NLN''''110 3/2013''''15 vl NGHIEN CUU LY THUYET CAC THONG SO THIET KE CUA ONG NHIET MAT TRITI LOAI TRONG TRITONG DE CAP NUtfC NONG H U V N H P H U O C HlfeN, NGUY6N THI MINH TRINH, LE CHI HIEP, DH Bach Khoa[.]
NLN'110-3/2013'15 vl NGHIEN CUU LY THUYET CAC THONG SO THIET KE CUA ONG NHIET MAT TRITI LOAI TRONG TRITONG DE CAP NUtfC NONG H U V N H P H U O C HlfeN, NGUY6N THI MINH TRINH, LE CHI HIEP, DH Bach Khoa - DH Qu6c Gia TP HCM HOANG AN QUOC - DH SlP pham K? thuat TP.HCM Bai bao trinh b^y kit qui tinh toan cac thdng so thiit ki cOa OMTT dipoc si> dung di cap nudfc ndng dieu ki§n cOa Thinh Ho Chi Minh Kit qua nghi§n cCru bai bao ia car s& quan trgng di nhdm nghien ctru che t^o mo hinh nhim tiip tuc thirc hien cic nghien cini thuc nghidm CAc tinh toan cho thay, dieu kien cua Thanh Ho Chi Minh, goc nghieng lam viec phu h p p ctia OMTT nen vao khoang 2(f Vai moi chat lam viec ben la nu&c, gia tn ty le nap duvrc di xuit n^n tCf 20% den 33,8% va ty /# toi wu gi&a dien tich phan ngung tu va bay hoi nen vao khoang 0,2 DANH M y c CAC CHU' V I ^ T T A T V A KY HIEU a Danh muc cdc chO> vidt tdt BXMT Bi>c xg m|t triri OMTT dng nhi^t mit tr&i logi trgng tru&ng ONTT Ong nhi^t tnr&ng NLMT Nang ItFg^g m^ttrO'i b Danh m u c cac ky hieu \ A A, Bl C( Cp dc d Fe F, G 1 L M T$ 1$ ngp cua moi chSt ldm vi$c ben ONTT Di$n tich hSp tbg cOa b£ mdt collector T i i t di$n mdt cdt ngang cOa ddng hci bSn tronq ONTT H$ s6 Bond Nhidt dung ri&ng cua nir6c it trgng thdi Idnq sAI Nhidt dung ridng cua n u ^ c b trgng thdi hci bdo hda khd Du'dnq kinh tronq phdn nqirnq cOa ON 11 Du'dnq kinh tronq phdn bay hvi cua ON 11 Didn tich bd mdt phdn ngirng tg cua ONTT Didn tich bd mdt phdn bay ho'i cua ONTT Clfdrnq dd BXMT Chidu ddi phdn dogn nhidt cua ONTT Chidu ddi phdn nqirnq tu cua ONTT Chidu ddi phdn bay ho'i cua ONTT Phdn ti> l u v n q cOa mdi chdt % m' m' P Per Q q Qb qc Qei Q» r R, P J/kgK J/kg.K m m m' m' W/m' m m m kq/kmol I G i d l THI$U C^c h$ thong c4p nude n6ng su- dung OMTT da d u c c ptid bien t u rit Idu tr6n the gidi Cdc hg th6ng nSy d u c c bien trfen thj tru6'ng t u thSp nien 70 80 ci3a t h i ky 20 tai chdu Au [1] vd hi^n d u c c sdn xudt chu yeu bai cdc cOng ty cua Trung Quoc Vdi tinh ndng: hi$u su4t Idm vi$c vd nhi^t d? nude d^t d u c c cao, thd-i gian ddp Crng nhanh hen so vdi cdc logi collector t n j y l n thfing, n6n OMTT thudng d u c c si> dgng tnang cdc h$ th6ng cap nude n6ng mdt trdi vdi cdng sudt Idn MOt nhOng y l u t6 quan trpng quyet djnh d i n h i l u qua cua OMTT chinh Id ONTT Cdc nghien cuu cho t h i y cdc y l u t l nhu: gdc nghilng ty l | ngp cua mfii chat Id cdc y l u t l quan trgng anh hudng d i n hogt d | n g cua ONTT Ngodi ra, d n g s u i t nhi$t cua ONTT cQng kh6ng d u c c v u c t qud cdc gidi hgn Idm v i l e (gidi hgn sdi, gidi