Multiphase flow dynamics Sirpa Kallio, VTT

Transcription

1 Multihae low dynaic Sira Kallio, VTT 1 Boiling water Turbulent luidized bed Outline Claiication o ulti-hae low Modeling aroache Hoogeneou low odel Lagrangian article tracing General decrition Method or dene uenion (DPM, MP-PIC) Eulerian-Eulerian two-luid odel Algebraic li ixture odel Other aroache Exale: Eulerian-Eulerian odeling o dene ga-olid low

2 3 Multihae low can be claiied according to the cobination o hae: ga-olid (luidized bed, coneying, cobutor, etc.) ga-liuid (ray, nuclear reactor) liuid-olid (crytalliator, edientation, iber uenion) liuid-liuid (oil-water earation) ga-liuid-olid (catalytic cracing) etc. 4 Multihae low can be claiied according to The olue (or a) raction o the diered hae dilute (relaxation tie t < colliion tie t c ) dene t d 18 (Re 1) t 4 d 3 C u D (Re 1) The tye o ditribution o the diered hae hoogeneou heterogeneou (e.g. cluter, ray, loc) The geoetry o the hae interace earated low ixed low diered low

3 5 Multihae low can be treated a ingle hae low when the aount o the diered hae() i ery all the carrier hae i not aected the diered hae() are o no interet In ecial cae ingle hae low can be treated a ultihae low, e.g. in ixing o luid trea o dierent teerature and/or concentration in the decrition o the dierent cale o turbulence A coutational hae in ultihae CFD i not ae a a hae in the hyical ene coutational hae rereent a a oing at a ingle elocity 6 TYPES OF PHASE INTERACTION One-way couling: Fluid low aect article/diered hae Two-way couling: Aboe + diered article odiy luid low Four-way couling: Aboe + article-article interaction

4 7 Multihae low and turbulence ultihae low are tyically by nature turbulent (hae interace ditort the low ield which lead to luctuation in elocitie and other roertie) diered hae odiie carrier hae turbulence big article enhance turbulence all article da turbulence carrier hae turbulence becoe uniotroic carrier hae turbulence enhance dierion and clutering o the diered hae in dene uenion the turbulent luctuation in the dierent hae are trongly couled and oten o a dierent character than in ingle-hae low 8 Aroach 1: Hoogeneou low odel - Silet ultihae CFD odel - Aue that diered hae trael at the ae elocity a the carrier hae - Mixture oentu euation - Mixture continuity euation - Phae continuity euation: tranort o diered hae through diuion - Fat; decribe well article ize and other ditribution - Decribe well eect o turbulence on ixing o the diered hae

5 9 Aroach : Particle tracing ethod alo called Lagrangian aroach utilize the euation o otion o a ingle article initially ued or dilute uenion (one-way and two-way couling) natural decrition or ixture o article with dierent roertie uable or teady tate iulation only in cae with ditinct inlet (eg. ray, burner) can be ued or dene uenion i colliion are accounted or (the o-called icro-cale odel; colicated and low) 10 Euation o otion d t r d d r r r r dt d dt d dt d t t ) ( g according to Maxey & Riley (Phy. Fluid, 6: , 1983) Note: odiied ro the older BBO-euation Force acting on the article: graity + added a + icou drag + Baet hitory eect

6 Validity o Maxey & Riley euation 11 For lainar low (and ean ield o turbulent low) r L 1, r W 1, ru 1 L L i characteritic length cale, W characteritic relatie elocity, U/L the cale o luid elocity gradient or unditurbed low. For turbulent low r 1, r W 1, r 1 and 3 1/ 4 are the Kologorow icrocale o length and elocity: ( ) 1/ 4 i the diiation rate o turbulent inetic energy 1 Euation o otion in Stoe regie (Re <1) Uually iliied: d dt ( ) g 6 r For raidly accelerating or ocillating low thi aroxiation can be oor. Proble can alo be exected when denity dierence between the hae i all.

