Analysis of Heat Transfer of Ribbed Turbulent Channel using ANSYS

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1 e Inenaional Jonal on Emeging Technologies (Special Isse NCETST-017) 8(1): 36-4(017) (Pblished by Reseach Tend, Websie: ISSN No. (Pin) : ISSN No. (Online) : Analysis of Hea Tansfe of Ribbed Tblen Channel sing ANSYS Mayan Bhola Assisan Pofesso Depamen of Mechanical Engineeing, Amapali Gop of Insies, Haldwani, (Uaahand), India ABSTRACT: This pape pesens he -D nmeical simlaion fo hea ansfe and ficion faco chaaceisics of ibbed blen channel, wih boom plae applied o consan fl hemal bonday condiion, and ppe plae is inslaed. The flid domain is designed sing ANSYS Wobench sofwae and simlaed sing ANSYS Flen sofwae, based p on finie elemen mehod. Paamees lie Nssel nmbe, ficion faco and hea ansfe coicien hae been obained fo he design, and conos of empeae and elociy ae pesened.the gooe lengh/ib lengh (B) o channel heigh (H) aios ae aen as 0.5, 0.75, 1.0 fo he geomey. The main objecie of he wo pefomed was o find he bes B/H aio nde simila bonday condiions. Keywods: Tblen channel, ANSYS, -D Analysis, Ribbed geomey, Realizable ε blence model I. INTRODUCTION In ecen yeas many eseaches hae conibed fo enhancing hea ansfe chaaceisics of paallel plae hea echange wih one plae inslaed and ohe sbjeced o consan fl hemal bonday condiion. Lo e al. (004) condced epeimenal sdies o eamine he foce conecion and flow ficion chaaceisics of flly deeloped blen flow in ai cooled hoizonal eqilaeal iangla dc wih inenal sface fabicaed wih nifomly spaced sqae ibs. They sdied he ec of dc geomey as well as Reynolds no. on he es ig, and deemined he opimm elaie ib heigh and elaie ib o ib spacing coesponding o maimm hemal pefomance. Sah and Gandhi (014) nmeically inesigaed he ec on hea ansfe and flow field chaaceisics de o an inclined ib wih a gap on sola ai heae dc. They deemined ha Realizable ε blence model wih sandad wall fncion poides bes esl fo hese ind of poblems o be soled nmeically. Tasmi e al. (00) condc ed a 3-D nmeical compaion fo deemining flow and hemal fields oe fll-span and discee aay of ib aached o a channel wih 90 inclinaion agains he flow diecion. They pediced ha geneaion of oices is ecie o edce he aea of he flow eciclaion egion and is ecie o incease he wall hea ansfe. Vijiapap and Ci (007) simlaed blen flow in a ibbed pipe sing lage eddy simlaion The spacing beween he ibs is aied o fom hee epesenaie ypes of sface oghness: d- ype, inemediae, and -ype. I has been noed ha boh inemediae- and -ype oghness podce song oghness ecs wih dominan pesse esisance, b he flows wih diffeen ypes of sface oghness ehibi qie diffeen chaaceisics in ems of mean flow qaniies and coheen eddy sces. Singh and Singh (014) pefomed a nmeical analysis of hea ansfe in blen channel flow sing iangla wingle ype longidinal oe geneao of diffeen angle a Reynolds nmbe 10,000. They obseed ha hea ansfe inceases wih incease in angle of aac fo same Reynolds nmbe. And conclde incease of pmping powe o flow flid hogh he channel. Mashila and Vae (014) condced a 3-D compaional analysis of hea ansfe agmenaion and flow chaaceisics de o hee diffeen aificial oghness geomeies in fom of blaos, pin-fin and conical fins on heaed wall of ecangla sola ai heae dc. They sed Realizable ε blence model wih enhanced wall eamen fo caping physics a nea wall. Kma and Agawal (014) also condced a CFD analysis o deemine ec on hea ansfe coicien and ficion faco de o ecangla ibs on ecangla dc of sola ai heae. Effec of apezoidal ibs on hea ansfe coicien of absobe plae of sola ai heae sed fo low empeae heaing ppose, and agicle dying ppose was sdied by Singh and Baaia (013). They conclded ha by imposed aificial oghness ficion faco also inceases wih incease in Nssel nmbe. Sohana Bhola 36

