mech3020-s11-hw12-solns

# mech3020-s11-hw12-solns - MECH 3020 Thermodynamics II...

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Unformatted text preview: MECH 3020 Thermodynamics II: Homework Set # 12, Due Monday 4/4 1. Calculate the required moles of air needed to stoichiometrically combust the following fuels: (a) Methane (CH 4 ) (b) Propane (C 3 H 8 ) (c) Ethanol ( C 2 H 5 OH) (d) The generic hydrocarbon fuel C x H y O z 2. Propane is burned with an excess amount of air. The oxygen mole fraction in the products, measured via an oxygen sensor, is y O 2 = 0 . 025. Calculate the fuel/air ratio on a mole basis and the equivalence ratio. The reaction is C 3 H 8 + 5 t (O 2 + 3 . 76N 2 ) → 3CO 2 + 4H 2 O + 5( t- 1)O 2 + 18 . 8 t N 2 and the mole fraction of O 2 is y O 2 = n O 2 n = 5( t- 1) 2 + 23 . 8 t = 0 . 025 Solve for t : t = 1 . 15. The equivalence ratio is Φ = 1 /t = 0 . 872, and F/A ) mass = 44 5 · 1 . 15 · 4 . 76 · 29 = 0 . 056 3. Methane is burned with 120% theoretical air. The products leave at 1 atm total pressure. (a) Calculate the dew point temperature of the products. Assume complete combustion....
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