IM!r»Mit*Mc6NG NGHE
DANH GlA HIEU QUA THU N A N G Ll/gNG MAT TRGll CUA ONG NHIET TRONG TRUCfNG CHAN KHONG SUf DUNG MOI CHAT ETHANOL
EVALUATING THE EFFECTIVENESS ABOUT SOLAR ENERGY COLLECTION OF VACUUM THERMOSYPHONS USING ETHANOL SOLVENT
D i n h Xuan T h a n h , Vu Van Minh, Cu Huy Thanh
Tom t i t
Bai bao trinh bay nghien ciJu ling dung ong nhiet trong trUcing chan khong sil dung moi chat Ethanol de thu nang lumtg mat trdi. Ket qua cho thay, bg thu nang lugng mat trili nay de dun mdc nong thi co hieu su3t nhiet kha cao khoang 62%, thdi gian dun nudc nong giam, khong co hien tuong cau b^n ong thCiy tinh, nhiet luong cOa nUdc nong trong thiing khong b\ mat liic trdi ram mat nhudot v6i bg thu nang lUOng kieu cu.
Iii khda: ong nhiet, chan khong, nang lu'ong, mat trcfi, dun nu'dc nong
Abstract
This paper presents the results of research and application of vacuum thermosyphons containing Ethanol solvent used to collect solar energy. The study results show that when using vacuum thermosyphons for solar collectors to heating water, the high thermal efficiency of about 62%, heating time is reduced, the glass pipe is not dirty and there is not loss of heat of water in cool days
Keywords: thermosyphons, vacuum, energy, solar, water heater.
TS.fimh Xuan Thanh -TrUetng Dai hoe Cong nghiep Hii Noi ThS VQ Van M[nh -TriTflng Cao dang nghe Cong nghiep Ha Noi PGS.TS. CiJ Huy Thanh - Hoc vien Ky thuat Quan sU Email, [email protected] vn
Ngaynhanbai: 15/01/2014 Ngay ch^p nhan dang: 21/03/2014
1.0ATVANDE
Ong nhiet diToc sang ehe tCf rat lau nhifng viee nghien eCTu Crng dyng no mcifi ehi phat trien manh trong thdi gian gan day. Ong nhiet trpng tradng la mot phan tCr truyen nhiet eo nhieu tinh nang tot hOn so vdi cac phan tCr truyen nhiet truyen thong nhU: gon, nhe, cau true don gian, d^ bao difdng, giam ap suat khi, an toan van hanh cao, de lap dat,... Hien nay, no daoc diing
trong eae thiet bj thu hoi nhiet tai cac nha may cong nghiep, tan dung nhiet khithai eua nha may.
Nguyen ly cua qua trinh truyen nhiet co ban giong nhau d cac ioai ong nhiet, nhUng eong suat nhiet phy thuoc vao eau tao va dieu kien lam viee cua ong nhiet. Bang each thay doi cau true cua ong, laong va loai moi ehat nap trong ong cd the che tao ra cac loai ong nhiet khac nhau.
OViet Nam, ong nhiet trong trUdng da bat dau dUoe nghien cCTu sCf cJung lam thiet bj thu hoi nhiet nham tiet kiem nang laong va bao ve moi tn/dng, nhang ket qua nghien cii'u ve ong nhiet trpng trUcfng chan khong co moi ehat Ethanol thi ehUa dUdc cdng bo.Vivay, nghien eiJu thiet ke, che tao va danh gia hieu qua trao doi nhiet cua bo thu nang lypng mat trdi dung dng nhiet trong trUdng chan khdng sd dyng m6i chat Ethanol trong bd dun nUde ndng nham nang cao dp tin cay va giam chi phi la hadng nghien cCru mdi, dap i^ng yeu eau thac t i i n .