7 Drag odel 13 a large nuber o eirical correlation exit odel that account article hae and deoration or dilute luid article low, the drag i gien by F 3 4 C D d ( ) Schiller & Nauann correlation C D 0.44 Re 1000 C D Re Re Re Dierion o article Eddy interaction odel/dicrete rando wal odel: a article i aued to interact with an eddy oer an interaction tie The interaction tie i the aller o the eddy lie tie t e and the eddy croing tie t c t e 0.6 t c t ln t u L e u The elocity luctuation during an eddy i obtained by aling a norally ditributed rando unction: u' ( u ' ) ( / 3)

8 Nuerical ethod 15 One-way couling Two-way couling 16 Lagrangian aroach, dilute exale: Pulerized coal boiler: Particle teerature along article trac

9 17 Lagrangian ethod or dene ga-olid low Lagrangian article tracing ethod hae been alied e.g. to luidized bed Seeral aroache that dier in the way a couted article correond to real article: one article can reent either one or a grou o article in the way article-article colliion are treated Dicrete Particle Method (DPM): no colliion (ued or dilute uenion) ot-here aroach (the dicrete eleent ethod, DEM) hard-here aroach Dene DPM, CPFD (coutation article luid dynaic): tatitical aroach 18 Lagrangian ethod or dene ga-olid low: ot- and hard-here odel Sot-here odel o article-article colliion: the intantaneou inter-article contact orce, naely, the noral, daing and liding orce are couted uing euialent ile echanical eleent, uch a ring, dahot and lider. a ery all tie te i reuired (< 1e-6 ) Hard-here odel o article-article colliion: oentu-conering binary colliion interaction between article air-wie and intantaneou ater than ot-here ethod due to longer tie te

10 19 Lagrangian ethod or dene ga-olid low: ultihae article-in-cell ethod (MP-PIC) Eulerian ga hae Lagrangian tracing o arcel o article Ga-article and article-article interaction orce calculated in the eh o the ga hae ro cloure written or Eulerian-Eulerian odel or dene ga-article uenion (inetic theory o granular low, ee later in the reentation) Alo called / iilar odel: Dene DPM (Dene Dicrete Particle Model; Any Fluent) CPFD (Coutational Particle Fluid Dynaic; Barracuda) Decrition o article ize ditribution eay Coare ga hae eh lead to inaccuracie Lagrangian iulation, dene exale: (LES or carrier hae, colliion odel or article-article interaction; Helland et al., Powder Technology, 110, (000)) 0

11 1 Lagrangian aroach, uary oentu and continuity euation or the carrier hae Newton euation or diered hae good or dilute uenion, uable alo or dene uenion i colliion are accounted or decrition o dierion o article in turbulent low reuire large nuber o article at or lainar low; decribe well article ize and other ditribution Aroach 3: Eulerian-Eulerian aroach ingle hae euation (oentu, continuity) are aeraged oer tie and/or olue and/or a article aebly (Newton euation) to obtain ultihae low euation ditribution o hae gien by olue raction odel or hae interaction reuired all hae are decribed a interenetrating continua

12 3 Volue aeraging Aeraging olue Phae interace 4 Starting oint in olue aeraging: Single hae euation + ju condition 0 t g τ t 0 n n A A A A A A A R R σ σ n τ I n τ I n n ) ( ) ( n Unit outward noral ector o hae A Velocity o the interace A R A A R R / = A R interace curature ector σ interace urace tenion A A R = = urace gradient oerator I unit tenor

13 Aeraging 5 ~ Volue aeraging: 1 V 1 V V V dv 1 dv Volue aerage Intrinic olue aerage dv V dv ~ V Ma-weighted (Fare) aerage V Volue raction, 1 V / 6 Continuity: t Eulerian-Eulerian balance euation ~ ~ Moentu: ~ ~ t ( ~ ) τ ~ g M τ M i the interaction orce.

14 7 Turbulent tre ter: τ ~ ( )( ) Coneration o a: 0 Surace tenion: M 1 V, A A σ σ R A R A da 8 Alternatie aeraging aroache olue aeraging tie aeraging eneble aeraging olue-tie aeraging two-te olue-olue or olue-tie aeraging (irt oer the local cale, then oer a larger cale) three-te aeraging

15 9 Cloure or turbulent tre ter no generally acceted turbulence odel exit; araeter in any odel are robably uenion deendent eeral alternatie uggeted ixture turbulence odel: ue ixture roertie to calculate icou tre; alicable or tratiied low and when denitie o the hae are o ae order diered turbulence odel aroriate or dilute uenion turbulence uantitie o the diered hae are obtained uing the theory o dierion o article by hoogeneou turbulence turbulence odel or each hae 30 Cloure or drag orce large nuber o odel exit drag orce i generally written in the or: M 3 4 C D d ( ) Note: in dene low, C D deend on α araeter in drag odel hould be unction o the aeraging cale in inhoogeneou low!

