45224 - Chemistry of Combustion Processes (Graduate Course)

Learning outcomes

The course provides students with the thermodynamics and kinetics of the chemical reactions occurring in the internal combustion engines and in the systems for energy production, in view of optimizing working conditions, taking into account also pollutant emissions to the environment.

Course contents

Fundamental Chemistry An outline of the electronic structures of the elements, their properties, the different kinds of chemical bond and their characteristics. Absorption spectra of atoms and molecules.   
Chemical Thermodynamics Standard reaction, formation and combustion enthalpies. The second law of Thermodynamics. The direction of spontaneous change at constant pressure and temperature: the Gibbs free energy. Spontaneous changes for different kinds of reactions. The oxidation reactions: the Ellingham plot. The chemical equilibrium on thermodynamic basis; the equilibrium constants for ideal and non-ideal systems. Heterogeneous reactions. Effect of temperature and pression on the equilibrium composition. The electromotive force and the Nernst equation derived by a thermodynamic approach.  
Chemical kinetics Fundamentals of chemical kinetics. Simple and complex reaction mechanisms. Molecularity and reaction order; the special case of monomolecular reactions. Kinetics of complex reactions: competitive, converging and consecutive reactions. The steady-state approximation. Reversible reactions. Kinetics of chain and chain-branching reactions. The partial equilibrium assumption. Effect of temperature on the reaction rate: the collision theory and Arrhenius equation; the activated complex and the steric factor. Other k(T) functional forms. General properties of catalysts; homogeneous and eterogeneous catalysis. Gas-solid catalysis: kinetics of adsorption with (or without) the dissociation of reagent molecules.  
Combustion   The combustion reactions: fuels and oxidizing agents. Higher and lower heating values. The adiabatic flame temperature and its calculation in various conditions. Chain-branching reactions and the conditions for explosion. Explosion limits for hydrogen, carbon monoxide, methane, hydrocarbons, etc. Nitrogen oxides formation during the combustion: thermal and prompt mechanisms. The effect of the presence of nitrogen in fuels. Formation of sulfur oxides and other S-containing compounds. Particulate structure and the effects on human health; an outline of the mechanisms of formation.
Enviromental effects of combustion The structure of atmosphere. The temperature and pressure gradient in troposphere. Thermal stability and thermal inversion conditions. Pollutants in the troposphere: the photochemical smog. Ozone, hydrogen peroxide, PAN and nitric acid formation. Acid rains and their environmental effects. Catalytic systems for the conversion of pollutants in engine exhausts: three-way converters and novel catalytic systems. Gas sensors: the lambda probe. The particulate matter removal from diesel emissions. Greenhouse effect and global warming: carbon dioxide and the other greenhouse gases. Characteristics of the main fuels, with special attention to those obtained from renewable sources: energy and fuels from biomass. Methanol and ethanol, biodiesel, hydrogen: favourable and unfavourable features. Production methods of hydrogen and stocking problems.
The Chemistry of stratosphere: the ozone layer. The absorption of UV radiation by oxygen and ozone. Formation and destruction of the ozone layer in the stratosphere and thermal effects. Catalytic mechanisms of ozone destruction: the effect of CFC and other pollutants. The periodic formation of the antartic hole.

Readings/Bibliography

R.A. Michelin, A. Munari - “Fondamenti di Chimica per Ingegneria”, CEDAM, IV Ed., 1998.

I. Glassman - “Combustion”, Academic Press, III Ed., 1996.

S.R. Turns - “An introduction to combustion”, Mc Graw-Hill, II Ed., 2000.

C. Baird – “Chimica Ambientale”, Zanichelli, 1997.

Assessment methods

Oral examination

Office hours

See the website of Andrea Munari