2. LlTA CHON K 6 T CAU CCPA 6NG N H I E T T R O N G T R U O N G C H A N KHONG Bd phan thu nang jyong mat trdi cd hai loai co ban la tam phang va tap trung, vdi cau tao kha phong phu, che tao bang nhieu loai vat lieu khae nhau, cac be mat ha'p thy ehpn Ipc eung r^t da dang. Tren cd sd phan tich v l dac diem ket cau, yeu eau eCia thiet bi, dieu kien eong nghe va vat tasSneddegi^ni gia thanh cua san pham; da li/a chpn phaong an sCr dung bd thu nang luong mat trdi kieu tam hut ehan khdng (l^e mat trong dng nhiet nhSn), day la mot bien the eua bp thu nang lUpng dang tam phang, cd hieu qua rat eao, cao
381 TapchiKHOAHOC&CONGNGHE. So 2 1 . 2 0 1 4
^ -f
Ni/dc ^ f-or NUdc
l-i^hap ihu ndng Img biic xg; 2- 6ng thuy tinb chdn khdng (phdn nhdn nhiet - phdn sdi); 3- Thiing chdo nudc, 4- Nudc ndng sddung 5- 6ng ddng (phdn tod nhiet hoac phdn ngi/ng); 6- Gid dd; 7- Chdt Idng nap trong dng nhiet,
fy - Nhiet dg khong khi bin ngoai; t^^ - Nhiet do be mat hdp thu;
q^- Nbiet bdcxa ddp vdo vd ngoai; q^- Hhiet bdcxo do tam hop thu nhdn;
q^ - Nbiet too ra mdi trudng; q - Nhiet cop cho dng nhiet Hinh 1. Cau tao bo thu ong nhiet trgng trUcing chan khong shon rat nhieu so vdi loai tam phcing thdng thudng khae. Dac ibiet, cd the sCr dung d nhCfng vung tt nang hoac cd nhiet dp mgoai trdi khdng cao. Hieu qua cua bd thu nang luong hau nhu it phu thupc vao toe dp gid d mdi tradng xung quanh.
Bd thu nang laong daoc eau tao t a nhieu dng chan khdng ighep song song dat tren ciing mdt tam phang nam nghieng,
•gdc nghieng cua tam p h i n g ve co ban phu thude vao npi lap dat, lien quan tdi gdc tryc xa cua tia nang mat trdi. Do tiet jdien ciia moi dng deu cd dang hinh trdn nen kha nang nhan ibac xa mat trdi cua dng loai nay tdt hon rat nhieu so vdi cac idng dang tam phang thdng thadng va vao bat ca luc nao cac tia bae xa mat trdi cOng co the den thang gdc vdi be mat ngoai ciia cac ong.
Cciu tao cua mot dng nhiet trpng trudng dang ehan khdng duoc trinh bay nhu tren hinh T. Vd boc hinh tru bang thu;;* tinh cd dang ong nghiem, gom hai Idp: ben ngoai va ben trong, d giCa hai Idp nay la chan khong. Ca hai Idp deu lam bang thuy tinh Borosilicate, Idp ben ngoai hoan toan trong suot, cdn Idp ben trong dupc san ehat hap thy ehpn Ipc d be mat dudng kfnh Idn hon (be mat tiep xuc vdi ehan khdng). Ben trong vd bpc bang thuy tinh hut chan khong sao cho ap suat tuyet doi khoang 5.10-^ Pa. Day la phan nhan nhiet bii'c xa mat trdi cua ong nhiet (goi la phan sdi eua dng).
::hinh nhd dp chan khdng trong vd bpc hinh tru bang thuy tinh ma cac ton that nhiet do doi lau va dan nhiet giam di Jang ke.
Mdi chat sCf dung trong dng nhiet la Ethanol, phu hop vdi feu cau lam viec va ket cau cua thiet bi (nhiet dp sdi d 1 at
-r--
' • - • V '
'Mo
la ys^C, khoang nhiet dd lam viec O-HISCC, phii hpp vdi ong nhiet bang dong). Vdi pham vi nhiet dd hoi trong dng nhiet khdng eao, d ap suat khiquyen nhiet dp sdi ciia Ethanol nho hon cua H^O, nen khi dng ed nhiet dp nhd hon lOO^C Ethanol se cd ap suat khdng thap nhu vdi HjO, dam bao khdng khi xam nhap vao ben trong dng [1].
Khi nhan nhiet bdc xa chat Idng se sdi bien thanh hoi ehuyen dpng len tren toa nhiet
cho nude trong thiing chi^a va se ngUng ty lai rdi quay ve phan dng thuy tmh, Phan ngUng tu d phia tren lam b^ng ddng de de dang tda nhiet cho nudc trong thung.
