ME643A

Combustion

Credits:


3000 (9 Credits)



Course Content:
Introduction, review of thermodynamics, adiabatic flame temperature, chemical equilibrium, chemical kinetics, steadystate approximation, partial equilibrium, mass transfer, conservation equations and transport properties, laminar premixed flame, flame speed, ignition, quenching, flammability limits and stability, laminar nonpremixed flame, conserved scalar concept, estimation of flame height, burning rate for a single droplet, turbulent premixed flames, Borghi diagram, flame height for turbulent nonpremixedflames, liftoff and blowout phenomena, flame stabilizationin turbulent flows, Soot and NOxformation in premixed and nonpremixed combustion.
Lecturewise Breakup (considering the duration of each lecture is 50 minutes)
I. Introduction: (2 Lectures)

Practical applications of combustion, motivation to study combustion, definition of combustion.

Classifications of fundamental combustion phenomena,challenges and approach to our study.
II. Combustion and thermochemistry: (6 Lectures)

Review of thermodynamics: extensive/intensive properties, equation of state, calorific equations of state, ideal gas mixture, latent heat of vaporization.

The first law of thermodynamics, concept of stoichiometry, heat capacity, standard enthalpy of formation.

Adiabatic flame temperature for constant pressure and constant volume systems.

Chemical equilibrium, the second law of thermodynamics, Gibbs function, Complex systems.

Equilibrium products of combustion, concepts of full equilibrium.

Watergas equilibrium, effect of pressure on equilibrium.
III. Chemical kinetics and reaction mechanism: (5 Lectures)

Global and elementary reactions, molecularity and order, elementary reaction rates.

Bimolecular reactions and collision theory, other elementary reactions.

Rates of multistep mechanisms, Arrhenius law, relation between rate coefficients and equilibrium constants.

Steadystate approximation, unimolecular reactions.

Chemical time scale, partial equilibrium.
IV. Introduction to mass transfer: (2 Lectures)

Fick's law of diffusion, molecular basis of diffusion (kinetic theory of gases), species conservation for a reactive system.

The Stefan problem, liquidvapor interface boundary conditions, droplet evaporation.
V. Conservation equations and transport properties: (4 Lecture)

Derivation of species conservation equation for a reactive system.

Integral and differential form of a general conservation equation.

Derivation of energy conservation for a reactive system, ShvabZeldovich form.

Transport properties: thermal conductivity, viscosity, mass and thermal diffusivity.
VI. Laminar premixed flame: (5 Lectures)

Physical description, flame speed and thickness, Bunsen burner, simplified analysis of a premixed flame.

Factors influencing flame thickness and velocity.

Ignition, ignition delay time for hydrocarbons, spark ignition.

Flame quenching, estimation of quenching distance, flammability limits.

Flame stabilization, flame extinction, flashback and lift off
VII. Laminar nonpremixed flame : (4 Lectures)

Physical description of jet diffusion flame, counterflow diffusion flame

Concept of a conserved scalar, mixture fraction, conservation of mixture fraction.

Functional dependencies under various conditions: cold mixing, complete and infinitely fast reaction, chemical equilibrium condition, finite rate chemistry

Analytical solutions for flame height.
VIII. Droplet evaporation and combustion : (4 Lectures)

Applications, simple model of droplet evaporation

Simple model for burning droplet, burning rate constant and droplet lifetime.

Droplet burning in convective environments

Realworld effects on droplet burning rate.
IX. Turbulent Reactive Flows: (6 Lectures)

Applications of turbulent premixed flames, turbulent flame speed

Structure andcharacteristics of turbulent premixed flame.

Different regimes of turbulent premixed flame

Applications of turbulent nonpremixed flames, estimation of flame height using scaling laws for turbulent diffusion flames.

Liftoff and blowout phenomena in turbulent jet flames.

Various flame stabilization mechanism in turbulent flows.
X. Pollutant emissions: (2 Lectures)
References:

An Introduction to Combustion: Concepts and Applications, S. R. Turns, McGrawHill Science/Engineering/Math; 3 edition (January 24, 2011)

Combustion by I. Glassman, Academic Press; 4 edition (September 8, 2008)

Combustion: Physical and Chemical Fundamentals, Modeling and Simulation, Experiments, Pollutant Formation, J. Warnatz, U. Mass and R. W. Dibble, Springer; 4th edition (November 9, 2010)