hgn Hi c u I n , gidi hgn dm thanh) d l ddm bdo ONTT Idm v i | c I n djnh A A, K Mi Mv Pi P Ol Apsudt Ap sudt td'i han Cdng sudt ntiiet cua ONTT Mat dd donq nhi^t liio'i nan SDI cua UN i i Mat dong nhidt tgi phdn ngu'ng tu cua ONTT Mdt dong nhidt phdn bav ho'i cua ONTT Gidi han ldi cuon cua O N i i l i i o i nan am tnann cua UN 11 Nhiet an hda hoi Nniet iro' tronq cua UN 11 u o c nqnienq cua UM 11 He so d3n nhl$l Hd so ddn nhidt cua nu'd'c if trgng thai Idng sdi Hd so d i n nhidt cija nu'd'c 6' trgng thdi hci bdo hda khd Dd nhdi tuydt ddi cua nu'd'c cr trgng Ihdi long sdi Dd nhdt tuydt ddi cua nird'c d' trgng thdi hoi bdo hda khd Khdi luvng ridng cua nu'd'c d'lr^ng thdi Idnq sdi Khdi lu'Q'ng ridng cua nu'dc cr (rgng thdi hoi bdo hda khd Su'c cdng mdt ngodi cua nu'd'c d' trgng Ihdi Idnq sdi bar bar W W/m' W W/m' W/m' W W J/kg Kfl/V dd W/mK W/mK W/m.K Pa.s Pas kg/m' kg/m^ N/m Theo cac tdc gia T r l n Vdn Vang - Bui Hdi [2], ONTT c6 the Idm v i | c binh thudng g6c nghiSng Idn hffn 6° Ngodi ra, cdc nghidn cii'u d u c c thuc hi|n bdi H Nguyen - Chi, M.Groll [3], Terdtoon, P et al [4], E Hahne vd U Gross [5] cho t h i y dnh hudng cua goc nghi&ng den cdng suat nhi|t ci/c dgi cua ONTT Cac nghidn cdu deu dua k i t ludn, ONTT CO the hoat d^ng vdi d n g suat nhi|t Idn n h i t d u c c d$t ngiiiing mOt g6c 40°, khflng phai ONTT dat t h i n g di>ng Cdc nghien cuu khdc cQng cho thay, lucng m i l chat ngp phu thuflc vdo logi mdi chat ngp bdn ONTT cung nhu dieu k i l n Idm v i | c (nhi|t dO, d n g s u i t nhidt) vd gdc nghidng Nhbm nghidn ci>u Hodng An Quoc, Ld Chi Hidp, Hodng Duang Hung [6] d l x u l t ty l | nap cGa ONTT s u dyng OMTT d gid trj vdo khodng 30% H Imura vd cdc d n g SM' [7] dd de xuat cdng thdc xdc djnh ty 1$ ngp c6 tinh den dnh hudng cua nhidt dd ldm v i | c vd logi mfli c h i t d u c c ngp vdo bdn ONTT 16* NLN-110* 3/2013 Ngodi ra, nhflm Kanhi Neghishi va Teruo Sawada [8] cQng da nghidn c d u anh hudng cua ca goc nghidng vd ty Id nap d i n hieu qua lam viec cua ONTT vdi mfli c h i t Idm vide ben Id nude vd methanol K i t qua thuc nghiem cho thdy, vdi ONTT vdi mfli c h i t Idm vide bdn Id nude, ONTT ndn d u c c ddt nghidng mdt gdc khoang t u 40° ddn 60", ty Id nap cOa mfli e h l t ndn co gia tri khoang tir 25% den 60% tl CO SCf L V THUYfeT a A n h h u d n g cua gdc nghieng - D l i vdi ong nhidt mat trdi, vide lua chon gdc nghidng phdi thoa man d u a c hai y l u to: luang BXMT nhdn d u c e nhieu nhdt vd ONTT phai hogt dflng hi0u qud nhat Do do, cdn phai xac djnh muc dd anh hudng cua gflc nghidng den hai ydu t6 ndy de lua chpn gid tri toi u u - B e xde dinh anh hudng eua goc nghidng den lucng NLMT nhdn d u a c nam tren mdt dan vi didn tieh be m§t, c6 the s u dyng cac cdng thuc t d 10.13 den 10.29 duae gidi thidu TL [9] de u d c