Performance Analysis of Ejector Refrigeration: Conditions & Geometric Parameters, Slides of Physics

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 Motivation

 Objective.

 Strategy.

 Ejector refrigeration system.

 Refrigerant selection.

 Ejector design.

 Flow pattern in ejector.

 Effects of operating conditions on performance.

 Effects of geometric parameters on performance.

 Results validation.

 Design an ejector for 0.15 KW cooling capacity for

Selected Refrigerant.

 Parametric Analysis of Designed Ejector using

FLUENT.

 Effects of Operating Conditions on Ejector

Performance.

 Generator Pressure.

 Evaporator Pressure.

 Effects of Geometric Parameters on Ejector

Performance.

 Area Ratio.

 Constant Area Section Length.

 Primary Nozzle Position.

 Secondary Convergence Angle.

 Comparison of FLUENT Results with the Analytical

Calculations.

 This system uses solar, geothermal or waste energy

from process industries to run the refrigeration

cycle.

 In this system compressor is replaced by an Ejector,

which is used as a compression device.

 A shock wave is produced in the constant area

section of secondary nozzle.

 When refrigerant pass through that shock wave,

compression is achieved.

Coefficient Of Performance

Entrainment Ratio

Pressure Lift Ratio

Double Choking Mode

Single Choking Mode

Back Flow Mode

R12 is therefore selected as refrigerant for the present study

because it is chemically stable, non-inflammable, non-toxic,

non-explosive, easily available and low cost refrigerant.

 Flow inside the ejector is steady and one dimensional.

 The kinetic energy at the inlets of primary and secondary

ports and the exit of diffuser are negligible.

 The mixing of the two flows is complete before a normal

shock wave occurs at the end of the cylindrical mixing

chamber.

 The inner wall of the ejector is adiabatic.

 Friction losses are incorporated using friction loss

coefficient.

 For simplicity in deriving the 1-D model, the isentropic

relations are used as an approximation.

1 2

1

2 1

x

x

e

e

M

P

P

M



  ^ 

1 2 1 1

x x

T

M

T

 

   

 m m vs. 2  m vp. 1 x  ms  mp. v 3

c t

c t

m c t

for A A

for A A

for A A

 

2 *2 2 3 1 2 3

1 * 2

2 2 2

x p p x s p s p p

v v v m C T m C T m m C T

       ^  ^  ^ ^ ^         

   

3 3 3

v M  RT

3 ^ 

4

2 3 2

1 1 2

1 2

M

M

M



 

        

 

4 2 3 3

P

M

P





4 3

3 3 4

4 P

T P

T 

2 4 3

3

2 3

M

M









4

04 2

4

1 1 2

T M T

     (^)     

1 2 4 4

04 1 1 2

M P

P



 ^    (^)     

 

1 2 1 2

5 4

4 2

5

5 4

A M

A

M

M

M





        (^)     (^)    

Geometry Dimension

Sec. convergence angle (αc) 25 deg

Constant area section length (lc) 25 mm

Constant area section diameter (dc) 2 mm

Sec. divergence angle (αd) 6.65 deg

Diffuser diameter (dd) 6.2 mm

Diffuser length (ld) 18 mm

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