Thermal Analysis Validation for Different Design Tubes in a Heat Exchanger

Transcription

1 Thermal Analysis Validain fr Differen Design Tubes in a Hea Exchanger Rshan. V. Marde, Ashk. J. Keche Deparmen f Mechanical Engineering, MIT, Aurangabad (M., India Aricle Inf Aricle hisry: Received 2 January 2015 Received in revised frm 10 January 2015 Acceped 20 January 2015 Available nline 31 January 2015 Keywrds Hea Exchanger, Waer, Al2O3-waer based, Opimal Design, Thermal analysis, Cmpuainal Techniques 1. Inrducin Absrac In a Hea Exchanger, cnsiss f bundle f ubes. One fluid s hrugh he ubes while he secnd fluid s space beween he ubes and shell. Tubes plays an impran rle while exchanging hea frm h fluid cld fluid. Alhugh hey are n specially cmpac, heir rbusness and shape make hem well suied fr high pressure perains. They have larger hea ransfer surface area vlume rai han he ms f cn ypes f hea exchangers, and hey are manufacured easily fr a large variey f sizes and cnfigurains. The main design bjecives here are accdae hermal expansin, furnish ease f cleaning, r prvide he leas expensive cnsrucin. T ge rbus, leas expensive and echnically sund design, we will be dealing wih fur differen designs viz. Circular Tube, Ellipical ype(oval, Twised ype and Cil ype Alng wih cnsrucin issue we cme acrss he difficulies in imprving hea ransfer raes, which means have high effeciveness, we were in cmprmise he design and rbusness. In rder achieve he maximum hea ransfer rae an analysis is made n single ube fr differen designs wih w differen fluids (Waer and Al2O3-waer based an fluid in a shell and ube hea exchange This paper shws hw maximum hea ransfer rae has been achieved by cmparing fur differen designs and geing pimal design sluins using cmpuainal echniques. T measure he perfrmance f differen designs, is mdel is suiably designed and fabricaed s as perfrm experimenal ess. Thermal analysis has been carried u fr fur differen designs wih w fluids and n he basis f cmparaive resuls is made which ne give he bes hea ransfer raes. Afer he mdificain f design an experimenal validain is carried u validae he resuls frm analysis. 2. Lieraure Review Crrespnding Auhr, address: rshan.marde@gmail.cm All righs reserved: hp:// hell and Tube Hea exchanger are he basic ypes f hea exchanger ne f he fluids hrugh a bundle f ubes enclsed by a shell. The uer fluid is frced hrugh a shell and i s ver he uside surface f he ubes. uch an arrangemen is emplyed where reliabiliy and hea ransfer effeciveness. In rder achieve he maximum hea ransfer rae an analysis is made n single ube wih w differen fluids (Waer and Al2O3-waer based an fluid in a shell and ube hea exchange Wih relae same have a maximum hea ransfer rae his paper gives varius pimal design sluins using cmpuainal echniques. T measure he perfrmance f differen designs, is mdel is suiably designed and fabricaed s as perfrm experimenal ess. Thermal analysis has been carried u fr differen design wih w fluids and n he basis f cmparaive resuls is made which ne give he bes hea ransfer raes. AlaHasan [1] experimenally invesigaed five val ubes and cmpared wih ha fr a circular ube in a crss way and cncluded ha val ube gives higher hea ransfer resuls. The ucme was aken fr cmparing resuls f val and circular ubes which helped fr pimized design. Abdul Kareem Abbase al [2] shws hea ransfer augmenain due wising parameer was invesigaed in a wised ube f recangular/square crss secinal area. Als swirling increases inernal mixing prcess which enhances inernal hermal equilibrium. The hea ransfer cefficien als increases as Reynlds number increased as velciy cmpnens are increased. This relain shwn was used as funcin and ne f he parameer in design. u The Mn Than e al [3] In his paper daa is evaluaed fr hea ransfer rae having spiral ubes and pressure drp and checking wheher he assumed design saisfies all requiremen r n by using cmpuainal echniques. aisfied design fund was used fr cil ype ubes fr analysing he hea ransfer rae. Jay J. Bhavsare al [4] bjecive f his paper is design and analyze f spiral ube hea exchange In his newly prpsed design h fluid s in axial pah while he cld fluid s in a spiral pah. The presened wrk was used in spiral ube designand has high hea ransfer rae cmpared wih helical cil hea exchanger and spiral plae hea exchange P. M. Deshpandee al [5] They sudied hriznal spiral cil ube (HTC fr varius frces (viscus, buyancy and cenrifugal frce acing n fluid elemen in cil; f which he cenrifugal frce is predminan and resuls in secndary. This phenmenn als depends n he physical prperies f fluid a a given emperaure. They als cncluded ha as he cil diameer reduces he curvaure rai increase ha increases he pressure drp. Relain was used fr designing cil ype ubes. 3. Design f Tubes 3.1 Circular ype ube Di=

