GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNGBI TP LN MN HC K THUT LNH NG DNG ti :Tnh ton thit k h thng b cy : Cng sut : 10 tn / m. Nhit b : -10o c Sn phm : cy Mi cht: NH3 n mn hc K THUT LNH NG DNGTrang 1LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNGCHNG I : S LC NC CY:Nc cy c vai tr quan trng trong i sng v trong cng nghip.Trong cng nghip ngi ta s dng nc cy bo qun p lnh thc phm , dng cho cc tu nh bt thy hi sn ...., trong i sng nc c s dng phc v cho nhu cu gii kht, gii tr ...Trong cng nghip ch bin nc , nc thng c sn xut di nhiu dng ty theo nhu cu s dng nh : cy, vy, tm ... y chng ta ch nghin cu h thng sn xut cy.Phng php sn xut cy l mt phng php dc ng dng t lu v c nhng u nhc im nht nh sau y :u im : v c dng khi ln nn c kh nng tch tr lu,tin li cho vic vn chuyn i xa v dng bo qun thc phm lu ngy.Phng php sn xut n gin, cc thit b dng cho h thng c th ch to c trong nc v khng i hi cc thit b c bit.Nhc im : chi ph vn hnh ln do phi tri qua nhiu khu trung gian nh: vo nc,ra ,vn chuyn...chi ph nhn cng lao ng ...chi ph u t ban u ln :chi ph xy dng b , b nhng ,kho bo qun sn phm...Tn tht nhit ln do qu trnh t sn xut n s dng phi tri qua nhiu khu trung gian.CHNG II: TNH KT CU B :I. Kt cu tng ,nn v np b :1. kt cu s b v quy trnh sn xut: b gm 1 b nc mui dc chia lm 2 ngn : 1 ngn t dn lnh cn 1 mt ngn t cc khun lm .Nc mui tun hon trong b nh bm tun hon .Nc mui t trong ngn cy c bm y vo ngn c dn bay hi (dn lnh xng c hoc dn lnh ng ng ). y nc mui c lm lnh v c y vo ngn cy .Cc cy thng c b tr thnh cc linh ,cc linh c t 5 n 7 khun ty theo c b .Cc linh chuyn ng trong b nh h thng vt y v chuyn dng ngc chiu vi nc mui .Khi thnh ,c linh s c cu trc nng ln khi b a sang nhng vo b tan gi trong khong t 2 n 4 pht sau dc a ln bn lt tho khun .khun c a n h thng vi rt t ng.Nc c y khong 90% khun(khi lm lnh nc gin n khng trn ra b lm gim nng nc mui dn n tn tht nhit) ri linh c a n u kia ca b ,khi linh chuyn ng ht chiu di ca b l sn sng ra khun.2. kt cu tng bao :B thng c xy bng gch sau c bc cch m v cch nhit,lp trong cng l lp thp tm dy t 5 n 6mm.C th b tr cc lp kt cu theo s sau: TT Lp vt liu dy (mm)H s dn nhit (w/m.k)H s dn m (g/mhMpa)1 Lp va xi mng 10 0,93 902 Tng gch 1100,82 1053 Lp va xi mng 10 0,93 904 Lp hc n qut lin tc 1 0,18 0,865 Lp giy du chng thm20,18 1,356 Lp cch nhit (polystirol) 0,047 7,57 Lp giy du chng thm20,18 1,358 Lp thp tm 545,3Mt ct tng bao : n mn hc K THUT LNH NG DNGTrang 2LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNGCh thch :1.lp va xi mng2.lp tng gch3.lp hc n dn giy du4.lp cch nhit polystirol5.lp thp tmTng chiu dy cc lp ca kt cu tng: ( ) ( ) [ ] 34 , 0 2 , 0 005 , 0 02 , 0 . 