Question

For calculating an "adiabatic flame temperature" it is customary to assume that the reactants (input) are at the reference temperature (298 K or 537 oR).

Your assigned value of wis (You will lose 1 pt if this is blank). Methane (CH) is burned with (110 +0.3 )% of theoretical air. (Hence, if y = 3 the methane is burned with 110.9% theoretical air). The mixture enters the combustion chamber at 25°C. A) Find the Air/Fuel ratio for this mixture: (+0.03) B) Find the adiabatic flame temperature for the mixture. Toebe llane C) Find the mole fraction of the Nz in the exhaust AF oC (+ 20°C) VN2

Psi is equal to 3

Answer 1

of Generaly the Enthalpy of combustion product is given at 298k. So it is customery to assume at 298 K but if it is not given at 298K or given at another temperature then that Temperature will be referace Point » If Question mention Reactent at some higher Temperature then we can calculate DH for new temp also by using simple Thermodynamic Equations + ing (T-298) Дн) 7 Tk 298K n is و where T is Temp in Question no of mole of Reactant

(1) stoichiomatric combustion of Methane. CH4 +20 +3-76N2) CO₂ + 2H₂0 +7.52N2 Now 110.9% of theoretical air means 2x1,109 ml air 2.218 mol. Equation at 2.218 mal air #CH4 + 2.218 (O2 + 3.76N2) CO₂ + 2H0+ 0.2180, +8.339 N2 9 AIR FUEL RATIO=. 2.218 2.218 Ans. 1 4 2 Standard Table @ 298k and I atm. compound Dr at 298k CC -72.1 kJ/mol. CHA -394.0 55.396 KI CO2 tho -244.5 -75.328kJ/ 3 ks hank Kolkmel 42.84 kJ/kmolks 33.0 /mak 33.03/malks N2 on Enthalpy of formation of Reactant (eq -(0) (A) = -72100 + 2. 218io + 3-1 6 x 3 -72100 o/

Enthalpy of formation of product & Conta (pdf) AH₂) = - 394 o o + 2x (- 244S) +,2|g xo + 8.339 X0 + 1x 55.396 (If - 298) + 2x 42-44 x (5 -298) +0.218 x 33 (17-248) + 8.339 X33x(TF 298) Ana = – 883000 + (Ty -298) {55-39+84-88+7.19+275} DH, = -88 3000 + (Ts – 298) X 422 -46 for Energy balance AH, = AH2 –72100 = -883000 + 422-46 (5-298) Tg-298 = 1919.4 I = 2217% = 1944°C Ans 80 3 Mole fraction of Ne in exhaust M(N₂) n (Product) 25 x = = 0.721 Ans. 8-339 1+2 to.218+8+339 2= 72.15% Ans