1. COMBUSTION TA : Donggi Lee PROF. SEUNG WOOK BAEK
DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA
ROOM: Building N7-2 #3304
TELEPHONE : 3714
Cellphone :
TA : Donggi Lee
ROOM: Building N7-2 #1304
TELEPHONE : 5754
Cellphone :

2. COMBUSTION ENGINEERING
CONSERVATION EQUATIONS OF MULTICOMPONENT GASES
CONSERVATION OF
MASS
MOMENTUM
ENERGY
OF A GASEOUS MIXTURE
OF DIFFERENT CHEMICAL SPECIES
NEW PHENOMENA
(MASS) DIFFUSION
TRANSPORT OF ENERGY BY DIFFUSION
CREATION OR DESTRUCTION OF CHEMICAL SPECIES BY REACTION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

3. COMBUSTION ENGINEERING
HOMEWORK : (pg. 390) #3, #18, #24, and #27 Attached a slide for your information
DEFINITION OF VARIOUS VELOCITIES
GAS CONSISTS OF MANY RANDOMLY MOVING MOLECULES
= VELOCITY OF PARTICLE OF STH KIND
= MASS AVERAGE VELOCITY OF MIXTURE,
VELOCITY OF THE C.G OF A FLUID ELEMENT
= PECULIAR VELOCITY OF PARTICLE OF STH KIND,
VELOCITY OF THE PARTICLES W.R.T
DEAL WITH DISTRIBUTION FUNCTION FOR PARTICLES
= PARTICLE DISTRIBUTION FUNCTION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

4. COMBUSTION ENGINEERING
PROBABLE NUMBER OF PARTICLES OF KIND S PER UNIT VOLUME, WHICH AT TIME t HAVE A VELOCITY IN UNIT RANGE ABOUT
NUMBER DENSITY, PARTICLES OF STH KIND PER UNIT VOLUME
AVERAGE VELOCITY OF PARTICLES OF STH KIND
MASS AVERAGE VELOCITY
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

5. COMBUSTION ENGINEERING
WANT TO KNOW AVERAGE MOTION OF A PARTICULAR SPECIES W.R.T.
= AVERAGE PECULIAR VELOCITY (DIFFUSION VELOCITY)
THE DIFFUSION VELOCITY OF CHEMICAL SPECIES s IS THE RATE OF FLOW OF MOLECULES OF s W.R.T THE MASS AVERAGE VELOCITIY OF THE GAS.
NET RATE OF MASS TRANSFER BY DIFFUSION IS ZERO, I.E.
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

6. COMBUSTION ENGINEERING
CONSERVATION OF MASS
LET NO. OF PARTICLES OF THE STH KIND FOUND BY CHEMICAL REACTION PER UNIT VOLUME, PER UNIT TIME
LET = MASS OF ONE PARTICLE OF SPECIES, s
MULTIPLY BY
MASS OF STH SPECIES FORMED PER UNIT VOLUME PER UNIT TIME DUE TO CHEMICAL REACTION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

7. COMBUSTION ENGINEERING
MASS IS CONSERVED IN CHEMICAL REACTION
OVERALL MASS CONSERVATION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

8. COMBUSTION ENGINEERING
DIFFUSION VELOCITY
DEPENDS ON
Maxwell-Boltzmann DISTRIBUTION FUNCTION
(GAS IN EQUILIBRIUM)
AS A PERTURBATION SOLUTION ABOUT Boltzmann DISTRIBUTION
Chapmann & Enskog OBTAINED
= MULTI COMPONENT THERMAL DIFFUSION COEFFICIENT
= DIFFUSION VELOCITY IN MULTI COMPONENT MIXTURE
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

9. MOLE FRACTION OF SPECIES P
= EXTERNAL FORCE ACTING ON MOLECULE l
MOLE FRACTION OF SPECIES P
MASS FRACTION OF SPECIES P
CONCENTRATION OF SPECIES P
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

10. COMBUSTION ENGINEERING
DIFFUSION FLUX ARISES FROM
(i) Gradient of concentration
(ii) Pressure gradient
(iii) Flux due to external forces such as electromagnetic
forces or gravity
(iv) Temperature gradient : Thermal diffusion
IN MANY PROBLEMS, THERMAL & PRESSURE DIFFUSIONS ARE NEGLECTED.
EXTERNAL FORCE DIFFUSION =
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

11. COMBUSTION ENGINEERING
FOR GRAVITY ONLY
= ACCELERATION OF GRAVITY
BINARY DIFFUSION
CONSIDER INTERDIFFUSION BETWEEN SPECIES 1 AND 2
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

12. COMBUSTION ENGINEERING
IF , PRESSURE DIFFUSION OF SPECIES 1 OCCURS IN THE DIRECTION OF INCREASING PRESSURE IN SPECIES 2 IF , THERE IS NO PRESSURE DIFFUSION.
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

