KHOA HQC COHO NGHft

n g h i Eim c u u t h i £t k £ c h £ t a o v a t h u c NGHlEiVl x a c d i n h c h £ d o sAy b o n g a t i s o

Nguy£n Hay1, Le Anh Due1, Pham Can2

t 6m t AtNghien cuu da ti£n hanh tinh toan thidt ke va ch£ tao mo hinh may sly bong atiso thai lat theo nguydn ly say bom nhidt, co dao chidu toe nhan saiy, nang suit 20 kg/me va thuc nghidm xac dinh chd dp saiy bong atiso thai lat. Mo hinh may da dupe tinh toan thifft k£ dua trdn cac tinh chat nhidt vat ly va tinh chit duoc hoc cua bong atiso, ly thuyet vd truydn nhidt, truydn Im va ly thuyet sly bom nhidt K£t qua khao nghidm da cho thiy may dat ydu diu, phu hop voi cac k£t qua tinh toan thidt k£. Kdt qua quy hoach thuc nghidm da ydu td theo phuong phap bai toln “hop den” da xac dinh dupe su anh huong cua chd1 do sly ddn cac chi tidu kinh t£ ky thuat cua may sly va chit lupng bong atiso sau khi sly. Ba phuong trinh hoi qui bi£u didn sir anh huong cua nhidt do sly, b£ day lop vat lidu sly va thoi gian dao chidu toe nhan sly ddn ham lupng xynann cua bong atiso sau khi sly, sai ldch vd Im do giua lop trdn va lop duoi va chi phi didn ning ridng cua qua trinh say da dupe xac dinh. Kdt qua lap va giai bai toan toi uu da tim dupe ch£ dp lam vide tdi uu cua may nhu sau: chi tieu toi uu cho qui trinh sly Cy,^, = 0,0354 mg/g; Ar,^ = 1,603 kWh/kg tai nhidt dp sly T - 44,6°C; thoi gian dao chidu toe nhan sly t = 5,7 gio va bd day lop vat lidu sly h = 0,6 m. K£t qua xay dyng phuong tnnh dy doan qua trinh giam Im cua bong atiso W (%) theo thoi gian sly (t): W « 83,5222 - 23,5236.t + 2,673-t2 - 0,108-t3, (R2 = 0,993) da dupe xac dinh.Tu khba: Atiso, xynarin, siy bom nhiit, chi phi diin ning ridng.

1 . BAT VAN BE

Bong atiso la mot loai thao duoc co gia tri, tuy nhien trong thuc t£ hien nay tai Da Lat bong atiso duoc lam kho bang cach phai ning hoSc dung lo say thu cong, vi vay bong atiso kho bj giam dang k£ vi mau sac, mui vi, ham luong duoc hoc va khong dam bao ve sinh an toan thuc pham.

Do cac dac tinh vat ly, nhiet vat ly, ham luong duoc hpc va gia thanh cua bong, than va re cay atiso la khac nhau nen moi loai se co che do say khac nhau. Viec nghien cuu danh gia va lua chon phuong phap say va che do say phu hpp cho bong atiso thai lat nham dam bao chat lupng san pham va phu hpp voi tinh hinh san xuat che bien atiso hien nay la rat cdn thi£t

Tir cac ket qua nghien cuu ve tinh chat vat ly, nhiet vat ly, ham lupng dupe hpc cua bong atiso, phan tich danh gia uu nhupc di£m, pham vi su dung cua tung phuong phap say va dac diem khi hau tai Da Lat, nghien cuu da xac dinh dupe phuong phap say bom nhiet dang me tinh, hoi luu va dao chieu tac nhan say la phu hpp nhat. Van d£ dat ra la can nghien cuu tinh toan thi£t ke may say phu hpp voi

' Truong D?i hoc Nong Lam TP. HCM

2 Truong Cao ding Cong ngh? va Kinh te Bao Lpc

cac dac tinh cua atiso va xac dinh che dp say phu hpp nham dam bao chat lupng atiso sau khi say la cao nhat va chi phi say la thap nhat

2. PHUONG PHAP VA PHUONG T ftl

- Phuong phap tinh toan thi^t ke: viec tinh toan thiet ke mo hinh may say dupe thuc hien dua tren cac tinh chat nhiet vat ly va tinh chat dupe hpc cua bong atiso, ly thuyet v i truydn nhiet, truyen im va ly thuyet say bom nhiet.

- Phuong phap che tao: may duoc che tao don chiec theo tung ho chi tiet dien hinh. Mot so chi ti£t tieu chuan dupe chpn mua tren thi trucmg.

