MAE204_F11_Exam1_Solutions

MAE204_F11_Exam1_Solutions - MAE 204 Exam 1 — Part 1...

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Unformatted text preview: MAE 204 Exam 1 — Part 1 §o\o¥l “(\3 Name: Instructions: 1. Print your name in the space provided. 2. Carefully read each problem before beginning the problem. 3. Show all work, partial credit will be given for written work only Neatness is important for you to get all possible credit. 4. No books, notes, or calculators allowed. 5. All answers must be circled and have the correct units. 6. If you need extra space, use the back of a page and make a note that you have continued elsewhere. 7. Unless otherwise stated assume gravity is 9.8 m/s2. 8. Unless otherwise stated assume atmospheric pressure is 100kPa. 9. Unless otherwise stated assume no change in kinetic or potential energy. October 13, 201 1 Salac \ MAE 204, Exam 1 — Part 1 Name QQ\U¥( “ A 3 Page 2 Score 1 /10 /5 3 /4 4 /4 5 /2 Total / 25 MAE 204, Exam 1 — Part 1 Name 2 O\U¥' "n '> Page 3 Problem 1 (10 points) Consider the following cycle, Where the numbers represent different states and also the ordering of the states: Polytropic 4 Process / <Y Problem 1(a) (3 points) List the phase of the states: 1. COMIMK‘SVL) L; 0013 (UP Suloco¢l03 lic’UA 2' 3 q* UPI-’A‘ft) 0’03) 3_ Mix-lam ( Llama + Uc‘eop) 4_ Ruth luck; V‘léofi _ Rug“ hccléa UQKE" 6- Comgpeaua llfiu.Q Problem 1(b) (3 points) For the following processes list what remains constant 2_>3 g QC7'Q4‘C. Uuldfl‘L C! F [SQCkUP;() 3H4 Presume C FSJ‘O‘WL} 4+5 PVA D1 v \ a MAE 204, Exam 1 _ Part 1 Name SO\Q¥‘ “S Page 4 Polytropic 4 Process / > V Problem 1(c) (3 points) Give the boundary work per mass associated with the following processes: 1&2 PM ~O§ an (33(0—0 4—)5 MW Problem 1(d) (1 points) Is there net work into or out of the system? 003$ C HM. no]? (work Oo"? S;de “but * w‘agq {‘ L)qu ifi \Gr‘gen “Elmo UJOAk ‘m UbSLB ‘ MAE 204, Exam 1 7 Part 1 Name g 0\L’ I on) Page 5 Problem 2 (5 points) A fan is to accelerate a gas from zero velocity to a velocity of 10 m/s. What is the volume flow rate of air that can be accelerated by the fan if the input power is 200 W. Assume that the density of the gas is 1 kg/ m3 and constant pressure. ~ ‘ A m V0:O\ j: V‘, [O [s 9O ‘ +9 ;0 ' -=9 . 1 A \ " P , V ,V ‘_ -_,£ .— O .f AErNd'x’ m t 4- I d k (m’lo)) Lghsao‘sbu Problem 3 (4 points) An experiment has determined that a hot plate with a surface area of 2 m2 and a temperature of 600 K exposed to moving air at a temperature of 300 K has a heat transfer rate of 60 kW. What is heat transfer rate coefficient associated with this system? 0:“ onJ‘C «"3; 5; e Hul— was? 57 CanUtQ‘L-forq , ’~————-—————-——-’,\ 2- Adm“ ’ a (Scene QM: h M18 an) : ‘\ Kid 19. W O FTC": \OO malé , \ MAE 204, Exam 1 — Part 1 Name a“; dim U fl) Page 6 Problem 4 (4 points) Define the following terms: A VLJl‘M Q Qh‘mge in Qn¢n§7 ho'l N<o\‘l‘ in 0‘ phmc Change , Compressed Liquid TM lesk when. Sg‘XVUI‘t'lPa U901} Q ’Vl‘Q Sam 0) Sq'itUrql-‘J Ucflon, Critical Point \ qua Q}? quc-r men k "H‘k WI“) '4 Q m;XJ"U/Q’ Quality The PNSSUIL 9* bhfchl goo 0‘ SPUM AVGMF¢AQ+UQJ [Al‘ch change to)“ dawn. Saturation Pressure Problem 5 (2 points) A closed, quasi—static system undergoes a process which only has energy transfer due to heat and boundary work. What must be true about the process for the heat transferred to be equal to the change in the enthalpy? Tkt [QV‘S5QV‘L mus)? films-in Conslenl~I MAE 204 Exam 1 ~ Part 2 QOMJSH ° n3 Name: Instructions: 1. Print your name in the space provided. 