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Advancements in Hydrogen Combustion Simulation using Lookup Tables (LUT)

Lisa Bachmann University of Stuttgart and Bosch Thermotechnology

Evert Bunschoten TU Delft

Nijso Beishuizen Bosch Thermotechnology and TU Eindhoven

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Hydrogen as the future green fuel source

Hydrogen combustion

Goal: Redesign of burners to make them suitable for large percentages of hydrogen

  • Ensure low emissions of Nox
  • Maintain thermal efficiency and safety
  • Ensure great lifetime

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🡪 Efficient simulation of hydrogen combustion

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Why is it so difficult?

Hydrogen combustion

  • Strong preferential diffusion
    • Partially premixed model
  • Mixture Fraction as a new independent variable
  • High risk of flashback

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Hydrogen diffuses out of the flame tip…

And moves towards the flame base

H2+air

L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Current issues

Hydrogen combustion

  • Detailed Chemistry (DC)
    • Many equations
    • Small reaction zone
    • 🡪 high computation costs
  • SU2: flamelet approach
    • Cantera 1D flamelets combined into lookup tables
    • Application of lookup tables (E. Bunschoten)
    • 1D flamelets overpredict source terms
    • Unphysical flashbacks

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

  • DC results for validation of simple use cases
  • Improvement of flamelet approach to eliminate overprediction of source terms
    • Improvement of lookup tables
    • Improvement of implementation in SU2

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Generation of lookup tables

Flamelet approach

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Idea: Map detailed 1D simulation

results in 3D space using

problem specific parameters:

here: progress variable C and enthalpy h

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  • Compute 1D simulations
  • Tabulate 1D solutions as functions of progress variable C and enthalpy h
  • Solve 3D transport equations for C and h using table look-ups to obtain values for source terms and physical quantities

Progress Variable

Progress Variable

1D flamelet

1800K

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700K

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300K

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Generation of lookup tables

Flamelet approach

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Progress Variable

Progress Variable

Progress Variable

Enthalpy

Mixture Fraction

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Improvements

LUT Generation

SU2 Code

  • Wider domains of the flamelets

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Progress Variable

H2+air

Source terms = 0

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Improvements

LUT Generation

SU2 Code

  • Wider domains of the flamelets
  • Enhancement of the mesh refinement
  • Only add preferential diffusion terms if they are wanted and the combustion has started
  • CFL Adaptation after x iterations to improve initialization

​

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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isothermal case Φ=0.5

Validation

2.0 m/s

1.5 m/s

DC

FGM

DC

FGM

DC

FGM

1.0 m/s

DC

Flame length is consistently shorter.

Twall=450K

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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scatter plot

Validation

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Source term

progress variable (YH2O)

burnt

unburnt

Source term is consistently too high in FGM simulations

→ Vance (2023)

SU2 – FGM

Detailed Chemistry

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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scatter plot

Validation

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Source term

progress variable (YH2O)

burnt

unburnt

corrections are necessary to limit burner heating and prevent flash-back

SU2 – FGM

Detailed Chemistry

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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scatter plot

Vance correction

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Source term

progress variable (YH2O)

burnt

unburnt

SU2 – FGM

Detailed Chemistry

T>1000K – no correction

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Conjugate Heat Transfer

Validation

2.0 m/s

1.5 m/s

1.0 m/s

710K

651K

682K

715K

827K

727K

SU2 – FGM

Detailed Chemistry

Larger source term leads to early flash-back

DC FGM

DC FGM

DC FGM

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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Summary

  • Improvement of LUT generation to limit overprediction of source terms
  • Improvement of simulation stability
  • Achieving of cases without flashback
  • Implementation of Vance’s correction
  • Improvement of source term overprediction
    • Alternative to Vance correction
    • Additional improvements in SU2 Code
  • Validation of MLP generation
  • Validation in three-dimensional domains

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

  • Agreement with detailed chemistry simulations not perfect
  • Vance correction not applicable for this testcase
  • Still overprediction of source terms

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Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

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L. Bachmann, E. Bunschoten, N. Beishuizen | 30.09.2024

THANK YOU!�����Lisa Bachmann Lisa@Lisa-Bachmann.de��Evert Bunschoten E.C.Bunschoten@tudelft.nl��Nijso Beishuizen Nijso.Beishuizen@nl.bosch.com� N.A.Beishuizen@tue.nl�

Internal | L. Bachmann, E. Bunschoten, N. Beishuizen | 2024-09-30

© Bosch Thermotechniek B.V. 2024. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.