NLN* 119-9/2014* 13
MO PHONG MAY DIEU HOA KHONG KHI MOT CHIEU LOAI NHO
TS. NGUYEN NGUYEN AN", ThS. TA V A N CHUONG, DH Bach khoa Ha npi Bai bio trinh bay viec xay dieng mot mo hinh mo phong may diiu hoa khong khi mot chiiu loai nho, cho phep xic dfnh cac thong so hoat dgng tir cac thong s6 mo ti cau tao cung nhw dieu ki§n lam viec cija may. M6 hinh duxyc xay dimg bang each mo phong tirng bo phan chinh ctJa may diiu hda khong khi mot chiiu loai nho gom may nen, thiit bi ngwng tu, thidt bi tiit Iwu va thiit bi bay hoi rdi kit hap iai di mo phong si/ tucfng tic giira chung. Su" dijng mo hinh da xay du-ng, anh hud'ng cua nhiet do mot tnrdng xung quanh va nhiet do khong gian duoc diiu hoa din nang suit lanh va cong suit tieu thu dien cua may da duxyc xac dmh. So vdi cac s6 lieu thuc nghiem do nha san xuat cong bd, sai s6 ldn nhit vi nang suit lanh va cong suit tieu thu dien khi xic dinh bing mo hinh da xay di/ng tirong irng la 3,7% va 5,1%.
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Dien tich b l mat trao (Joi nhi$t cua thilt bi nqu'nq tu
H? s6 truyin nhiet cua thilt bj bay hai H? so truyin nhi$t viing bao hoa cua thiet bi nqu'nq tu
He s6 truyin nhi^t vung qua nhi§l cCia thilt bj ngu'ng ty
Conq nen rienq thu'c cua may nen Cong nen rieng (Jogn nhi^tthugn nghjch cua m^y nen
Toe dQ quay ly thuyet cua may nen Lu'U lu'p'ng khoi lu'p'ng moi chat Conq suat co cua may nen Conq suat n6n {thi,J'c) cua m^y nen Cfing suat di^n cua mciy n6n Ndnq suat lanh nenq cua thilt bj bay hci NSng suat Ignh
Nang suat thai nhiet rieng cua thiet bj nqu'nq ty
Nang suat thai nhi§t Nhiet dp bay hai cua moi chat i^nh Nhi§t d$ ngu'ng ty ciia moi chat Ignh Nhiet dO khang gian du'gc dieu hoa Nhiet ao mfli truang xung quanh T h i tich qu6t cua may nen Lu'U lu'png t h i tich ly thuyit tgi d i u hut mdv n6n
ChSnh l#ch nhiet d$ trung binh vung bSo hod trong thiet bi ngu'ng tg
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Hipu suat the tich cua may nen He so lam lanh
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I. DAT VAN D £
Miy dilu hda khdng khi mot chilu lopi nhd du'pc SIJ' dung phd biln trong thtfong mai eung nhir trong dan dung de tao ra mdi tofdng cd nhipt dd va cd the la ca dd Im theo yeu clu. Chi ridng trong phpm vi cac ho gia dinh, tieu tin dien nang cho loai thilt bj nay, theo u-dc tinh, da chilm ti> 28% din 50% tdng dipn nang tieu thu [1, 2]. Do vay, viec tdi wu hda thilt ke cung nhu' ehl dd hoat ddng eho loai may nay nhlm muc dich nang eao kha nang tilt kiem inang lu'png se mang lat lpi ich khdng nhd v l kinh t l . Giup thu'c hien viee ndy, nhilu chu'ong trinh mo phdng may dilu hoa khdng khi da du'pc phat triln [3], cho phep tiln hanh cac nghien cdu tren mdt he thing ao, vdi sij' tra giiip cua may tinh. Tuy nhien, cho din nay, phin Idn eac md hinh nay edn cd mdt sd nhu-ac dilm nhu' khd ap dung do ddi hdi qua nhilu thdng so md ta, dd chinh xdc ehu'a dap ting dupc yeu clu nghien cu'u do md hinh du'pc xdy di^ng tren ca sd cac phan tich ly thuyit la chu ylu... Vi vpy, trong bai bao nay, mot md hinh md phong may dilu hoa khdng khi mdt chilu loai nhd se du'pc xay di/ng vdi mye dieh giai quylt eac vin de vi>a neu.
