16*KH&CNN - 89*09/2009
TIET KIEM NANG LlTaNG NHCT CHU TRINH BAG THANG
VA / HOAC HdN Hgp KHONG DONG SOI TIEM CAN CHU TRINH LORENZ TRONG KY THUAT SAY BUM NHIET
ThS. TRLfaNG MINH THANG Dai hoc Giao thong Van tai Bai bao trinh bay kha nang tiet kiem nang luang cua he thong say bom nhiet thong qua chu trinh bac thang va dac biet la kha nang tiet kiem cua chu trinh bac thang cd su dung hon hpp mdi chat lanh khdng dong so; khi tiem can chu trinh Lorenz.
- Bam nhiet kieu gid/gid vdi 2 may ndn true vit S3-1800
- Ngudn nhiet; Khdng khi am ra khdi phdng say - Ngudn thai nhiet; Khdng khi dugc khii' am - Mdi chat lanh; R22
- Nang suit lanh; -, 5. nhiet 36 max 2x616kW Ingung 50 °C va - Nang suit nhiet: 1"^'^' ^^ ''^^
J hai 0°C
L D A T V A N D ^ :
Bam nhiet su dtJng rlt thuan Igi trong ky thuat say nhiet dd thip vi ed the kit hgp silr dung ea chiiu ndng va chiiu lanh trong ciing mdt qua trinh.
Trong thifc t i , bam nhiet cung da duge sir dijng thanh cdng trong rlt nhieu ITnh vijc nhu say gd, sly cac loai ndng lam thuy san khac [1 -^ 4]. Dau tien khdng khi Im dugc dua qua dan bay hgi
"lanh", ma nhiet dd b i mat dan lanh phai thip han nhiet dp dgng suang. Mdt phin am trong khdtig khi se ngung ttj lai tren b i mat dan lanh va chay xuing, ggi la nude ngung. Khdng khi lanh da khu am mdt phin dd se duge dua qua dan ngung tiJ
"ndng" de nang len din nhiet do yeu eau. Thdng thudng do cd thanh phan nhiet I n d dan bay hai nen cd mdt phin nhiet thira d dan ngung. Nhiet thira dd cln thai bd va ed the si> dijng d i dun nude ndng sinh hoat. Sau day, bai bao se gidi thieu mgt sa dd say bam nhiet thiJC t i va phan tich kha nang tiet kiem nang lugng khi chuyen thanh chu trinh bae thang tiem can chu trinh Lorenz.
2. MOT s a D 6 THONG THUaNG D^ SAY PHIM:
Hinh 1 gidi thieu sa dd mdt bam nhiet de san xuit khdng khi khd cho xudng lam phim [3]. He thing bam nhiet dugc VEB Kuehlautomat Berlin thiit k i va c h i tao [3] eho phan xudng rdt khudn va sly eija nha may c h i tao phim anh Berlin. He thing bao dam cung d p khdng khi khd d nhiet do 40°C vdi nhiet do dgng sugng 8°C. De diiu chinh nang suit nhiet yeu eau ngudi ta mlc them 2 dan ngung phij giai nhiet nude noi tiip vdi dan ngung chinh.
Cdng trinh cd nhu'ng dac tinh sau:
- Luu lugng gid: 60.000 4- 80.000 m^/h -Nhiet dp khong khi khd; 30-=-40°C - Nhiet dp dpng suang; 8 -H 12 °C
- Thanh phan khi tuai: 0 ^ 100%
- Dp am khong khi: 30-f 100%
max 2x857kW'
- Cdng suit dien MN; max 2 x 268 kW - Vdn dlu tu; 1,4 trieu Mark - Tiet kiem nang lugng moi nam: 0,6 trieu Mark - Tong tiet kiem hang nam; 1,2 trieu Mark i - Thdi gian hoan vdn; 1,5 nam
So vdi he thing sly bang hai nude, he thing sly bang bam nhiet da mang lai nhieu lgi ich rd rang, khdng nhO'ng giam tieu tin nang lugng ma chit lugng san pham duge cai thien ro ret do dugc sly d nhiet do thip han, nang suit say dugc tang len do thdi gian sly giam.
Tuy nhien neu tiem can chu trinh Lorenz bang chu trinh bac thang va hdn hgp mdi chit lanh khdng ding sdi thi kit qua cdn ed the tiip tuc dugc nang len han nO'a.
3.T1EM CAN CHU TRJNH LORENZ BANG CHU TRiNH BAC THANG:
Qua thtjc t i hoat ddng ciJa h# thong bieu dien tren hinh 1 ta ed nhan xet sau: Do nhigt dp bay hai to = 0°C va ngung tu IK = 50°C, nhiet dp khdng khi vao va ra dan lanh lan lugt la 50°C va 17°C, nhiet do khdng khi vao va ra khdi dan ngung la 17°C va 40°C. Nhiet dg khdng khi qua dan ngung tang len 23K va giam dl qua dan bay hgi la 13K. Do chenh nhiet dp max giua khong khi va mdi chit lanh a dan ngung len tdi 33K.
