Binder8 - Assignment 8 Availability or Energy D55 A freezer...

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Unformatted text preview: Assignment 8 Availability or Energy D55 A freezer is maintained at 20°F by removing heat from it at a rate of 75 Btufmin. The power input to the freezer is 0.70 hp, and the surrounding air is at 75°F. Determine (a) the reversible power, (3)) the irreversibility, and (c) the second-law efficiency of this freezer. Answers: (a) 0.20 hp, (3:) 0.50 hp, (c) 28.9 % D56 The radiator of a steam heating system has a volume of 20 L and is filled with superheated water vapor at 200 kPa and 200°C. At this moment both the inlet and the exit valves to the radiator are closed. After a while it is observed that the temperature of the steam drops to 80°C as a result of heat transfer to the room air, which is at 21°C. Assuming the surroundings to be at 0°C, determine (a) the amount of heat transfer to the room and (b) the maximum amount of heat that can be supplied to the room if this heat from the radiator is supplied to a heat engine that is driving a heat pump. Assume the heat engine operates between the radiator and the surroundings. Answers.“ (a) 30.3 k], (b) 114.8 kJ D57 A 1.2-m3 insulated rigid tank contains 2.13 kg of carbon dioxide at 100 kPa. Now paddle-wheel work is done on the system until the pressure in the tank rises to 120 kPa. Determine (a) the actual paddle-wheel work done during this process and (b) the minimum paddle-wheel work with which this process (between the same end states) could be accomplished. Answers: (a) 87.0 kl, (b) 7.66 k] D58 Steam enters an adiabatic turbine at 6 MPa, 600°C, and 80 mfs and leaves at 50 kPa, 100°C, and 140 mr's. If the power output of the turbine is 5 MW, determine (a) the reversible power output and (b) the second-law efficiency of the turbine. Assume the surroundings to be at 25°C. Answers: (a) 5.81 MW, (13) 86.1 % D59 Steam expands in a turbine steadily at a rate of 15,000 kg/h, entering at 8 MPa and 450°C and leaving at 50 kPa as saturated vapor. Assuming the surroundings to be at 100 kPa and 25°C, determine (a) the power potential of the steam at the inlet conditions and (b) the power output of the turbine if there were no irreversibilities present. Answers: (a) 5513 kW, (5) 3899 kW g: COHBge of Engineering #5 i I// m gf ARKANSAS _W_UW_W- IZFK‘d// flf ’70“ I x a I f" v fr ) L " /37"b.’ ' 57 #7141 MP 2? £26 {gag/z KNEW» 6/: £2” 3:: College of Engineering UNI-VERSITY WARRANSAS mmWwWw ___________ M ,,,,,, _;,___D£éfi_»/ flag/Mde In/ {/74 / flra c fin 0' L #3 (20¢ Qou/ ¢o a )_ x ’2; i 4 Ear-70 C f“ (7400/? 7,;W-6L/ C G a 7:26wa raw/k 7:7 J’O L lb 64; 62 __ ‘ n (I “fix/2' fl 6* fliéf'“ 5A,») fl/fJ/Mf if 747%: j 71%” 4’ (arm fig Yaw/@f +6» radar-w. flsramflg /%.£ Jfl'o/mnfiéar égfugbh Minis/4w 9L .5“/// / K (I,‘../i/ ’z‘j/I': 5777—- #5: “3:- UNIVERSITY Qf ARKANSAS College of Engineering m_______m_me____ ....... ML__W__D_é:€_:_/_;W Maw; [41 r M55“? @Es //g f; 3 1‘3 *7 ML : A0} a; flfiy A’f 3, M7; ,9, A 51': X1: fia‘I’GV-QCM/fll'l #42 fr): : 0.0179134: N” Ami-3 ma rat/f“ : LV/flfl/ 3: ¢I - 4b [<5 4, <‘ M5 ff )r'j armmwg, (’édfv/sw [OW/3a Q00 49%? ” [if )4)“ * Zia/fray. ,-: $3 @7— E; College of Engineering i j N IVERSITY 9f ARKANSAS E: College of Engineering _am._ UNIVERSITY #ARKANSAS _ a (ar'v-r’-r,,_(af{;‘z_7___/c -~ 27mm) __ ._ .._ __._--——-——"_ x’dfaé -, 33%;, College of Engineering DRIER—51W ‘ 9" ARKANSAS W_Wm.wm ____ .‘_____n_m____wmQ:$-_.IZ__ZZ£M " College of Engineering 1 UNIVERSITY “JARKANSAS M m ‘_____. //’ -._ .fl V, Z, e 594m 3 635/145. 71:05“ {*1 f0: ffl/épa 43" §mw 7-: 600% 7= mead # '4 - = m : 4 ’y 9/”-025C Viv/f V //4: Fin/A9 W Mm I z A): 5}: ’Z/{Wl’fizj/d J/J L46 A) A: : zé’l'g/fij Wk / 3,“: 7,49” egg?“ m1. E 0%“: m 5 $1 “ M W :— wa ~7;(s'-£2) dz «5:1 ffiz 401:3“ /$7LL¢'/w 44/: m’Uw/AJ) + 1431/; ~"L. v I I: —- —- Z5; 11...? __ g f 155; m 214/ 1 +1: 3 AKA _ 59/- M03, 5149 “"9 6 tuitf‘fiv 014$ ' E '5 (’3’ 3”“ UNIVERSITY #ARKANSAS £27447, (’4) ’3'” WWW ormm @ rpm {/9} fi"’""”’ €""I’7‘5’--‘1r‘f' I’M xifirf’M 5m _4£. 6 $57.??fo "An *fiK—gm-CJ ._ a (f E 5 55/3 kw? Ants/['6‘]? h! (a f_ f" /9(‘/‘0& I? a 3‘ 0 3475/ All" 34;“. z .917, ‘32: "3" 3 mfiaréz) J70- j KAT“—“H*'XF‘J7 K w} A; : 3017.2. 6:; A? :féé/fiw‘yrff 16; 5; :3 (.43...) 5'2. ...
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Binder8 - Assignment 8 Availability or Energy D55 A freezer...

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