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Unformatted text preview: MAE 5310: Fundamentals of Combustion Name: Exam #1 October 6, 2011
Exam is worth 100 points. Clearly articulate your thought process and problem formulation.
The setup of the correct governing equations and correct physical modeling principles far
outweigh the actual numerical solving of the problem. Question 1 (5 points each): Answer each question as brieﬂy as possible. 1. Consider the hypothetical exothermic reaction A + B —> C + D. Which has the larger
activation energy, the exothermic forward reaction or its backward analog? 2. Why does the ﬂame temperature for many fuels peak not at the stoichiometric value, but at
an equivalence ration between 1.0 and 1.1? y x: ﬂébgﬁ’fﬂ“ fﬂﬁzﬂf’ Mﬁ Wm’gX/j ifs/ya ‘“ /4~%fa:s‘ m My gar/grew? 77/7” 205‘? e” We?” éTﬁWé’WK .
3. Determine the enthalpy of formation in kJ/krnol for methane, given the lower heating val of 50,016 kJ/kg at 298K. Answer this question using only the appendices in Turns. Question 1 (10 Points): Consider the production of the stable product, HCl, from H2 and C12.
The following complex reaction mechanism is thought to apply: M ,+Clz,/<: Cl +Cl +M 1
Cl+H2—)HCZ+H 2
H+HCl—>CI+H2 3 Write an expression for the change in C1 molar concentration with time. Write an expression that can be used to determine the steady—state concentration of the hydrogen
radical. ‘ Question 2 (25 Points): In class we have commented that the oxidation of carbon monoxide
with oxygen is a slow process relative to other reactions we have seen. To get a feel for how long
the oxidation process takes, consider a closed chamber which initially contains 1,000 PPM of
CO, 3% 02 (by volume), and the remainder is N; at 1,500 K and 1 atmosphere pressure.
Determine the time it takes for 90% of the CO to react assuming only the elementary reaction: C0+02‘—>C02+0 with k = 2.5x106exp(24,060/T) in units of (m3 gmol'l s'l) jﬂra/ 5"”
MA? //J /f£/A;f£: iggﬁn/Vﬂﬂ‘fyﬂfjﬁf Question 3 (25 Points): You have decided to modify your Lamborghini Murcielago to run on
propane fuel. When checking exhaust emission you notice that 3% (by volume) is 02. Assuming
complete combustion, What (1) airﬁlel ratio and (2) What equivalence ratio was being supplied to your engine. Lamborghini Murcielago exhaust gas and climate test bed §§ \ @NKWW fit“ {SW/“‘MM Question 4 (25 Points): Examine Table 2.2 in Turns which shows the equilibrium compositions
at various temperatures and pressures for CO2 ¢:> C0+§02 Part a: Verify if the value of AGOT correct for T=2,000 K.
Part b: Calculate the equilibrium constant for the case of P=0.l atm and T=2,000 K. Part c: Calculate the equilibrium constant for the case of P=10 atm and T=2,000K Part (1: Does this reaction favor products or reactants? Extra Page ﬂﬂl 7 5 Vf/Mf g??ng Wﬂwgﬁfgﬁ ﬂﬁﬁygﬁ? ...
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 Fall '09
 DANIELKIRK
 Combustion

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