Download presentation
Presentation is loading. Please wait.
Published byRandall Fitzgerald Modified over 6 years ago
1
COMBUSTION TA : Donggi Lee PROF. SEUNG WOOK BAEK
DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA ROOM: Building N7-2 #3304 TELEPHONE : 3714 Cellphone : 010 – TA : Donggi Lee ROOM: Building N7-2 # 1304 TELEPHONE : 5754 Cellphone : 010 –
2
SYLLABUS (1/4) COURSE CODE : AE 410
COURSE NAME : COMBUSTION ENGINEERING PROFESSOR : SEUNG WOOK BAEK (Rm #3304, Ext. 3714) GRADING SYSTEM 1 Final Exam ( June 8th, 2017 ) Homeworks
3
CURRENT ISSUES IN COMBUSTION SCIENCE & TECHNOLOGY
How to efficiently mix fuel and oxidizer Convection and diffusion How to efficiently burn fuel and oxidizer: energy saving How to reduce pollutant emission such as CO,CO2 and NOx How to improve safety and reduce impact on environment To develop green, sustainable and alternative energy
4
SYLLABUS (2/4) REFERENCES
F.A.Williams, “Combustion Theory,” Addison Wesley, 2nd Ed. D.B.Spalding, “Combustion and Mass Transfer,” Pergamon Press I.Glassman, “Combustion,” Academic Press, 2nd Ed. M.Kanury, “Introduction to Combustion Phenomena,” Gordon and Breach Science Publishers P.A.Libby and F.A.Williams (Editors), “Turbulent Reacting Flows,” Springer Verlag L.A.Kennedy (Editor), “Turbulent Combustion,” Progress in Astronautics and Aeronautics, Vol.58
5
SYLLABUS (3/4) JOURNALS K.K.Kuo, “Principles of Combustion,” Wiley
V.R.Kuznetsoz and V.A.Sabelnikov, “Turbulence and Combustion,” Hemisphere Publishing Corporation JOURNALS Combustion and Flame Combustion Science and Technology Symposium (International) on Combustion Combustion Theory and Modeling AIAA Journal Progress in Energy and Combustion Science
6
SYLLABUS (4/4) Combustion, Explosion and Shock Waves
Progress in Astronautics and Aeronautics Fire Safety Journal International Journal of Heat and Mass Transfer Journal of Heat Transfer Journal of Thermophysics and Heat Transfer Journal of Propulsion and Power
7
Combustion Engineering
Thermochemistry Combustion- high temperature, moderate or high pressure, perfect gas, real gas effects for high pressure environment Thermodynamic properties of a single perfect gas Equation of state : : Universal gas constant : Molecular weight : Concentration PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
8
Combustion Engineering
Internal Energy : per unit mass : Internal energy of formation : Specific heat PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
9
Combustion Engineering
Enthalpy or = : Enthalpy of formation PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
10
Combustion Engineering
Only change in or is important (not the absolute level) Need a convention for and 1) Prescribe a standard state, i.e., and 2) The formation enthalpy of the chemical elements in their natural phase at and will be zero. 3) , for, : : : : : PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
11
Combustion Engineering
Entropy Let = Entropy at and any temperature . Gibbs Free Energy per unit mass basis PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
12
Combustion Engineering
On a molar basis : Molar basis Helmholtz Free Energy PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
13
Combustion Engineering
Mixture of perfect gases ; : Total number of moles per unit volume : Total number of moles of species K per unit volume : Mole fraction of species K PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
14
Combustion Engineering
: Density of the mixture : Partial density of species K : Mass fraction of species K : Molecular weight of species K , PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
15
Combustion Engineering
: Mean molecular weight of the mixture PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
16
Partial pressure exerted by species K if it occupies