2 001 , 0 11 , 0 01 , 0 . 2 + + + + + + cn i m =340 mm3. kt cu cch nhit nn :nn b c kt cu nh sau :di cng l lp lm nn v t m k sau l lp b tng dm M200 dy 150200 mm,lp cch m bng hc n dy 1mm,lp giy du dy 12 mm ,lp cch nhit polystirol ,lp giy du dy 12 mm,lp b tng ct thp dy 66 100 mm,lp ct lt mng dy t 1015 mm v cui cng l lp v b bng thp tm dy 56 mm.TT Lp vt liu Chiu dy(mm)H s dn nhit (w/m.k)H s dn m(g/mhMPa)1 Lp thp tm 52 Lp ct lt mng 10 3 Lp b tng ct thp 100 1,6 304 Lp giy du chng thm 2 0,18 1,355 Lp cch nhit 0,047 7,56 Lp giy du chng thm 20,18 1,357 Lp hc n qut lin tc 1 0,18 0,868 Lp b tng dm 150 309 lm nn v t m k n mn hc K THUT LNH NG DNGTrang 3LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNGMt ct nn b:Ch thch :1. lp thp tm2. lp ct lt mng3. lp b tng ct thp4. lp giy du 5. lp cch nhit polystirol6.lp hc n dn giy du7.lp b tng dm M2008.lp lm nn v t m kTng chiu dy ca cc lp kt cu nn :( ) + + + + + + + + 470 200 150 1 2 2 100 10 5cn i mm = 0,47 m4.kt cu np b : tin li cho vic ra ,np b c y bng cc tm g dy 30 mm .trn cng c ph lp vi bt do tn tht nhit qua np b kh ln.II. xc nh chiu dy lp cch nhit v kim tra ng sng:1. tnh chiu dy lp cch nhit:t cng thc tnh h s truyn nhit k cho vch phng nhiu lp :k=2 1 11 11 + + + cncnni ii n mn hc K THUT LNH NG DNGTrang 4LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG1]1

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+ + ni iicn cnk1 2 11 1 1 (m)Trong :K: h s truyn nhit ph thuc vo nhit bung lnh ,tra bng 3-3 sch HNG DN THIT K H THNG LNH Nguyn c Li,chn k = 0,23 (w/m2.k)cn:h s dn nhit ca lp vt liu cch nhit ,i vi vt liu l polystirol tra bng 3-1 ta tm ccn=0,047 w/m2.k1 : h s ta nhit ca mi trng bn ngoi (pha nng)ti tng cch nhit .Tra bng 3-7 sch HNG DN THIT K H THNG LNH chn 1 23,3 (W/m.k)2 :h s ta nhit bn trong b ,ta nhit khi nc mui chun ng ngang qua vch ng .Tra bng 3-7 chn 2 = 8 W/m2.ki:b dy ca lp vt liu xy dng th i (m).i: h s dn nhit ca lp vt liu xy dng th i. 18 , 0813 , 45005 , 018 , 0002 , 0 . 218 , 0001 , 082 , 011 , 093 , 001 , 0 . 23 , 23123 , 01047 , 0 1]1

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+ + + + + + cn (m)Chiu dy lp cch nhit phi ly ln hn hoc bng chiu dy tnh c theo kch thc tiu chun .Ta chn tng chiu dy lp cch nhit l 200 mm vi 2 lp x 100. Tng chiu dy ca tng bao ( ) 34 , 0 2 , 0 005 , 0 002 , 0 . 2 001 , 0 11 , 0 01 , 0 . 2 + + + + + + cn imH s truyn nhit thc kt qua cc lp :k m W kcncnni iit. / 2 , 081047 , 02 , 03 , 4505 , 018 , 0004 , 018 , 0001 , 082 , 022 , 093 , 004 , 03 , 23111 1122 1 1+ + + + + + ++ + + 2. Tnhkim tra ng sng :Tra bng 1-1 sch HNG DN THIT K H THNG LNH Nguyn c Li ,ta tm c nhit trung bnh thng nng nht TP.HCM l 37,2oC, m trung bnh =74% .Tra th h-x ta s tm c : ts =31,5oC v t =33oC. khng ng sng b mt bn ngoi b h s truyn nhit thc phi tha mn iu kin sau:

