mech3020-s11-hw12 - products Note that some of the water...

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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. 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. (b) Say the product mixture is cooled to T P = 30 C. Determine the mole fractions for the gas–phase
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Unformatted text preview: products. Note that some of the water will condense out, since this temperature is below the dew point. 4. The lean flammability limit of methane – which describes the minimum concentration of methane in air that can be ignited – corresponds to a equivalence ratio of Φ min = 0 . 5. Say a natural gas pipe begins leaking into a basement room, of volume V = 200 m 3 , at a rate of ˙ V g = 2 L/min. The natural gas (which can be taken to be methane) becomes completely mixed with the air in the room. Assuming the room stays at 1 atm total pressure, how long will it take for the air in the room to become explosive? 1...
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This note was uploaded on 09/24/2011 for the course MECH 3020 taught by Professor Mackowski during the Spring '11 term at Auburn University.

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