exam3soln

exam3soln - Name: SOL UTZOA/ Instructor: ME 364 Elementary...

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Unformatted text preview: Name: SOL UTZOA/ Instructor: ME 364 Elementary Heat Transfer Exam 3 Closed Book 1. (46) 2. (12) '3. (20) 4. (22) TOTAL You are allowed three sheets with notes Show all of your calculations clearly. 1. Figure 1 shows a schematic of a pressurized water nuclear reactor; The primary coolant loop, in contact with the fuel rods, is pressurized and this water does not achieve boiling. Heat exchangers called steam generators are used to transfer heat to a secondary coolant which is allowed to boil to produce steam for electricity generation. In this problem, you will be analyzing a heat exchanger of the same dimensions as those used in a pressurized water nuclear reactor. Containment Structure Pressurizar Steam Genera? Figure 1. Pressurized water nuclear reactor (taken from wikipedia.com) The heat exchanger consists of 1000 vertical pipes of diameter 0.025 m and length equal of 7 m. Water that is in contact with the nuclear fuel rods is pressurized at 125 atm. It enters the top of the heat exchanger at 315°C, and for security reasons must leave at a temperature of 305°C. The water from the secondary cooling loop enters at the bottOm of the heat exchanger as a saturated liquid at 275.6°C and 60 atm and exits as saturated steam. THERMOI’HYSICAL PROPERTIES FOR WATER Pressure 11 h CPI C I ’ t (atm) (kJ/kg) (fir/kg) (kJ/kgK) (iéikg—K) 1213 2784 5.2 4.63 1511 2673 9.07 9.02 a) (6 points) What is the required mass flow rate of cold Water (in the secondary loop) to transfer 3.2 GW of thermal power betWeen the two streams? beam CW %3 (LW AT lo P ah c '. Le CF 5T 51;: mWC c) (6 points) Plot the temperatures versus length of heat exchanger that both streams will experience. Label the inlet and outlet temperatures of both streams. d) (10 points) What is the overall heat transfer coeffiejient of the heat exchanger? (.5 f: (it: URN/(M -,//\""»"W as: (3.257% (S‘W‘T— M C4340 New: W‘WCIWE’.) : On???an ATM: (2W "27§2t»)-(3<>§»27§e ME?" 927519/(309— 2’1ng a» “swath - ‘ but: Ntw Cw A ,—.- ‘1T(.U‘Z§m)(7m)(tobc>> :(Ci‘l—CWQXKVSKDéQYQ«07%)33” :3 5'50 m1 7 ‘ Mg‘k n w. V \N ' . u: 3, .7 Z 3.2mm 0115 73W“ 7“ Am (590m9t3‘t't‘9 ‘t‘ ‘i‘: = (ii-£5192: a may :1 Ljoxtos W/MZ‘C” . I; V m2..¥ e) (10 points) What is the effectiveness of the heat exchanger? ._ 1 or; A ., . u CLW N '— im= CW“ ’5me t: 01 Stasst ram 2‘ (2(9wa C‘ ’5."2.2L(0 ‘ W :1 353me q_e7xu:?5/Zflg.z7g,(g l4 '3.‘“5’$x.(d‘:l‘§ I /" ‘io‘hg '3 £4344 a 02me W . t rag mdc’w f) (8 pts) qualitatively describe the change in effectiVeness if the mass flow rate of the primary water flow were increased by a factor of three, While the mass flow rate of the cooling water remains constant. gimme Cm‘m is €5~§$C>Ca1€w€€€£ MK “3%., :17Ptl/MCNV5, 915:2.“ Mex-msfvfi Cmr‘a who new. N+\~ , Cr mm n5 ":0 fit , , g “Via; ~z¥§~zofvwam£3 our, ("t-@6442, 2. (12 pts) A diffuse surface at 300 K emits radiation primarily in theinfrared region and has a spectral hemispherical emissivity as shown below: ‘ 1.0 0.8 0.6 9x 0.4 0.2 ’20 40 6O 80 100 W» l r N" >1 We. - Determine the total hemispherical emissivity of the diffuse surface (to three decimal places) a: S t‘O/JLIM'L‘P’ M 30'?” {CDT 6 '9 0'7" o (o Stbrfllffi €10“? OH 509°” EE 4» gal” Er E5 54;; Liam 3w :4: lapse/W34. ' QM: wang /\-\L:‘ “Z: fight; Mt: WW3“ t: 3©,®°/*w~‘< eilggommq a 3 O '2 ( FOW7H> + F: “'in Foalt) F0”?ka FC)""/\t2,> '3 0.7,. (Cb.qu Sift?) 4/063 (OHQO‘B‘K «~().°tq$“c5‘té§_) + oJ-M‘qqflukfiqofi 1: o.l8fi + o.<>27s<+ 0.(x>r7% :: 0.218 3. (20 pts) A thin metal hemispherical shell of diameter D : 0.5 In is suspended inside a 1,0 m cubical enclosure. Find the view factors F11, F13, F23, and F33. zaurfcxae, ALT ag <1 (“JR/Le . F 2 V2, 0.7? m bmSC LS9? 11 _ Act: h Alas Afi—‘l F13: 1 fl v 1 F23: l TIM)!» ‘01 (“Catwmc’ufi F33: 0‘90; ,. Ac - 1W5 z ‘ ' r1"! w 7:? (F¥(>: L6 @2103: Sufi-E A115) CmV—Qlc £2.20 .) Alan gfitwo c MW ... m 10% D‘WW‘ ‘ rag W1 Z— ) r. 0.361% m" 157, magmaqu F32:- EFZ'E ” (43 w A M... t ('3' w. Fae 1:93 B- ; (21; w .0327 6 F33: |~'Fz-2:'Fsl == 0 m. A}: l A3: @klmzz (DMZ C) ‘qu a... (f l) '2 0.0435163" 4. (22 pts) The cylinder, closed on both ends has the temperatures and emissivities on its internal surfaces as shown. List all of the equations one would need to determine the heat flows to (or from) each of the three surfaces. Circle the unknowns and ensure that you have an equal number of unknowns and equations. - T1: 1000K e1:0.05 a. I OLE: Ala. (3513“) + ALF”, (grog) 7' ‘ Ufa/c. awn. \“uiog R54“ 61:63; gazcg’z, ...
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This note was uploaded on 08/08/2008 for the course ME 364 taught by Professor Rothamer during the Spring '08 term at Wisconsin.

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exam3soln - Name: SOL UTZOA/ Instructor: ME 364 Elementary...

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