2 (010) condced a simlaion o deemine he flid flow and hea ansfe chaaceisicss hogh a ib- he sed oghened dc of sqae coss-secion, SIMPLEC algoihm o cople pessee and elociy in he solion. He conclded ha, hogh agmenaion inceases he hea ansfe b he consan blen Pandl nmbe of he blen model sed also has a significan ec on he simlaion esls of hea ansfe. Deylami e al. (013) condced a nmeical inesigaion o sdy he ec of cogaion on hea ansfe and pesse dop in a cogaed channel. They made he changes in ib-heigh o channel-heigh and also hee concen was o find adeqae blence model fo nmeical solion.bhola and Singh (015) nmeically inesigaed he epeimens of Loenz e al. (1995) sing Realizable K- blen model and esls wee fond close o he esls of Eiamsa-ad and Pomonge ( 008) fo gooed blen channel. In he pesen eseach, nmeical inesigaion of -D ibbed blen channel is condced o eify he siable B/H aio fo bee hea ansfe fo sch geomey. II. GEOMETRY OF THE PRESENT PROBLEM The geomey ceaed fo analysis was made of alminm of 0.68 m lengh and has hydalic diamee of 0.08 m in which ai flow occs. Posions made on plae wee ib wih 9 ibs. Thesee geomeies ae sed fo sdying he ecs of he aiaion of geomeies on he pefomance of plae hea echange. Vale of S will change accoding o he aiaions in B.The dimension of he consan hea fl es secion menioned aboe is he same as he gooed channel of Eiamsa-ad and Pomonge [4], b insead of gooes, ib posions ae sed. A nifom ecangla mesh is sed o esole he lamina sb-laye. To obain gid independence solion, nmbe of cells is aied beween 55,000 and 158,000 meshes. The mean inle elociy beween 1.19 and.19 m/s is based on Reynolds nmbe cied aboe, zeo pesse gadiens a he ei and no slip wall bonday condiions ae aen fo he pesen compaion. In peios eseach, Chabe e al. [] sggesed ha he calclaion wih - dimensional flow model yields he esls close o measemens as compaed ha wih 3-dimensional flow. In his wo, he D flow is heefoe caied o fo saing compe memoy and compaional ime. Table 1: Geomeic descipion of model. Toal lengh (m) 1.88 Eny lengh (m) 0.8 Lengh of es secion (m) 0.68 Ei lengh (m) 0.4 Rib heigh (e), (m) 0.0 Rib lengh (B), (m) 0.0, 0.03, Disance beween wo plaes (H), (m) 0.04 Lengh of peiod (P),(m) 0.08 Fig. 1. Schemaic diagam fo channel flow configaion. Bhola 37

coniniy, he imeaeaged incompessible Naie Soes eqaions and he enegy eqaion.

3 Bhola 38 Fig.. Geomey of ibbed channel. Fig. 3. Mesh geneaion of Ribbed Channel. III. MATHEMATICAL MODELING The flid domain nde consideaion is goened by he seady - Dimensional fom of he coniniy, he imeaeaged incompessible Naie Soes eqaions and he enegy eqaion. These eqaions can be wien as: A. Coniniy eqaion ( ) 0 1 ) ( B. Momenm eqaion Aial componen [ ] ( ) ( ) ( ) ( ) p 1 1 Radial componen [ ] ( ) ( ) ( ) ( ) w z p 1 1

