cee11-fa07-final-Harley-soln

cee11-fa07-final-Harley-soln - Page 1 ofll Final Exam CE 11...

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Unformatted text preview: Page 1 ofll Final Exam CE 11 — Engineered Systems and Sustainability University of California at Berkeley Fall Semester 2007 NAME: g0 0 [1:2 Instructions: answer the questions that follow directly on these pages in the spaces provided. Use the back of the page if you need more room for your answer. If you believe there is insufficient information provided to answer a question completely, state reasonable additional assumptions and proceed from there. The exam is ciosed-book/ciosed-notes. You may use a calculator. Please write vour name in the space provided above! Time: 3 hours. Question: Score: Out of: l m 5 2 W 5 3 _ S 4 _ 5 5 W 5 6 5 TOTAL 30 Page 2 of 11 1. SEA LEVEL RISE Though the timing is uncertain, a rise in sea Eevel is expected as a result of global warming. Estimate ocean water level rise due to (a) thermat expansion of sea water, and (b) melting of the entire Greenland ice sheet. Given information: Earth radius R m 6378 km Fraction of surface covered by oceans : 75% (assume constant) Average ocean depth 2 4 km Volume of Greenland ice sheet V : 3><106 kin“ of ice Assume pi“. = pwater = 1000 kg m‘3 Amount of warming AT 1* 4°C 2 4 K Water thermal expansion coefficient [3 a a 2.1x10‘4 K“ V (IT CE”) V: Agni 'W‘A’Lt xiv WHW‘F F:- 1L4!» EL? Ali” (SKA—r" ilsétowacp'x‘lkmx Ltli 1" ail-Fm 6 3 (to All: M: 3m he 1 z 7.3% fat “rail—PW (' £378 km.) S} L sale )CM (c) Name 3 major greenhouse gases that are known to be contributing to global warming. Cam!) mm «DUO kg oh L LOL) . (if: Miracm OSLt'cLL. (N10) C“ 4+ ) Page 3 of 11 2. HYDROGEN AS A FUEL (a) Calculate the lower heating value of hydrogen, H3 (g) in units of kJ g'i. The enthalpy of formation of water vapor is 4.242 kJ moi"‘. H1 -+— £0; *5» “20 .- O __ n J x. M _, ~ £4 4512c: AQJLO 5/15“; Z¥LOL "* lqim" L3 . Utv~ ‘jéé‘t ,t “Ni W‘ W 12.1163" 'wugo' 3‘ % (b) Proponents claim that when hydrogen is burned with air in internal combustion We engines, the only exhaust emission is water vapor. Thai is not correeti What other air pollutant could be emitted from the engine? Give oniy one answer. H2 I‘S “mt-L M} NL+ (9L *9 9'1 No C 3'5 Cad-(1L4 N0): ) - W mg, m Wham my (w we) MUM/3 (53 T) Mutt; M’maa NOV. Page 4 of 11 (c) Calcuiate the adiabatic flame temperature for combustion of hydrogen in air, with 25% excess air, assuming complete conversion of H2 to H30 (g). Air (20% O2 and 80% N2) and fuel (H2) enter at 298 K. Heat capacities for H1, 02, N3, and H20 are 31, 34, 32, and 41 J mol" K" respectively. ng'C/Cbi o M W LIL 4% [.QSinL + GZNLJ “ma, Hag) ,{_ 2,5N2‘ 4-0,:18 OZ " ‘ - W i on: L‘Prigo—‘v R‘s ("rigid (Ln-0L (3 _ LH ~+ 2f~><‘32.+ O.l’2.3‘7< 3'4 #th U M31+M8 1:: 92013:; K H T Page 5 of 11 3. GROUNDWATER Drawdown at a 0. lO—m diameter groundwater well, which has been pumping at a steady rate of 1000 m3/day, is determined to be 0.50 m. Far from the well, the aquifer from which water is being pumped is 20 m thick. An observation well 10 m away from the pumping well has been drawn down by 0.20 m. Determine the hydraulic conductivity of the aquifer. 