lucng lucng NLMT md m^ be mat nhan d u c c ndm vdi cdc gdc nghieng khac nhau, b l u trdi d u c c gia thilt dat dieu kidn sdng tieu c h u i n - Anh hudng eua gdc nghieng ddn hieu qua hogt ddng cua ONTT: s u dyng cdc ket qua nghien cuu cua H Nguyen - Chi and M.Groll [3] Theo dd, cong suat nhidt cua ONTT ddt nghidng gfle p (1° < p < 80°) se ty 1^ vdi cflng s u i t nhidt cue dgi cua ONTT dat thing ddng mflt gid trj ftp) (ju-cc xde djnh nhu sau: fO} = ( — ^ , ' I ^ ) (1) b Ty le nap cua m o i c h i t lam viec ben t r o n g dng nhi^t - Trong ky t h u | t I n g nhidt, ty le nap d u a c djnh nghTa Id the tfch cua moi c h i t nap chia cho t h i tich phan bay hai eua dng nhiet: I = V / V e , % c Cac g i d i han lam viec cua d n g ntiiet t r o n g tru'dng G i d i h^n Idi c u d n (Entraiment or f l o o d i n g limit): cong t h u c Terdtoon, P et al [4] [10] Bing ^nghop c^ct^lenap diroc ^xuittveSc nghi§n cOv dg duoc Uii/c hi0n yd ngdiindi^' Trdn Van Vang BUI Hai [2] Gid tr| d i x u i t hoac c6ngthi>c i, = 30% ddn 5% Hoang An Qudc Ld Chi Hidp Hoang Du'ong Hung 16] Daviij Reay and Peter Kew 110] (Tdng hgp cdc kdt qua lir cdc nghidn dm khac) Ghi chd Mdi chdt n^p I j nuo'c nhigiad lam vide SO'C aSn 90°C Mdi chdt ngp la nude C6ng thOc Bezrodnyi va Alekseenkodd xuat g = 20% ddn 80% H Imura, K Sasaguchi and H.Kozai [7] 'iAf^l fl' It Kanji Negishi and Teruo Sawada [8] H.Nguyen - CN and M.Groll [3] I, 'li^j = 25% den 60% Mdi c h ^ n ^ Idnudv = 40% adn 75'% MOI d l j t ngp la eUianol, Kdl qud nghidn cihi thvc nghidm vdi cac ty t€ ngp 0,38:0,53, 0,71; 0,88 cho thdy ty Id nap anh hudng it len gid tri cQng sudt hogt ddng ci/cdgicda ONTT •\-> (4) Trong 46: f,, fj, f,: li cic he so Kutatelaita - f|: dirge xic dinh t[r h | s6 Bond (Bo) va d6 thj sau: ^ "' - fi aifoc xSc ainh tCr gia tri ip nguyen Kp (5) suat khang tt\(i P N e u K p < ^ f ^ K.-"' N l u Kp> 4.10'; f2 = 0.165 - fa : h§ phg thuoc vio goc nghigng cOa ONTT vi gi4 til ciJa h$ so B„, auac xio dinh tir thi sau Hinh Quan hf glQ-aglitrlfjVigie nghieng dia OlfTT imgv6iciel\^a6 Boner M i t e nAau [10] Bond nuirdter Hinh Quart h^glQ^ gii trj f1vih$s6 Bond[iOl NLN'110-3/2013* 17 Gicri han sdi (Boiling limit): cong th(K Rolisenow - Griffith [10] [Pl-Pvf qi, =0,012 r ^ j (7) Pr Gioi han am (Sonic limit) [10]: qs = r.(p, P,.r= (8) Nhi§ttrdr cila ong nhiet Nhigt trd va chSnh Igch nhigt dd xuat hien ben ONTT co the du-ac tinh tocin nhu- sau; At *^ * ' ' ' R (9) _it_it,+att_ 1 Q Q F a, ' F f O j (io) a,; hg s6 trao doi nhiet ciJa qua trinh soi cua mdi ch^t bgn ong nhigt, c6 thi du'p'c xgc dinh bing c^c cdng thCrc sau: Cong thii>c Rohsenow [10J_ l-iiT„, 0,013 «-rJ6-(Pi-P.