16 31 Decrition o article ize ditribution in the Eulerian-Eulerian ethod Silet way would be to treat each ize cla a a earate coutational hae (ethod o clae) Continuity and oentu euation or each ize cla Coutationally low Nuerical diicultie: at leat earlier erion than Any Fluent 14 roduced non-hyical reult Particle ize ditribution decribed by ethod o oent QMOM (Quadrature Method O Moent) DQMOM (Direct QMOM) In rincile reuire olution o oentu euation or elocitie o the oent Moentu euation can in oe cae be relaced by algebraic euation Nuerical ethod or the Eulerian-Eulerian aroach 3 eeral algorith; uually extenion o ingle hae one e.g. IPSA (Inter Phae Sli Algorith) eror the ollowing te in one iteration loo: ole elocitie o all hae ro oentu euation ole reure correction euation (which i baed on the joint continuity euation) udate reure correct elocitie calculate olue raction ro haic continuity euation

17 33 Exale: iulated olid olue raction in a circulating luidized bed Two-hae low Large article Sall article Three -hae low 34 Eulerian-Eulerian odel, uary oentu and continuity euation or each hae eeral aeraging ethod ued to derie the euation bet alternatie or dene uenion with large elocity dierence/acceleration oten ery low article ize and other ditribution diicult to account or

18 35 Aroach 4: Mixture odel A local euilibriu between the continuou and diered hae, i.e. at eery oint, the article oe with the terinal li elocity relatie to the continuou hae elocity coonent or diered hae can be calculated ro algebraic orula igniicantly le euation to be oled Alo called / iilar odel: Algebraic li (ixture) odel Diuion odel Suenion odel Local-euilibriu odel Drit-lux odel 36 Motiation or iliied ultihae odel Full Eulerian odel - roble Nuerical roble - long couting tie - all tie te Diicultie in conergence Only a ew econdary hae oible More diicultie, i a traner and cheical reaction are conidered Siliied odel are recoended, i alicable By Mio Manninen, VTT

19 37 Detailed deriation o the ixture odel (1) Starting oint: Eulerian odel euation Continuity euation or hae : t u Moentu balance or hae : t u uu τ τt g M Mixture euation are deried by taing a u oer all hae By Mio Manninen, VTT 38 Detailed deriation o the ixture odel () Continuity n u t n n Deine ixture denity and elocity a n 1 u 1 u n 1 c u Reulting euation t u 0 u j j0 I all hae are incoreible By Mio Manninen, VTT

20 39 Detailed deriation o the ixture odel (3) Moentu balance t 1 n n 1 u 1 n n 1 u u n τ τt g 1 n 1 M Diuion elocity u u u (not li elocity!) M Deinition n 1 n T I u F u F 1 Vicou tre Turbulent tre D n 1 u u M M Diuion tre By Mio Manninen, VTT 40 Detailed deriation o the ixture odel (4) Aution: all hae hare the ae reure, Uing the deinition o ixture denity and elocity and the tree aboe, we obtain the reulting oentu balance or the ixture u t uu τ τt τ D g M By Mio Manninen, VTT

21 41 Detailed deriation o the ixture odel (5) Eliinate the hae elocity in the continuity euation or a hae t u u M Or i hae denitie are contant and a traner i zero: t u u which i a balance euation or hae olue raction and include the eect o li. Note that thi the ae a the intuitie reult excet or the diuion elocity intead o li elocity. M By Mio Manninen, VTT 4 Detailed deriation o the ixture odel (6) Relation between the li elocity and the diuion elocity u u u C c li elocity (c denote the continuou hae) u M u u u C For only one diered hae l c u l Cl u 1c u Md d Cd Note: o ar no additional aution or aroxiation ha been ade (excet the hared reure, coonly ued alo in ull Eulerian odel) By Mio Manninen, VTT

22 43 Sli elocity (1) The oentu euation or the diered hae i u u u T g M t Moentu euation or the ixture (with M =0) u t u u τ τ τ g T D Eliinate reure gradient and ole or M M u t M u u u u t u τ τ τ τ τ g T T D By Mio Manninen, VTT 44 Sli elocity () Now, the ollowing aroxiation are ade: All turbulent ter are oitted or the oent Vicou and diuion tre ter are all and are neglected The local euilibriu aution ilie u M t 0 ( u ) u ( u ) u The oentu traner ter i gien by M 1 A V C D u c C u C By Mio Manninen, VTT