2 D=19.05 Thickness==18BWG Lengh= 100m 3.3 Twised Type Tube Lengh (L = 100m Thickness ( = 1.2 Breadh f recangular ube (b = 22 Deph f recangular ube (d = 8. f wiss ( = 05 (Each a 20 urce: 1 Design f Hea Exchange equipmen. 2 Design shell and ube hea exchanger [Rajiv Mukherjee Engineers India Ld.] 3 Handbk f TEMA. 3.2 Ellipical Type Tube (Oval Axis Rai = R a =3 Majr Axis = 2a=22 Minr Axis =2b=8 urce: 1 Thermal-Hydraulic perfrmance f val ubes in a crss- air- ALA-HAA 2 rucural and Thermal Analysis f Hea Exchanger wih Tubes f Ellipical hape -awras H. MsafaQusay R. Al-Hagag urce: 1 Twised Tube Hea Exchanger Technlgy-R. Dnald Mrgan 2 Twis parameer influence n hea ransfer cefficien augmenain fr a square wised ube- A. Kareem 3.4 Cil Type Tube Diameer (D0 =3/4 =19.05 Lengh (L = 100m umber f urns (n = 6 Thickness ( = 1.2 Effecive cil diameer (D = 52 Pich (p fr helical i is aken as 1.5D0 3m T knw he unknwn parameer, D (Cil Diameer Equain is given by, L = 79

3 1000 =6 IB = = = Therefre, R = D 52 urce: 1 AME German AD-Merkbla 2 Eurpean pressure equipmen direcive (PED Designing a helical-cil hea exchangers- K. Ramchandra 4. Experimenal Wrk We achieved emperaure range by placing hermcuple a apar fr fur design ubes. T1 = Temperaure a inle f ube. T2=Temperaure a a disance f 25m frm inle. T3= Temperaure a a disance f 50m frm inle. =Temperaure a a disance f 75m frm inle. T5=Temperaure a ule f ube. 4.1 Fr (Waer Waer as a fluid Fr circular ype Temperaures a differen pins f ube (⁰C T3( 50 ( T5( Fr Ellipical ype Temperaures a differen pins f ube (⁰C T3( 50 ( 75 T5( Fr Twised ype Temperaures a differen pins f ube (⁰C T3( 50 ( 75 T5( Fr Cil ype Temperaures a differen pins f ube (⁰C T3( 50 ( 75 T5( Calculains fr hea ransfer cefficien 5.1 Fr case I (waer-waer Fluid prperies fr waer are: μ = 0.467xs/ ρ = 1000 kg/ Cp = 4.18xJ/kg⁰k k w = 0.625w/m⁰k Fr Circular ype: A c/s = (π[d 0 2 -d i 2 ] 80

