Prelim2_solutions

Prelim2_solutions - CHEME 219 — Fall 200 Prelim Total...

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Unformatted text preview: CHEME 219 — Fall 200? Prelim ]: October 16, 2007 Total points: 100 Time: 7:30 — 10: 00 PM Name: flflffi if" /[f ’# (Please put your name on every sheet) Please write your solutions in the allocated spaces below the questions. You can use the back of the sheets for scratch work. The last two sheets of the exam are blank. Write on these sheets if you need extra room, but be sure to label your notes so that I know which problem they correspond to. If you take apart the pages, staple them when you turn in your exam. Partial credit will be given, but you must show your work to get credit. You must box your answer and give appropriate units. When you use equations, charts, tables, etc. from your text, be sure to cite the source, e.g. equation 5.4-2, page 245. Permitted materials: Felder & Rousseau textbook and study guide, your lecture notes, your homework solutions, and a calculator. No other materials or aids are permitted, including other books, computers, other notes. Don 't risk it: cheating results in immediate expulsion. The following total point values are assigned to each problem: Problem]: pts ._ Problem 2: pts ’13 Problem 3: pts '29 Problem4: pts ’50 Name: Problem 1: Propane is burned in 100% excess air. Combustion is complete and takes place at 100 kPa. You may assume air contains 21 mol% oxygen and 79 mol% nitrogen. State all assumptions explicitly. (a) Determine the dew point temperature of the products of combustion. [W {0! (00%) W: {M + 3mm. +50} ML *7 [/1119 NC); a $11} /§f/«/z ('gyg 4 Ionz + 32W: F7 Who 4m? + 37.0 m. M 14M}?!wa #19 Vat/all gym ; fl"— .pv fin? f7” t}- fl/Mh’ 0/ fimfid: [alt/{r+§7‘w) W : I/fib hag,” MW- Vlho: M ._ 0-6"th mam V57.me MC Pm» : who V707 f (0.086110% more) ; YOU Ma. dffimhlw “'7 [—7-pr ‘— Name: Problem 1 continued lows) (b) Calculate the number of moles of H20 condensed per mole of fuel burned, if the products of combustion are cooled to 25“C 6 Head pm 0 3' I96] {(4% Elém-J of m VII/w) I;th 7 2”?” , u ' ‘ PM?! , I; :- 0.0%"? [MM 414/160 {Aw/er) 0. #MMW #23: (7.93/7 T Vih‘ro H fih" H1!) ram Coding) I’m 4 ’1?er “#10 7‘ “Sr-OM04!)— SUIW fl“ H1474: I' LLWZM/v—e— fun—é “:0 l'm ua/ar‘ fdaf {if-41' Ylbl (“magi-fife”. _._.—— so Mn Mme-,0 _ n - H—H-——~ '1'} «A. val/w “wan-1»: I’M/W {g H? m Ltm W, m i an! [fl/“(L’fiv‘lffl/ : / Z. 57 $1111: MI) 3: f; #d’ I fl]:ij ("I #3; I L . Name: Problem 2: A mixture of benzene (CfiHfi) and toluene (C7Hs) in a molar ratio of (0.7f0.3), initially at 8818 psi (abs) and 572 °F, enters a pipeline of 12 inch inside diameter, at a rate of 70 113 mass! sec. and initial velocity in fifsec of the mixture. b) (21) Using the generalized compressibility factor chart, calculate the inlet density in 1b massif ; [7 (4 . 17V 5 EMF? f): 5* 50 {a 2 in”? B . '1 )3» if! $241.3}!— 1 {2“ (“4"”) {Fli- Lo (LL) 1 f f T “L I“: : (w) {UM 4/0.?)(‘1’0J)= Wham C ) TUE-U 693.9 1 Tc = (commie) merm): {Mien Peter-51pm Ia’m > : Wow», 70. 