The document discusses key thermodynamic properties relevant to combustion, focusing on thermal conductivity, specific heat, calorific value, heat of formation, and heat of reaction. It highlights how these properties affect heat transfer, reaction rates, and combustion efficiency in various contexts like engine cylinders, insulators, and fuel optimization. Understanding these parameters is vital for improving combustion performance and energy efficiency.

1. COMBUSTION
THERMODYNAMICS
By
Er. T. AYISHA NAZIBA, Dr. D. RAMESH, Dr. S. PUGALENDHI

2. THERMAL CONDUCTIVITY
 Thermal conductivity (k) is a material's inherent ability to conduct heat.
 It quantifies the rate of heat transfer through a material due to a
temperature difference.
 Heat transfer occurs via microscopic mechanisms like vibration of atoms
and molecules.
 Thermal conductivity influences heat distribution within the combustion
chamber.
 Materials with high k transfer heat away from the flame zone, affecting
reaction rates.
 Combustion chamber walls with low k can help maintain high flame
temperatures.

3. ROLE OF THERMAL CONDUCTIVITY IN
COMBUSTION
 Engine cylinders: High k materials like aluminum promote heat transfer for
cooling.
 Insulators: Refractory linings in furnaces have low k to retain heat within the
chamber.
 Heat exchangers: Optimize material selection based on desired heat
transfer rates.
 Thermal conductivity influences heat distribution within the combustion
chamber.
 Materials with high k transfer heat away from the flame zone, affecting
reaction rates.
 Combustion chamber walls with low k can help maintain high flame
temperatures.

4. SPECIFIC HEAT
 Specific heat (c) is a material property that signifies the amount
of heat required to raise the temperature of 1 unit mass of the
material by 1 unit of temperature.
 It is an intensive property, meaning it depends on the material
itself and not the amount of material present.
 Specific heat is typically expressed in units of joules per gram
per kelvin (J/g∙K) or joules per kilogram per kelvin (J/kg∙K).

5. ROLE OF SPECIFIC HEAT IN
COMBUSTION
 Specific heat influences the heat transfer required to reach the desired combustion
temperature.
 Materials with high specific heat capacity absorb more heat to achieve the same
temperature rise as materials with low specific heat.
 Understanding specific heat is crucial for calculating the heat required to raise
reactants to ignition temperature.
 Engine coolants: Water's high specific heat makes it a good coolant, absorbing heat
from the engine.
 Preheating combustion air: Preheating air with high specific heat can improve
combustion efficiency.
 Optimizing fuel consumption: Understanding specific heat aids in calculating fuel
requirements for desired temperature changes.

6. HEATING VALUE / CALORIFIC VALUE
 Calorific Value
The calorific value is the measurement of heat or energy produced, and is
measured either as gross calorific value or net calorific value. Gross calorific value
(GCV) assumes all vapour produced during the combustion process is fully
condensed. Net calorific value (NCV) assumes the water leaves with the
combustion products without fully being condensed. Fuels should be compared
based on the net calorific value.
 Fuel Oil Gross Calorific Value (kCal/kg)
Kerosene - 11,100
Diesel Oil - 10,800
LDO - 10,700
Furnace Oil - 10,500
LSHS - 10,600

7. HEAT OF FORMATION
 Heat of formation (ΔHf) is the amount of heat absorbed or evolved
during the formation of one mole of a substance from its constituent
elements under standard conditions (25 °C and 1 atm pressure).
 It is represented by the symbol ΔHf, where ΔH signifies the change in
enthalpy, a thermodynamic property related to a system's total energy.
 The heat of formation of elements in their standard states is assigned a
value of zero (ΔHf° = 0 kJ/mol).

8. HEAT OF REACTION
 Heat of formation (ΔHf) is the amount of heat absorbed or evolved
during the formation of one mole of a substance from its constituent
elements under standard conditions (25 °C and 1 atm pressure).
 It is represented by the symbol ΔHf, where ΔH signifies the change in
enthalpy, a thermodynamic property related to a system's total energy.
 The heat of formation of elements in their standard states is assigned a
value of zero (ΔHf° = 0 kJ/mol).

9. THANK YOU