4 Tangenial componen C. Enegy eqaion 1 [ ] [ ] [ ] [ ] z ( ) [ ( ) ( ) ( ) D. Kappa-Epsilon model ( ) ( ) ] Κ Eqaion [ ] [( l ) ] 1 [ ( l ) ] Whee, G is he podcion em and is gien by G [{( ) ( ) ( ) } ( - Eqaion [ 1 l l ] [( ) ] ( ) ] C S1G C s Hee C s1, C s, and ae he empiical blen consan. The ales of Cμ, C s1, C s, and ae 0.09, 1.44, 1.9, 1.0 and 1.3 especiely. E. Bonday Condiions Flid flow is consideed o be blen. The qaniies U,, ε ae obained by sing nmeical calclaions based on he -ε model fo high Reynolds Nmbe. The bonday condiions ae lised below: 1) A he inle of he channel Uin, 0 in 0.005U in 0.1K in in K in sands fo he admission condiion fo blen ineic enegy and in is he inle condiion fo dissipaion. ) A he walls: 0 ε 0 3) A he ei: P P am Bhola 39 ) Re g ] The Reynolds nmbe based on cicla diamee in case of cicla be and hydalic diamee D h in case of ecangla be, paallel plaes.. U. 0 D IV. SOLUTION PROCEDURE h The ime-independen incompessible Naie Soes eqaions and he blence model wee disceized sing he finie olme mehod. Second ode pwind scheme was applied fo conecie and blen ems. To ealae he pesse field, he pesse elociy copling algoihm SIMPLE (Semi Implici Mehod fo Pesse-Lined Eqaions) was seleced. A he inle, nifom elociy pofile has been imposed. Impemeable bonday condiion has been implemened oe he channel wall while consan hea fl condiion is applied o he lowe wall of es secion. The blence inensiy was ep a 10% a he inle. Two paamees of inees fo pesen case ae: ( 1) Nssel Nmbe () ficion faco. The ficion faco, f is comped by pesse dop, Δp acoss he lengh of es secion, L, haing he hydalic diamee, DhH as 4( ) The hea ansfe is meased by Nssel nmbe which can be obained by V. RESULTS The esls fo smooh plae ae calclaed accoding o he coelaion se by Loenz e.al. [6], fige 4. shows he hea ansfe esls fo ai (Ti 99 K) flow in he channel fo hee diffeen ib widh aios (B/H 0.5, 0.75, 1). In he fige, he Nssel nmbe ae elaedas a fncion of Reynolds nmbe. The esls fo smooh channel is also pesened in he fige fo compaison.i is shown ha he Nssel nmbe inceases wih incease in Reynolds nmbe. In all cases, ibbed channel flow gies highe ale fo Nssel nmbe han ha fo smooh channel flow de o indced blence.the maimm Nssel nmbe is obained fo B/H 0.75.

5 85 75 VARIATION OF NUSSELT NUMBER WITH REYNOLDS NUMBER B/H 0.5 NUSSELT NUMBER B/H 0.75 B/H 1 Smooh plae REYNOLDS NUMBER Fig. 4. Vaiaion of Nssel nmbe wih Reynolds nmbe VARIATION OF FRICTION FACTOR WITH REYOLDS NUMBER FRICTION FACTOR B/H 0.5 B/H B/H REYNOLDS NUMBER Fig. 5. Vaiaion of Ficion faco wih Reynolds nmbe. Bhola 40

X- Velociy fo B/H 0.5 X-Velociy fo B/H 0.75 The incease in Nssel nmbe ales by sing diffeen aios of B/H ae abo 143% o 16%. Fige 5. shows esls fo ficion faco fo diffeen B/H aios.

6 X- Velociy fo B/H 0.5 X-Velociy fo B/H 0.75 The incease in Nssel nmbe ales by sing diffeen aios of B/H ae abo 143% o 16%. Fige 5. shows esls fo ficion faco fo diffeen B/H aios. I is obseed ha he ficion faco deceases wih incease in Reynolds nmbe in all cases de o incease in pesse dop. Maimm ficion faco is fond fo B/H 1. X-Velociy fo B/H 1 Conos of X-elociy a Reynolds nmbe 9000 ae also poided in aboe figes showing he eciclaion zone fo diffeen B/H aios. I is obseed ha wih incease in B/H aio hee is decease in eciclaion zone. B he elociy of flid in eciclaion zone is nealy same fo all hee B/H aio. Bhola 41

