NGHIEN cufu - TRAO DOI
"^NGHIEN C(yU MO PHONG FLUENT-CFD VA THLTC NGHEM QUA TRINH TRUYEN NHIET TRONG THIET Bj SU'dl AM
DICH TRUYEN DUNG TRONG Y TE
FLUENT-CFD SIMULATION AND EXPERIMENTAL HEAT TRANSFER PROCESS IN INFUSION WARM DEVICES FOR MEDICAL USE
Nguyen Ti^n DongS Nguyen Thi Phiidng Giang', DUdng Van Huy^, Vu Dinh Dung', Phan Quang D6^
'Vien Cd khi, TrUdng Dai hpc Bach Khoa Ha Ngi
^Vien Dupe lieu 'Vu Khoa hpc Dao tao, Bp Y te TOM TAT
Sudi dm dich truyen giup gidm toi da cdc dnh hUdng ve nhiet trong qud trinh truyen dich cho benh nhdn, ndng cao hieu qud cua dich truyen. Nhieu thiet bi sUdi dm dUdc nghien cdu, sii dung cdc mo hinh truyen nhiet khdc nhau de dat dUdc hieu qud sUdi dm dich truyen. Mo hinh Sngxoan dang Id xo dUdc diing nhieu trong bdi todn truyen nhiet tai cdc nhd mdy dien, Id phdn Ung hat nhdn, dien Ignh, xd ly dieu hoa khong khi, cdng nhU trong cdc thiet bi trongy te. Tuy nhien, xdc dinh quy ludt qud trinh truyen nhiet trong cdc he thong do dgc biet quan trgng, lien quan den hieu qud vd sU an todn cua he thong. Bdi hdo ndy trinh bdy nghien cUu qud trinh truyen nhiet trong thiet hi sUdi dm dich truyen vdi md hinh xoan loxo bdng phUdngphdp mo phong Fulent-CFD, dUdckiim chdng bdngthUc nghiem.
TU khoa: Mo phong, thiet biy te, sUdi dm dich truyen, Fluent-CFD.
ABSTRACT
In the infusion, warm devices helps a patient to reduce bad effect of heat, to increase potency of the drug. Helically coiled heat exchangers are the important engineering systems with wide variety of applications including power plants, nuclear reactors, refrigeration and air-conditioning systems, heat recovery systems, chemical processing, food industries and medical devices. Control process transfer heat is really importance for safety This paper shows the results CFD & experiment of heat transfer in infusion warm devices.
Keywords: Simulation, medical equipments, infusion warm device, Fluent-CFD
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NGHIEN C U T U - T R A G D O I
1. GlOtI THIEU
Kha nang trao doi nhi^t ciia dong chay trong ong xoan dang 16 xo dUpc Ung dung trong cac nha may dien, 16 phan Ung hat nhan, dien lanh, sU dieu hoa khong khi, he thong thu hoi nhiet ciing nhU trong cac thiet bi y te [ 10].
Khi dong chat long chay trong 6ng xoan se chiu lUc li tam. K^t qua la lUc nay la nguyen nhan hinh thanh ddng thU cap trong ong xoan. Dong thd cap anh hu6ng tich chat dpng hpc, dong chay, dp nhott ciia chat long trong ong va lam tang dang ke kha nang trao doi nhiet eiia ehat long trong ong vdi vach thanh ong. Do dong chay thd cap la hai xoay vuong goc vdi hUdng dong chay dpc theo chieu dai ong, truyen nhiet lue khong ehi xay ra bang each khuyech tan theo hudng xuyen tam ma con bdi sU doi lUu [2],[6|,|111.
Mpt trong nhdng nghien cUu sdm ve tinh chat cua dong chay trong ong xoan dang 16 xo cua Dean da dUa ra cong thUc xap xi eho he so dac trUng eho ddng chay trong ong xoan dUa tren he so Reynolds va ty le giUa dUdng kinh ong va dUdng kinh uon. Ong ket luan rang dong chay trong ong cong on dinh hdn so vdi dong chay trong ong thang [12]. Nam 2004, Devarahalli cung cac dong nghiep da thUc dieu tra thUe nghiem truyen nhiet doi lUu tU nhien til ciia mo hinh ong cupn xoan trong nUdc. Ong da xay dUng phUPng phap de dU doan nhiet dp dau ra cua dong chay va he so dan nhiet dUa tren dieu kien dau vao cho ket qua rat gan vdi thdc nhiem [7]. Nam 2012, Pramod Purandare ciing cac cgng sU thUc hien mgt phan tich so sanh cdc moi tUPng quan khac nhau dupe dUa ra bdi cac nha nghien cUu cho trao doi nhiet trong dng xoan 16 xo; Ket qua nghien cdu eho ring ty so dUdng kinh ong va dUdng kinh vong cugn i n h hUdng manh tdi dong chay thU cap [8]. J.S Jaya kumar cung cac cgng sU da thUc nghien cUu trao doi nhiet chat long tdi chat
long trong dng xoan 16 xo nam 2008, va ddng chay ddn trong 16 xo 2010 bang thdc nghiem va modul mo phong Fluent cua CFD, cho thay ket qua cua mo phong la phii hdp vdi ket qua cua thuc nghiem [4],[3]. Nam 2010, Ivaan Di Piazza cung cac cpng sU da thu dugc ket qua tinh toan cho ddng chay rdi va nhiet truyen thdng qua dudng ong xoan dang 16 xo. He so Nusseft dUdc tinh toan qua cae mo hinh roi khac nhau va cho thay mo hinh RSM-to cho ket qua tot hdn sd vdi cac mo hinh khac [1].