14* NLN-119* 9/2014 II. c a S d LY THUYET
Hien nay, cd 2 phu'ang phap chtnh d l xay dLfng cdc md hinh md phdng may dilu hoa khdng khi la md phdng tirng bd phan eua may roi k i t hp-p lai d l md phdng SLF tu-ang tdc giiia ehiing [4 - 7] va md phdng toan bd mdy nhu' mdt phin ti> duy nhlt [8]. Phu'ang phap diu tien thu-dng du'pc SLP dung trong nghien ciru phat triln eac mlu may dilu hoa khdng khi mdi cdn phuang phap sau thu'dng du'pc u'ng dung trong eac bai toan phan tich tieu thu nang lu'p'ng md d dd, may dilu hoa khdng khi chi Id mdt bp phan eua he thing dang nghien ed'u.
Vdi muc dich phdt then mpt phin mIm md phdng iam edng cu d l nghien cdu hoat ddng ciia may dieu hoa khdng khi, qua dd giiip hilu rd han su tuang tae giua cac bd phan cung nhu anh hudng ciia ti>ng bd phan din hieu nang ehung eua may, phuang phap md phdng dau tien se dupc lua chpn.
2.1. Md phdng chu trinh lanh cua may d i l u hoa khdng khi mot chilu loai nho
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ti^tlirn ThUt biThiet bi bay bai
Hinh 1 Sa do nguyen ly cua may didu hoa khdng khi _ May dilu hoa khdng khi mpt ehilu loai nhd gdm 4 thilt bi chinh la may nen, thilt bi ngung tu, thilt bj tilt luu va thilt bi bay hai, dugc kit ndi vdi nhau nhu so do Hinh 1 [9], May nen se tieu ton naing lupng cho qua trinh (1 - 2r) d l tao ra "lanh" khi thilt bi bay hai liy nhiet tu khdng gian dilu hod d qua trinh (4 -1). Sau dd, nhiet do thilt bi bay hai liy di se duac thilt bi ngung tu thai ra mdi trudng xung quanii trong qua trinh (2r - 3). Qua trinh xay ra trong van tilt luu (3 - 4) duac xem Id doan nhiet a hau hit eac nghien ciru v l may dilu hoa khdng khi.
Hinh 2 bieu diln ehu trinh lanh cOa mdy tren do thi log{p) - i vdi cac qua trinh nen, ngung tu, tilt luu va bay hai nhu vua md ta
Can bang nang luang trong may cd t h i duac bilu diln bdi edng thuc (1) nhu sau [9]:
q»( = Qo +/., kJ/kg (1) Theo do, nhipt that ra d thilt bj ngung tu q^ se
ed gia tri blng ting ciia nhiet nhan dup'c d thilt bj bay hai QO va edng nhan dupc d may nen Ir.
'3 - u 11 iit iir i Hmh 2. Do thi log(p)-i cua chu trinhnhi^f dpng cho miy BHKK Theo [9], cac gia tri nang lup'ng nay cd t h i dupc xae dmh bd'i cac cdng thu'c (2) - (4).
- / j , kJ/kg (2)
? „ - i | - / " ^ , k J / k g (3) /,. = /,, - /[, kJ/kg (4) Trong thue t l , qua trinh xay ra trong may ndn (1 -
2r) thudng dup'c xde djnh gian tilp qua qua trinh nen doan nhiet thuan nghjch (1 - 2s) thdng qua hi§u suit khdng thuan nghjch 7,, dup'c djnh nghTa bdi edng thuc (5).
U.=j- (5) O day, cdng do mdi chit nhan dupc d may
nen trong qua trinh nen dopn nhidt thuan nghjch (1 - 2s) cung dup-e tinh thdng qua su thay dfll entanpi theo cdng thuc (6).
A =h^-h' kJ/kg (6) Dua tren cdc dai lupng vua neu, nang suit
lanh QQ, cdng suit nen N, va nang suit thai nhipt Qk cua may se duae xae dinh theo cac cdng thiJc ( 7 ) - ( 9 ) .
