperature separation does in fact occur when a sufficiently high inlet pressure is used.
The hydraulic characteristics of an intensely swirling flow in the energy separation chambers in Ranque-Hilsch vortex tubes
are investigated analytically and experimentally. Computer codes are developed and realized numerically for the calculation
of the aggregate coefficient of hydraulic drag under conditions of swirling flow in an axisymmetric channel of a vortex tube.
The results are treated in the form of criteria equations for the calculation of coefficients of hydraulic drag as functions
of the basic process and geometric parameters of the vortex tube. The vortex tube hydraulics are studied experimentally, and
the results of calculations performed using our procedure are compared with the data of numerical calculation using the commercially
available CFX-TASCFlow package and with experimental data. Adequate agreement is observed between the experimentally obtained
and numerical calculation results.
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 Ranque–Hilsch vortex tube is a device by which cold gas can be generated using compressed gas. To understand the cooling mechanism of this device, it is necessary to know the pressure, temperature, and velocity distributions inside the tube. In order to investigate this, a simple vortex tube is built and nitrogen is used as its working fluid. A special Pitot tube is used for the measurement of the pressure and velocity. This Pitot tube consists of a capillary which has only one hole in the cylinder wall. With this Pitot tube, the pressure and velocity fields inside the tube were measured. In the same way, the temperature field was measured with a thermocouple. The results of three different entrance conditions are compared here. With the measurements results, the analysis based on the two thermodynamic laws has been made. It is found that rounding off the entrance has influence on the performance of the vortex tube. The secondary circulation gas flow inside the vortex tube can be enhanced and enlarged, the performance of the Ranque–Hilsch vortex tube improved.
An experimental investigation has been performed to realize thorough behavior of a vortex tube system. In this work attention has been focussed on the classification of the parameters affecting vortex tube operation. The effective parameters are divided into two different types, namely geometrical and thermo-physical ones. A reliable test rig has been designed and constructed to investigate the effect of geometrical parameters i.e. diameter and length of main tube, diameter of outlet orifice, shape of entrance nozzle. Thermo-physical parameters which have been designated and studied are inlet gas pressure, type of gas, cold gas mass ratio and moisture of inlet gas. The effects of these parameters on the cold temperature difference and efficiency are discussed and presented.
The process of energy separation in a vortex tube with air as a working medium is studied in detail. Experimental data of the temperatures of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the vortex tube surface provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. Experimental results indicate that the Görtler vortex produced by the tangential velocity on the inside wall of the vortex tube is a major driving force for the energy separation. A similarity relation for the prediction of the temperature of the cold exit air, obtained from the dimensional analysis, is presented and confirmed by experimental data.
Vortex tube (VT) is a simple energy separating device which is compact and simple to produce and to operate. Although intensive research has been carried out in many countries over the years, the efficiency is still low. In order to improve the energy separate efficiency of vortex tubes, three innovative technologies were applied to vortex tubes. A new nozzle with equal gradient of Mach number and a new intake flow passage of nozzles with equal flow velocity were designed and developed to reduce the flow loss. A new kind of diffuser invented by us was installed for reducing friction loss of air flow energy at the end of the hot end tube of vortex tube, which can greatly improve the performance of vortex tube. The experiment results indicated that these modifications could remarkably improve the performance of vortex tube. The developed vortex tube was not only superior to the conventional vortex tube but also superior to that made by two companies in world under big cold gas mass flow ratio.
A novel Pitot probe was used to measure the axial and azimuthal velocities in a vortex tube. The probe has only a single measuring port and is hence smaller than standard devices. It monitors stagnation and reference pressure sequentially as the probe is rotated around its axis. From the measured velocity field in the 25 mm diameter vortex tube the local mass flux was determined and it was observed that the return flow at the center of the tube is much larger than the cold mass flow emerging out of the cold end. Therefore, the vortex tube must have a secondary circulation imbedded into the primary vortex, which moves fluid from the back flow core to the outer regions.
Numerical solutions of viscous, swirling flows through circular pipes of constant radius and circular pipes with throats have been obtained. Solutions were computed for several values of vortex circulation, Reynolds number and throat/inlet area ratio, under the assumptions of steady flow, rotational symmetry and frictionless flow at the pipe wall. When the Reynolds number is sufficiently large, vortex breakdown occurs abruptly with increased circulation as a result of the existence of non-unique solutions. Solution paths for Reynolds numbers exceeding approximately 1000 are characterized by an ensemble of three inviscid flow types: columnar (for pipes of constant radius), soliton and wavetrain. Flows that are quasi-cylindrical and which do not exhibit vortex breakdown exist below a critical circulation, dependent on the Reynolds number and the throat/inlet area ratio. Wavetrain solutions are observed over a small range of circulation below the critical circulation, while above the critical value, wave solutions with large regions of reversed flow are found that are primarily solitary in nature. The quasi-cylindrical (QC) equations first fail near the critical value, in support of Hall's theory of vortex breakdown (1967). However, the QC equations are not found to be effective in predicting the spatial position of the breakdown structure.
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.
The phenomenon of the selective adhesion of staphylococci to immobilized human plasminogen was discovered and studied in the reaction of bacteriosorption. The study, made with S.aureus cells, strain Cowan 1, revealed that the degree of adhesion depended on the amount of immobilized protein and the time of its contact with bacterial suspension. The dose-dependent inhibition of adhesion with plasminogen and plasmin solutions, found to occur also with IgG, was demonstrated. Staphylococcal protein A did not inhibit adhesion. The plasminogen-binding receptor structure was shown to be highly sensitive to proteolysis, which is indicative of its protein nature.
Experience from the operation of a variable vortex tube in a gas separating station
- Nikolaev
V.V. Nikolaev, V.P. Ovchinnikov, M.A. Zhidkov, Experience from the
operation of a variable vortex tube in a gas separating station, Gaz. Prom.
10 (1995) 13.
- Brendon Adams
- Michael Jones
Brendon Adams, Michael Jones, et al., Hysteresis in the open pipe flor with
vortex breakdown, in: Second International Conference on CFD in the
Minerals and Process Industries, CSIRO, Melbourne, Australia, December
1999.
- H Takahama
- N Soga
H. Takahama, N. Soga, Studies on vortex tubes: 2nd report, Bull. JSME 9 (33)
(1966) 121-137.
Studies on vortex tubes: 1st and 2nd report
- Takahama
Studies on vortex tubes: 2nd report
- Takahama