Bai bao trinh bay nghien cdu qua trinh truyen nhiet trong thiet bi sUdi am dieh truyen vdi md hinh xoan 16 xo, phan tich sU phan bo nhiet trong ddng chat Idng tren chieu dai day truydn bang cong cu Fluent-CFD va duge kiem chUng bang thUe nghiem.
2. CAC THONG SO THIET BI S l / d l AM DICH TRUYEN
2.1. Thong sd md hinh thiet hi sUdi am dich truyen
Thiet bi sUdi am dich truyen d nghien eUu nay gom cd mpt thiet bi gia nhiet dang hinh tru lam bang dong va dUpc tao ranh xoan nhu hinh 1, vdi cae thdng sd (dUdng kinh ngoai eua tru D=70mm, dUdng kinh trong d=46mm, ehieu dai L. = 90 mm, bUdc cua ranh xoan
ong
t = 6.5 mm, ranh xoan dUdng kinh d'=4mm) va day truyen dich dUdng kinh 4mm theo ehuan cua Bo Y te theo hinh 2.
Hinh 1: Thiet bisUdi dm dich truyen
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NGHIEN cufu - TRAO D O I
PhUdng trinh dpng lUc:
t^".^^-^*V\^ d\ ,M^^^,_ —1
fin:; dx dx Sx, ' ^ PhUdng trinh nang lUdng:
Hinh 2: Ddy truyen dich Trong thiet bi sUdi am dich truyen qua trinh truyen nhiet la qua trinh tru dong dUde cap nhiet tdi nhiet do on dinh 42*'C (315 do K), sau do nhiet dugc truyen qua day truyen dich dupc cuon quanh ong dong tdi dich truyen de dat dUdc nhiet dp mong mudn. Dich truyen dung trong thi nghiem la H^O nguyen ehat d nhiet dp 5°C {278K). Toe dp dich truyen trong day truyen dieh la 80 gipt/ phut.
2.2. Thong sd trong tinh toan mo phong Cae he so dUpc sU dung de tinh toan phan tich truyen nhiet qua cupn xoan 6c dUpc cac nha nghien eUu khac nhau sU dung:
dx dx- Pr &
3. QUA TRINH THU'C NGHIEM
0. K
He so Reynolds: Re pud He so D e a n : o ^ . ^ ^ ^ , ^ . "
(1) (2)
Nu = 0.023 R e " ' P r " <5°' v6i Re >2000 iVH = 3.313.31D/">Pr»"™
TVuxt n =
(3) [9]
neu8<De<1200(4) |5l
Hinh 3: Dich truyen Hinh 4: KD-133 3.1. Dung dich thi nghiem
Dich truyen la nUdc muoi sinh ly vdi cac thdng so chuan eua Bp Y te vdi nhiet dp dich truyen ban dau S'^C, hinh 3.
3.2. Thiet bi do
Nhiet ke dien tU dau mem khdng tham nude Polygreen KD-133, hinh 4.
3.3. Bp thong so thi nghiem
Toe dp chay cua dich truyen 80 gipt/
phut.
PhUPng trinh lien tue: —(^[y ) ^ o
5.Y, Nhiet dp cai dat cua thiet bi 37.5°C.
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NGHIEN cufu-TRAOD6|
3.4. Trinh tU thi nghiem
Thiet lap thiet bi hoat ddng d 37,5 "C.
Toe dp dich truyen 80 gipt/phut.
Khao sat nhiet dp dau ra cua dich truyen vdi chieu dai day truyen dich L (200mm, 200mm, 400mm, 500mm, 600mm 700mm, 800mm, 900mm).
4. KET QUA THI NGHIEM VA THAO L U A N Hinh 7: Phdn bo nhiet do trong dich truyen khi mo phong vdi 10 vong cuon
4.1. Chieu dai dap dng nhi^t dd ciia thiet hi Hinh 5, gidi thieu ve qua trinh tinh toan phan bo cua trUdng nhiet dp trong khong gian 3D cua dich truyen khi bat dau vao thiet bi ra
khdi thiet bi sUdi am.
c^bfuz'n)
I^^H
1^3^ Y'J -^
/' ...
t^tr
X
Kinh 8: Nhiet phdn bo lgi mat edt 0mm,250mm,500mm khi mo phdng Bieu do 1: So sdnh mo phong vd thiic nghiem
Bi^uddsosanh
Hinh 5: Phdn bo nhiet do trong djch truyen khi mo phong vdi 3 vong cuon
4.2. Thao luan
Ket qua md phdng tren FLUENT dUpc dem so sanh vdi ket qua do thUc nghiem ve chieu dai day dUpc cudn trong thiet bi sUdi am, bieu dd 1 cho thay tren md phdng gan gidng vdi Hinh 6: Phdn bo nhiet do trong dich truyen khi mo thUe nghiem. Ve cd ban khdng ed sU khac nhau phong vdi 5 vong cuon nhieu ve chieu dai dap dng nhiet, md phdng*^'
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NGHIEN cufu-TRAODOI
thi sU tang nhiet dp luon cao h d n thUc nghiem khong dang ke do sai s6 phep do, phUdng phap, do thUc nghiem cd sU chao doi nhiet giula mdi trUdng vdi thiet bi sUdi am.
