CFD SIMULATION OF HYDROGEN COMBUSTION

1
CFD SIMULATION OF HYDROGEN COMBUSTION
2
INTRODUCTION

• Hydrogen as alternative fuel
• Evaluation of Hydrogen combustion using CFD

3
OBJECTIVES AND SCOPE

• Understanding of the basics of Hydrogen-oxygen
  reaction mechanism.
• To develop a two dimensional numerical mesh and
  flow model.
• To prepare a mathematical model for hydrogen-air
  combustion system.
• The objective of this is to study CFD-package
  FLUENT.

4
HYDROGEN AS A FUEL

• It readily combines with oxygen to form water.
• It has a high-energy content per weight.
• Hydrogen is highly flammable.
• Hydrogen burns with a pale-blue, almost-invisible
  flame.
• The combustion of hydrogen does not produce
  carbon dioxide (CO2), particulate, or sulfur
  emissions.

5
Hydrogen can be produced from renewable
resources.
6
Table Properties of fuels
7
PROPERTIES OF HYDROGEN AS A FUEL 

• Limits of Flammability
• Minimum Ignition Energy
• Quenching Gap or Distance
•  Self Ignition Temperature
•  Flame Speed
• Diffusivity
• Density
• Flame characteristics 

8
Figure Invisible Hydrogen Flame Igniting
Broom 
9
Figure Hydrogen Flame from Ruptured Fuel
Cylinder 
10
BENEFITS OF HYDROGEN ECONOMY

• Strengthen National Energy Security
• Reduce Greenhouse Gas Emissions
• Reduce Air Pollution
• Improve Energy Efficiency

11
HYDROGEN STORAGE AND DELIVERY 

• Compressed Gas and Cryogenic Liquid Storage
• Materials-based Hydrogen Storage
• Current Technology

12
COMBUSTION

• Combustion accounts for approximately 85 of
  the worlds energy usage.
• Eg Gas turbine and jet engine.
• Rocket propulsion.
• Piston engines.
• Combustion is a complex interaction of physical
  and chemical processes.

13
The general characteristics of combustion

• The first and second limits are ones that
  correspond to conditions of very low pressures .
• As the pressure increases, the initial densities
  of the reactants increase and a lower temperature
  is necessary for the reactions to become fast
  enough for explosion.

14
Hydrogen Combustion 
15
GRID GENERATION AND MATHEMATICAL MODELING
Model geometry
16
Grid Generation
17
MATHEMATICAL MODELLING  Continuity Equation
18
Momentum Equations
19
Boundary conditions 

• Inlet temperature of hydrogen and air 300 k
• velocity 90 m/s
• Exit a pressure 101325.0 Pa

20
CFD SIMULATION

• A number of numerical simulations have been
  performed to study the combustion phenomena under
  adiabatic wall conditions when hydrogen air
  mixture changes from lean to rich and also at
  different mass flow rate of mixture. Figure.
  shows the contours of temperature (K) on the
  cross section along central axis of combustion
  chamber at stoichiometric air fuel ratio i.e. at
  ?1.

21
Figure Temperature Contours at
?1  
22
Figure Contours of Mole
fraction of h2O  
23
Figure Contours of Mole fraction
of N2
24
Figure Contours of Mole
fraction of O2
25
Figure Contours of Mole
fraction of H2
26
Figure Contours of Mole
fraction of OH
27
Figure Contours of Mole
fraction of O
28
CONCLUSION

• CFD based combustion simulations have been done.
• The combustor performance is evaluated by
  predicting the temperatures of exit gas of the
  combustor and outer wall of the combustor.