23 45 Sli elocity (3) Finally: 1 c A C D u C u C V u u u g t For all article (Stoe drag) in graitational and centriugal ield u Cd d ( ) u e 18 r r g Thi i the li elocity. The diuion elocity ued in the odel euation ut be calculated a hown aboe. By Mio Manninen, VTT 46 Cloure or icou tre in ixture odel Vicou tre: T ( ) Mixture icoity (Ihii & Zuer, 1979): 1,ax.5,ax By Mio Manninen, VTT where 1,ax 0. 4 i the axiu acing and or bubble or dro or olid article

24 Treatent o turbulence in ixture odel 47 in dilute uenion, ixture turbulent tre i aued ae a carrier hae turbulent tre at higher concentration, odeling reuired turbulence enhance reading o diered hae -> taen into account in continuity euation: t ~ ~ D ~ where D i a dierion (diuion) coeicient: D c Tc / 3 By Mio Manninen, VTT 48 Turbulent dierion Turbulence i couled in the ixture odel in a traightorward way, becaue the treatent ha a ingle hae nature. A tandard odel, e.g. - odel, can be couled to the ixture euation. The turbulent tre and the luctuating art o M are odeled uing a turbulent dierion (diuion) coeicient D T u u D T A uitable odel i needed or the dierion coeicient, or exale (Picart et al., 1986) D T u Cd T By Mio Manninen, VTT

25 49 Mixture odel - alidity The eential aroxiation i the local euilibriu aution: the article are accelerated intantaneouly to the terinal elocity Conider again the iliied one-article euation du dt 1 V g AC D u Solution o article elocity a a unction o ditance (Stoe regie) The characteritic length o acceleration i t ut with d t u t gt x By Mio Manninen, VTT Mixture odel - alidity Virtual a and hitory eect 0. l (c) 0.01 Stoe drag only c I the denity ratio i all, the irtual a and hitory ter cannot be ignored (both eect increae the reone tie) A uitable reuireent or the local euilibriu i l << tyical yte dienion By Mio Manninen, VTT

26 51 Validity range o ixture odel, cont. - Mixture odel i uually not uitable or ga-article low, becaue the characteritic length can be large - Not uitable or clutering low, where aerage li elocity i greater than ingle article li - Tyically ued or liuid-olid low and bubbly liuid-ga low (not or ery big bubble) Validating iulation Solid article in an agitated eel Gla bead o three dierent ize in water d = 30 5 Exerient: Barrei and Baldi (1987) D = 0.390, H = bale (0.039 ) 45 itched 4-blade turbine (D t = 0.130, H tb = ). Ieller ower nuber: 1. Aerage a raction: 0.5 % d,ex.() d,i.() (g/ 3 ) N (re/) By Mio Manninen, VTT

27 53 Validating iulation Solid article in an agitated eel 1.0 d = 140 Exeriental Mixture odel Multihae odel 1.0 d = 30 Exeriental Mixture odel Multihae odel 1.0 d = 460 Exeriental Mixture odel Multihae odel z/z ax 0.5 z/z ax 0.5 z/z ax c/c a e c/c a e c/c a e By Mio Manninen, VTT 54 Bubbe drag correlation Toiyaa 1 Toiyaa Eo a d Ihii-Zuber By Mio Manninen, VTT

28 55 Bubble terinal elocity Sli Uli elocity I-Z, g I-Z, 10g I-Z, 0g Toiyaa, 0g d () d () In graitational ield Eect o acceleration By Mio Manninen, VTT 56 MUSIG-odel Deeloed riarily or bubble colun alication Bubble otion deterined by graitational acceleration The baic aroxiation o eual li elocitie o all bubble ize i airly good In trongly wirling low (tirred reactor, u) the odel ay not be jutiied Reduce the nuber o euation to be oled I a two-hae odel and ha thereore the conergence and tability roble o ultihae CFD By Mio Manninen, VTT

