ME 475/675 Introduction to Combustion Lecture 9 Textbook’s computer programs: HPFLAME, TPEQUIL, Example 2.8

Announcements HW 3 due now Midterm 1 (two weeks from today) HW 4 Due Monday, September 21, 2015 Ch 2 (33, 35, 47, 50, 54, 57, 63) ABET PEV: Dr. Sriram Somasundaram at 9:30

Computer Programs Provided by Book Publisher Described in Appendix F (pp 113-4) For “complex” reactions (11 product species) Fuel: CNHMOLNK Oxidizer: Air Download from web: www.mhhe.com/turns3e student edition Computer codes Access to TPEquil, HFFlame, UVFlame Extract All

TPEQUIL (TP Equilibrium) Use to find Equilibrium composition and mixture properties Required input Fuel CNHMOLNK Temperature Pressure Equivalence ratio (with air) to determine initial number of moles of each atom

Input file Equil. Calc. for Specified Fuel, Phi, T, & P Using Olikara/Borman Code 1 /NUMBER OF CARBON ATOMS IN FUEL MOLECULE 4 /NUMBER OF HYDROGEN ATOMS IN FUEL MOLECULE 0 /NUMBER OF OXYGEN ATOMS IN FUEL MOLECULE (NOT AIR) 0 /NUMBER OF NITROGEN ATOMS IN FUEL MOLECULE (NOT AIR) .9 /EQUIVALENCE RATIO, PHI 1700.0 /TEMPERATURE, T(K) 101325. /PRESSURE, P(Pa)

Output File The mole fractions of the product species are: H: .00000074 O: .00000607 N: .00000000 H2: .00002523 OH: .00025824 CO: .00004276 NO: .00088941 O2: .01871378 H2O: .17257236 CO2: .08632078 N2: .72117064 Above properties printed below in a column for cut & paste: -.922763E+06 .146408E+04 .125787E+01 .277417E+02 .863635E-01 .737811E-06 .606849E-05 .470998E-11 .252284E-04 .258241E-03 .427597E-04 .889405E-03 .187138E-01 .172572E+00 .863208E-01 .721171E+00 Equil. Calc. for Specified Fuel, Phi, T, & P Using Olikara/Borman Code Data below are as read from the input file. Compare with INPUT.TP. If they do not agree, your input data have not been entered correctly. CARBON ATOMS 1.0 HYDROGEN ATOMS 4.0 OXYGEN ATOMS .0 NITROGEN ATOMS .0 EQUIVALENCE RATIO .900 TEMPERATURE (K) 1700.0 PRESSURE (Pa) 101325.0 CALCULATED COMBUSTION PRODUCTS PROPERTIES Mixture Enthalpy [J/kg] = -.9228E+06 Mixture Specific Heat, Cp [J/kg-K] = .146408E+04 Specific Heat Ratio, Cp/Cv = 1.2579 Mixture Molecular Weight [kg/kmol] = 27.7417 Moles of Fuel per Mole of Products = .08636354

HPFLAME (HP Flame) Use to find Required Input Adiabatic flame temperature for constant pressure Required Input Fuel, equivalence ratio, enthalpy of reactants HR, pressure For constant pressure: HP = HR Find TAd In our initial examples we assume ideal combustion so we knew the product composition But this program calculates the more realistic equilibrium composition of the products from a (complex) equilibrium calculation (multiple equilibrium reactions) But this requires TProd = TAd, which we are trying to find! Requires program (not humans) to iterate

Input File Adiabatic Flame Calculation for Specified Fuel, Phi, P, & Reactant Enthalpy Using Olikara & Borman Equilibrium Routines Problem Title: USER SPECIFIES TITLE HERE 01 /CARBON ATOMS IN FUEL 04 /HYDROGEN ATOMS IN FUEL 00 /OXYGEN ATOMS IN FUEL 00 /NITROGEN ATOMS IN FUEL 1.1 /EQUIVALENCE RATIO 2000. /TEMPERATURE (K) (Initial Guess) 101325.0 /PRESSURE (Pa) -74831.0 /ENTHALPY OF REACTANTS PER KMOL FUEL (kJ/kmol-fuel)

Output File The mole fractions of the product species are: H: .00066587 O: .00005318 N: .00000001 H2: .01249557 OH: .00142913 CO: .02604837 NO: .00051800 O2: .00034275 H2O: .18943796 CO2: .07544214 N2: .69356704 Above properties printed below in a column for cut & paste: .221064E+04 -.281602E+06 .182404E+04 .121092E+01 .269694E+02 .101491E+00 .665868E-03 .531751E-04 .117609E-07 .124956E-01 .142913E-02 .260484E-01 .517995E-03 .342749E-03 .189438E+00 .754421E-01 .693567E+00 Adiabatic Flame Calculation for Specified Fuel, Phi, P, & Reactant Enthalpy Using Olikara & Borman Equilibrium Routines Problem Title: USER SPECIFIES TITLE HERE Data below are as read from the input file. Compare with INPUT.HP. If they do not agree, your input data have not been entered correctly. CARBON ATOMS 1.0 HYDROGEN ATOMS 4.0 OXYGEN ATOMS .0 NITROGEN ATOMS .0 EQUIVALENCE RATIO 1.100 TEMPERATURE (K) guess 2000.0 PRESSURE (Pa) 101325.0 ENTHALPY OF REACTANTS (kJ/kmol fuel) -74831.0 FLAME TEMP. & COMBUSTION PRODUCTS PROPERTIES Flame Temperature [K] = 2210.64 Mixture Enthalpy [J/kg] = -.2816E+06 Mixture Specific Heat, Cp [J/kg-K] = .182404E+04 Specific Heat Ratio, Cp/Cv = 1.2109 Mixture Molecular Weight [kg/kmol] = 26.9694 Moles of Fuel per Mole of Products = .10149051

Example 2.8, Page 54 A recuperator (heat exchanger) is employed in a natural-gas-fired heat-treating furnace. The furnace operates at atmospheric pressure with an equivalence ratio of 0.9. The fuel gas enters the burner at 298 K, and the air is preheated. (a) Determine the effect of air preheat on the adiabatic temperature of the flame zone for a range of inlet air temperatures from 298 to 1000 K. (b) What fuel savings results from preheating the air from 298 to 600 K? Assume that the temperature of the flue gases at the furnace exit, prior to entering the recuperator, is 1700 K, both with and without air preheat.