EQUATION OF STATE Partial pressure exerted by species K if it occupies the whole volume at temperature T. PROPULSION AND COMBUSTION LABORATORY
17
Dalton’s Law but Internal Energy PROPULSION AND COMBUSTION LABORATORY
18
where PROPULSION AND COMBUSTION LABORATORY
19
Enthalpy when is fixed Entropy PROPULSION AND COMBUSTION LABORATORY
20
PROPULSION AND COMBUSTION LABORATORY
21
PROPULSION AND COMBUSTION LABORATORY
22
Caution ; When there is reaction PROPULSION AND COMBUSTION LABORATORY
23
Specification of Composition
Problem for notes Binary mixture of Specification of Composition For same PROPULSION AND COMBUSTION LABORATORY
24
For same P and T, partial volume of species K
Here, is not so that PROPULSION AND COMBUSTION LABORATORY
25
Material Balance for Chemical Reactions
Ex) Combustion of Octane with Air Air: Molecular Weight: For complete combustion (stoichiometric) Stoichiometric Coefficients: PROPULSION AND COMBUSTION LABORATORY
26
or 15.1 kg of air/ 1 kg of octane For reactants
On a mass basis, or 15.1 kg of air/ 1 kg of octane For reactants PROPULSION AND COMBUSTION LABORATORY
27
MASS OF PRODUCTS = 1831 : MEAN MOLECULAR WEIGHT OF REACTANTS
PROPULSION AND COMBUSTION LABORATORY
28
EQUIVALENCE RATIO : FOR PROPULSION AND COMBUSTION LABORATORY
29
ENERGY Eq. FOR CHEMICAL REACTION CONSTANT VOLUME SYSTEM – NO MOTION
: STOICHIOMETRIC : FUEL LEAN : FUEL RICH FOR FOR ENERGY Eq. FOR CHEMICAL REACTION CONSTANT VOLUME SYSTEM – NO MOTION PROPULSION AND COMBUSTION LABORATORY
30
(POSITIVE WHEN ADDED TO THE SYSTEM) : INTERNAL ENERGY
1st LAW : : HEAT TRANSFER (POSITIVE WHEN ADDED TO THE SYSTEM) : INTERNAL ENERGY : WORK DONE BY THE SYSTEM 1: REACTANT STATE 2: PRODUCT STATE PROPULSION AND COMBUSTION LABORATORY
31
ONLY IMPORTANCE IS , NOT THE ABSOLUTE VALUES.
: REFERENCE OR BASIC TEMPERATURE : INTERNAL ENERGY OF REACTION, DETERMINED IN A BOMB CALORIMETER PROPULSION AND COMBUSTION LABORATORY
32
FOR CONSTANT PRESSURE PROCESS;
PROPULSION AND COMBUSTION LABORATORY
33
FOR PERFECT GASES; : ENTHALPY OF REACTION
:INTERNAL ENERGY OF REACTION AT FOR PERFECT GASES; PROPULSION AND COMBUSTION LABORATORY
34
ENTHALPY OF FORMATION AND ENTHALPY OF COMBUSTION
ENTHALPY OF FORMATION -THAT CHANGE OF ENTHALPY WHICH OCCURS WHEN A COMPOUND IS FORMED FROM THE ELEMENTS, WHICH ARE IN THEIR STABLE STATE, AT SAME STANDARD TEMPERATURE AND PRESSURE. PROPULSION AND COMBUSTION LABORATORY
35
GIVES OFF 94052 cal :exothermic reaction
HEAT OF FORMATION = ALSO A COMBUSTION PROCESS ENTHALPY OF COMBUSTION HEAT OF COMBUSTION HEAT OF COMBUSTION OF PROPULSION AND COMBUSTION LABORATORY
36
HEATING VALUES; FOR C+O2 REACTION,
ENDOTHERMIC REACTION HEATING VALUES; FOR C+O2 REACTION, , BECAUSE THERE IS NO WORKS. IN GENERAL, HIGHER HEATING VALUES AND LOWER HEATING VALUES DEPEND ON STATE OF PRODUCTS. PROPULSION AND COMBUSTION LABORATORY
37
IMPORTANT CASE IS vs. IF IS LIQUID,
LHV DIFFERS FROM HHV BY HEAT OF VAPORIZATION. PROPULSION AND COMBUSTION LABORATORY
38
REFERENCES FOR THERMOCHEMICAL DATA
NBS, “Tables of Selected Values of Chemical Thermal Properties”, Circular Letter 500 JANAF Thermo-Chemical Tables (1993) Penner’s Book Van Wylen & Sonntag (SI units) CHEMKIN: Software package for the analysis of gas-phase chemical and plasma kinetics (2000) EXAMPLE 10g OF H2 (g) BURN IN AIR (=1) AT CONSTANT PRESSURE. INITIAL TEMPERATURE IS 298K AND FINAL TEMPERATURE IS 2000K SO THAT H2O IS GASEOUS. CALCULATE THE HEAT LIBERATED ; PROPULSION AND COMBUSTION LABORATORY
39
PROPULSION AND COMBUSTION LABORATORY
40
IF THE PROBLEM WERE AT CONSTANT VOLUME,
MINUS INDICATES THAT HEAT WAS TRANSFERRED OUT OF THE SYSTEM. IN OTHER WORDS, THE FLAME TEMPERATURE, IF ADIABATIC, WOULD BE HIGHER THAN 2000 K. IF THE PROBLEM WERE AT CONSTANT VOLUME, PROPULSION AND COMBUSTION LABORATORY
41
CALCULATION OF ENTHALPY OF REACTION FROM THE ENTHALPY OF FORMATION
PROPULSION AND COMBUSTION LABORATORY
42
EX) GASEOUS CH4 + O2 REACT TO YIELD H2O(l)+CO2(g).