1) two I r : ——- I (3: 228.04%... - - m“ {L Wm M’Lfizm V??? F Wu) fl { libriflégzg row‘i'fil’iirj +(o.2)( Gigi) f p : '40.? entity/“77¢ if} “a ' 32.1ufit:::: (p, 3‘!) ‘: — — fl —— — 70 lit/mu : {IL/03V g Li “J?” Name: Problem 2 continued WW“ The-liquid in the pipe flows through a heat exchanger where the temperature of the stream falls to 100 6C. The mixture is then sent into a compressor. If the temperature in the compressor is held at 100 “C, answer the following: (b) To what minimum pressure must the compressor operate in order to form the first droplets of liquid? What would be the composition of these first liquid droplets? (c) To what minimum pressure must the compressor compress the stream in order to change the stream completely to liquid? What is the composition of the last bit of vapor, just before everything is compressed to liquid? P. 20L 0AM (no) 0)) Pic/Mi W 04 WJJT‘ 405?) Mm Hg, in é/m flmu/ 18704 m2 10-? / 003477 :r 5-977 7 0.3 (m imm- 194 «ii 1103+ JIOOMmH; {'0 {WM/t W vaporfi: (iJfLiIi. Name: Problem 3: The proper conditions for growing tomatoes in a greenhouse require that the environment be maintained at a temperature of 25 OC, 1 atm pressure, and 67% relative humidity. In order to achieve these conditions, the process below is used to condition outside air before it is sent into the greenhouse. Outside air is sent into unit 1 where, depending on the inlet conditions of the air, moisture is either added or removed. The outlet stream of unit 1 is sent to heat exchanger (unit 2) were the moist air is either heated or cooled to achieve the proper temperature before it is sent out to the greenhouse. The weather forecast for a particular day is: 32 °C with 78% relative humidity and barometric pressure of 1 atm. Tl i D U M fire, I atm saturated 100(mol) nU{mol) 32°C 1 atm Li I I’M/fl mo 1' rift-3’2 Yahoo] H20! mol} Ill; jigs; ll. ll” I ' r EV" 0‘ n m0 1 2 ._ T... 23—4—3: J‘}T1rr (a) Complete the flow chart by properly labeling the streams so that you can answer questions (b) through (d). DA : dry air. lair/"4 1 l. DIEM—bar“ (b) Calculate TI. Does unit 2 need to heat or cool the stream to meet the temperature specification? flirt) {afi’ulwfi “F. rolled f1) flat first. LJ‘ ado}: CD- 07 I flew 6M 7 a4 aw“- pmwrww -‘ we” flW‘WL " (j; P : {OoLrMLmBZS-j : atom), bar t W as -——v M? L._._._. .._____.__. ____.#_l. __.. Lil/mart 7, MLU’ Mot/fl Eff—gab]: Name: Problem 3 continued 0 (c) Calculate the total moles fed to unit 1 and the total moles of water either added to or [99 removed. Specify whether water was added or removed. INN“ (401 ljo “I ll? plmlnoa _ (w) ._ now/mm 4P ‘- lrol‘TZIbfir W DA baflomt mm; acme) 2‘— {Do {boom} ho : lorwmm 711W biology: Cg '. “Ll-Mb :[00 n1 : loo — [01.01 L: ., -iioi'ag‘ WW3 ((1) Calculate the ratio of kg of water added or removed to kg of dry air entering the process. (3' Pl 3) Kg HLO Mmmdi /"l.01m»€)(l?.01i\(l_lfl.): (J. 019% #10 MM M903. 