Q„ = f^r •<3.. ='", -(^'i - ' 4 ) . k W (7) JV^ = m^.l^ = m^.{/\^ - / , ) . kW (8) Qk =^r-9k =/«r-('2r - 4 ) . KW (9) O day, Wr la luu luang khdi luang mdi chit trong mdy, ed thu nguyen la kg/s, do may nen t^o ra va eung la mdt trong nhOng dai lupng quan trpng eIn duac xac djnh trong md hinh.
Do ludn tdn tat t i n thit ea, khi cac chi tilt ca khi eua may nen ma sat vdi nhau, va ton thit dien, tai ddng ea dien eua may nen, cdng suit cin eip tren tryc co mdy nen N^s va cdng suit di^n clri d p eho dpng eo may nen P, se Idn hon cdng suit nen N^ va duae tinh qua hipu suit ca Ome va hieu suit dipn q^i theo cac cdng thi>c (10), (11).
^ =/L.JJL:L.m (10)
'" 1., n„.
NLN'119-9/2014'15
/ . ^ i ^ ^ J ^ c / ^ k W (11) ' '',/ 1„1.,
Tren CCT SO cac dgi lipgng vOa trinh bay. c6 t h i xac dinh he s6 iam ianh, tnOt dai lu-ang quan trong dSc tarng cho hieu qua iam viec cua may theo cong thi>c(12).
Q
e=^ (12)
Nhu vay, ed t h i xae djnh tit ca cdc thdng so hopt dpng cua mdy dilu hoa khdng khi mdt chilu loai nhd Xir chu trinh lanh vd luu luang khii luang mdi chit tuin hodn trong may Trong bat bao nay, luu luang mdi chit tuin hoan trong may se duae xae dinh ehu ylu nhd md hinh mdy nen. Dh dan gian trong tinh toan, vdi gia thilt la do qud nhiet sau thilt bi bay hai ^fgn va do qua lanh sau thilt bi ngung tu M^i da bilt, viee xac dinh chu trinh tanh se duae thue hien thdng qua 2 dai luang quan trong la nhiet dp (hoae dp suit) eua eac qua trinh bay hai, t^ (po). va qua trinh ngung tu, /*, (p^. Viec kit hpp giua md hinh may nen vdt md hinh thilt bj bay hai se giiip xac djnh nhiet dp bay hoi to tren ca sd dam bao su can blng gi&a lupng nhiet ma mdi chat nhan dupc tu khdng gian dilu hoa (thdng qua qua trinh trao dot nhiet) vdi Iuong nSng luang do may nen "hiit" di Tuong tu, nhiet dp ngung tu f^ cung se de dang dupc xac dmh khi kit hpp md hinh may nen vdi md hinh thilt bj ngung ty. Phin tilp theo cua bai bao se trinh bay vi0c xay dung eac md hinh nay cung nhu qua trinh md phdng su tuang tdc giiJa chiing,
2.2. Md phong cac thilt bj chinh cua may a. Miy nen
May ndn (hay edn goi Id may nen lanh) la mOt thilt bi ca khi - dien giiip thuc hien qua trinh nen (1 - 2r) ciia chu trinh lanh. D l iam dugc dilu dd, trude hit, mdy nen se hiit mdi chit d trang that (1) vao khoang nen va blng nhilu nguyen ly hoat ddng khac nhau, luang mdi chit ndy se duoe "nen" len trang thai (2r) r i i sau dd dupe dly vao thilt bj ngung tu. Vdi ca ehl hopt ddng nhu vay, luu lupng t h i tich mdi chit ma may nen hiit vao V,, (cdn gpi la luu lupng t h i tich ly thuyit) hoan toan cd t h i dupc xdc djnh thdng qua t h i tich quet cua may ndn ^/s^,, t i c dp quay ly thuyit n^ va he s l trupt rj . cua dpng co mdy nen blng cdng thue (13)
Do cd mdt sd anh hudng khdng mong mudn nhu SIF gian nd cua t h i tich chit d l i vai may nen piston, sy rd ri mdi chit ti> phia dp suit cao sang phia ap suit thip cua may nen... nen luu luang mdi chit ma may nen tao ra cho chu trinh (luu luang thuc) ludn nhd han luu luang ly thuyit va hipn tuong ndy dugc dac trung bdi hieu suit t h i tich X . Do dd, khi bilt t h i tieh rieng cua mdi chit tat diu vao may nen v, tu chu trinh, luu lugng khdi lugng mdi chit tuin hodn trong may nen cd t h i d l dang duae xac dmh theo cdng thuc (14).
m^ = ^ , kg/s (14) I'l
Theo [10], hipu suit t h i tich cua mdy nen cd t h i xdc dinh theo ap suit bay hai Pg va ap suit ngung tu p^^ blng cdng thuc (15).