- Phuong phap thuc nghiem: tien hanh quy hoach thuc nghiem da yeu to theo phuong phap bai toan “hop den”. Am do cua bong atisd dupe x£c djnh bang phuong phap tu say. Ham lupng xynarin cua bong atiso dupe gui di xet nghiem tai Cong ty C6 phan Duoc Lam Dong (Ladophar).

- Vat lieu va dung cu do dac: bong atiso tuoi dupe thu hoach tai Da Lat Sau khi thu hoach bong dupe rua sach, che doi va bo nhuy, thai lat mong bang dao thai chuyen dung voi be day lat thai 3 - 5 mm. Am dp trung binh cua bong atiso truoc khi say la 80%. Am do cua bong atiso sau khi say < 10%.

- Phuong phap xu ly s6 lieu thuc nghiem: dp

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dung phuong phap phan tich phuong sai. Sir dung phan m£m Statgraphis 7.0 trong thiet ke thi nghiem va xu ly so lieu.

- Bai toan toi uu dugc xac dinh tren co scr cac phuong trinh hoi quy tim dugc trong qua trinh quy hoach thuc nghiem. Bai toan toi uu dugc giai tren may tinh bang phin m£m Excel.

8. K fr Q(U HfiHEN CUU

3.1. K^t qui tinh toAn thiet ke v l che tao m6 hinh miy siy

Mo hinh mly sly bong atiso thai lat nang suat 20 kg/me theo nguyen ly say bom nhiet dang me tinh, hoi luu va dao chieu tac nhan say dugc trinh bay tren hinh 1.

Hinh 1. Sa dd nguyen ly miy siy b6ng atisd

1. Cua buong say; 2. Buong say; 3. Van chinh hudng hoi luu tac nhan siy; 4. Ong hoi luu tac nhan say; 5. Quat siy; 6. Dan bay hoi; 7. Dan ngung tu; 8,9. Van diSu chinh huong tic nhin siy; 10. Tu dien diSu khien

Hinh 2. M iy sly bdng atisd theo nguyen ly sly bom nhi^t dugc che tao v i Up rip hoin chinh

Nguyen ly lam viec: bong atiso thii lit dugc cung cip vio buong say (2) qua cua (1). T ic nhan siy dugc qu^t (5) thdi qua din bay hoi (6) de tich im va tiep tuc qua din ngung tu (7) de gia nhiet den nhiet dd siy. Sau khi qua bo bam nhiet, tic nhin sly dugc dua vio buong say (2) bang cich dieu chinh cic van chinh huong tic nhin siy (8) v i (9). Tac

nhan say sau khi qua buong say dugc hoi luu hoan toan ve bo bam nhiet va lap lai chu tnnh nhu tren. Qua trinh dao chieu tac nhan siy cung dugc thuc hien nho cac van chinh huong tac nhan say (3), (8) va (9).

Vat lieu che tao may say la inox SUS304. Mpt so thong so ca ban cua may nhu sau:

- Kich thuoc buong say: dai x rong x cao: 0,5 x0,4 x 0,8 m.

- Nhiet do say co the thay doi 35 - 55°C.

- Luu lugng tac nhan say can thiet Q = 0,17 m3/s, tuong ung voi van toe tac nhan say trong buong say v= 0,85 m/s. Luu luong tac nhan say co the dieu chinh dugc.

- Bo bom nhiet cong suat 1 HP, su dung moi chat lanh R22.

- Quat say dang quat ly tam, cot ap 200 mmH20, cong suat 1 HP.

- He thong dieu chinh, hien thj va giam sat nhiet do tac nhan say.

Tu cac ket qua tinh toan thiet ke, mo hinh may say bong atiso thai lat 20 kg/me dugc che tao hoan chinh nhu hinh 2.

3.2. K^t qui nghien cuu thyc nghiem

Sau khi che tao, may da dua vao khao nghiem de kiem tra kha nang lam viec va kiem tra cac ket qua tinh toan thiet ke. Ket qua cho thay cic thong so lim viec cua may dat yeu cau, phu hgp voi cac ket qua tinh toan thiet ke.

3.2.1. Ket qua xay dung bai toin “hop den ”md ta qui trinh nghien cuu

+ Cac thong so dau vao cua bai toan “hop den”:

Dua tren ly thuyet mo hinh hoa, sau khi loai bo cac yeu to ngau nhien khong the dieu khien duoc, hoac cac yeu td anh huong qua nho khong cin dua vio nghien cuu, cic thong sd dau vao cua qua trinh nghien cuu nhu sau:

- Nhiet do say: T = 37 - 53°C, khoang bien thien AT = 5°C.

