NUMERICAL ANALYSIS OF FLOW BEHAVIOUR AND ENERGY SEPARATION IN VORTEX TUBE

Guided by Karthika. A.S Assistant Professor Dept. of Mechanical Engg. CET, TVM

Presented by John wills N Fourth semester Thermal Science Roll No 702M103

CONTENTS

• Introduction• Vortex tube• Literature survey• Objectives • Methodology• Modeling of vortex tube• Results and discussion• References

INTRODUCTION• 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.

• When high-pressure gas is tangentially injected into the vortex chamber via the inlet nozzles, a swirling flow is created inside the vortex chamber. Part of the gas in the vortex tube reverses for axial component of the velocity and move from the hot end to the cold end. At the hot exhaust, the gas escapes with a higher temperature, while at the cold exhaust, the gas has a lower temperature compared to the inlet temperature.

• There are two types of vortex tube: Uni-flow vortex tube and Counter flow vortex tube.

VORTEX TUBE

Uni-flow vortex tube

Counter flow vortex tube

Working of Vortex tube

Applications • Cooling electronic controls• Cooling machining operation• Cooling soldered parts• Electronic component cooling• Cooling heat seals

Advantages

• No moving parts• No electricity or chemicals• Small, lightweight• Low cost• Maintenance free• Instant cold air• Adjustable temperature

Literature Survey1. U. Behera, CFD analysis and experimental investigations towards

optimizing the parameters of Ranque–Hilsch vortex tube, International

Journal of Heat and Mass Transfer 48 (2005), pp. 1961–1973. • Different types of nozzle profiles and number of nozzles are evaluated by

CFD analysis.• The swirl velocity, axial velocity and radial velocity components as well

as the flow patterns including secondary circulation flow have been evaluated.

2. N.Pourmahmoud, Numerical Investigation of the Thermal Separation in a Vortex Tube, proceedings of world academy of science, engineering and technology volume 33 september 2008 ISSN 2070-3740.

• Simulations were conducted for different cold mass fractions by changing the hot end pressure.

• The effects of cold mass fraction on the temperature separation effect were studied.

3. Maziar Arjomandi et al, The effect of vortex angle on the efficiency of the Ranque–Hilsch vortex tube, Experimental Thermal and Fluid Science 33 (2008) 54–57.

• A small vortex angle demonstrated a larger temperature difference and better performance for the heating of the vortex tube.

• Small vortex angles resulted in better cooling only at lower values of

input pressure.

4. Sachin U. Nimbalkar et al, An experimental investigation of the optimum geometry for the cold end orifice of a vortex tube, Applied Thermal Engineering 29 (2009) 509–514.

• The diameter of cold orifice influence the energy separation in a Vortex tube.

OBJECTIVES

• Analyze the flow parameters and energy separation mechanism

inside the vortex tube.

• To determine the effect of different parameters such as aspect

ratio, number of inlets, inlet air pressure and hot exit pressure.

• Optimization of critical design parameters of the vortex tubes.

• Investigate the effect of cold mass fraction on temperature

separation.

Methodology

• Modeling Gambit 2.4

• Numerical analysis Fluent 6.3

3D, segregated, implicit scheme.k -ε Turbulence model.

Vortex tube diameter, D = 12 mm. Length, L = 120 mm.Cold end diameter, dc = 7mm.

Modeling of vortex tube

Gambit model

Meshed model

RESULTS AND DISCUSSION

Temperature Plot L/D = 10, inlet pr. = 5bar, Hot out pr. = 1 bar

Cold stream Hot stream

Axial distance, m Axial distance, m

Tem

pera

ture

, K

Tem

pera

ture

, K

Temperature distribution along axial direction

Pressure, Pa

Cold stream Hot stream

Pres

sure

, Pa

Pres

sure

, Pa

Pressure distribution along axial direction

Axial distance, mAxial distance, m

Axial velocity , m/s

Cold stream Hot stream

Axi

al v

eloc

ity,

m/s

Axi

al v

eloc

ity,

m/s

Axial distance, m Axial distance, m

20

Axial velocity along axial direction

Variation of axial velocity in radial direction

Variation of tangential velocity along radial direction

Static Temperature, K

Variation of static temperature along radial direction

Variation of temperature with number of inlets

0 0.04 0.08 0.12

280

285

290

295

300

305

Gra p h 1tw o in le ts

four in le ts

six in le ts

Tem

pera

ture

, K

Axial d istance, m

Variation of Swirl velocity

Swirl velocity, m/s

Variation of temperature for different inlet pressure

Conclusions• A numerical computations have been carried out to

predict vortex tube flow.• Variation of pressure, velocity and temperature inside

vortex tube were studied.• The obtained profiles indicate a hot peripheral flow

and a reversing cold inner core flow.• The results showed that temperature separation inside

the vortex tube exists.• At any axial location, the static temperature of the

fluid particles moving towards cold exit is more than the hot exit. This sets up the direction of heat transfer between the core and the peripheral flow in vortex tube.

Contd……

• A minimum of 4 bar pressure is required to generate vortex with sufficient strength for attaining temperature separation.

• Very high inlet pressure have no significance in temperature separation.

• From the parametric study, the best results were obtained for the case of four tangential inlets.

References• U. Behera et al, CFD analysis and experimental investigations towards

optimizing the parameters of Ranque–Hilsch vortex tube, International Journal of Heat and Mass Transfer 48 (2005), pp. 1961–1973.

• N.Pourmahmoud et al, Numerical Investigation of the Thermal Separation in a Vortex Tube, proceedings of world academy of science, engineering and technology volume 33 september 2008 ISSN 2070-3740.

• Maziar Arjomandi et al, The effect of vortex angle on the efficiency of the Ranque–Hilsch vortex tube, Experimental Thermal and Fluid Science 33 (2008) 54–57.

• Sachin U. Nimbalkar et al, An experimental investigation of the optimum geometry for the cold end orifice of a vortex tube, Applied Thermal Engineering 29 (2009) 509–514.

• P K Singh et al, An Experimental Performance Evaluation of Vortex Tube, IE (I) Journal.MC, Vol 84, January 2004.

• Upendra Behera et al, Numerical investigations on flow behavior and energy separation in Ranque–Hilsch vortex tube, International Journal of Heat and Mass Transfer 51 (2008) 6077–6089.

• SMITH Eiamsa-ard et al, Numerical prediction of vortex flow and thermal separation in a subsonic vortex tube, Journal of Zhejiang University SCIENCE ISSN 1862-1775.

• Saeid Akhesmeh et al, Numerical Study of the Temperature Separation in the Ranque-Hilsch Vortex Tube, American Journal of Engineering and Applied Sciences 1 (3): 181-187, 2008 ISSN 1941-7020.

THANK YOU

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