2 111. 95 , 0t tt tkst Trong :1t nhit khng kh bn ngoi ,t1= 37,2oC 2tnhit b ,t2 =-10oC st nhit ng sng ng vi t1 = 37,2oC( )67 , 210 2 , 375 , 31 2 , 37. 3 , 23 . 95 , 0 t tk kVi kt =0,2 tnh c trn ,vy vch ngoi ca b khng b ng sng.CHNG III: XC NH KCH THC B : n mn hc K THUT LNH NG DNGTrang 5LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG xc nh c kch thc ca b phi cn c vo s lng ,kch thc ca cy ,linh ,dn lnh v cch b tr dn lnh ,loi khun ,h thng tun hon nc mui trong b ...I.Xc nh s lng v kch thc khun :S lng khun dc xc nh da vo nng sut b v khi lng cy :N=mM Trong :M :khi lng trong b ng vi mt m (kg) chnh l nng sut ca b :M =10000 kgm: khi lng ca mi cy (kg).N: s lng khun .Kch thc v khi lng khun c th ly theo kch thc tiu chun theo bng 6-12 sch HNG DN THIT K H THNG LNH Nguyn c Lii vi cc h thng my cy c cng sut ln (trn 5 tn / m )u s dng khun loi 50 kg/cy .N =2005010000 mM khun II. xc nh s lng kch thc linh :Cc khun c b tr thnh cc linh , mi linh gm c nhiu khun . y chng ta s dng loi linh c 7 khun x50kg/cy .s lng linh c xc nh:11nNm vi1m :s lng linh

1n:s khun trn 1 linh N :s khun 57 , 2872001 m chn291 mKhong cch gia cc khun tronh linh l 225 mm,hai khun hai u cch nhau 40 mm mc cu,25 mm hai u l khong cch t linh n thnh trong ca b .Chiu di mi linh :1805 80 150 225 . 7 40 . 2 75 . 2 225 .1 + + + + n LmmChiu rng ca linh :425 mmChiu cao ca linh :1150 mm n mn hc K THUT LNH NG DNGTrang 6LP TCDLO7AKhi lng cy Khi lng khunKch thc khun Thi gian ng cao y ln y bKg Kg mm mm mm h3,5 3 300 340x60 320x40 412,5 8,6 1115 190x110160x80 825 11,5 1115 260x130280x1101250 27,5 1115 380x190340x16016 GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG180542525 7540225 225 225 25 22540225 75123Kch thc linh c 7 khun 50 kg1. khung linh 2. v tr mc cu3. khun 50 kgIII. Xc nh cc kch thc bn trong b :Kch thc b phi b tr cc linh ,dn lnh, b cnh khuy v cc khe h cn thit nc mui chuyn ng tun hon .C hai cch b tr dn lnh :b tr dn lnh mt bn, khun mt bn v cch th hai hay c sdng hn l b tr dn lnh gia b (c rng t 600-900mm)hai bn b tr hai dy linh i xng,cch ny c u im l c hiu qu truyn nhit cao v tc nc mui chuyn ng cng ng u hn .1. Xc nh chiu rng b :A L W + + 4 . 2W :Chiu rng ca b.L:Tng chiu di ca hai linh b tr hai bn dn lnh (mm):Khe h gia linh v vch trong ca b (mm) A:Chiu rng cn thit lp t dn lnh,t 600-900mm,i vi b c cng sut 10 tn/m chon A = 700 mm.4410 700 25 . 4 1805 . 2 + + W(mm)2.Xc nh chiu di b :b m C B l .2+ + B :Chiu rng cc on h lp t b cnh khuy v v tun hon nc, chn B =600 mmC: Chiu rng on h cui b,c = 500 mm.b :Khong cch gia cc linh c xc nh da trn rng ca linh v khong h gia chng :b = 475 50 425 +mm2m :S linh dc theo chiu di trn mt dy , vi 291 m