-) (11) Cgng thOfc Mostinski [10] o, = 0,106 !f,^' (l,8 If -" + P,' - • 10,P,'=)-< quan dua trgn ngin ngir MATLAB vg dg thuc hign nhieu thi nghigm tinh toan de xgc dinh cgc thdng s l thilt kg OMTT duoc su dgng d l cgp nude ndng dieu kign cGa Thgnh H i Chi Mmh III K^T QUA T I N H TOAN a Mo ta ong nhiet mat troi loai trud'ng Cgu t^o hoan chinh cua OMTT: Cng thuy tinh chan khdng hai ldp Cgnh truyen nhiet tir be mgt hip thu din phgn bay hoi cOa Ing nhigt Ong nhiet trud'ng Thong so hinh hoc cua OMTT: Bang Ong thuy t i n h chdn khong hai \&P +1 = 1500mm + D„/Di = 47mm/34mm + Didn tich hap thu: A = 0,0747m^ + Pct = ' P a + a = 0,92, t = 0,08, -•- T (khi goc ton cua BXMT Id 0°) 0,91 Ong nhidt t r o n g tru'd'ng Cdnh truydn nhidt + V3t lieu dong + Mdi chdt Idm viec nu'dc +1 = 1650mm ( l , = 1400mm, le = 150mm, la = 100mm) + d , = 6mm + dc= 14mm + Vdt lidu: nhdm + Chidu d^y canh 0,2mm + Bidn dgng cdnh: /""H^^^N^ / ( (12) \ ' Ji J CV) T ^ (13) Cdng thu'c Copper [10] o, = 55.qJ''.P,?"':-logP/r ,(14) Cdng th(i>c nhdm IM.Shiraishi et al de xuat [11]: '.XT' Pv •-"••'^ •'.' (16) Trong cgc cdng thCfc trgn, cdng thirc Rohsenow vg l^ostinski cd xgt din anh hud'ng cQa tinh chat cua b l mgt gia nhigt den qug trinh sdi Cdng thirc nhdm M Shirciishi de xult cho qug trinh sdi xay bgn mdt Ing kin o,; hg s l trao doi nhigt cda qug trinh ngu'ng tu mdi chit xgy bgn Ing nhigt Qug trinh ngung tg xgy bgn Ing nhigt cd the duoc xem lg ngung mgng vg sii' dyng cdng thirc cua Nusselt de xgc djnh hg s l trao doi nhigt ngung [2][10],[11],[121; 1.47.Rer'.X,.(-7 ^, Hinh Cau (90 hoiin chinh cua O, Cong s u i t nhift cua OMTT: Co the xac djnh cong su3t nhi^t cua OMTT theo cuang dg BXMT chieu den be m^t h^p thg cua ong thuy tinh nhu* sau: Q=AG (19) —:) (16) •"! •" !•: r,, = «, tT„, - !„>.-= - p (17) J,jj Trgn CO s* cgc md tg togn hpc dg trinh bgy, chiing tii dg vilt cgc chuong trinh tinh togn cd lign Hinh Cvdng tfd BXMT vd s6^l& ttfong u-ng nhw bing Ar^tvngiy 01/04/2011 din 01/04/2012 t^l Tp Ho ChiMinh 18* NLN-110'3/2013 Hinh trinh bSy cu'dng d6 BXMT va so g\ir tieang iing khoang thai gian tir 01/04/2011 den 01/04/2012 Cac s6 lieu du'p'c bffi Tram theo doi thai tiet Davis Vantage PR02 dat tgi B6 mdn Cdng Nghe Nhiet Lanh - DH Bach Khoa Tp H6 Chi Minh Trdn ca so* cac so lieu diu vao trinh bay a hinh 4, ket qua tinh tOcin cho thay cong suat nhi$t cyc dai cua OMTT c6 the dat gi^ tri Q = 74,7l'V'(khi G = lb00lV/m^, so gidr ning co G > MOOW/m^ cd g\A tri kh6ng dang ke nam nfin co the bo qua) b Xac dmh goc nghieng cua dng nhiet mat trai lo^i trpng tru'dng Hinh Anh hu^g cua gdc nghieng p l§n OMTT (HAio IA ty If giira NLMT collector nh0n dirgK nim vdi cdc Qia Anh hipong cda goc nghieng din luyng Ui p khic so vdi p = 1(f) NLMT nh|n dv^c nam trgn mot den vi dien tich be mat: c Xac djnh ty le nap cDa mdi chit lam vi^c Ket qua tinh to^n lu'O'ng NLMT den 1m^ mat I n g nhidt trpng tru'd'ng ph^ng vdi cac gdc nghidng