29 Mixture odel exale Coarion o odel or bubbly low General Eulerian odel (4xN balance euation) Continuity euation or all hae (N) Moentu euation or all hae (3N) Nuerically diicult and low MUSIG-odel (CFX): (N+6) Continuity euation or all hae (N) Moentu euation or one bubble hae (aerage diaeter) (6) All other bubble clae: ae elocity a the cla with aerage diaeter A large nuber o bubble clae oible Mixture odel (FLUENT): (N+3) Continuity euation or the ixture and all bubble hae (N) Moentu euation or the ixture (3) Bubble: li elocitie ro algebraic balance euation Nuerically well behaed, a large nuber o bubble clae oible By Mio Manninen, VTT

30 59 Mixture odel uary - Length cale o article relaxation ut be all coared to the eh acing - Local euilibriu aution yield the li elocity - Tranort o the diered hae calculated ro the hae continuity euation - Fat; decribe well article ize and other ditribution - Decribe well eect o turbulence 60 Other aroache VOF (olue o luid) ethod or tracing hae interace in earated low Eulerian-Eulerian + Lagrangian Eulerian-Eulerian + ixture odel Meocoic iulation ethod (e.g. Lattice-Bolzann ethod) MP-PIC (ulti-hae article in cell; Lagrangian tranort o arcel o article + Eulerian inetic theory decrition or olid)

31 61 Suary o ultihae CFD: Seeral way to derie euation Siliication in all odel Ju condition at hae interace colicated (drag orce ) Multitude o tie and length cale -> diicult to chooe uitable aeraging and iulation cale Flow oten tie-deendent alo in acrocoic length cale (e.g. bubbling luidized bed) 6 Suary o ultihae CFD, cont.: Neer ully lainar Turbulence odelling diicult; no general odel exit; uniotroy caue roble Dene uenion doinated by article-article colliion Dilute uenion doinated by article-turbulence interaction Meaureent till neceary or deriation o euation cloure and or alidation; oten not aailable

32 63 Suary o ultihae CFD, cont. : Chooe the ilet oible odel Follow the literature Coare with eaureent data i aailable Reult or dilute uenion already good Een dene uenion can be iulated Increaing couter eed will acilitate iulation o ore deanding cae in the uture 64 Exale o Eulerian-Eulerian odeling: Fluidized bed - inhoogeneou low attern - low characteritic change a a unction o luidization elocity CFB (circulating) TFB (turbulent) BFB (bubbling) Re.: U. Ojaniei, S. Kallio, A. Heranon, M. Manninen, M. Seälä, V. Taiaalo, Coarion o iulated and eaured low attern: olid and ga ixing in a D turbulent luidized bed, Fluidization XII, Harrion Hot Sring, BC, Canada, 007

33 65 Eulerian-Eulerian aroach baed on KTGF bacground Kinetic theory o granular low (KTGF) A ecial odel deeloed or dene ga-olid uenion, ee e.g. (Gidaow D., 1994, Multihae low and luidization: Continuu and inetic theory decrition, Acadeic re, Boton) Theory iilar to ga inetic theory Solid hae euation are deried by eneble aeraging oer the ingle article elocity ditribution unction Thi aeraging i done in a local cale auing locally rando ditribution o article 66 Eulerian-Eulerian aroach baed on KTGF liitation and iliication Becaue o the randone aution, the theory i baically only uitable or tranient iulation in airly ine ehe In deriation o the odel, only binary colliion between article are accounted or, and thu KTGF i not alid in dene uenion, lie in bubbling bed In ractie it i ued ro acing liit to ery dilute condition The theory wa originally written or a ingle article ize Later rigorou extenion o the theory to ixture ha been deeloed Here we ocu on odel or a ingle article ize

34 67 Eulerian-Eulerian aroach baed on KTGF otware inleentation Kinetic theory o granular low i today ound in coercial code oen ource code reearcher and unieritie own code Alternatie cloure baed on dierent aution hae been uggeted in the literature Here we ainly reent odel aailable in the coercial Fluent otware 68 Eulerian-Eulerian aroach baed on KTGF balance euation Continuity euation or hae : ( ) ( ) 0 t Moentu euation or ga hae g: ( g g g ) ( g g g g ) g ( g g ) g gg Kg ( g ) t Moentu euation or olid hae : ( ) ( ) ( ) g K g ( g ) t

