Question

(a) Consider methane is burned in an internal combustion engine using 200% theoretical air. Locate the following unknown parameters:

I. Air/fuel ratio on mass basis

II. Composition of products

III. Dew point temperature of the products

Answer 1

solution The stoichiometric Equation for pure Hydrocarbons Ccm Hn can be written as, em Hn & fmth O₂ + 3.76 -76 (m + h) Nem → m CO₂ + H₂O +3.76 lm th Na Since the fuel given is methane (CHA). The combustion Equation for methane (CHA) can be written with m=1& n=4 calq + ((+ 1/0 2 + 3.76 (1+1 J Ng 1 CO2 + 2 H20 + 3-76 (1+1) Na CHq + 202 + 7.52 Ng Coa + 2 H2O + 7.52 Ng since Methane is burned with 2004. Theoritphal atr, the Combustion equation becames, CH4 + 2(202) + 2 (7.52N2) → Cose + 4H20 + 15.04N2+ 20 The combustion equation for Methane (CHg) with was theoritical aur is given as CHA + 402 + 15.04 Na CO2 + 2H20 +15.04 Nat 20g O Als fuel Ratio on Mass Basis: Actual apy fuel Ratipo = Mass of air Mass of fuel. (A/I) actual = (mass of g + mass of Na) per mode fuel Mass of fuel per mole fuel. (4x32) + (15.04x23), 128+421.12 (12x1) + (1x4) (A/E actual - 16 549.12 16 34.32. Al fuel Ratio on Mass Basis, (A/F aether = 34.32. 1 Composition of Products: Total Number of Moles in products, 1 mole coat 2 Moles Hot 15.04 moles Net 2 moles og = 20.04 moles. Mole fraction of the products, are as follows, L 0.0499 20.04 coa = = 0.0988 H2O 20.04 Ng = 0.7505 15.04 20.04 og 0.0998 2. 20.04 Composption of products, coa = 0.0499x100= 4.997. H20 = 0.0988x100 = 9.984. Nq = 0.7505x100 75.054. = 0.0988 x100 = 9.984. ..Y. Composition of products, CO2 = 4.99-1., H₂O=9.98&-, Ng = 75.054. Og = 9.98% (j) Dew popent temperature of the products, Let the air is supplied art 1 bar, partial pressure of hilater vapour= 0.0998* Ibar 0.0998 bar The dew point temperature is the saturation tempercture Corresponding to partial pressure of 0.0998 bar = 45.78°c Cobtained from stream tables) :. Dew point temperature of the products = 45.78°c