4 = (π[ ] = 6.73x10-5 m 2 As Reynlds number fr circular ube is given by, Re=ρvd/μ (1 find V, We knw cninuiy equain, Q=AxV As densiy = mass/vlume (ρ=m/vl. Therefre, m= A x ρ x V (1a Fr mass rae =m=0.14kg/sec 0.14 = Vx1000x6.73x10-5 V= = 2.08m/s V= 2.08 m/s, Re = Frm Reynlds number, is urbulen.(re>2000 Type f. Design Crrelain used fr urbulen is; u= = CRe a Pr b-m (1b Where C = fr gases, = fr nn-viscus liquids, = fr viscus liquids u= = CRe a Pr b-m = 0.023xRe 0.8 Pr (1/3 x1 = 0.023x( x(pr (1/3 (1c Pr =μcp/k. (Depend nly n fluid prperies = 3.12 Equain 1c, = x ( x (3.12 (1/3 ȟ = w/m 2 ⁰K Likewise, calculaed hea ransfer rae fr her hree ubes are: V Re Pr h P Q є 1 Circular Ellipical Twised Cil Calculaed ucme f Case-II (AL2O3-Waer as a an fluid Fluid prperies fr Al 2 O 3 - waer (0.1 % cncenrain are: μ=0.35 cp=3.5xs/ ρ=1022 kg/ Cp=3.1xJ/kg⁰k k=0.72w/m⁰k, Prandl number bained frm calculain is cn fr all ype f deign as fluid prperies are cn, viz 1.5 Type f. Design V Re H Q є 1 Circular Ellipical Twised Cil Thermal Analysis f Tubes wih w differen media 6.1 CFD-Resuls f Case-I rae: 0.14 kg/s Temperaure Cnurs 1. Fr Circular ube V Re Pr h Q є Circular Ellipical Twised Cil 81

5 2. Ellipical Tube : 3. Twised Tube : 4. Cil Tube: (Fr hree planes i. Temperaure Cnurs ii. h-cnurs fr inner wall 6.2. CFD-Resuls f Case-II (Al 2 O 3 as a an fluid: We have fcused nly n wised ype ube as in abve sequence f calculains we are geing high hea ransfer rae and high effeciveness by calculain. 82

6 In abve clurful diagram, if we cmpare d he wised ube emperaure cnurs wih waer as base fluid, an CFD analys may bserve ha fr 4 h and 5 h plane we are geing blue clur cnurs as cmpared case 1, which direcly shws he emperaure gradien in abve case is high alng wih effeciveness. 7. Cnclusin This sudy shws he design and hermal analysis f differen ubes. Experimenally, same designs are made and resuls are evaluaed. Wih relae same design ubes are hermally analysed in AY sfware and cmpared bh he resuls. Afer cmparing he resul fr bh waer-waer (Case-I and waer-al2o3 (Case-II fr fur differen References [1] K. riharsha, V. R. Mamilla, rengh Analysis f Tube Tube hee Jin in hell and Tube Hea Exchanger, IJETR, 1(4, 2012 [2] Haran, R. Reddy, Thermal Analysis f hell and Tube Hea Ex-Changer Using C and Ansys, (IJCTT, 4(7, 2013 [3] Effecively Design hell-and-tube Hea Exchangers, Chemical Engineering Prgress, 1998 [4] Paresh Pael, Amieshpaul, Thermal Analysis Of Tubular Hea Exchanger By Using Ansys, (IJERT, 1(8, 2012 ubes we are in cnclusin ha wised ype f ube is giving high hea ransfer cefficien as cmpared her i.e 1.14 mre. Alng wih effeciveness, wised ube is a higher side by accrding my research ne shuld g fr wised ube. Hwever, a gd undersanding f he underlying principles f exchanger design is needed use his sfware effecively. The pssibiliy increase in hese characerisics using he laes echnlgy and varius mehds has raised applicain range f hese designs. Mdified design ubes are having grea applicains due heir large hea ransfer area and high hea ransfer cefficiens. They are used in many indusrial prcesses like wase waer reamen, refrigerain, wine and beer making, perleum refining [5] Vikil D. Malwe, M. B. Mawale, Thermal Analysis f Hea Transferring Cmpnens in he Pwer Plan - A Review, (IJERT, 2(1, 2013 [6] TEMA, andards f he Tubular Exchanger Manufacurers Assciain, ew Yrk 7 h ed., 1988 [7] D. Buerwrh, A. R. Guy, J. J. Welkey, Design and Applicain f Twised Tube Hea Exchangers [8] W. M. mall, R. K. Yung, Hea Transfer Engineering, 1, 1979 [9] P. Pael, Amieshpaul, Thermal Analysis Of Tubular Hea Exchanger By Using Ansys, Prc. IJERT, 1(8, 2012 [10] C. C. Genry, Chem. Engng. Prgress, 86(7,