Cong suat ciia mdt dng nhiet trong tradng dape xac dinh theo cdng thdc [1,6]:
Hinh 2. So do phan bo nhiet trd cua ong nhiet
At
R R v , . + R. + Rh + f^n + Rv.n + Rw (1) 6 day R -Tong nhiet trd (K/W) [hinh 2);
At - Hieu so nhiet dp gida nhiet dp tam hap thu t va
So 2 1 . 2 0 1 4 . TapdiiKH0AH0C&C0NGNGHr39
EEEEElcQNG NGML
hOngnhiet, 2-Ihdng chda nudc, 3-Gid dd; 4-Tdm phdn xa Hinh 3 Cau tao bo thu nang lUOng mat trdi ong nhiet ehan khdng
nhiet do nudc trong thiing t^; Bd thu nang lupng dun nadc ndng R^^ - Nhiet trd dan nhiet qua vach sCf dung 10 dng nhiet trong trUdng ong phan sdi (phan thuy tinh); chan khdng mdi ehat Ethanol cd eau
R^-Nhiettrdsdiehatldng{Ethanol...) tao nhutren hinh 3.
trong ong nhiet d phan sdi;
R|^ - Nhiet trd hoi ehuyen dpng ta vung sdi (dng thuy tinh) tdi viing ngUng (dng ddng). Gia tri nhiet trd nay rat nhd ta thudng bd qua R|_ = 0;
R^ - Nhiet trd qua trinh ngUng hoi trong dng nhiet d phan ngUng (phan dng b^ng dong);
R^^ - Nhiet trd dan nhiet qua vach dng phan ngUng (phan ong ddng);
R^^ - Nhiet trd ddi luu cua nude trong thiing vdi be mat ngoai phan ong ddng cua ong nhiet.
Ky hieu Rg= R^^ + R^^ + R^ la tdng nhiet trd ngoai va R - R^ + R^ la tong nhiet trd trong va bd qua nhiet trd eiia hoi R^ = 0, ta cd:
R = R^ + R, (2)
Q ' = - (3)
Gpi Q^- Cdng suat nhiet ben trong cua 1 dng nhiet, ta cd:
I-Ddu ngp moi chdt;
2- 6ng ddng $22; 3- Khdp ndi;
4- Ong thuy tmh chdn khdng.
Hinh 4. Cau tao cua dng nhiet Vd thung nude lam bang Inox day
2mm, ben ngoai bpc mdt Idp cac^
nhiet day 50mm, hinh try, dUdng kinh trong 470mm, dadng kinh ngoai Idp each nhiet la 570mm.
6r\g nhiet gom hai phan: Phan phia dudi nhan nhiet bufc xa mat trdi (phan sdi), la ong thuy tinh chan khdng ben trong cd tam hap thy nang lupng mat trdi, phan tren la phan tda nhiet (phan ngUng) eho nadc trong thiing la ong bang dong. Mdi chat nap Ethanol (95%), bang thue nghiem da laa chpn di/ot luong nap phu hpp la kholing 30% th^
tieh eua phan dng thiiy tinh. -De noi phan ong bang dong vdi phan ong thfiy tinh chan khdng, diing mdt khdp nS bang cao su va keo dan (hinh 4).
Tam phan xa ia tam bSng Inox daj' 1 mm, dat phia dUdi phan dng thiiy tinh ehan khdng, vifa de dd cac ong vifa de ph^n xa lai tia bifc xa mat trdi vao 6ng de tang lUpng nhiet hap thu.
- Do nhiet dp be mat ngoai ong nhiet va nhiet dp khdng khi ngoai trcd:
So do lap dat dau do dUpc trinh bay tren hinh 5.
Diing cap nhi§t do nhiet do b^r ngoai phan thiiy tinh va phan ong dong, do theo chu vi dng va chieu dai dng, sau do lay trung binh duac gia tri nhiet do ben ngoai phan sdi t^^, va nhiet dp ben ngoai phan ngang t^^. d 3ay, nhiet dd ben ngoai phan dng dong^
coi bang nhiet dp ben trong t, (t,,^ ='^, vi ddng ed he so dan nhiet idn v^ chieu dai eua dng nhd). Nhiet dd ben ngoai phan dng thOy tinh t^^ chinh la nhi§td6 mat ngoai kinh phii dng thiiy tinh chSri
d day, t^, t^ - nhiet dp be mat ben trong phan sdi va phan ngung eiia dng nhiet. d che do dn dinh: Q' = Q.