linh , b tr dn lnh gia,cc linh c b tr thnh hai dy i xngvy s linh trn mt dy 152 m n mn hc K THUT LNH NG DNGTrang 7LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG8225 475 . 15 500 600 + + lmm3. Xc nh chiu cao ca b :chiu cao ca b phi ln c khong h cn thit gia y khun v b. Mt khc pha trn linh l mt khong h c 100mm, sau l lp g dy 30mm dng lm np b.i vi ccb c cng sut t 5 tn/m tr ln thng c tng chiu cao l 1250 mm.Bng thng s kch thc bn trong ca b:S khun 200Tng s linh 29S dy linh 2S linh trn mt dy 15 h gia cc linh (mm) 50B rng A(mm) 700Chiu di(mm) 8225Chiu rng(mm) 4410Chiu cao (mm) 1250 Kch thc linh : S khun/linh 7 B di(mm) 1805B rng(mm) 425Chiu cao (mm) 1150 Kch thc khun :Khi lng cy (kg) 50Khi lng khun (kg) 27,2Chiu cao (mm) 1115y ln (mm) 380 x 190y b (mm) 340 x 160 n mn hc K THUT LNH NG DNGTrang 8LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG600 m2 x 4251925A1925500B tr b vi linh 7 khun IV. Xc nh thi gian lm :Thi gian lm cy c xc nh theo cng thc :( ) B b btAm+ 0 0. . Trong : : thi gian lm (gi)mt: nhit trung bnh trong b (oC) ,chnmt= -10oC0b: chiu rng khun (m),ly cnh ngn nht ca tit din ln nht ca khun.0b= 0,19 mA,B l cc hng s ph thuc vo t s n = 00ba, l t s gia cnh di v cnh ngn ca y ln khun 2190380 n.Vi n = 2 chn A = 4540 v B = 0,026 ( ) 6 , 18 26 , 0 19 , 0 . 19 , 0 .104540 + giCHNG IV: TNH NHIT B :Dng nhit tn tht qua b c tnh bng cng thc :Q = Q1+Q2+Q3+Q4+Q5(w)Q1: dng nhit i qua kt cu bao che ca b .Q2: dng nhit lm lnh khun v ng Q3: dng nhit do thng gi ( y bng 0)Q4: dng nhit do vn hnhQ5: dng nhit do sn phm h hp ( y bng 0)I. Dng nhit truyn qua kt cu bao che:V b c t trong nh xng nn kh nng b tn tht nhit do bc x mt tri rt t, v vy tn tht nhit qua kt cu bao che ch yu gm 3 thnh phn :Nhit truyn qua tng b :Q11Nhit truyn qua np b :Q12Nhit truyn qua nn b :Q13 n mn hc K THUT LNH NG DNGTrang 9LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG Q1 = Q11 + Q12 + Q13Tn tht lnh qua kt cu bao che c xc nh theo cng thc 4-2 trang 77sch HNG DN THIT K H THNG LNH Nguyn c Li :( )2 1t t F k Qt Trong : tk: h s truyn nhit thc ca kt cu bao che.F : din tch b mt ca kt cu bao che.1t: nhit mi trng bn ngoi.2t : nhit trong b.1. xc nh chnh lch nhit :- i vi tng ngn : t 2 1t t l chnh lch nhit gia khng kh bn ngoi b v bn trong b. Theo bng 1-1 77sch HNG DN