Presentation is an overview of NASA Computer program CEA (Chemical Equilibrium with Applications) calculates chemical equilibrium product concentrations from any set of reactants and determines thermodynamic and transport properties for products.

1. ___________________________________
SHARATH C M
Research Associate
Fire and Combustion Research Center
Jain University, Bengaluru

2. Fuel + Oxidizer =
If, controlled
Combustion
Heat
 Thermodynamics of Combustion
Heat Work Temperature Energy Thermodynamics

3.  Mixture
Thermal Properties of a pure substances are described by quantities such has U, h, Cp, etc…
Intrinsic properties of a mixture classified by,
• Mole Base or
• Mass Base
Species ,
Mass fractions yi = mi / M , Mole fractions xi = ni / N
From Dalton's law of additive pressure and Amagat’s law of additive volume
𝑃𝑖
𝑃
=
𝑛𝑖
𝑁
=
𝑣𝑖
𝑉
= 𝑥𝑖

4.  Mixture
For instance, the internal energy
per unit mass of a mixture, u;
Similarly, enthalpy per unit
mass of mixture is
specific heat at constant pressure per
unit mass of mixture is
Assuming constant heat during a process change in properties per unit area
Energy
Enthalpy
Entropy

5.  Chemical Energy - enthalpy

6.  Combustion Stoichiometry
A stoichiometric mixture contains the exact amount of fuel and oxidizer such that after
combustion is completed
Exercise – Combustion of HC
• Reaction
• Balancing for stoichiometry (use mole)

7.  Combustion Stoichiometry
A stoichiometric mixture contains the exact amount of fuel and oxidizer such that after
combustion is completed
Exercise – Combustion of HC
• Reaction
• Balancing for stoichiometry (use mole)

8.  Combustion Stoichiometry
A stoichiometric mixture contains the exact amount of fuel and oxidizer such that after
combustion is completed
Exercise – Combustion of HC
• Reaction
• Balancing for stoichiometry (use mole)
Generalizing

9.  Combustion Stoichiometry
A stoichiometric mixture contains the exact amount of fuel and oxidizer such that after
combustion is completed
Exercise – Combustion of HC
• Reaction
• Balancing for stoichiometry (use mole)
Generalizing

10.  Quantifying Fuel and Air Content of Combustible Mixtures
Equivalence Ratio φ : Normalizing the actual fuel-air ratio by the stoichiometric fuel-air ratio;
φ =
𝑓
𝑓𝑠
Alternative variable called llambda (λ):
(fuel lean, fuel rich and stoichiometric)

11.  Quantifying Fuel and Air Content of Combustible Mixtures
Percent Excess Air: The amount of air in excess of the stoichiometric amount is called excess air.The
percent excess air,
%EA, is defined as

12.  Exercise problem
 Considering a stoichiometric mixture of isooctane and air, determine;
i. mole fraction of fuel
ii. fuel-air ratio
iii. mole fraction of H2O in the products
iv. temperature of products below which H2O starts to condense into liquid at 101.3 kPa

13.  Exercise problem
 Considering a stoichiometric mixture of isooctane and air, determine;
i. mole fraction of fuel
ii. fuel-air ratio
iii. mole fraction of H2O in the products
iv. temperature of products below which H2O starts to condense into liquid at 101.3 kPa

14.  Exercise problem
 Considering a stoichiometric mixture of isooctane and air, determine;
i. mole fraction of fuel
ii. fuel-air ratio
iii. mole fraction of H2O in the products
iv. temperature of products below which H2O starts to condense into liquid at 101.3 kPa

15.  Exercise problem
 Considering a stoichiometric mixture of isooctane and air, determine;
i. mole fraction of fuel
ii. fuel-air ratio
iii. mole fraction of H2O in the products
iv. temperature of products below which H2O starts to condense into liquid at 101.3 kPa
(d) the partial pressure of water is 101 kPa * o.141 = 14.2 kPa :: saturation
table of steam ___

16.  Exercise problem
 Considering a stoichiometric mixture of isooctane and air, determine;
i. mole fraction of fuel
ii. fuel-air ratio
iii. mole fraction of H2O in the products
iv. temperature of products below which H2O starts to condense into liquid at 101.3 kPa
(d) the partial pressure of water is 101 kPa * o.141 = 14.2 kPa :: saturation
table of steam around 52~55 0 C.

18. NASA Computer program CEA (Chemical Equilibrium with Applications) calculates chemical equilibrium
compositions and properties of complex mixtures.
NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

19. NASA Computer program CEA (Chemical Equilibrium with Applications) calculates chemical equilibrium
compositions and properties of complex mixtures.
NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

20. Temperatures and
pressures
(Known conditions)
2
File name,
Problem Type,
Ex. P, T problem
1
Add a Slide Title - 1

21. NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

22. Selection of fuel and
oxidizer
3
Temperatures and
pressures
(Known conditions)
2
File name,
Problem Type,
Ex. P, T problem
1
Add a Slide Title - 1

23. NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

24. Stating,
Oxidizer to fuel ratio
to be inferred
4
Selection of fuel and
oxidizer
3
Temperatures and
pressures
(Known conditions)
2
File name,
Problem Type,
Ex. P, T problem
1
Add a Slide Title - 1

25. NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

26. Setting up output type
• Transport properties
• Trace values, graphs, etc…
5
Stating,
oxidizer to fuel ratio to
be inferred
4
Selection of fuel and
oxidizer
3
Temperatures and
pressures
(Known conditions)
2
File name,
Problem Type,
Ex. P, T problem
1
Add a Slide Title - 1

27. NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview

28. NASA Computer program CEA (Chemical Equilibrium with Applications) calculates chemical equilibrium
compositions and properties of complex mixtures.
NASAhttps://www1.grc.nasa.gov/research-and-engineering/ceaweb/
 NASA CEA – overview
https://cearun.grc.nasa.gov/