2. Carefully read each problem before beginning the problem. 3. Show all work, partial credit will be given for written work only Neatness is important for you to get all possible credit. 4. You may use one textbook and one calculator. 5. All answers must be circled and have the correct units. 6. If you need extra space, use the back of a page and make a note that you have continued elsewhere. 7. Unless otherwise stated assume gravity is 9.8 m/sz. 8. Unless otherwise stated assume atmospheric pressure is 100kPa. 9. Unless otherwise stated assume no change in kinetic or potential energy. October 13, 2011 Salac MAE 204, Exam 1 — Part 2 Name gL)\\.\kf‘l C1 (\ 5 Score Page 2 \ MAE 204, Exam 1 — Part 2 Name QQ \QSW on) Page 3 Problem 1 (20 points) Your PHB has requested that you spec a pump to compress liquid water. Assume that water enters the pump from a still and large reservoir at a pressure of 100 kPa, a temperature of 20°C and at a height of 500m above sea level. The pump must be capable of compressing the water to a pressure of 30 MPa, a temperature of 372°C at a height of 500m above sea level with an outlet velocity of 4 m/s and a constant flow rate of 2 kg/s. Problem 1(a) (3 points) What is the specific volume of the fluid entering the pump? macaw; em out M Sui-wives ow) m.- l0:qu wake to . at We =7 CUMPNUAJ The: use» ' (450.3 odm 93v Problem 1(b) (4 points) What is the specific volume of the fluid exiting the pump? " ~ 99°C 5 ‘Oot - C).ooie;>a°.- 0.044376: 0.001979% -— avg PM = 30“”)9 2,9,0 — 360 ' 320 ~10; USQ A 'W \ ’— 0 s Ins\(rq')o\t\1 bcsl‘lvh'q #jbob : 0| Cb m ’5Q>Q°C i’ ECSQQC' .— Problem 1(c) (5 points) What is the change in the mechanical power of the water? 0 O . AEmmkr' EM " Eiq " , ° F" ‘3 i h r ° Part k ,1 E!“ ~ MK 1;?“ +§Vln JC Stlfin Cove- 761-; A" avut/‘t +81"!— g‘mu (EfG'QWe d~ VIO:O w. gefl‘ 55mm: locfloQH W 2 losses»; to] \ MAE 204, Exam 1 — Part 2 Name gok‘év' b A) P age 4 Problem 1(d) (8 points) There are three pump which are available. Each of these pumps runs on electricity and has a fixed input electrical power, efficiency and equipment cost listed. Which should you recommend? (You must show your reasoning for credit.) ‘ ‘0 A. We=170kW 7720.6 Cost=$50,000 w . , B. Wezigokw 77:0.57 Cost=$65,000 “L: ‘30“ go bosznz'bt c. We=200kW 77:0.57 Cost=$60,000 be A ‘_, P055',l)‘Q Dork Cue :— QGO‘C, : w (6‘. (Save: (cicadas? -: lO%.$lr,L¢ Cl Looth Qw-xoS72H1/(ku, \[Oo mail [Oelgkb 09V POW‘ pd???) Qqfi Qauppir ‘(tl'vg Chemo iOIHQh C035? 0m . Recommem.) POM/3 C‘E got}: a a) MAE 204, Exam 1 # Part 2 Name Page 5 Problem 2 (26 points) A steam engine operates on 0.2 kg of water in the superheated vapor regime. The initial state is vapor at a pressure of 10 MPa and a temperature of 500°C. The cycle is given by (all states are superheated vapor): 1 ——> 2 Isochoric heat addition until the pressure is 20 MPa. 2 —> 3 Polytropic expansion with a constant of n = 1.3. 3 —> 1 Isobaric compression back to the initial state. Problem 2(a) (2 points) Sketch this cycle on a pressure—volume plot in relation to the saturation curve. Q) B a) C3) 1/ Problem 2(b) (5 points) Determine the heat required for the first process. Lil/l " Hulélfi ‘ q&_LI; " QIO ‘ .waw- @31va :7 a}: #332, '90 v: lWe, 2) ll}: mot; 2 Eats 5*!) m m Quailykl, : 12mm: M? :n ] 20K.» \Jt ° 0 '> Page 6 MAE 204, Exam 1 a Part 2 Name Problem 2(c) (4 points) What is the specific volume of state 3? ’R-b's (x Po\7£m ,1 13h» PQ‘A: Combo], .. “3.. '3 L: \'g P ‘ I: ’7 Pas; ’ 'sas =3 o3 :QDQ 3 Problem 2(d) (10 points) Determine the boundary work and heat exchange associated with the second process. P1: \0 MP3 3 Ofopscfillfi " It, mg =- P3 81" P; G} Q0xl0$>(O‘O§CciéN$s)-— (20x101)(0.0 319,”) Us} 2 93%.ch 1c? (MA 13) qa‘rn'herpakk P: \Q Npr» gram thlvc A‘G.