1 = 1,277-0,885 l//j„-0,02442.Pi (15) Di xac djnh cac gia trj nang lugng tieu tin eho may nen tu edng nen rieng doan nhipt thuan nghieh /j, cin phai bilt cac gia trj hipu suit d|c trung eho may nen. Hieu suat ca do ma sat tgi cac chi tilt CO khi va hieu suit dien cua ddng ea may nen thudng cd gia tri it phu thupc vao ehl do hogt dong nen d day, chung dupc coi la cac hing sd vdl gia tri cu thi Id /;,„^, = 0,876 va 7^.,= 0,873 [11], Oai lugng cdn lai Id hipu suat khdng thuan nghieh, phu thudc vao ap suit bay hai /?„ va ap suit ngung tu p^ , se dupc xac djnh theo cdng thu'c (16) nhu sau [10].
77, =0,8939-0,2852/p,;-0,0003077./?; (16) b. Thiit bi bay hoi
Trong thilt bi bay hai. mdi chit tao ra "lanh" blng each liy nhiet tu khdng khi thdng qua qua trinh truyin nhipt, duac bilu dien blng cdng thu'c (17).
^,, = / f , A , A / . , k W (17) 6" day, k^ va Fe la he sd truyin nhipt trung binh
va dien tich b l mat trao ddi nhipt eua thilt bj bay hai; Ate la chenh lech nhiet dp trung binh giOa mdi chit va khdng khi trong thilt bj bay hoi, ed the xac dinh tu nhiet dp khdng khi vao thilt bj tnaoor va nhiet dp bay hot fo
Trong chu trinh lanh, nhiet lupng ndy se phai can blng vdt nhiet luang do mdi chit lanh mang di d l xae lap nen nhiet dd bay hai to- Co ehl hoat ddng nay se dugc md phdng qua tuang tac giua md hinh may nen vd md hinh thilt bj bay hot
16* NLN-119* 9/2014 c. Thiit bi ngung tu
•Tugng tu, md hinh thilt bj ngung tu cung se duge xdy dung qua viec md ta qua trinh truyen nhiet vdi cdng Xhirc (18).
kW (18) O* day, d l ndng cao dd chinh xdc md phdng, thilt bi ngung tu dugc ehia thanh 2 vung theo trang thai mdt ehit ben trong la vung bao hoa va vung qua nhiet vdi fsat la ti le dien tich b l mat trao dli nhipt eua vung bao hoa; F^ la dien tich be mat trao doi nhiet cua tinilt bi ngung tu; kcsat va kcsup tuang ung Id he sd truyin nhiet eua thilt bi ngung ty d vung bao hoa va vung qua nhiet; At^sai va Atc.sup tuang ung la chenh lech nhiet do trung binh giua mdi chit vd khdng khi xung quanh trong vijng bao hod va viing qua nhipt.
Vdi gia thilt dien tieh b l mat trao ddi nhiet eua thiet bj Fc, ti le dien tich viing bao hoa fsat, cac he s l truyin nhiet k^sst va kc.sup da bilt va dupc xem nhu nhung thdng sd md ta thilt bj ngung tu, cdng thuc (18) se hoan toan xdc dinh khi bilt cac chenh lech nhiet dp Atc.sai va Atc,sup- Tuang tu nhu vdi thilt bj bay hai, gia tn cac ehenh leeh nhiet dd nay se dupc xac djnh diia tren nhiet dp khdng khi khi vao thilt bj touiaoor va nhiet dp ngung tu tj,.