3. O A N H GlA HIEU QUA TRAO DOI NHliTClJAONGNHieTTRpNGTRU'ONG 3.1. Xac dinh cong suat va hieu suat bo thu nang lUcrng
dau do(tnn) 100
/ - Bdu do be mat phdn ong ddng;
2- Bdu do be mat phdn dng nhiet bong thuy tinh chdn khong Hinh 5. So do vi tri dat dau do cam bien nhiet cDa ong nhiet
d a u g o ( t - = t . )
X
401 TapdiiKHOAHOC&CONG NGHE. S 6 2 1 . 2 0 1 4
SCIENCETECHNOLOGYl
t^ft^- Cdc vj tri ddt ddu do nhiet do nudc trong binh Hinh 6. So do vi tri dat dau do cam bien nhiet ciia binh nudc khdng t^ (t^ = tJ. Nhiet dp khdng khi nhan dape trong 1 gid:
ingoai trdi 1,^^ dupc do bang nhiet ke.
1 -Do nhiet dp cua nudc trong thiing:
,Diing hai cap nhiet dat d vi tri gida
•thiing (hinh 6), roi lay trung binh dUOc iinhiet dp nUdc trong thiing 6 mdt thdi rdiem do la t^.
I Tien hanh do trong 15 ngay, mdi ngay do 7 lan, thdi gian bat dau do t a
;10 gid, khoang each moi lan do la 1 gid, nhiet dp nadc ban dau vao thiing i,la20''C. Ket qua do trung binh trong 15
ngay (bang 1).
6 day: At^- Gia trj nhiet dp nUdc ,tang trung binh trong 1 gid.
Ket qua cho thay, nhiet dp nUdc cua thung tang trung binh trong mdt gid khoang 7,5°C.
, - Xac dinh cdng suat va hieu suat bp .thu nang laong:
. LUOng nhiet ma nadc trong thiing Being 1. Ket qua do nhiet dp bang thifc nghiem
Q*„ = G^. C^. At^ (5) 6 day: G^- Lapng nUde trong thung
(kg);
O Nhiet dung rieng ciia nudc d nhiet do trung binh t^ = 45°C, C^- 4,174 kJ/kg.K [4];
At^- Gia tn nhiet dp nUde tang trung binh trong 1 gid, At^ = 7,5''C (theo bang 1);
C -Thdi gian do, trong 1 gid;
Tacd: Q*„ - 9 0 . 4 , 1 7 4 . 7 , 5 - 2818 kJ/h
LUOng nhiet ma nUde trong thiing nhan dUOc trong 1 giay: Q^ = Q ^ / ^ (6)
Taed:Q„ = 2 8 1 8 . 1 0 V 3 6 0 0 - 7 8 3 W Nhiet luong eua mdt dng nhiet cung cap cho nUdc trong thung trong 1 giay (W):
Q' - Q / n (7) d day: n - sd ong nhiet, vdi n = 10; ta
cd cong suat ciia mpt ong nhiet:
Q' = 783/10 = 78,3W Nhiet lapng bi^c xa mat trdi dap vao tam hap thy cua dng nhiet chan khdng trong 1 giay duoe xac dmh theo cdng
thufc Q',, = F \ * q , , (8) 6 day: q^_ - Nhiet bdc xa dap vao
tam hap thu, (W/m^);
F^^ - Dien tich mat ngoai phan sdi ciia ong, m^•
Theo Liu-Jordan, nhiet lapng bdc xa dap vao tam hap thu gom 3 thanh phan: true xa, khueeh tan, phan xa cua mat dat; dupe xac dinh theo b^ng cdng thifc [5]:
(1 + C 0 5 ^ )
l i n do 1 2 3 4 5 6 7
Thdi diem do lOh l l h 12h 13h Mh 15h 16li
U t 29,9 34,0 40,0 42,0 42,0 40,0 36,0
u-c
32,0 35,0 42,0 45,0 46,0 46,0 44,0
U t 35,0 35,5 39,0 48,0 53,0 60,0 67,0
t ^ t 20,0 26,8 33,8 44,5 50,0 57,5 65,0
Mn,t 6,8 7,0 10,7 5,5 7,5 7,5 Bang 2, Nliiet t o [«(& nong trong thung coa thlet bi don nuSc sii dung ong nhiet trgng truing moi cha't Ethanoi (t^^) v « thiet bi ciia hang SEiLAR ( t ^ J
Lin do Tlidi diem do 9h 12h 13h 14h 18h
tu,'C 29,9 35,5 35,6 38,1 35,0
t,-SEItM,°C 28,0 40,6 45,6 65,0 73,0
t.-,i,"C 28,0 49,6 60,0 81,0 85,0
Loht)an,°C 0 9,0 14,4 16,0 12,0
f t , = q R, + q'^
(q',+q'K
(9) ( l + c o s ^ 6 day: q', - Ddng biic xa trye xa tdi mat nam ngang, (W/m^);
q'^ - Ddng bire xa khueeh tan mat nam ngang, (W/m^);
p - He sd phan xa cua mat dat; R, - He sd true xa;
P - Gdc nghieng cCia be mat khao sat so vdi mat nSm ngang;
Neu chpn gdc lech cua mat trdi 5 = 23,3"; goe phuong vi cua be mat khao sat Y = 0° {hinh chieu cua phap tuyen triing vdi phupng nam); vi dp vi tri be mat khao sat ^ = 20°; gdc gid cua mat trdi LiJ = -30°; gdc nghieng cua be mat khao sat so vdi mat nam ngang p = 30°.