‘ M“? «w 3°»;ch “of—Ix o‘oi‘SZM — 0.0mm» ‘ .os‘mam— 0.0rsrw) =3 Mlzgomg 3‘ km) mm: 795.; he? QM: Mg’da-Q \ MAE 204, Exam 1 — Part 2 Name %Q\°¥' an 5 Page 7 Problem 2(e) (5 points) What is the net work associated with this cycle? “\C‘F Lt)¢r\‘ 7— 80M MRS Q-\\ Loor\S M eat/L} ()3: O‘OS‘C (3/ng mvb g3 wk,“2(\oxco$§(0.osa<m—0.o§r%|®)(o.2) 143‘ “\e". “OAK GS" {‘5 (CDL$.Q:6%~%,DM3HT: “my”; )4? ] MAE 204, Exam 1 — Part 2 Name QO\U¥N {\5 Page 8 Problem 3 (19 points) A closed system of R134a is compressed isothermally from a pressure of 100kPa and a temperature of 80°C until the volume is reduced to 51% of the original volume. Problem 3(a) (5 points) Assuming that the R134a is modelled as an ideal gas determine the final pressure. P‘ ’2 [00 M33 T7 '2 BOQ’L {a}? (7 Trsa‘oug C)?” ‘3 I Problem 3(1)) (5 points) Assuming that the R1343. is NOT modelled as an ideal gas deter— mine the final pressure. A+ \oo \cm Tsw;'3.(..3') “C. (Teak A41) Hm Hm is P‘rWM Vapor» UK He. A43 is as inlml 3: \oo we: 0.) MM (2/ god; (3|:o,38'-I¢,S‘m$/LJ’ (39': .2 O! M‘s/k3, Ma A—n 'me tut; alum 6 l >EX3OC‘ (JR/\A‘S a— i P: d‘\% Fllpfi ‘l' 0.2-0 'flpc. I Oil/lo?” — O.i\”673 o.Iu§I'>/T ——o.IS‘67§ W 1 ,- 0; £1 0,» — ems {0‘} :3 : MAE 204, Exam 1 7 Part 2 Name g°\‘éfi y A> Page 9 Problem 3(c) (4 points) Assuming that the R134a is modelled as an ideal gas show why the change in internal energy for this process is zero. Ta‘ QR CULT M 1“ IX— RM e. ‘1) 3'15 bu ‘ l U S‘mes "Fr—R =7 lbw—<3. Problem 3(d) (5 points) Assuming that the R134a is modelled as an ideal gas determine the rejected heat per mass to make the process isothermal. E10097 bg\<n(¢ I ’3 E : NA:- ‘wb 'Qoufr, Simg ISM-:0 (‘4‘ 3d— QOUE : FLOIO. L{Abli P‘C)\ g2: glfltc ‘33:“ M 9¢'\\ l cob; RT\\A%3 Use R2002”qu {Si—’1 (Me A—:) l T| 1(gmavs,«§‘)k_: 535%; cob: (o.O&II—l°.\(?>§1d'\‘) \q 51 :"lol.$'783 kT/kg MAE 204, Exam 1 w Part 2 Name go\°\fi an 5 Page 10 Problem 4 (10 points) You are given an unknown gas and asked to determine What it is. Problem 4(a) (4 points) You place 0.25kg of the gas into a constant—pressure piston. You measure that it takes 112.685J of energy to raise the temperature from 299.9K to 300.1K. Based on this information What gas do you think it is? Us: “‘1 deg-Pniifim A CF: (‘13: (%\P= L fill m l at p: TM «a 1— alfl : J. Ham? 3“ T > m P 0.9%" 3Mtl‘acl‘lfi T P its}; = 22.9957 32-1. Us“ Mu Aja em mcitlg lh’le’rlflene Problem 4(b) (4 points) You then place 0.45kg of the gas into a rigid tank. You measure that it takes 144.881J of energy to raise the temperature from 299.9K to 300.1K. Does this information dispute or confirm your result in part (aK'.P p-533; LCM fl____ Misery: 00],“; CV, (“iv ‘0‘ m v3T V “om- gamma Lilo 16’ '7 LL " \‘CoOo’lg kTilf-JL. % CV all" MeirlnC-nc, Rh: Pauli, .37 Problem 4(c) (2 points) Assuming that the gas is an ideal gas and based on your results for parts (a) and (b) determine the gas constant associated with this gas. ...
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This document was uploaded on 10/27/2011 for the course MAE 204 at SUNY Buffalo.

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MAE204_F11_Exam1_Solutions - MAE 204 Exam 1 — Part 1...

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