62 get 000 w? Page 6 of 11 4. ECONOMIC ANALYSIS (a) Estimate the payback period for purchasing a hybrid vehicle ($4,000 higher price), that achieves better gas mileage (45 vs. 30 miles per gallon) compared to a conventional gasoline engine—powered car. Assume 15,000 miles per year of driving, $3.50/gallon fuel price, and an interest rate of 5%. Assume both vehicles last the same amount of time, with zero salvage value at end of life. [$79790 fvwlé’za . @163, ##1— wc‘ i 3573 m [Am 7" m. r liorog 7 G§7 “‘ l” 373% ‘ WHL . -l.0§ 13/33. (.0? to?” Page 7 of ll (b) Compute the total life—cycle cost (as a present value) of the following car purchase: Purchase price $21,000 (paid fully up front, in cash) Fuel price as in (3) assuming 45 mpg 8:: 15,000 miles driving per year insurance $1,000 per year Parking $1,000 per year Maintenance $500 per year Salvage value (resale price) in year 10 = $2,000 Interest rate 5% NPV —_—_— “$Q—{i6'019 + a K + fill ‘ 2: 7,71 ,03‘.‘ : O.(o(‘+ —e> "V3 p u 6 F U 1: r; algae—o NJ}wa angles [Oyrs UL : M 4- 'thm.+ FLA/Mug + I'MIMWWQL» :wOHO‘Tj— 1m ei- iW—o +m‘) = -— 3(067 NPvz.~ameo-+77x(4an)+.acwignwj Z “"4308! :H Lb Mme“? lo mt: 'M I b 'mdflwfitflwd wapmwwg 2004 F l a I %M& ‘h {A The W (La/7». Page 8 of 11 5. HABER—BOSCH PROCESS An industrial process to make ammonia (NI-I3), an important fertilizer, involves the reaction of nitrogen (N2) with hydrogen (H2): N2+3H2<=~2NH3 (a) How is the hydrogen needed for this reaction most commonly produced? Siuv’vw railwwMg 5’!) WWW. @@ C4u+Hs0 We Co + 3H2, co ~i— Lilo a CO; ~"r Hi, (b) What is the effect of increasing pressure on the equilibrium yield of N143? lWWVfi, ? imam Qawciwwm yidlaL Q) n43 (L2 Chiin (c) The reaction as written is exothermic (i.e., heat is released going from left to right). What is the effect of increasing temperature on the equilibrium yield of NH3? imamng Wm «W. (d) Why do pi'acticai reactors for the Haber»Bosch process operate at high T? Aime/5L 'i’tAL bflwir 0]) mow}; T W I yidgd is cover,an M, ‘71“ (“mica (1.}xe -%cec,éi. imM-Vaéfl . (e) What surface water quality probiem may result from the use of fertilizer on agricultural lands? ibL‘i’V‘OFi/‘Ji Cain" 0m mm Imam Ugh with Rafi—S ML SIM—J‘cfigfi NW IQJZflqig/i WM Ling Watt: W1 flaw/12%; ea.» {2) at/issa Dme @Mafigm in (a im. Page 9 of 11 6. CHERNOBYL A major nuclear reactor accident in the Ukraine is estimated to have released about 5 MegaCuries (MCi) of radioactive Krypton—85 to the atmosphere. Recall one Curie corresponds to an activity of 3.7’x10i0 atomic disintegrations per second. Avogadro’s number, NA = 6.0x1023 molecules per mol. (a) How many neutrons and protons does a {Cr—85 nucleus contain? Identify the decay product of Fir—85 given that it is a B~decay. Show mass and atomic number of the product. Nearby eiements in the periodic table and associated atomic numbers (Z) are: Selenium (Se, 2:34) Bromine (Br, 2:235) Krypton (Kr, 2:36) Rnbidium (Rb, 2237) Strontium (Sr, 2:38) Kings flag Zv3t 1mm) M 854w as y, 357 ‘ to was lit + (3 3e 37 . (b) Given a half-life for Kr-SS of 10.8 years, estimate the fractiou of the emitted Kr—SS that would remain in the atmosphere today, 21 years after the accident at Chernobyl. {7 "i . Cl . T: ': 0:993 £0 £3- : 0,064—yr 1/1 (0.971" R. 0.29 Page 10 of £1 (c) Estimate the moi fraction of Kr—SS atoms in the earth’s atmosphere today, resuiting from the Chernobyl accident. [tr] 2 5 /\/\C; D ’ G) " [Kr] : 0.2944,”: HMO C1 Come/JP 1L0 fig (Cw—BE“ . m :; LgXiogC/k‘ 5C 3-7XH3 cb‘o’iwl—{se’c an C \ H w E C) G‘- p 7“ UK? \J K or» o 9:. f i .1... ________ . 4 ’2. _ * 3 L .o 1; M r _ CLAY" WMJY (3‘ .fl/‘Mr, ‘51“ MAC»! 1 I 3 X (090 who] L “(‘1‘ '_ 39(- g mo ‘ Q (l X (D ykv‘ w ...
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This note was uploaded on 12/01/2011 for the course CE 13972 taught by Professor Chow during the Spring '09 term at University of California, Berkeley.

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cee11-fa07-final-Harley-soln - Page 1 ofll Final Exam CE 11...

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