35 69 Eulerian-Eulerian aroach baed on KTGF balance euation or granular teerature Granular teerature i deined a an eneble aerage 1 ' 3 where i the luctuating olid elocity. Balance euation or Granular teerature: 3 t ( I τ ) : g Firt ter on the right i the generation ter, the econd ter i the diuion ter, the third the diiation ter and the ourth exree the energy exchange between ga and olid. Alternatiely, the granular teerature i couted ro an algebraic euation obtained ro the original tranort euation by neglecting conection and diuion ter. 70 Eulerian-Eulerian aroach baed on KTGF cloure or granular teerature Radial ditribution unction related to the robability o colliion (Lun et al): , 1 g,ax where α,ax exree the olid olue raction o a aced bed. The colliional diiation o energy can be couted ro (Lun et al.) 1(1 e ) g d 0, 3/ and the energy exchange between ga and olid ro (Gidaow et al.) g 3K g

36 71 Eulerian-Eulerian aroach baed on KTGF cloure or granular teerature, continued The diuion coeicient i couted, according to Syalal et al., ro 15d 1 1 (4 3) g 4(41 33 ) 5 0, 16 (41 33 ) g 15 0, where 1 (1 e ) Gidaow ugget intead: 150d 384(1 e 6 1 g ) g 5 0, 0, (1 e ) d (1 e ) g 0, / 7 Eulerian-Eulerian aroach baed on KTGF granular reure Lun et al.: (1 e ) g 0, Syalal & O Brien: (1 e ) g0, Ahadi & Ma: 1 1 0, ric) 4 g (1 e )(1 e

37 73 Eulerian-Eulerian aroach baed on KTGF olid hear tre baed on KTGF Phae tre-train tenor T ( ) ( ) I 3 Solid hear icoity i gien a a u o the one redicted by the inetic theory and a rictional hear icoity, tg, r, col, in, r The colliional icoity (Gidaow et al) : The granular bul icoity (Lun et al) 4 5, col d g0, (1 e ) 1 4 dg 3 0, (1 e) 1 Kinetic icoity (Syalal) (Gidaow) d 1 (1 e 6(3 e ) 5 1 g, in )(3e ) 0, 10 d 4, in 1 (1 ) 96 (3 ) e e g 0, 5 g 0, 74 Eulerian-Eulerian aroach baed on KTGF rictional tre Johnon and Jacon (1987) Shear tre: Solid reure: Frictional reure: Frictional icoity: T r ri, r ( ) tg,ax r (,in ) r Fr ( ) in, r r n, Fr=0.05, n=, =5. In FLUENT Fr=0.1α Schaeer (1987) Frictional icoity:, r r in I D

38 75 Eulerian-Eulerian aroach baed on KTGF rictional tre Syalal et al. (1993): Shear tre: Solid reure: Frictional reure: 76 Eulerian-Eulerian aroach baed on KTGF ilentation in the otware The odel are oten not ileented a uch in nuerical oler. Siliication are introduced in the ileentation to iroe the nuerical tability. For exale, the radial bai unction need to be retricted cloe to the acing liit to aoid nuerical roble The anual o coercial code don t reeal detail o thee odiication. Soetie it i oible to trac down the actual euation ued by a tediou coarion o the alue gien by the coercial code and dierent erion o the euation.

39 77 Validation o the KTGF odel in a D CFB Siulation in a ine eh (0.65 acing) Coarion o eaured olid olue raction and elocitie with the iulation reult at 0.8 and 1. height in the D CFB at Åbo Aadei. Particle ize 0.44 and luidization elocity 3.75 /. 78 Reult without drag correction in a coare eh -> the aution o local hoogeneity in the cloure euation lead to roble -> ubgrid cale cloure reuired

40 79 Modiied drag orce odel ued in CFB and turbulent bed iulation - larger article ize aller cluter correction - iner eh aller correction neceary Voidage unction ued at li elocity 1 /. The drag odel by Gidaow et al., recoended in Fluent anual, i hown or coarion. Re.: U. Ojaniei, S. Kallio, A. Heranon, M. Manninen, M. Seälä, V. Taiaalo, Coarion o iulated and eaured low attern: olid and ga ixing in a D turbulent luidized bed, Fluidization XII, Harrion Hot Sring, BC, Canada, 007 Siulation o a 1 X 7.3 rier in D with acrocoic drag odel 80 Eect o the eh: the iner the eh, the iner tructure are roduced. Aerage oidage attern are unaected. Solid olue raction 8000 cell ized.5 c X 3.65 c 4400, and eleent S. Kallio, The role o the ga-olid drag orce in CFD odeling o luidization, Åbo Aadei, Heat Engineering Laboratory, Reort 005-3, 005