Cac s i lieu tuang tij' cung dugc ghi nhan d dan bay hgi. De cai thign do khdng thugn nghjch eua qua trinh trao doi bang each ti^m can chu
KH&CNN - 89*09/2009*17
trinh Lorenz thi k i t qua t i i t kiem nang lugng se dugc nang len. Vi du cd the mac n i i t i i p hai chu trinh lanh rieng biet vdi nhiet do bay hai va ngung tu khac nhau d i tiem can chu trinh Lorenz nhu hinh 2 gidi thieu. Khi chia ra nhu vay ta cdn ed t h i chay 50% nang s u i t khi can thiit.
Do chenh nhiet do trung binh gitfa nhiet do ngung tiJ va nhiet do bay hai se giam khi phan chia lam hai chu trinh rieng biet de thich irng vdi nhiet do khdng khi. D i i u dd lam cho dien nang tieu thiJ giam rd rang. Chu trinh bam nhiet cd nhiet do ngung tij 50°C va nhiet do bay hai 0°C cd he so bam nhiet theo chu trinh Carnot la:
cpc= TK/AT = (273+50)/50 = 323/50 = 6,46 Chu trinh dd duge thay t h i bang 2 ehu trinh cd dan bay hai va dan ngung mac ndi t i i p nhu hinh 2.
Chu trinh "ngoai" (vdi ky hieu chan 1) lam viee vdi TK = 323K va AT = 50 - 10 = 40K, nghTa la: gci = 323/40 = 8,08
Chu trinh "trong" (vdi ky hieu chan 2) lam viec vdi TK = 313K va AT = 40 - 0 = 40K, nghTa la vdi: (pc2= 313/40 = 7,82
Vdi gia thiit la eae bam nhiet ed ciing nang s u i t nhiet (day cung la d i i u kien thiit k i m u i n dat tdi) thi he s i nhiet trung binh cua ca he t h i n g se la: cpctb = (8,08 + 7,82)/2 = 7,95
So vdi chu trinh tren hinh 1 thi he s i nhiet eua chu trinh tren hinh 2 tang them:
Agc/(Pc= (7,95 - 6,46) / 6,46 = 23%
12
Hinh 1. He thong bom nhiet de san xuat khong khi khd cho nha may san xuat phim.
1. Din bay tiai; 2. Quat gid; 3. Dan ngung; 4. Dan gia nhi$t bo sung; 5. Gia am bing hoi;
6. CAc dan ngung ptiv lim mit bing nuttc; 7. Uiy n6n; 8. Phim; 9. Hinh trinh say phim;
10. Hai niriic ip thip; 11. Khdng khi bSn ngodi; 12. Khi xi; 13. Nu^c lam mit
. D i i u dd cd nghTa la dien tieu thtJ che may nen d chu trinh thiJC cd t h i giam tdi 23% bdi vi hieu suit exergy thiJC t i la khdng d i i (v a 0,5). Do ed sir giam hieu nhiet do giCfa mdi chit lanh va khdng khi ben ngoai nen dien tich trao doi nhiet phai tSng len tuang irng. De dam bao ton that ap suit khdng qua Idn cung nhu edng suit ddng cd quat khdng tang dang ke thi ngoai viec tang sd hang i n g cua thiit bj trao d i i nhiet cung d n tang tiit dien ddng chay cua khdng khi. Day cung la thanh phin trong bai toan tdi uu nang lugng eiia he thong. Cdng suit quat tang g i n ty le thuan vdi so hang i n g nhung ty le nghich vdi tiit dien ddng chay. Bdi vay, khi tang s i hang i n g khdng nhlt thiit phai tang edng suit dgng ca quat. Vi n i u tang tiit dien ddng chay tuang irng tang sd hang i n g thi cd t h i giu"
nguyen edng suit quat gid. Von d l u t u tang len do cac thiit bi trao doi nhiet va viec tach he thong lam 2 se nhanh ehdng duge hoan von.
De tiem can chu trinh Lorenz t i t han nifa ta cd t h i phan tiep ra 3, 4... ehu trinh bam nhiet rieng le. Chu trinh nay da duge thirc hien d HaihaCo [4]. Q day da s u dung 4 chu trinh rieng le ghep n i i tiip. Tuy nhien d i dam bao nhiet do s l y trong buong s l y khoang 20°C, nhiet thira phia ngung tu dugc thai ra ngoai bang mgt dan ngung cua mpt ehu trinh, cd nghTa la he thong s u dijng 4 dan bay hai, nhung ch? 3 dan ngung dat tren dudng xi> ly gid sly.