3 K (M 1 1 _ a K 00“ / O‘Ol/lw MEL) —_ ZYSQJKE; PA ' [0003 ‘____._---—""'—-—v--—— ._.._._.._._._._ o. 0:07. K3 J/w Mm,” r3 fid-Pflfiflflv (91 Ho '5 0.010; 213? f Name: Problem 4: ( minutes) The vapor leaving the top of a distillation column goes to a condenser in which either total or partial condensation takes place. If a total condenser is used, a portion of the condensate is returned to the top of the column as reflux and the remaining liquid is taken off as the distillate. If a partial condenser is used, the liquid condensate is returned as reflux and the uncondenscd vapor is taken off as the distillate. ’Xn, ’lg . TOTAL CON DEN SER PARTIAL CONDENSER Vaporfrorn topof column Vaporfrom top of column {_ Distillatelvapor} Refluxlliquid} Distillateiliquidl —> [3: “Jr imam 4— ' [5:73-"Wihr _ - Refluxtliquid} I . _ I')/l '~ nib i-Sli T “[0 dr'; :33. The vapotfiecd-fi'om thfiofifian n-butane n-pentane distillation column is 96 mol% butane. The temperature of the cooling fluid limits the condenser temperature to 40 °C or higher. (a) Estimate the minimum pressure at which the condenser can operate as a partial condenser and the minimum pressure at which it can operate as a total condenser. Parana? WC is lb daupr on 4(00/0 (“Mb 447., (“forL Vapor WWW. f/ll‘ p3 pmiq 11%; i‘lrp *3 pm.“ H__. l WHO?) pfflt-{NO l’la 9f 4 m, amt) wg‘fWC) Q in 19.11)‘. pqi (WOT) 1 p§¥{‘f0“(\ 2 (0 cm“; %s*— cream/(ac mean) IO 2 3 30.70 Mm H5, 0,.er u tow-743 {MHz/51H _ . /[ )' €07.22thfigv I _ - ~ ' I. . _ A m ; quijmmHgP Mme); pmm ' 0.6%, gov ._.____ Zd 1(. 30.70 KW. 11 mag '. ({o‘c, }5 M4 LJLQBQ padd- 0% n 4'07!) (9)40 '- y‘gff’é/FL l'tfl‘“ M P: fan/Uh P: [4L], P 4 Ljr P = \LHPV'Y—{VD‘ZS 4— Vg— 9;“?va P 2 (0%)(mono) ¢ {awflwum :. EEIMMHHWLDWJ Name: Problem 4 continued (b) Suppose the condenser operates as a total condenser at 40 “C, the production rate of distillate is 1'5 kmolfh, and the mole ratio of reflux-to-distillate is 1.5:1. Calculate the molar flow rates and compositions of the reflux stream and the vapor feed to the condenser. D: wimmw 5' 2 1'5 ' L La: HLSKmé/hZ] 75‘JLM [ah -— - —— WU (up a i I I W/ b ONCE V — (3+0 : (Ill‘r+ 7y) jcmfif'hr sum m3 :5 a ow (moan/ing map 5L; : 9f 2 0.0;; NQLV‘ Ljaq ': 9"“, 3115— : o-UV F- dtSH/(fillf' got! 2 0.6“, I; ML M Audra-a 0/ m Name: Problem 4 continued (e) Suppose now that a partial condenser is used, with the reflux and distillate in equilibrium at 40 °C and the distillate flow rate and reflux-to-distillate ratio having the values given in (b). Calculate the operating pressure of the condenser and the compositions of the reflux and vapor feed to the condenser. ‘fbi’up Wilma i) M féwao... iii (b).- rj .— 7r rtmwlhw £20" ll'Z-fffimM/lir 5:: “Or am}; in, . a CH: 3:1. Inf-cm {Via-P row. 05C I‘d; p: 1!. Pl‘+ For mum: (0%) P : 7L, (2 320.70mm143.) arts—us: WW: (r-wwmm'fi‘ J 00?”! {IA} ’KL, 2 am? VMA-e (with. _______,_.— mzvé 0(5‘: 0,“?7 My? (leL J .5" __ Em fzaovlllj law; Km 80 ’11-? {JIM \— I'deflPc =09, +0 ob-l'fly'h (M-{JQJ'HJMJF' quul [if-’0’! (2 : (QM/M) : {(2.}(03503) +- fellatio) (lilrjmlpq); (Htrflawolj-t (15){0.%] 4w 2 Ola/:11 mamas/me “If? 1 0- 0573' Mafia/Mae, ...
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This note was uploaded on 02/13/2008 for the course CHEM 3890 taught by Professor Hines, m during the Fall '08 term at Cornell.

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Prelim2_solutions - CHEME 219 — Fall 200 Prelim Total...

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