P15-112

Equations

Thermodynamics - An Engineering Approach (5th Ed) - Cengel, Boles - Mcgraw-Hill (2006) - pg. 791

Sa se determine excesul minim de aer folosit la arderea CH4(g), C2H2(g), CH3OH(g), C3H8(g), si C8H18(l)astfelincat temperatura flacarii adiabatice sa ν depaseasca o valoare impusa: 1200 K, 1750 K, si 2000 K

Adiabatic Combustion of fuel CnHm entering at Tfuel with Stoichiometric Air at Tair:Reaction: CxHyOz + (y/4 + x-z/2) (Theoair/100) (O2 + 3.76 N2)←→ xCO2 + (y/2) H2O + 3.76 (y/4 + x-z/2) (Theoair/100) N2 + (y/4 + x-z/2)(Theoair/100 - 1) O2

Tprod is the adiabatic combustion temperature, assuming no dissociation. Theoair is the % theoretical air.

The initial guess value of Tprod = 450K .

$INCLUDE Fuels-Procedures.TXT

$UnitSystem K Mole

Marimi de intrare:

Tcomb = 298 [K] ; (1)

Input data from the diagram window

$IfNot DiagramWindow

Tair = (25 + 273) [K] ; (2)

Fuel$ = ‘C2H2(g)’ ; (3)

Tprod = 1500 [K] ; (4)

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$EndIf

Rezolvare:

Excessair = Teorair − 100 [%] ; (5)

call Fuel(Fuel$, Tcomb : x, y, z, hcomb, Nume$, MM); (6)

Ath = y/4 + x− z/2; (7)

Thair = Teorair/100; (8)

HR = hcomb+(y/4 + x− z/2)·(Teorair/100)·h (O2, T = Tair)+3.76·(y/4 + x− z/2)·(Teorair/100)·h (N2, T = Tair) ; (9)

HP = HR; Adiabatic (10)

HP = x·h (CO2, T = Tprod)+(y/2)·h (H2O, T = Tprod)+3.76·(y/4 + x− z/2)·(Teorair/100)·h (N2, T = Tprod)+(y/4 + x− z/2)·(Teorair/100− 1)·h (O2, T = Tprod) ; (11)

MoliO2 = (y/4 + x− z/2) · (Teorair/100− 1) ; (12)

MoliN2 = 3.76 · (y/4 + x− z/2) · (Teorair/100) ; (13)

MoliCO2 = x; (14)

MoliH2O = y/2; (15)

T1 = Tprod; xa1 = Teorair; (16)

Data$ = Date$; (17)

SolutionVariables in Main program

Ath = 2.5 Data$ = ‘2014-04-06’ Excessair = 156.251Fuel$ = ‘C2H2(g)’ hcomb = 226730 [kJ/kmol] HP = 226596 [kJ/kmol]HR = 226596 [kJ/kmol] MM = 26 [kg/kmol] MoliCO2 = 2MoliH2O = 1 MoliN2 = 24.09 MoliO2 = 3.906Nume$ = ‘Acetilena’ Teorair = 256.3 Thair = 2.563

Tair = 298 [K] Tcomb = 298 [K] Tprod = 1500 [K]

x = 2 y = 2 z = 0

Variables in Procedure FuelComb$ = ‘C2H2(g)’ TComb = 298 [K] x = 2y = 2 z = 0 hComb = 226730 [kJ/kmol]Nume$ = ‘Acetilena’ Masamolec = 26 [kg/kmol] ERROR = notdefined

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Tprod

Run Fuel$ Tprod Excessair[K]

1 CH4(g) 1200 175.9302 CH4(g) 1400 117.7133 CH4(g) 1600 77.7304 CH4(g) 1800 48.6415 CH4(g) 2000 26.5676 C2H2(g) 1200 255.9397 C2H2(g) 1400 183.2888 C2H2(g) 1600 133.4899 C2H2(g) 1800 97.338

10 C2H2(g) 2000 69.96611 CH3OH(g) 1200 198.74712 CH3OH(g) 1400 133.18013 CH3OH(g) 1600 88.12314 CH3OH(g) 1800 55.32315 CH3OH(g) 2000 30.41716 C3H8(g) 1200 183.39317 C3H8(g) 1400 124.10818 C3H8(g) 1600 83.41519 C3H8(g) 1800 53.83020 C3H8(g) 2000 31.39521 C8H18(l) 1200 182.03422 C8H18(l) 1400 123.16823 C8H18(l) 1600 82.77124 C8H18(l) 1800 53.40725 C8H18(l) 2000 31.146

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Excessair

4