with Heat Exchanger Naseh Hosseini The 3 rd TANGO Meeting and - - PowerPoint PPT Presentation

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with Heat Exchanger Naseh Hosseini The 3 rd TANGO Meeting and - - PowerPoint PPT Presentation

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Numerical and Experimental Study of Thermoacoustics of Domestic Burner with Heat Exchanger Naseh Hosseini The 3 rd TANGO Meeting and Workshop KTH Royal Institute of Technology, Stockholm, Sweden 19-23 May, 2014 Introduction - Started PhD on

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SLIDE 1

Numerical and Experimental Study of Thermoacoustics of Domestic Burner with Heat Exchanger

Naseh Hosseini

The 3rd TANGO Meeting and Workshop KTH Royal Institute of Technology, Stockholm, Sweden 19-23 May, 2014

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SLIDE 2

Introduction

  • Started PhD on August 15, 2013
  • Eindhoven University of Technology (TU/e), Eindhoven, the Netherlands
  • Started in TANGO on November 1, 2013
  • Bekaert Combustion Technology B.V. (BCT), Assen, the Netherlands
  • R&D researcher thermoacoustics
  • Task 3.5 – Numerical and experimental study of domestic burner

with heat exchanger

2

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SLIDE 3

My Research

  • Previous Works
  • Development of a model for the interaction between acoustic waves and different

types of premixed conical flames

  • Acoustic response of the flame in open environment
  • For industrial burners with large perforations (2mm diameter)

3

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SLIDE 4

My Research

  • Interactions of burner with heat exchanger
  • Effects on flame shape (hydrodynamic or impingement)
  • Changes in the temperature of different surfaces
  • Can the heat exchanger itself have TF and cause time delay?

4

Structures and performances of laminar impinging multiple premixed LPG–air flames

  • U. Makmoola et al. (2013)
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SLIDE 5

Outline

  • Inclusion of heat exchanger and investigation of its hydrodynamic

and thermoacoustic effects

  • Solving the problems associated with modeling combustion in

small perforations (around 0.8mm)

  • More sophisticated modeling of thermoacoustics and terminations

methods (e.g. DNS of anechoic terminations)

5

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SLIDE 6

Numerical

  • Geometrical challenges in modeling

6

2D axisymmetric 2D plane Full 3D

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SLIDE 7

Numerical

  • Computational domain
  • Slit burner, plane 2D
  • One tube per one row of slits
  • Based on future experiments

7

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SLIDE 8

Numerical

  • Computational grid
  • 164689 cells of 20m size
  • Proper size achieved through pseudo-1D simulations

8

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SLIDE 9

Numerical

  • Model specifications – combustion
  • Laminar premixed methane-air at 0.8 equivalence ratio
  • Time step size 10s
  • Single step modified chemistry for proper flame speed calculation
  • The global reaction
  • Reaction rate
  • Ar = 2.291019 (consistent units), pre-exponential factor
  • r = 2.8 and 1.2 (dimensionless) for CH4 and O2, temperature exponent
  • Er = 1.38108(J/kmol), activation energy
  • R = 8314.34 (J/kmol-K), universal gas constant

9

 

4 2 2 2 2 2

2 3.76 2 7.52 CH O N CO H O N     

r r

E RT r r

k AT e

 

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SLIDE 10

Numerical

  • Model specifications – transfer function
  • Definition
  • Excitation: step profile for velocity with 5% increase at the domain inlet
  • For TF calculations, velocity above burner deck was considered
  • Response: sum of heat of reaction in the whole domain

10

     

q f q TF f u f u   

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SLIDE 11

Numerical – Pseudo-1D

  • Finding suitable flame speed through pseudo-1D simulations
  • 0.0235mm computational domain
  • Same boundary conditions as 2D
  • Defining a proper inlet velocity
  • Observing flame (maximum reaction rate) movement – must remain constant

11

time

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SLIDE 12

Numerical – Pseudo-1D

  • Finding suitable flame speed through pseudo-1D simulations
  • Flame speed dependency to grid size was checked
  • Coarse grid fluctuations due to temporal and special resolution mismatch

12

Cell size 20m

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SLIDE 13

Numerical – Pseudo-1D

  • Finding suitable flame speed through pseudo-1D simulations
  • Equivalence ratio sensitivity

13

5 10 15 20 25 30 35 40 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 Sl (cm/s) Equivalence Ratio This Study Lange (1992) Dyakov (2001) Kishore (2008)

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SLIDE 14

Numerical – Pseudo-1D

  • Finding suitable flame speed through pseudo-1D simulations
  • Unburned temperature sensitivity

14

10 20 30 40 50 60 70 80 90 150 200 250 300 350 400 450 500 550 Sl (cm/s) Unburnt Temperature (K) This Study Sharma (1981) Brown (2003)

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SLIDE 15

Numerical – 2D

  • Case studies

15

Burner Deck – Heat Exchanger Distance (mm) Inlet Velocity (cm/s) 25 50 5 Hex05-V25 Hex05-V50 10 Hex10-V25 Hex10-V50 15 Hex15-V25 Hex15-V50 N/A NoHex-V25 NoHex-V50