THIT K H THNG LNH Nguyn c Li, t1 c chn l trung bnh cng nhit ti cao ghi nhn c ca thng nng nht: t1 37,3oC, nhng do b c t trong nh xng nn ta ly thp hn 4-5oC (chn = 5) t1 = 32,5oC.Nhit bn trong b l :-10oC 3 , 42 ) 10 ( 3 , 32 toC- i vi np b t l chnh lch nhit gia khng kh bn ngoi b vi lp khng kh bn trong b (di np b ),nhit lp khng kh ny ly chnh lch vi nhit ca b vi (chn bng 5oC ) ( ) 2 , 37 5 3 , 32 toC- i vi nn b, 3 , 42 ) 10 ( 3 , 32 t oC2. Cc kch thc ca b :cc kch thc tnh c u l kch thc bn trong, mun tnh kch thc bn ngoi ta phi cng thm chiu dy ca cc lp kt cu tng .Chiu di v chiu rng ca kt cu tng c tnh t tm ca cc tng bao:chiu di =8225 + 340 = 8565 mm =8,565 mchiu rng =4410 + 340 = 4750 mm = 4,75 mchiu cao ca b c tnh t mt nn ngoi n thnh b :chiu cao =1720 470 1250 1250 + +n mm = 1,72 mTng din tch ca cc mt tng bao ;( ) [ ] 8 , 45 72 , 1 . 75 , 4 565 , 8 . 2 + tF m2 Din tch ca np v ca nn b c xc nh theo kch thc bn trong b : 27 , 36 41 , 4 . 225 , 8 F m23. H s truyn nhit thc t qua cc b mt bao che:i vi kt cu tng :kt = 0,2 W/m2.ki vi np b :2 1'1 11 + +nK1: h s ta nhit bn ngoi t khng kh trong nh xng ln np b,W/m2k2' : h s ta nhit bn trong, t np b ra lp khng kh di np b, W/m2kTra bng 3-7 sch HNG DN THIT K H THNG LNH Nguyn c Li, ta chn 1 = 23,3 W/m2k v 2' = 7 W/m2k. : chiu dy lp np bng g : = 30 mm:h s dn nhit ca g : = 0,2 W/m.k n mn hc K THUT LNH NG DNGTrang 10LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG978 , 2712 , 003 , 03 , 2311+ +nKi vi nn b : h s truyn nhit thc t qua nn ly theo gi tr ca h s truyn nhit quy c :Vng rng 2m dc theo chu vi tng bao : kt = 0,47 W/m2kVng rng 2m tip theo : kt = 0,23 W/m2kVng cn li : kt = 0,12 W/m2k82 , 0 12 , 0 23 , 0 47 , 0 + + nk W/m2kTn tht lnh :STT Tn kt cu Kch thc(m) Fi (m2) Ki (W/m2k)t( oC)Q (w)1 Tng8,565 x 4,75 45,8 0,2 42,3 387,4682 Np4,41 x 8,225 36,27 2,978 37,2 40183 Nn 4,41 x 8,225 36,27 0,82 42,3 1258,06Tng : Q1 = 387,468 + 4018 + 1258,06 = 5663,5II. nhit ng v lm lnh khun :2Q 21 21 2Q Q Q + 1. Dng nhit lm lnh nc : 21Q Q21 = 0.qE(w)E : Nng sut b ( kg/m): thi gian ng ( giy), = 18,6.3600 = 66960 giy0q: nhit lng cn lm lnh 1 kg nc t nhit ban u n khi ng hon ton, 0qc xc nh theo cng thc :2 1 0t C r t C qpd pn+ + pnC: nhit dung ring nc,pnC = 4186 J/kgr : nhit ng c ca nc ,r = 333600 J/kgpdC:nhit dung ring ca nc ,pdC = 2090 J/kg1t : nhit u vo ca nc, chn 1t= 30oC2t : nhit ca cy , chn 2t= -7oC473810 7 2090 333600 30 . 