thay doi tiF d^n 45° dat Su* dgng cdng thO-c (3) Imura dd xuat de xdc tai Tp Ho Chi Minh ca nam du'o'c th^ hi^n qua djnh gia tn ty Id ngp vdo ONTT, vdi mdi chit la thj sau: nu'dc Khi q thay doi gid tri tCr 106 den 2123MWn^ (i>ng vdi cu'dng dO BXMT thay doi tir 50 din 1000W/m^) nhi^t tinh todn: 70*C, ta cd kit qua M '"" 1D 15 20 30 2.S 35 40 45 Hinh NLMT nh$n dirgv trSn Inf be mat nghiSng ci nSm Crng v6i Ctic gdc nghieng khAc Anh hipo'ng ciia gdc nghieng d i n hifu qua ho^t dpng cua ONTT: Ap dung cdng thu-c (1), quan h$ gi&a gia frj p vS f(|3) du'Q'c the hi$n qua thj sau: • 12 on / Inr -•*-t""" * OA • • 10 211 31D 4D SD aa 7a 30 Hinh Anh htrdng ciia gdc nghi§ng I6n cdng suit nhi^t cyv a$l cda 6ng nhi^t T6ng hp'p hai ket qua da trinh b^y a tren, chung tdi x^c djnh gdc nghidng cua OMTT ISm vi§c t$i Tp H6 Chi Minh ndn vdo khoang 20° DONQ NHIET ( W M Hinh GiA tri luting n^p c(re dai vd cjfC tieu Oiay dm theo m$t dg ddng nhl^ tinh theo cdng Oi&c Imura - Kit qua cho thiy, t/ Id ngp tfnh theo cdng tht>c Imura cd gid tri vdo khoang 20% den 33,8% cu'dng BXMT G thay dli Gid trj ty Id ngp t6i thilu tinh theo cdng thi>c Imura cung khd phd hgp vdi kit qua bang Do thj cQng cho thay cdc gid trj ^mm va ^max thay doi khdng ddng ke mdt d$ ddng nhi^t thay doi d Cac gi6i han lam vide cua ONTT - Ap dung cdc cdng thCrc (4), {7), (8) d l xac djnh cdc gidi han lam vi^c cQa ONTT nhif midu td myc 3.8 khoang nhigt dd tir 30''C den llCC Kit qua cho thiy cdc thdng s l gidi hgn diu cd xu hu'dng tdng theo nhidt dd Idm vi|c cua ONTT vS gidi han Idi cudn cd gid trj nhd nhit cdc logi gidi hgn ndi tren Cdc gidi hgn Idm vide cua ONTT diu cd gid trj Idn hen cdng suit nhidt ci/c dgi cd thi cIJa ONTT dang nghidn ci>u (74,7W) Tuy nhifin, vide t)m hilu cdc gid trj gidi hgn ndy rlt quan trpng ONTT du'pc si> dyng kit hg'p vdi cdc collector NLN MIO-3/2013 M9 mat trdri kjgi tdp trung 06 thi sau cho thay SLF thay doi cdc gid trj gidi hgn Idm vide cda ONTT ^eo nhidt dd ldm vide (HETDOfq Hinh Gidi h^ lAm v/#c ciia ing nhi^ tttay doi theo nhl^ di> ldm W$c ci}a ong nhi$t e Nhi^t trv xult hi$n bdn 6ng nhidt trpng trvd-ng ldm vide khdc {40''C, 70''C, lOO^C) cdng suit nhidt eua ONTT thay doi f xy le tdi mi giira di^n tich phdn ngimg tu vd bay hai ciJa ONTT - Trdn ca sa cdc tinh todn nhidt trd ben cua ONTT, ed thi thiy rd nhidt trd bdn khdng ChT phu thudc vdo cdng suit nhidt vd nhidt dd Idm vide eua ONTT, md cdn phy thudc vdo ty 1$ giGra didn tfch phan ngung bJ vd phin bay hai Tuy nhidn, cdn luu y, kich thud'c phan bay hai cua ONTT bj gidi han bdi kfch thudc cua dng thuy tinh chdn khdng hai Idp, dd kfch thudc phan ngung tu cua ONTT ed the dup'c lua chpn linh dpng han Bdt El = dc/de Id ty Id gi&a dudng kfnh phdn ngung tu va phan bay hai 6ng dong dup'c chi tao tidu chuan nen vdi dudng kfnh d-^ = 8mm, ede gia tri cua E, cd the la: 1; 1,37; 1,73; 2.11; 2,49; 3,25 - Dat Ej = I A t9 Id giO'a chilu ddi phdn ngung tg vd chieu dai phan bay hai - Ty Id giOa didn tfeh b l mdt ngung tg va bay hai Fc/Fe=E,.