1. INTERNAL COMBUSTION ENGINES LECTURER PROF.Dr. DEMIR BAYKA

2. FOR A MIXTURE OF GASES MOLECULAR WEIGHT: SPECIFIC GAS CONSTANT where R 0 =8.314 kJ/kmol-K

3. SPECIFIC HEAT OF A GAS MIXTURE

4. SPECIFIC HEAT RELATIONS units are kJ/kmol-K also

5. ALGORITHMS coefficients A ij can be obtained from pages 131 & 133 of your reference book

6. CHAPTER 3 COMBUSTION PROCESS 1. SPARK IGNITION ENGINES AIR + FUEL REACTANTS PRODUCTS

7. AIR = OXYGEN + NITROGEN (and some CO2 and Argon) CO2 and Argon may be assumed as part of Nitrogen such that

8. FOR UNIT VOLUME OF O 2 4.773 units of AIR = O 2 + 3.773 units of N 2 ’ O 2 is approximately 21% of AIR (on a volume basis)

9. FUEL IS MIXTURE OF HYDROCARBONS OTHER FUELS ARE ALCOHOLS, NATURAL GAS, LPG and HYDROGEN GENERAL FORMULA C N H M O L

10. MOLECULAR WEIGHT OF THE FUEL C N H M O L M f = 12N + M + 16L EXAMPLE : C 8 H 18 (octane) M f = 12 x 8 + 18 = 114

11. ON A MASS BASIS CARBON PERCENT OF FUEL

12. ON A MASS BASIS HYDROGEN PERCENT OF FUEL

13. ON A MASS BASIS OXYGEN PERCENT OF FUEL

14. ASSUMING NO OTHER ELEMENT C + H + O f = 1

15. PRODUCTS OF COMBUSTION LEAN MIXTURE CO 2, H 2 O, O 2, N 2 COMPLETE COMBUSTION RICH MIXTURE CO 2, CO, H 2 O, H 2, N 2 INCOMPLETE COMBUSTION

16. STOICHIOMETRIC REACTION

18. ACTUAL REACTION

19. …..COMPLETE COMBUSTION

20. …INCOMPLETE COMBUSTION

21. TEMPERATURE OF THE PRODUCTS

22. n i = The number of moles of species u i = Molar specific internal energy of species (kJ/kmol)

23. LET US ASSUME FOR SIMPLICITY:

24. INTERNAL ENERGY OF THE REACTANTS

25. INTERNAL ENERGY OF THE PRODUCTS

27. INTERNAL ENERGY OF THE PRODUCTS

29. THE PROCEDURE FOR FINDING THE PRODUCT TEMPERATURE 1. COMPUTE T R ……... (= T 2 ) 2. COMPUTE LHS LHS = (Q R-P + U R ) 3. ASSUME T P and COMPUTE RHS 4. IF RHS<>LHS then ASSUME NEW T P and COMPUTE RHS 5. INTERPOLATE OR EXTRAPOLATE TO FIND T P