CALCULATE PER MOLE OF CH4 EXOTHERMIC PER MOLE OF CH4 PROPULSION AND COMBUSTION LABORATORY
43
CONSIDER A CHEMICAL SYSTEM OF CONSTANT MASS EITHER HOMOGENEOUS OR HETEROGENEOUS IN MECHANICAL AND THERMAL EQUILIBRIUM BUT NOT IN CHEMICAL EQUILIBRIUM. THE SYSTEM IS IN CONTACT WITH A RESERVOIR AT TEMPERATURE T AND UNDERGOES AN INFINITESIMAL IRREVERSIBLE EXCHANGE OF HEAT, Q, TO THE RESERVOIR. PROCESS MAY INVOLVE CHEMICAL REACTION AND TRANSPORT BETWEEN PHASES. PROPULSION AND COMBUSTION LABORATORY
44
FROM SYSTEM dS: ENTROPY CHANGE OF THE SYSTEM
dSO: ENTROPY CHANGE OF THE RESERVOIR dS+dSo: ENTROPY CHANGE OF THE UNIVERSE FROM SYSTEM PROPULSION AND COMBUSTION LABORATORY
45
CASE A ; HOLD E AND V CONSTANT
1ST LAW FROM SYSTEM VARIOUS CONSTRAINTS CASE A ; HOLD E AND V CONSTANT ISOLATED SYSTEM CASE B ; HOLD p AND T CONSTANT GIBBS FREE ENERGY DECREASES PROPULSION AND COMBUSTION LABORATORY
46
WHEN ; HAVE CHEMICAL EQUILIBRIUM
- WHEN ; HAVE CHEMICAL EQUILIBRIUM CASE C ; HOLD V AND T CONSTANT AT EQUILIBRIUM ; PROPULSION AND COMBUSTION LABORATORY
47
EQUILBRIUM OF A MIXTURE OF PERFECT GASES UNDERGOING CHEMICAL REACTION
CONSIDER THE REACTION, WE KNOW GIBBS FREE ENERGY FOR AND ANY TEMPERATURE T PER MOLE. AT ANY T AND P ; , ETC PROPULSION AND COMBUSTION LABORATORY
48
LET PROPULSION AND COMBUSTION LABORATORY
49
DEFINE AT EQUILIBRIUM NOTE THAT PROPULSION AND COMBUSTION LABORATORY
50
EFFECT OF T ON EQUILIBRIUM COMPOSITION IS GIVEN IN Kp
WHERE EFFECT OF T ON EQUILIBRIUM COMPOSITION IS GIVEN IN Kp EFFECTS OF p ON THE TERM. FOR THE CASE OF , IE. C + D = A + B NO PRESSURE EFFECT EQUILIBRIUM CONSTANT BASED ON CONCENTRATION ; PROPULSION AND COMBUSTION LABORATORY
51
VALUES OF KP ARE TABULATED FOR SPECIFIC CHEMICAL REACTION.