Ta cd [5]:
n + cosSO")
= 852.0,81-1-64- 2
2
F\=n.d^.L- 3,14.0,033.1,6=0,166 m';
Q'^„ = 0,166.762-126,3W;
Hieu suat cua bd thu nang lUpng mat trdi: n= Q'/Q^^,, - 78,3/126,3 = 62%.
3.2. Danh gia tinh nang cDa thlet bj thu nang luomg
De danh gia tfnh nang lam viec ciia thiet bi thu nang luong mat trdi dun nUde ndng sif dung ong nhiet trong tradng chan khdng vdi mdi chat Ethanol,
So 2 1 . 2 0 1 4 • Tap diiKH0AHpC&CCNGNGH^41
•EI5HIEiC6NG_NGHE
da che tao thiet bi sif dyng 18 ong nhiet trpng trUdng (dudng kinh 58mm, chieu dai 1800mm) sif dyng mdi chat Ethanol, so sanh vdi thiet bi tUong dUOng cua hang SEILAR (ma sd SS158/18, dung tieh thiing chira nudc la 216lit). Ket qua do nhiet dp d cac thdi diem khae nhau duoc trinh bay tren bang 2.
Ketquaehothay, nhiet dd nude trong thiing ciia thiet bj dun nude sCf dyng ong nhiet trong trUdng chan khdng vdi mdi chat Ethanol ludn luon eao hon so vdi thiet bl cua hang SEILAR, vao thdi diem cudi budi chieu cao hon tdi 12''C, khang dmh tinh nang vupt trdi cua thiet bi.
4. K^T LUAN
Nghien ciiu sCf dung ong nhiet trpng tradng chan khdng sif dung mdi chat Ethanol trong bd thu nang lUOng mat trdi d e d u n nudc ndng la giai phap kha thi, gdp phan kh^e phue dUOc cac nhupc diem ciia bd dun nUdc ndng hien nay dang SLf dyng d Viet Nam.
Bp thu nang lapng mat trdi sif dung
dng nhiet trpng trudng chan khdng vdi mdi chat Ethanol cd thiet ke don gian, sir dyng cae thiet h\ s i n cd tren thi tradng, de dang lap dat, dam bao ha gia thanh, cdng suat cua ong nhiet khoang 78,3 W, hieu suat cua bd t h u nang laong dat khoang 62%, thdi gian dun nudc giam so vdi bd t h u kieu cu,
Nhiet ciia nadc ndng trong thung it bj tdn that liic trdi ram mat, ong nhiet trpng trudng lam viec nhU mdt didt nhiet mdt chieu, khi nhiet do nUdc trong thimg chda Idn hon nhiet d d ciia phan dng nhiet thuy tinh thi dng nhiet khdng hoat dpng.
iVldi chat Ethanol sif dyng la phii hpp vdi yeu eau lam viec va ket cau cua thiet bi, khdng xay ra hien tUOng nudc sinh hoat ddng cau can ben trong dng nha vdi kieu cu, khdng bi nUde xam nhap vao ben trong cua ong nhiet.
Phin bien khoa hoc: TS. Bill Manh Tii
T A I L I C U THAM KHAO
[1]. Bill HSi, Tran Van Vang, 6ng nhiitvJ:iJiij dung cua ong nhiet, NXB Bach khoa. Ha Npi, (200B).
[2]. Bill Hai, Tinh toan thiet ke thiet bi t r a o i nhiet, NXB Giao thdng van tai. Ha Ngi, (2002).