Trong chu trinh lanh, nhiet lugng Q^ se phai can bang vdi nhiet lupng do mdi chit lanh mang din di xac lap nen nhiet dp ngung tu ti<. Co che hoat ddng ndy cung se dwcfc md phdng qua tuang tdc gii>a md hinh mdy nen va md hinh thilt bj ngung tu nhu da d l cap
d. Thiit bi tiit luu
Trong bdi bao nay, gua trinh xay ra trong thilt bj tilt luu duge eoi la ding entanpi va dugc md ta bdi cdng thuc (19) nhu sau:
iy^i, [kJ/kg] (19) III. X A Y DU'NG MO HiNH M A Y DIEU HOA
KHONG KHI MOT CHI^U LOAI NHO cac edng thuc (1) - (19) trinh bay trong Muc 2 giitp mo phdng toan bp may dilu hoa khdng khi mpt chilu Iogt nhd, ehi tilt din ti>ng bd phan clu thanh ciJa nd la may nen, thilt bj bay hai va thilt bi ngung tu, Cac cdng thifc nay cung cd t h i dugc xem nhu mdt he phuang trinh md ta may dilu hod khdng khi mdt ehilu loai nhd md viee giai nd blng may tinh, mdt each tu ddng, se giiip xdy dung mdt md hinh md phdng cho loai mdy nay, Tuy thudc vao ung dung ma md hinh se nhlm toi, viec diu tien c i n tiln hdnh la lua chpn cac thdng s l vao, ra va thdng sd md ta cua md hinh se xay dung.
3.1. Lya chpn thong s6 vao, ra va mo ta cua mo hinh
Vdi mye dich lam edng cu nghien cuu, toi uu hoa hoat dpng cua mdy trong cac ehl dp lam viec khac nhau, nhiet do khdng khi khi vao thilt bj bay hoi tindoor va khi vao thilt bj ngung tu toutdoor se dugc lua chpn lam cac thdnq sd diu vao cija md hinh.
nm-
Hinh 3. Cac thong s6 vao. ra va mo ta trong mo hinh may diSu hoa khong khi
v l ca ban, nang suit lanh Qo va he so l^m lanh £ cua mdy se la nhijng thdng s l diu ra chinh ciia md hinh, Tuy nhien, d l khao sdt hoat dpng cua cac thilt bj trao ddi nhiet cung nhu may n6n, cae dgi lugng nhu chenh leeh nhiet do trong c^c qua trinh truyin nhiet Ate, ^^csaf. ^^c.sup vi cac dgi lupng v l hipu suit may nen nhu X va rj^cQng dugc chpn iam thdng s l d i u ra cua md hinh.
Ngodi ra, d l xae djnh eae bd phan clu thanh nen may dilu hoa khdng khi dang md phdnp, con cin din eae thdng s l md ta nhu dugc the hi§n tren Hinh 3,
3.2. Lya chon p h i n m I m va lap trinh xay dyng md hinh may dieu hoa khong khi
Cd nhilu phuang phap d l tgo ra mdt phan mIm giiip giai he (1) - (19). Phd biln, vin dupc ap dung tu' trude tdi nay la SLP dung mgt ngdn ngCr lap trinh "bac cao" nhu Basic, Pascal, C, Fortran...
Phuang phap nay thudng ddt hdi ky nang va ca kmh nghiem lap trinh rieng cho tu-ng ITnh vuc. Don gian han, cd t h i su dung cdc phin mIm chuySn dung nhu EES (vilt t i t cua Engineering Equation Solver) [12] cho muc dieh nay. EES vua la mOt cdng eu lap trinh theo ngdn ngd' tuong ty nhi/
Delphi (phien ban iam viec trong mdi trudc MS Windows cua Pascal), vira giiip giai ty ddng cdc hp phugng trinh ky thuat vgi sd lugng phuang trinh.
I n sd len din 2000. Ngodi ra, EES cung ho trg vi$c xac t^nh cae thdng sd nhiet ddng va tinh chit nhi^t vat ly cua rit nhieu logi mdi chit dung trong kJ thu^t
NLN* 119-9/2014* 17
ndi Chung, trong dd cd nganh Nhiet - Lgnh. Vi vay, EES se d u a c l y a chpn lam edng cy de phdt t r i l n p h i n m I m md phdng trong bai bao.