7 VII. CONCLUSION Nmeical inesigaion of foced conecion in a wodimensional blen channel wih peiodic ansese ibs on he lowe channel fo eamining hea ansfe and ficion faco is pefomed. I is fond ha Nssel nmbe inceases abo 143% o 16% by se of ibbed posion, and maimm enhancemen is shown by B/H 0.75 wih an incemen of 149%, 160% and 16% fo especie eynolds nmbe, he incemen is abo 6% o 15% when compaed o ohe wo B/H aio. REFERENCE [1]. Bhola, M., Singh, S.,015, Analysis of Hea Tansfe in Tblen Channel Using Gooes, Inenaional Jonal of Science and Reseach, 4, 5, []. Chabe, A., Sahoo, P.K., Solani, S.C., 006, Analysis of Hea Tansfe Agmenaion and Flow Chaaceisics De o Rib Roghness Oe Absobe Plae of a Sola Ai Heae, Renewable Enegy, 31, [3]. Deylami, H.M., Amanifad, N., Sanaei, M., Kohiamali, R., 013, Nmeical Inesigaion of Hea Tansfe and Pesse Dop in a Cogaed Channel, Inenaional Jonal of Engineeing, 6, 7, [4]. Eiamsa-ad, S., Pomonge, P., 008, Nmeical Sdy on Hea Tansfe of Tblen Channel Flow Oe Peiodic Gooes, Inenaional Commnicaions in Hea and Mass Tansfe, 35, [5]. Kma Manoj and Agawal Ashish, 014, Analysis of Hea Tansfe Agmenaion And Flow Chaaceisics De o Rib Roghness of a Sola Ai Heae, Inenaional Jonal of Emeging Technologies in compaional and Applied Science, 8, [6]. Loenz, S., Momilow, D., Leine, W., 1995, Disibion of he Hea Tansfe Coicien in a Channel wih Peiodic Tansese Gooes, Epeimenal Themal and Flid Sciences, 11, [7]. Lo, D.D., Leng, C.W., and Chan, T.L., 004, Foced Conecion and Flow Ficion Chaaceisics of Ai-Cooled Hoizonal Eqilaeal Tiangla Dcs wih Ribbed Inenal Sfaces, Inenaional Jonal of Hea and Mass Tansfe, 47, [8]. Mashila, B.B. and Vae Nilesh, 014, Nmeical Inesigaion of Hea Tansfe Agmenaion in a Recangla Sola Ai Heae Dc, Inenaional Jonal of Engineeing Reseach and Technology, 3, [9]. Sah, R.K. and Gandhi, B.K., 014, Nmeical Simlaion of Hea Tansfe Enhancemen De o a Gap in an Inclined Coninos Rib Aangemen in a Sola Ai Heae Dc, Inenaional Jonal of Adanced Mechanical Engineeing, 4, [10]. Singh Dhaam and Baaia, V.N., 013, CFD Sdy on Hea Tansfe Thogh Sola Ai Heae Absobe Plae wih Sface Roghness, Inenaional jonal of Engineeing Bsiness and Enepise Applicaions, 6, [11]. Singh, A.P. and Singh, N.K., 014, Nmeical Analysis of Hea Tansfe in Tblen Channel Flow wih Longidinal Voe Geneaos, Inenaional Jonal of Reseach in Managemen, Science and Technology,, [1]. Sohana, A., 010, Hea Tansfe and Flid Flow Thogh a Ribbed Passage in Saggeed Aangemen, Ianian Jonal of Science and Technology, Tansacion B: Engineeing, 34, [13]. Tasmi, K., Iwai, H. and Inaoa, K., 00, Nmeical Simlaion fo Hea and Flid Chaaceisics of Sqae Dc wih Discee Rib Tblaos, Inenaional Jonal of Hea and Mass Tansfe, 45, [14]. Vijiapap Sowjanya and Ci Jie, 007, Simlaion of Tblen Flow in a Ribbed Pipe Using Lage Eddy Simlaion, Nmeical Hea Tansfe, Pa A: Applicaions: An Inenaional Jonal of Compaion and Mehodology, 51, Bhola 4

NUMERICAL ANALYSIS OF THERMAL PERFORMANCE OF AN EXTERNALLY LONGITUDINALLY FINNED RECEIVER FOR PARABOLIC TROUGH SOLAR COLLECTOR

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