[3]. Bill Hai, Duang fitfc Hong, Ha Manh Itia, Thiet bl trao dm nhiet. NXB Khoa hoc va liytiiual (2001).
[4]. Bang Quoc Phii, Tran The Son, Trln Van Ptifi, Truyen nhiet, NXB Giao due, (1999)
[5]. Le Chi Hiep, May lanh hap thu trong kytfiuai dieu hoa khongkhi, NXB Dai hpc Quoc gia TP HDOU' Minh, (2004).
[6]. Amir Faghri, Heat pipe science mi Technology, TaylorS Francis, (1995).
[7]. Caivin, Silvertein, Design and technologyof Heat pipes for cooling and heat Exchange, Taylor i Francis, (1992).
[8]. Jon A Duff, William A. Beckman, Soli Engineering of Thermal Pmcesses, John Wtleyfi Sons, lnc.715p,(1980).
[9]. J.Andrew, A. Akbarzadeh, I. Saucius, HHI pipe Technology, Pergamon, (1977).
NGHIEM THU DETJ^I NCKH
^•mm^
Chi^u ngay 18/3/2014, Hpi dong khoa hpc da td chilc nghiem thu 02 de tai
"Nghien ciht mile do hai long cua sinh vien khoi nganh Kinh te tai trUdng Dai hoc Cong nghiep Ha NSi" va de tai "Nghien culu xay diAig mo hinh va tai lieu thiic hanh ke toan ao die sinh vien chuyen nganh Ke toan - Trirotng Dai hoc Cong nghiep Ka Noi"
-Thong qua kh^o satthutte va nghien ciJu mo hinh lythuyS ve cac yeu to^nh hu'dng den mile dp hai long cua sinh vien (SV) WJOI kinh te tai trudng QH Cong nghiep Ha Noi, TS. Bang Ngoc Hiing cung nhom tac giJ khoa Ke toan - Kiem toan va khoa QuSn ly kinh doanh da hoan thanh de tai "Nghien cvfu mdcdg hdi Idng cua sinh vien khoi nganh Kinh te tgi trddng Bgi hgc Cong nghi^
Ha Ndr. Qua nghien ciJti, nhom tac gia da xac dinh difflc 6 yeu to chinh co tac dpng den sir hai long cua SV: Nang lire giang vien, chifong trinh dao tao; Nang lire nhin vien phue vu; Phong hpc vh may moc thiet bi; Giao trinh phuc vu dao tao; Thif vien phuc vu dio tao; To chiic quin ly, danh gia trong dao tao va Kly dung thang do sifhai long cua sinh vienvechatli/tmgdaotaode tien hanh dieu tra. Tif do, nhom tac gia dira ra nhifng khuyen nghi nhSm nang cao chat luong Ska tao SV khoi nganh Kinh te tai trifiing DHCNHN
• f)e tai "Nghien cdu xay dying mo hinh va tai liia thdc hdnh ketodn ao cbo sinh viin chuyen nganh Ketoan - Trddng Bgi hgc C6ng nghiep Ha Ngi"
do TS. Nguyen Thi Hong Nga chu nhiem. Tren ccfsd nghien cUu i^ thuyet va viec ling dung trien khai tai mpt so trifcing dai hpc, trung tam dao tao ke toan,...
nhom nghien ciJu da: He thong hoa cac van de ly luan chung ve to chiic cong tac ke toan, nhSng van de co ban ve dao tao ke toan ao. Qua dd, xay dung te mo hinh phong ke loan mo phong, bo tai lieu thuc hanh ke toan thu cong, thiJc hanh ke toan tren may, bien soan bo bai giang ve ky nang mem cho ngudi Iam ke toan; xay difng duac 35 tinh huong thifc te phuc vu dao tao ky nang cilng va ky nang mem cho ngucii hpc. Bong thoi, tac gia da tien hanh dao tao ftiJ nghiem tai phong thifc hanh ciia khoa va tham do y kien ciia ngu6i hpc, Ket qua cho thay ngUOi hoc danh gia rat cao tinh tinh cUc va ling dung ciia moiiiiih.
Hai de tai ^uoc Hoi ddng khoa hoc danh gia cao, cd y nghia thietthi/c trong thift te dao tao va dupc nghiem thu xep loai Xuat sac.
4 2 i Tap Chi KHOA HOC&CONG N G H E - S 6 2 1 . 2 0 1 4