P H A N IMfilVI M O PHONG BltV H O A K H O N G K H I
THONG SO DAU VAO Lo^ may Mot ctiatlsU'))') (MCLI Nhi^I d? khong klii vao TBBH Nl-il^t d9 kliong khi vao TBNT THdNG S6 OAU RA Nhi^t <\<f bay hoi cua MCL Nhl^t d9 ngu'ng t^i cua MCL Nang suae lay nlii?l cua TBBH Cong s u * tieu thu dien H » . o l . m l ^ h
|DHKKOI-OI :i,j R* R22 - r«™=[27]['Cl N..^= [35] IX 1
_Q.-'--.d i„ = i i 06 1-ri U = 50 17['C]
0..= S.235[kWl Pi = l 605 [kW]
£ = 3 262 Hinh 4. Giao di$n phan mem mo phdng may diu hda khong l^i
Di nang cao tinh u'ng dung cho md hinh, mpt giao di^n vdi n g u d i s u d y n g eung da d u g e xay d y n g n h u trinh bay tren Hinh 4.
IV. D A N H GlA SAI S 6 M O HiNH
Vi$c danh gia sai so md hinh may dieu hod khdng khi mdt e h i l u logi nhd vira xay d y n g da d u p c thye hipn eho m l u may FTKD50FVM/RKD50BVM do hang Daikin (Nhat ban) san x u l t , Cae thdng sd md ta may, n h u trinh bay trong Bang 1, d u g e l i y va tinh toan t u so lipu do nha san x u l t cung c i p trong Catalog di kem.
May s u dyng mdi c h i t lanh la R22.
So sanh k i t qua md phdng nang s u i t Ignh Qo va cdng suat tieu thu dien P, cua m l u may lua chpn vdi cae so lipu thuc nghiem do nha san x u l t cung c i p d u p c trinh bay tren cac Hinh 5 va 6.
Tr§n hinh, cac d i l m b i l u dien s l lieu thue nghipm cdn cac d u d n g b i l u d i l n k i t qua md phdng b l n g m d h i n h da xay d y n g .
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____
^ s
^ ^ , = 3S«C m^ ! _
=^==^
" •
•
•
'^m^^-t 1
,. = 32-C , = 30 "C
Hinh 6- Banh gia sai s6 ket qua mo phdng cong su§t (Sen t§u Siu Theo k i t qua so sanh tren hinh 5 va 6, sai sd md phdng Idn nhat ddi vdi ndng s u i t lanh va cdng s u i t dien tieu thu ciia may d i l u hda khdng khi l l n indoor' : 32 "C , / otildoor' •• 4 0
= 40 °C).
° C ) v a 5 , 1 % ( t a i / ^ ^ ^ ^ ^ = 2 2 ° C , 4
Bang 1. Thong so cua mau may si> dung de danh gia sai so md hinh
TT
1
2
3
4 5 6
M o t a He so truyen nhiet toan phan cua thilt bi bay hai He s6 truyen nhipt loan phin, p h i n bao t i o a c u a l h i l t b l ngung tu He sd tnjyen nhiet toan phin, phin qua nhiet ciia thiet bi ngung tu The tich quet cua may nen Toe dd quay ly thuyltcuamaynen He s l tnjot cua dpng CO may nen
Ky hieu
^A.
/sA s,Ac
^-f...),K..A
v...
^m Vshp
Gia tri 328,5
230,0
98,6
36,5 50 0,96
D a n v i do W/K
W/K
W/K
cm^ 1/s
Hinh 5 DAnh gi6 sat so ket qua md phdng nSng suit l$nh
V. K^T LUAN
Bai bao da xay d y n g d u a c mot md hinh md plidng mdy d i l u hda khdng khi mpt e h i l u logi nhd b l n g each md phong tung bd phan chinh cua mdy gdm may nen, t h i l t bi ngung tu, thilt bj t i l t luu va thiet bi bay hgi roi k i t h g p lai d l md phdng s u tuong tac giua chung, V d i md hinh da xay dung, thdng sd hogt dpng ciia may phu thupe vao 2 yeu t l quan trpng la nhipt dp khdng gian d i l u hoa Indoor vd nhiet dp mdi trudng xung quanh fouwoor da d u g c md phdng. K i t qua md phdng t i l n hanh vdi m l u may
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