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ME 300 Special Problem Homework Set #14 SP39-SP40
Due Friday, April 28, 2017
SP 39. N-butane (C4H10) is burned with 80 percent theoretical air, and the products of combustion, an
equilibrium mixture containing only O2, CO, CO2, H2, H2O, N2, and NO, exit from a combustion chamber at
2000 K, 0.2 MPa. The n-butane and air are premixed and the reactants enter the combustion chamber at 600 K,
0.2 MPa. The average specific heat at constant pressure for butane is 1.71 kJ/(kg K) in the temperature range
298 K- 600 K.
(a) Determine the equilibrium composition in the product stream.
(b) Assuming determine the heat transfer to or from the combustion chamber in kJ per kmol of n-butane.
(Hint: the concentrations of O2 and NO will be much lower than the other concentrations and do not
need to be included in the thermochemistry calculations).
Given:
SP 40. A premixed stream of water vapor (H2O), oxygen (O2), and carbon monoxide (CO) enter a constant
pressure reactor. The flow rates for the H2O, O2, and CO are 0.5, 0.1, and 1.0 kmol/s, respectively. The species
CO, CO2, H2O, H2, and O2 are present in the exit stream (a table of properties for H2 is attached.). The reactor
pressure is 10 bar.
(a) Determine the mole fractions for all species in the product gas mixture. (Hint: The concentration of O2
in the product stream is very low. If you use EES to solve this problem (and it is strongly recommended
that you do so), the solution will not converge unless you solve for y2,O2 explicitly, i.e.,
y2,O2 = f  K (T ) , y2 k , p2  .
(b) Determine the product stream temperature T2 ( K ) .
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Assumptions:
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Atom Balances, n Equations: +4
K eq Equations: +4
Energy Balance Equations: +3
n values: +4
T2 value: +2
yO 2 value: +2
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