41 3D iulation o large BFB and CFB Relationhi between the nuber o eleent and eleent ize: 81 3D iulation, urnace olue 10 x 30 x 40 3 Eleent Eleent ize D iulation, urnace area 30 x 40 Eleent Eleent ize At leat when eh acing > 0.5 c, drag law need to be adjuted. When eh acing > 10 c, drag law need urther odiication and robably alo tre ter need to be odiied?!? Macrocoic/teady tate/coare eh odel hould be deeloed! 8 Macrocoic CFD odel tae into account large control olue ize are written or teady tate large luctuation ter in the euation euation cloure highly deanding euation cloure reuire eaureent roduce reaonable olid ditribution ee e.g. S. Kallio, V. Poiolainen, T. Hyänen, Reort 96-4, Åbo Aadei/Väreteni Taiaalo, V., Kallio, S., Peltola, J.: On tie-aeraged odeling o circulating luidized bed. 1th Int. con. on ultihae low in indutrial lant, Ichia, Italy, , aer 69. coare eh odel (iltered odel) iilar; eant or tranient iulation o large rocee no generally acceted acrocoic odel aailable today!

42 83 Siulation o real luidization rocee - ecial eature Colicated by a ultitutude o article ize/tye Colicated by dierence in teerature energy balance Colicated by hoogeneou and heterogeneou reaction ecie balance neceary Laboratory cale rocee can be odeled in ore detail in the tranient ode 84 Additional euation/odel reuired (exale) Energy balance euation or each hae Heat caacity or each hae Inter-hae heat traner odel, deend on article ize, teerature, uenion denity, elocitie etc Reaction enthalie Radiatie heat traner Conductiity o each hae Secie balance euation Model or hoogeneou and heterogeneou reaction Inter-hae traner rate Diuion/dierion Coinution (attrition, ragentation) Solid-olid oentu traner

43 85 Siulation o large indutrial rocee Colicated by a ultitutude o article ize/tye Colicated by dierence in teerature energy balance Colicated by hoogeneou and heterogeneou reaction ecie balance neceary Colicated by a large ize coare ehe, long coutation Siliication/ecial aroache neceary 86 Exale o aroache or large indutrial urnace BFB odeling Siliied odel or the bed and 1-hae + Lagrangian article in the reeboard Coare eh odel CFB odeling Eirical bul olid ditribution + balance euation or ga hae, energy, ecie; uel ixed uing Lagrangian odel or dierion odel Full two-hae odel (tranient (low!!!) or teady-tate (cloure being deeloed and alidated e.g. at VTT) Full ulti-hae odel (low!!!) Particle-in-cell ethod (roble with coare eh)

44 87 Exale: teady-tate iulation o Chaler boiler with a tieaeraged odel Ga hae: 5 coonent Solid hae: ah and and a one Eulerian olid hae Coal: article tracing; drying, deolatilzation, cobution; two-way couled with ga hae Soled uing rigorou tie-aeraged euation or teady-tate hydrodynaic, with balance eu or Reynold tree Secie balance euation oled or all the coonent Source ter calculated ro hoogeneou and heterogeneou reaction Mixing o enthaly and cheical coonent decribed by dierion coeicient in energy and ecie balance euation; dierion calculated ro Reynold tree and tie cale Re.: Taiaalo et al., FBC1, Nale Exale: teady-tate iulation o Chaler boiler with the tie-aeraged odel (Taiaalo et al., FBC1, Nale 01) a) b) c) d) e) a) Tie-aeraged olid olue raction,. b) tie-aeraged a-weighted ertical olid elocity, c) tyical athline or a 1 uel article coloured by the reidence tie, d) ole raction o O and e) the tie-aeraged ga teerature ( o C).

45 89 Concluion on iulation o dene ga-olid low Eulerian-Eulerian i a good aroach; MP-PIC i alo uable and good or decrition o article ize ditribution Cluter oration i characteritic o dene ga-olid low Tranient iulation roduce correct luctuation attern and aerage ditribution, but a uch uable only or all geoetrie Indutrial rocee large, large rocee reuire coare ehe Reeber: cloure odel araeter or tranient euation coare-eh iulation hould be eh-deendent! No uch odel aailable! Steady-tate odel now aailable at VTT and ued or iulation o CFB boiler urnace