£2 - Do thj sau thi hidn sg- thay doi gid tn chdnh Idch nhidt dp xuat hidn ben ONTT anh hudng cGa kfch thudc phin ngung tg trudng hpp cdng suit nhidt cua ONTT Q = 74,71V, nhidt dp tdm vipc cua ONTT 70*C —V^.= Hinh 11 Anh hu-dmg cOa Meh thudvphan ngung f(f d^ chdnh l$ch nhl^ dd xuat hi^n bSn ong nhift (oroOlSIHrTHOSI Hlf^HO Hinh 10 ChSnh l^ch nhl$t dd xuit hi^n b6n ong nhlft nhl^t df vi cdng suit nM^ thay doi Kit qud tinh todn cho thiy, nhidt tra bdn ONTT cd xu hudng gidm nhilt dd Idm vide eOa ONTT tang Cdc kdt qud nhdn du-p-c h$ s l trao all nhidt sdi a, cdng tht>c (10) dmyc tfnh theo cdng thi>c Copper vd Mostinski cd gid trj gin nhu khodng nhidt dd vd cdng suit nhilt khdo sdt Bilu d l sau thi hidn chdnh Idch nhidt dO xult hidn bdn ONTT tgi cdc nhi$t dd - Cdc kit qua trdn eho thiy, nlu ty Id giCra didn tieh phin ngung vd phan bay hai cua ONTT qud nhd, sd din din nhidt trd cua ONTT Idn, chdnh Idch nhidt dd Idm vide cua ONTT cao Dilu ndy cd thi duae giai thfch hd s l trao dli nhidt tgi vj trf ngung ty (tfnh theo cdng thdc Nusselt) ty 1$ nghjch vdi mdt dO^ddng nhidt ndn mdt dp ddng nhidt qud Idn se dan den tdng nhidt Ira phin ngung taj cua ONTT Dd thj hinh 14 cho thiy ty 1$ giOa didn tfch phin sdi vd phin ngung vdo khodng 0,2 (vdi ONTT c6 kfch thudc phin bay hai dd trinh bdy phfa trdn) thi chdnh Idch nhidt dd xult hidn bdn ONTT khodng 5°C Nlu tilp tgc tdng gia trj ndy thi chdnh Idch nhidt dO cd gidm nhung gidm khdng ddng k l (khoang I^C), ndn vide chpn kfch thudc phin * N L N - 1 * 3/2013 ngung qud Idn cOng khdng tot khoi lugng kim loai d l chd tao va kich thudc cua dng nhiet se tang len IV K t T LUAN Cdc k i t qua nghien c u u ly t h u y l t trinh bay phia trdn cho thay ddi v d i OMTT dup'c nghidn c u u bai bdo, goc nghidng cua OMTT l i p dat tai Tp Ho Chi Minh ndn co gia trj khoang 20° V d i mdi chat Idm viec ben ONTT la n u d e , ty Id ngp cOa mdi chdt lam viec bdn ONTT nen co gtd tri t u % d i n 33,8% Ty Id t i i u u giiJa dien tich phan ngung ty vd bay h a i cua ONTT ndn vao khoang 0,2 Cac k i t qua la c a s d de nhom nghidn CLPU tnen khai c h i tao md hinh OMTT, tir dp t i l p tyc cac nghidn cij'u thiFC nghiem hudng den vide ddp ung nhu cdu n u d e nong d quy md cdng s u i t Idn tai Tp Hd Chi Minh ABSTRACT This paper presents the results of theoretical study on finding the design parameters of solar gravity heat pipe used to supply hot v/ater In Ho Chi Minh City Our results sftoiv that, the solar gravity heat pipe should be installed with the inclined angle about 2(f In the case v\/here water is used as worl