41860 + + q , J/kg70760669604738101000021 Q (w) = 70,76,kw2. Nhit lm lnh khun :22Q ( )2 122k k pkt t Cm Qm: tng khi lng khun (kg), m = 200.27,2 = 5440 kgpkC: nhit dung ring ca khun,pkC = 460 J/kg (khun lm bng thp)1 kt : nhit ban u ca khun bng nhit ban u ca nc = 30oC2 kt: nhit khun sau khi nc hon thin, ly nh hn nhit trung bnh ca cy t 2 3oC, chn2 kt = -10oC( ) [ ]86 , 14946696010 30 . 460 . 544022 Q ,w n mn hc K THUT LNH NG DNGTrang 11LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG86 , 72254 9 , 1494 707602 + Q,wIII. Dng nhit do vn hnh: 4Q1. nhit do b cnh khuy gy ra: 41QB cnh khuy c b tr bn ngoi b mui, nhit nng do b cnh khuy to ra c xc nh theo cng thc sau: N Q 100041 : hiu sut ng c in, = 0,8 0,95. Chn = 0,8N : cng sut ca b cnh khuy.Chn my cnh khuy dng cho b c cng sut 10 tn :Model Tc (vng/pht)Lu lng (m3/pht)Cng sut (kw)Nng sut b (tn)230VGM 1000 12,8 1,5 10-141200 5 , 1 . 8 , 0 . 100041 Q w 2. Nhit do nhng cy : 42QTn tht nhit do lm tan c tnh theo cng thc: 0 042. . . . .qf nqg n Q , wn: s khun , n= 200 khun.g: khi lng phn tan.0q: nhit lng cn thit lm 1 kg nc t nhit ban u n ng hon ton,0q= 473810 , J/kgf: din tch b mt cy : i vi cy loi 50kg/cy c f = 1,25 m2: b dy phn tan khi nhng (m) c th tho ra khi khun, = 0,001 (m): khi lng ring ca nc : = 900 kg/cm3: thi gian ng , = 66960 giy.159266960473810. 900 . 001 , 0 . 25 , 1 . 20042 Q, w2792 1592 12004 + Q , w + + + + 16 , 75613 2792 86 , 72254 5 , 56634 2 1Q Q Q Q , wCHNG V: TNH TON CHU TRNH V CHN MY NN:I. Tnh chn cc thng s ca ch lm vic:1. cc thng s cho trc:Cng sut b cy: 10 tn/mNhit b: -10oCMi cht lnh: NH32. Tnh nhit ngng t: ktChn mi trng lm mt ca h thng l nc tun hon qua ng trao i nhit. So vi khng kh th nc lm mt c nhng u im sau:H s ta nhit cao hn nn lm mt tt hn.t chu nh hng ca thi tit.- Tnh nhit nc vo v nc ra thit b ngng t:Khi s dng nc tun hon qua thp gii nhit ly nhit nc vo thit b ngng t ( 1 wt) cao hn nhit nhit k t t 3 4oC (chn = 3oC) n mn hc K THUT LNH NG DNGTrang 12LP TCDLO7A GVHD: L QUANG HUY HSTH: PHNG XNG CPHM MNH HNG1 wt = 36 3 33 3 + +ut ,oCNhit nc ra khi thit b ngng t2 wt cao hn1 wt 2-6 oC, chn = 4oC40 4 362 + wt oCNhit ngng tkt cao hn nhiot nc ra khi thit b ngng t khong t 3 5 oC (chn bng 3oC).43 3 40 32 + + w kt t oC.Vi 43 kt oC, tra bng 2-2: hi bo ha NH3 sch MY V THIT B LNH-Nguyn c Li-Phm Vn Ty chn kp16,895 bar = 1,6895 Mpa.3. Chn nhit bay hi:0tNhit bay hi ca mi cht lnh ph thuc vo nhit ca b(10 btoC), v my cy l h thng lnh gin tip dng cht ti lnh l nc mui. Nhit nc mui ly thp hn nhit b t 8 10oC (chn bng 8 oC) v nhit si ca mi cht ly thp hn nhit nc mui t 5 6 oC (chn bng 5 oC).0 0 t bt t , oC0 t: hiu nhit yu cu, 13 5 80 + t oC bt: nhit b .23 13 100 toC, tra bng 2-2 tm c0p = 1,6655 bar = 0,16 Mpa4. Chn cp ca chu trnh:T s nn : 0ppk = 1 , 106655 , 1895 , 16