Experimental Investigation of

Vortex Tube Refrigerator

Seminar:Anand Krishnan N : S7 – M1 : CET

Introduction The vortex tube (also called Ranque-Hilsch vortex

tube) is a simple mechanical device Which splits a compressed gas stream into cold

and hot streams. having No moving parts and long operation time. No Freon, No Electricity, No Chemical Reaction. Used for cooling

Cutting tools Electronic control cabinets Food storage Firemen’s suits

But has low thermal efficiency.

WorkingCompressed Gas In

Vortex GenerationChamber Control

Valve

Hot Gas OutCold Air Out

Pressurized gas enters the vortex tube tangentially through Nozzles.

Strong swirling flow is generated. Stream separates into a cold and hot stream. Cold stream in the central region and Hot stream

in the annular region. Cold stream leaves the cold tube through a

central orifice near the entrance nozzle. Hot stream flows towards the hot end and leaves

the hot tube

Objectives

Investigation of influence of geometrical

parameters on vortex tube performance

• Divergence angle of hot tube

• Length of divergent hot tube

• Number of nozzle intakes

• Inlet pressure

Experimental setup

1.Heat exchanger 2. Pressure tank 3,5. Rotameter4.Vortex tube P: pressure Gauge T: thermocouple

Flow diagram of experiment

Compressed Gas

Hot gas out

Cold gas out

V1: cold end tube V2: nozzle V3: divergent hot tube V4: Conical valved-diameter of cold outflow tube L-length of the vortex tube D-diameter of the vortex tube β-divergence angle

o Compressed nitrogen is processed through the heat exchanger (1) and pressure regulator (2)

o Guided tangentially into the vortex tube (4) via a nozzle after passing through a rotameter (3)

o Temperature of inlet nitrogen before the nozzle inlet is regulated to 293.15 K

o Mass flow rate of the cold flow is measured using rotameter (5)

o Flow rate of the hot stream is regulated by a conical valveo Temperatures of the inlet and outlet streams are measured with

thermocoupleso Pressures of the streams are measured by pressure gauges

Vortex tube parameters

Inner diameter of hot tube, D =10 mm

Diameter of cold end tube, dc=4.5 mm.

Cross-section (w x h) of nozzle=1 mm x 3 mm

Results and discussion• Operational characteristics of Vortex tube

o Cold stream fraction

o Cold temperature difference

Cold stream fraction, XC =

Cold temperature di erence, ff ΔTc = Inlet stream temperature - Cold stream temperature = Ti - Tc

1.Angle of divergent tube

Influence of the angle of divergent hot tube on the cold temperature difference

• Four different angles , β=0°,2°,4°, 6°,8°• Tube with length,L =100 mm, No. of nozzles inlet = 3• Inlet pressure = 0.4 Mpa

• Development trend of ΔTc for different angles is almost same

• ΔTc has maximum value around XC = 0.2

• β should be neither too large nor too small

• β= 4° is best to get highest ΔTc

• Highest ΔTc = 44.8 K at 0.2 cold flow fraction

• 11.7 % higher than that of β=0°• β=0° and β= 6° has almost same curve.• As β increases,friction loss and viscous loss decreases

Length of divergent tube

Influence of the length of divergent hot tube on thetemperature difference

• L = 80, 100, 120 and 140 mm are employed

• With β= 4° , N=3 , Pi= 0.4MPa

• ΔTc has relative small difference at XC < 0.2 but high range for

different lengths

• For XC > 0.2 ,ΔTc increases with increase in length

• Curve for L=120 mm and L=140 mm are almost equal

• There is a critical length over which no improvement

• Here critical length is 120 mm

Number of inlet nozzle intakes

Influence of the number of nozzle intake on the cold temperature difference

• N = 3, 4 and 6 intakes are studied

• With β= 4° , L=100 mm, Pi= 0.4 MPa

• Change of ΔTc for N = 6 is intensive compared with the mild

change for N = 3

• Increase in N will increase sensitivity of ΔTc

• ΔTc maximum for N=6 and minimum for N=3 for XC < 0.3

• Increase in N will decrease performance for XC >0.4

• Effect of nozzle intakes on the refrigeration performance

firmly relies on the cold flow fraction

Inlet Pressure

Influence of the length of divergent hot tube on thetemperature difference

• Different inlet pressures 0.2,0.3,.04 MPa are studied

• With β= 4° , L=100 mm, N=6

• Trend of variation is same for different pressures

• ΔTc has maximum value around XC = 0.2 for all pressures

• As pressure increases ΔTc increase for all values of XC

• ΔTc relative difference for different pressures decreases with

increase in cold mass fraction

Conclusions• The performance of vortex tube can be improved by using a

divergent hot tube, and the divergent angle should be small and not more than 6°

• Optimum divergence angle is 4° at which performance is highest which exceeds the cylindrical one by about 11.7 %

• The highest temperature reduction will be obtained at about XC=0.2

• There is a critical divergent tube length, which is 120mm• The effect of nozzle intakes on the refrigeration performance

relies on the cold flow fraction.• Cold temperature difference increase with increase in pressure

References• Experimental investigation of vortex tube refrigerator with a divergent hot

tube by Kun Chang ,Qing Li ,Gang Zhou, Qiang Li

International journal of refrigeration 34 (2011) 322-327

• A critical review of temperature separation in a vortex tubeby Yunpeng Xue, Maziar Arjomandi, Richard Kelso

Experimental Thermal and Fluid Science 34 (2010) 1367–1374

• A new vortex generator geometry for a counter-flow Ranque-Hilsch vortex tube

by Orhan Aydin, Burak Markal, Mete Avci

Applied Thermal Engineering 30 (2010) 2505-2511

Thank You