CFD SIMULATION OF
HYDROGEN COMBUSTION
INTRODUCTION
Hydrogen as alternative fuel
Evaluation of Hydrogen combustion using CFD
OBJECTIVES AND SCOPE
Understanding of the basics of Hydrogenoxygen reaction mechanism.
To develop a two dimensional numerical mesh
and flow model.
To prepare a mathematical model for hydrogenair combustion system.
The objective of this is to study CFD-package
FLUENT.
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, almostinvisible flame.
The combustion of hydrogen does not produce
carbon dioxide (CO2), particulate, or sulfur
emissions.
Hydrogen can be produced from
renewable resources.
Table : Properties of fuels
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
Figure : Invisible Hydrogen Flame Igniting Broom
Figure : Hydrogen Flame from Ruptured Fuel Cylinder
BENEFITS OF HYDROGEN ECONOMY
 Strengthen National Energy Security
 Reduce Greenhouse Gas Emissions
 Reduce Air Pollution
 Improve Energy Efficiency
HYDROGEN STORAGE AND DELIVERY
Compressed Gas and Cryogenic Liquid Storage
Materials-based Hydrogen Storage
Current Technology
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.
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.
Hydrogen Combustion
GRID GENERATION AND MATHEMATICAL
MODELING
Model geometry
Grid Generation
MATHEMATICAL MODELLING
Continuity Equation
Momentum Equations
Boundary conditions
• Inlet temperature of hydrogen and air =300 k
• velocity 90 m/s
• Exit a pressure =101325.0 Pa
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
Ф=1.
Figure :
Temperature Contours at Ф=1
Figure : Contours of Mole fraction of h2O
Figure : Contours of Mole fraction of N2
Figure : Contours of Mole fraction of O2
Figure : Contours of Mole fraction of H2
Figure : Contours of Mole fraction of OH
Figure : Contours of Mole fraction of O
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.