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SLIDE 16

Numerical – 2D

  • Reaction rate

(kmol/m3s)

  • V = 25cm/s

16

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SLIDE 17

Numerical – 2D

  • Temperature

(K)

  • V = 25cm/s

17

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SLIDE 18

Numerical – 2D

  • Temperature

(K)

  • V = 50cm/s

18

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SLIDE 19

Numerical – 2D

  • Reaction rate

(kmol/m3s)

  • V = 50cm/s

19

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SLIDE 20

Numerical – 2D

  • Flow through flame front
  • Wake behind the tube cylinder

20

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SLIDE 21

0.99 1.00 1.01 1.02 1.03 1.04 1.05 1.06 5 10 15 20 25 30 35 40 Normalized Heat Release Time (ms)

Numerical – 2D

  • Periodic step (square)
  • Slight increase just before

the decrease

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SLIDE 22

Numerical – TF – V25-QReac

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  • 3.0
  • 2.5
  • 2.0
  • 1.5
  • 1.0
  • 0.5

0.0 100 200 300 400 500 600 700 800 900 1000 Phase/ (rad) Frequency (Hz)

NoHex Hex15 Hex10 Hex05

0.0001 0.001 0.01 0.1 1 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

NoHex Hex15 Hex10 Hex05

 0.0 0.2 0.4 0.6 0.8 1.0 1.2 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

NoHex Hex15 Hex10 Hex05

0.99 1.00 1.01 1.02 1.03 1.04 1.05 1.06 5 10 15 20 25 30 35 40 Heat Release Rate (kW) Flow Time (ms)

NoHex Hex15 Hex10 Hex05

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SLIDE 23

Numerical – TF – V25-QHex

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0.0 0.2 0.4 0.6 0.8 1.0 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

Hex15 Hex10 Hex05

 Normalized Gain

  • 1.0
  • 0.8
  • 0.6
  • 0.4
  • 0.2

0.0 100 200 300 400 500 600 700 800 900 1000 Phase/ (rad) Frequency (Hz)

Hex15 Hex10 Hex05

0.01 0.1 1 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

Hex15 Hex10 Hex05

 1.00 1.00 1.01 1.01 1.02 1.02 1.03 1.03 1.04 1.04 5 10 15 20 25 30 35 40 Normalized Heat Exchanger Heat Flux Time (ms)

Hex15 Hex10 Hex05

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SLIDE 24

Numerical – TF – V50-QReac

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0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

NoHex Hex15 Hex10 Hex05

 0.001 0.01 0.1 1 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

NoHex Hex15 Hex10 Hex05

0.99 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 5 10 15 20 25 30 35 40 Normalized Heat Release Time (ms)

NoHex Hex15 Hex10 Hex05

  • 7.0
  • 6.0
  • 5.0
  • 4.0
  • 3.0
  • 2.0
  • 1.0

0.0 100 200 300 400 500 600 700 800 900 1000 Phase/ (rad) Frequency (Hz)

NoHex Hex15 Hex10 Hex05

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SLIDE 25

Numerical – TF – V50-QHex

25

  • 5.0
  • 4.0
  • 3.0
  • 2.0
  • 1.0

0.0 100 200 300 400 500 600 700 800 900 1000 Phase/ (rad) Frequency (Hz)

Hex15 Hex10 Hex05

0.01 0.1 1 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

Hex15 Hex10 Hex05

 0.0 0.2 0.4 0.6 0.8 1.0 1.2 100 200 300 400 500 600 700 800 900 1000 Gain Frequency (Hz)

Hex15 Hex10 Hex05

 0.96 0.97 0.98 0.99 1.00 1.01 1.02 1.03 1.04 5 10 15 20 25 30 35 40 Normalized Heat Exchanger Heat Flux Time (ms)

Hex15 Hex10 Hex05

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SLIDE 26

Numerical – TF – Gains at Zero Frequency

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  • Calculated via FFT

and steady state values

1− 𝑟2

𝑟1

1− 𝑣2

𝑣1

  • 0.6
  • 0.4
  • 0.2

0.2 0.4 0.6 0.8 1 1.2 1.4

  • 0.6 -0.4 -0.2

0.2 0.4 0.6 0.8 1 1.2 1.4 TF Calculated Gain at 0Hz Physical Gain at 0Hz

QHex H05V50 QHex H10V50 H15V50 QHex H05V25 H10V25 H15V25 QReac all Hex & NoHex

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SLIDE 27

Experimental

  • Rigidity issues in small dimensions
  • Portability

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Version 2.0 Version 1.0 Version 3.0

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SLIDE 28

Future Works

  • Further investigations on the available results (better boundary

conditions, transfer matrix, etc.)

  • Starting the experimental part and making required modifications
  • Starting modeling of smaller perforations

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SLIDE 29

better together

www.bekaert.com