, ETC VALUES OF KP ARE TABULATED FOR SPECIFIC CHEMICAL REACTION. EX) DISSOCIATION OF CO2 (1) PROPULSION AND COMBUSTION LABORATORY
52
EQUILIBRIUM COMPOSITION
(2) (3) EQUILIBRIUM COMPOSITION EX) 100% WATER VAPOR, INITIALLY AT 1 atm AND 2200 K DISSOCIATES INTO H2 (g) AND O2 (g). ASSUMING PERFECT GASES THROUGHOUT, DETERMINE THE EQUILIBRIUM COMPOSITION PROPULSION AND COMBUSTION LABORATORY
53
EQUILIBRIUM COMPOSITION
CHEMICAL REACTION EQUILIBRIUM COMPOSITION PROPULSION AND COMBUSTION LABORATORY
54
EQUILIBRIUM COMPOSITION PROPULSION AND COMBUSTION LABORATORY
55
EXAMINE LIMITING CONDITIONS
CASE I - LOW TEMPERATURES ; VERY LITTLE DISSOCIATION LET OR HIGHER PRESSURE ; LOWER ; GREATER LESS DISSOCIATION B) HIGHER TEMPERATURE ; HIGHER KP GREATER ; SMALLER MORE DISSOCIATION PROPULSION AND COMBUSTION LABORATORY
56
CASE II - HIGH TEMPERATURES ; HIGH DISSOCIATION
OR HIGHER PRESSURE ; HIGHER ; HIGHER LESS DISSOCIATION HIGHER TEMPERATURE ; HIGHER KP ; LOWER = MORE DISSOCIATION PROPULSION AND COMBUSTION LABORATORY
57
EQUILIBRIUM WHEN SIMULTANEOUS REACTIONS OCCURRING
THE NUMBER OF INDEPENDENT REACTIONS, WHICH MUST BE CONSIDERED IN EQUILIBRIUM CALCULATIONS, IS EQUAL TO THE LEAST NUMBER OF EQUATIONS WHICH INCLUDE ANY REACTANT AND PRODUCT WHICH ARE PRESENT TO AN APPRECIABLE DEGREE IN THE EQUILIBRIUM MIXTURE. EX) CALCULATE THE COMPOSITION OF THE EQUILIBRIUM MIXTURE OBTAINED WHEN 5 MOLES OF STEAM, H2O (g) REACT WITH 1 MOLE OF CH4 AT ELEVATED TEMPERATURE AND SOME ARBITRARY PRESSURE PROPULSION AND COMBUSTION LABORATORY
58
MECHANISM FOR REACTION ; 2 ACTUAL REACTIONS ARE ;
C : 1 = a + c + e H : 14 = 4a + 2b + 2d O : 5 = b + c + 2e MECHANISM FOR REACTION ; 2 ACTUAL REACTIONS ARE ; PROPULSION AND COMBUSTION LABORATORY
59
(1) (2) PROPULSION AND COMBUSTION LABORATORY
60
PRODUCT RULE FOR KP’s (1) (2) (3) ADD
PROPULSION AND COMBUSTION LABORATORY
61
ADIABATIC FLAME TEMPERATURE
POINT (2) FINAL TEMPERATURE AND H AFTER A NON-ADIABATIC REACTION POINT (2i) ISOTHERMAL REACTION POINT (c) ADIABATIC FLAME TEMPERATURE ; H2=H1 PROPULSION AND COMBUSTION LABORATORY
62
CONSTANT PRESSURE REACTION – GENERAL CASE
DETERMINE TC FROM H2=H1 H2 DEPENDS ON THE bi WHICH DEPENDS ON Tc WHICH DEPENDS ON THE bi. PROPULSION AND COMBUSTION LABORATORY
63
FOR PERFECT GASES TO CALCULATE Tc WHERE ASSUME TC FOR GIVEN PRESSURE
CALCULATE THE bi FROM THE KP’s SUBSTITUTE INTO H2=H1 ITERATE UNTIL H2=H1 PROPULSION AND COMBUSTION LABORATORY
64
CALCULATE THE ADIABATIC FLAME TEMPERATURE OF A = 0
CALCULATE THE ADIABATIC FLAME TEMPERATURE OF A = 0.8 METHANE – O2 MIXTURE AT p = 10 atm, TAKING INTO ACCOUNT THE DISSOCIATION OF CO2 AND H2O 2 UNKNOWNS PROPULSION AND COMBUSTION LABORATORY
65
Combustion Engineering
etc. Dissociation Reactions PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
66
Combustion Engineering
Procedure ; assume Tc; Calculate a,b,c,d,e Substitute into H2=H1 (from Energy Equation) If Tc=3000K Hco2 HH20 a[ kcal/mole ]+b[ ] +c[ ]+d[ ] +e[ ] = 0.8[-17.89]+2[0] Hco HH2 Ho2 HCH4 Ho2 PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
67
Combustion Engineering
Tables of Thermodynamic Properties PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
68
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
69
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
70
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
71
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
72
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
73
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
74
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
75
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
76
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
77
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
78
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
79
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
80
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.