TU ket qua cua bai toan md phdng cac qua trinh truyen nhiet cua thiet bi giup eho ta ed ed sd de danh gia, lUa chgn md hinh vdi nhflng kich thudc chap nhan dUpc cho tat ea eae tham sd eua cae ket cau thanh phan cua thiet bi va dien hinh la bd phan gia nhiet nhU chpn gia tri dp day, ehieu dai cua ong tru gia nhiet. Xem xet nhflng anh hudng vat ly tren toan bp qua trinh truyen nhiet d tat ca cac dieu kien thUe thi nhU hudng tda nhiet tfl ngudn nhiet, tac dpng cua nhiet dp mdi trUdng. Cac gia tri nhiet dp dau ra cua dieh truyen trong qua trinh md phdng la cd sd quan trpng trong viec tinh toan va lUa chgn phupng phap dieu khien cua thiet bi.
5. KET LUAN
Bai bao de cap den viec nghien cUu qua trinh truyen nhiet trong thiet bi sUdi am diing trong y te bang phUpng phap md phdng va thUc nhiem. Ket qua eho thay, vdi chat long la dieh truyen nUdc muoi sinh Iy nhiet dp cua dau vao la 5"C, de ed dau ra la 37"C thi chieu dai day can dupc cap nhiet la 530 m m tUdng dUOng vdi khoang gan 3 vdng cudn. Tinh chat cua dong chay trong ong xoan cua thiet bi dam bao sU chenh lenh nhiet dp gifla cae vung d mat cat la dudi 1"C.
Thiet bi vdi thiet ke cd the cudn dUdc 10 vdng hoan toan ed the dap Ung dupe viec eung mpt luc gia nhiet cho dich truyen eho 3 benh nhan khac nhau, hay gia nhiet cho 3 loai dich cho eimg 1 benh nhan.*>
Ngay n h a n bai: 10/7/2014 Ngay p h a n bien: 16/8/2014
Tai lieu tham khao:
[1]. Di Piazza Ivan, Ciofalo Michele (2010), "Numerical prediction of turbulent flow and heat transfer in helically coiled pipes", International Journal of Thermal Sciences, 49{4), pp. 653-663,
[2]. Greenspan D (1973), "Secondary flow in a curved tube", Journal of Fluid Mechanics, 57{01), pp. 167-176.
[3]. Jayakumar )S, Mahajani SM, Mandal JC, et al. (2010),
"CFD analysis of single-phase flows inside helically coiled tubes", Computers & chemical engineering, 34(4), pp. 430-446.
[4]. Jayakumar JS, Mahajani SM, Mandal JC, et al. (2008),
"Expermiental and CFD estimation of heat transfer in hehcaUy coiled heat exchangers". Chemical engineering research and design, 86(3), pp. 221-232.
[5]. Kalb CE, Seader JD (1972), "Heat and mass transfer phenomena for viscous flow in curved circular tubes", In- ternational Journal of Heat and Mass Transfer, 15(4), pp.
801-817.
[6]. Mori Yasuo, Nakayama Wataru (1967), "Study of forced convective heat transfer in curved pipes (2nd re- port, turbulent region)". International Journal of Heat and Mass Transfer, 10(1), pp. 37-59.
[7]. Prabhanjan Devanahalli G, Rennie Timothy J, Vijaya Raghavan GS (2004), "Natural convection heat transfer from helical coiled tubes". International Journal of Thermal Sciences, 43(4), pp. 359-365.
[8]. Purandare Pramod S, Lele Mandar M, Gupta Rajkumar (2012), Parametric Analysis of Helical Coil Heat Exchanger, International Journal of Engineering Research and Technology, ESRSA Publications,pp.
[9]. Rogers GFC, Mayhew YR (1964), "Heat transfer and pressure loss in helically coiled tubes with turbulent flow". International Journal of Heat and Mass Transfer.
7(11), pp 1207-1216.
[10]. Xin RC, Ebadian MA (1996), "Natural convection heat transfer from helicoidal pipes". Journal of thermophysics and heat transfer, 10(2), pp. 297-302.
[11]. Yasuo Mow, Wataru Nakayama (1965), "Study on forced convective heat transfer in curved pipes:(lst report, laminar region)" International Journal of Heat and Mass Transfer, 8( 1), pp. 67-82.
[12]. W.R Dean (1928), "Stream line motion of fluid in a curved pipe". Philosophical Magazine, series 7, Vol 5{30), pp. 673-695.
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