13. IN THE ABSENCE OF , WHILE NEGLECTING
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

14. LET (THERMAL DIFFUSION RATIO) =
MASS FRACTION
MOLE FRACTION,
MASS FRACTION
Fick’s LAW
(EXACT FOR BINARY DIFFUSION)
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

15. APPROXIMATION: FREQUENTLY USED (AS A DESPERATE MEASURE)
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

16. COMBUSTION ENGINEERING
CONSERVATION OF MOMENTUM
VERY FEW CHANGES DUE TO CHEMICAL REACTIONS
STRESS TENSOR
= THERMODYNAMIC OR HYDROSTATIC PRESSURE = KRONECKER DELTA = VISCOUS STRESS TENSOR
= BULK VISCOSITY ACCOUNTING FOR
INTERNAL RELAXATION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

17. COMBUSTION ENGINEERING
FOR MONATOMIC GAS, = 0 (Stokes HYPOTHESIS) = RADIATION STRESS TENSOR = i th COMPONENT OF BODY FORCE
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

18. COMBUSTION ENGINEERING
CONSERVATION OF ENERGY
= VISCOUS STRESS DIADIC
= HEAT FLUX VECTOR
= RATE OF HEAT GENERATION PER UNIT MASS E.G. : RADIATION
= INTERNAL ENERGY PER UNIT MASS
REMEMBER FORMATION ENERGY INCLUDED !
IF IS FOR ALL SPECIES,
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

19. COMBUSTION ENGINEERING
THE HEAT FLUX VECTOR
= ENERGY TRANFERRED PER UNIT AREA PER UNIT TIME DUE TO TRANSPORT EFFECTED AT A SURFACE
PLANE SURFACE DIRECTION
Boltzmann CONSTANT
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

20. COMBUSTION ENGINEERING
THE ADIABATIC REACTION
SECOND ORDER REACTION TO REPRESENT THE ACTUAL KINETICS
: specific reaction rate constant
WHERE : ACTIVATION ENERGY
: STERIC FACTOR
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

21. COMBUSTION ENGINEERING
MIXTURE OF IDEAL GASES
AFTER REARRANGEMENT
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

22. COMBUSTION ENGINEERING
SINGLE STEP KINETIC IS OFTEN GENERALIZED TO THE FORM
WHERE A,a,b,n,m,E ARE DETERMINED BY COMPARISON WITH EXPERIMENTS OR DETAILED KINETICS CALCULATION.
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

23. COMBUSTION ENGINEERING
SIMPLY CHEMICALLY REACTING SYSTEM (SCRS)
FOR A SYSTEM OF UNIT MASS
MASS OF FUEL
MASS OF OXIDANT
STOICHIOMETRIC FUEL MASS
HEAT RELEASED BY COMBUSTION OF A UNIT MASS OF FUEL FOR THE REACTION GIVEN
INITIAL ENERGY FOR THE SAME SPECIFIC HEAT
FOR AN ADIABATIC REACTION
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

24. COMBUSTION ENGINEERING
LET
CONDITIONS WHEN COMBUSTION IS COMPLETE
THIS DEPENDS ON AND
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

25. COMBUSTION ENGINEERING
USING
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

26. COMBUSTION ENGINEERING
DIMENSIONLESS TEMPERATURE
DURING REACTION
: PROGRESS VARIABLE
BECOMES
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

27. COMBUSTION ENGINEERINGAS
PREVIOUSLY, WE OBTAINED
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

28. COMBUSTION ENGINEERING
AS ,
EXPONENTIAL TERM INCREASES DRASTICALLY
HOWEVER, OR
, SO THAT
1.0
PROPULSION AND COMBUSTION LABORATORY
COMBUSTION ENGINEERING

29. Homework #1 4th reference : M. Kanury (pg.390) #3, #18, #24, and #27
1. Calculate the pressure of 28g of hydrogen contained in 1 liter vessel at 25℃
2. Hydrogen Peroxide is used sometimes as an oxidizer in special power plants such as torpedoes and rockets. Determine the standard enthalpy of combustion per gram mass of the fuel for the following combustion reaction :
H2O2(l) CH4(g) → 1.5H2O(g) CO2(g)
Also Compare this enthalpy of combustion with that calculated for methane burning in pure oxygen. Assume h0f 298 = kJ/mole of H2O2(l).
3. A mixture at 298oK and 1 atm. Pressure consists of 1 mole of H2 and 0.5 mole of O2. They are slowly heated to 2,500oK keeping pressure constant. What is the final equilibrium composition?
4. A heated tube reactor is operated at 2,500oK. The flowing mixture initially contains 2 moles of H2O and 1 mole each of O2 and N2. If the total pressure is approximately 2 atm. And the outlet equilibrium mixture contains only H2O, O2, H2, N2 and OH, calculate the outlet composition.