4. TIEM CAN CHU TRJNH LORENZ B A N G H O N HOP MOI C H A T L A N H KHONG D O N G SOI.
Tiem can chu trinh Lorenz d i t i i t kigm nang lugng cung ed the duge thuc hign nhd hon hgp mdi c h i t lanh khdng d i n g sdi do ehiing ed su trugt nhiet dd sdi va ngung tiJ dgc theo chieu dai thiet bj trao d i i nhigt ngugc ddng, tuang img vdi sij" b i i n doi nhiet do cua c h i t tai nhigt va c h i t tai lanh. P h i n nay da d u g c trinh bay rd trong [5] nen d day khdng nhac lai.Trong h l u h i t cac irng dung lam lanh hoac bam nhiet, c h i t tai lanh va c h i t tai nhiet d i u thay doi nhiet dg khi di qua thiit bj bay hai hoac ngung ty, vi dy d may san xuat [5],
arLTLTS
18*KH&CNN - 89*09/2009
5 TIEM CAN CHU TRJNH LORENZ B A N G CHU TRiNH BAC THANG VA H O N HOP MOI C H A T LANH KHONG D 6 N G SOI.
Hinh 2 b i i u d i i n 2 bcrm nhiet vdi mdi c h i t dan c h i t R22, nhung n i u chiing ta s u dyng hdn hgp mdi c h i t lanh khdng ddng sdi R407C chang han thi d cac t h i i t bi trao doi se ed dd trugt nhiet do khoang 7K. Cd nghTa d dan bay hai 1 nhiet do b i t d l u bay hai la 10 °C k i t thiic la 17°C, trung binh la 13,5°C (xem bang 1)
Tuang t u nhu each tinh neu d myc 3 ta cd:
Chu trinh "ngoai" (vdi ky hieu chan 1) se lam viec vdi
TKtb = 273 + 46,5 = 319,5K
va AT = TK - To = 46,5 - 13,5 = 33K, nen cp<;i = 319,5/33 = 9,68
Chu trinh "trong" (vdi ky hieu chan 2) lam viee vdi T^b = 273 + 36,5 = 309,5K
va AT = TK - To = 36,5 - 3,5 = 33K,
Hinh 2. He thong bo'm nhiet vdi hai chu trinh rieng biet di san xuat khdng khi khd.
1. Dan bay hoi to = KfC; 2- Dan bay hoi h - CfC; 3. Quat;
4. Dan nqwng IK = 4(fC; 5. Dan ngwng tK=50°C: Moi chat lanh R22.
Bang 1. Nhiet dp bat dau va kit thuc ly thuyet khi sir dung R407C
Thi4t bj Bay hm 1 Bay hci 2 Nqyng tu 1 NqU'nq tu 2
b i t dilu qua trinh (°C) 10 0 33 43
k i t thuc qua trinh (°e) 17 7 40 50
trung binh (°C) 13.5 3,5 36,5 46,5
ghi chu 3Q tru-pt 7K dp tru-ot 7K do tru'pt 7K do tru'Ot 7K
nen: cpc2 = 309,5/33 = 9,38
He s i nhiet trung binh cua ca he t h i n g se la:
(Pctb= ( 9 , 6 8 + 9,38)/2 = 9,53
So vdi chu trinh hinh 1 thi he s i nhiet cua chu trinh tang them:
A(pc/<Pc= (9,53 - 6,46)/6,46 = 47,5%
N h u vay khi tiem can ehu trinh Lorenz vira b l n g chu trinh bac thang, vira b l n g mdi chat lanh khdng d i n g sdi ta cd t h i t i i t kiem tdi 47,5% nang lugng dien tieu thy rieng trong trudng hgp nay.
6. K^T LUAN
D i i vdi moi yeu c l u cdng nghe, n i u chung ta b i i t each tiem can chu trinh Lorenz thi cd the t i i t kiem d u g e nang lugng s a d p mgt each dang k i . Va trong tinh hinh khd khan v i nang lugng n h u hien nay thi eae nghien ciru md rpng v i chu trinh Lorenz cang cd y nghTa to Idn.
Abstract: This paper presents an ability to save energy of the drying system using heat pumps through the "step refrigeration cycle", further its could be reach an approximate performance of the Lorenz refrigeration cycle by using zeotropic mixture.
TAI LIEU THAM KHAO [1]. NguySn Dire Lgi, Giao trinh Ky thuat lanh, NXB Bach Khoa 2008.
[2]. Heinrich, Najork, Nestler:
Waermepumpenanwendung in Industrie, Landwirtschaft, Gesellschafts-und Wohnungsbau, VEB Verlag Berlin 1982
[3]. Mann. W.: Die Waermepumpe in Anwendung fuer die Filmtroeknung. Votrag auf der Fachtagung Waermetechnick, Waerme-und Stoffuebergang bei Klimaprozessen, vom 27.10 + 28/10/1997 in Karl-Marx-Stadt [4]. NguySn Dire Lgi, Pham Van Tiiy: He thong say lanh bang bam nhiet d Haihaco, Tap chi KHCN Nhiet, 2/1998 tr 6+ 8.
[5]. Truang Minh Th^ng; Tiet kiem nang lugng vdi hon hgp moi chat lanh khong dong sol va c^c kha nang khSc, Tap chi KHCN Nhi$t 3/2009 tr14 H-18.
Phan biin:
PGS. TS Nguyen Due Lpi