- Be diy lop vat lieu say: h = 0,43 - 0,77 m, khoang bie'n thien Ah = 0,1 m.

- Thoi gian dio chieu tic nhin say: t «= 4,7 - 6,3 h, khoing bien thien At = 0,5 h.

+ Cac thong sd dau ra cua bii toin “hop den” dac trung cho muc dich nghien cuu:

N6NG NGHlfP VA PHATTRlfrl N 6NGTH 6n -K Y 2 -TH A N G 1/2014 67

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- Ham luong xynarin: (Cy, mg/g): la mot tinh chat dupe hoc quan trong, phan anh chat luong bong atiso sau khi say.

- Sai ldch do am giua lop trdn va lop duoi (W, %): phan anh su dong nhat vd am do cua san pham sau khi say.

- Chi phi didn nang ridng: (Ar, kWh/kg-atiso): phan anh chi tidu kinh te ky thuat cua may.

T - — ► — >C y

h — ► May say bong atiso — ► W

t — » ----► Ar

Hinh 3. M6 hinh bii toin “hQp den” md ti qui trinh nghi£n cuu

Tidn hanh thuc nghidm theo phuong an bac hai, muc va khoang bidn thidn duoc trinh bay trong bang1. Trinh tu thuc nghidm thuc hidn theo phuong phap ngau nhidn hoan toan.

Bang 1. Muc vi khoing bidn thidn cic ydu 16 diu viocua bii toin “hQp den"

^ \ Y e u to Nhiet Bd day lop Thdi gian daodo say vat lieu chieu tac

Muc T(°C) siy, h (m) nhan siy t (h)+1,682 37 0,43 4,7

+1 40 0,5 50 45 0,6 5,5-1 50 0,7 6

-1,682 53 0,77 6,3Khoang

bien thidn A5 0,1 0,5

- Phuong tnnh hoi qui cho ham luoni: v-Tiarin trong bong atiso:

Cy = 0,035625 - 0.00069.T - 0,00102.t ♦ 0.000508.h- 0.00182.T2 - 0,00125-t2

- 0,00063.h2 + 0,000589.T.t - 0.00079.T.h -0,0008.Lh ; (R2 = 0,985).

Hinh 4. Quan h£Cy-T-tCr«fT

Hinh 5. Quan h£ C y -T -h

3.2.2. Xuly ket qua thuc nghiem

Cac so lieu thi nghidm duoc tien hanh phan tich phuong sai dang da thuc bac hai. Trong qua trinh phan tich phuong sai, nhung he so hoi qui khong dam bao do tin cay se bi loai bo khoi mo hinh. Cac hd so hoi quy kiem tra theo tidu chuan Student, tinh phu hop cua mo hinh duoc kiem tra theo tieu chuan Fisher. Kdt qua di xac lap dugc ba phuong trinh hoi qui bieu didn su anh huong cua nhidt do say, bd diy lop vat lidu siy va thdi gian dao chieu tic nhan say ddn ham lupng xynarin cua bong atiso sau khi say, sai lech am do giua lop trdn v i lop duoi va chi phi dien ning ridng cua qui trinh say nhu sau. Do thj bieu didn moi quan hd giua cic thong so bieu di&n tren hinh 4 ddn hinh 12.

Hinh 6. Quan h£ Cy - 1- h

- Phuong trinh hoi qui cho him sai ldch am do giua lop trdn v i lop duoi:

W = 1,367781- 0.46227.T - 0,60539.1 - 0,51821.h + 1.259337.T2 + 1,259337. t2 + 0,552374.h2 + 0,575.T.t; (R2 = 0,968).

OMNham W-»T I)

Hinh 7. DA thj bi£u diin mdi quan h£ W - T - 1

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io *

Hinh 8. Dd thi bi£u diin mdi quan hd W - T - hOolNham W -ft.h)

IS

Hinh 10. Quan h^Ar-T-t

Hinh 9. Bd thi hiiu diin mdi quan h£ W - 1 - h

- Phuong trinh hoi qui cho ham chi phi didn ndng ridng khi say:

Ar = 1,642289 + 0.477924.T + 0,090524.t +0,129797.h + 0,457049-T2 +0,103568.t2

+ 0,138916.h2 + 0,3125.T.t - 0,1875.Lh ; (R2- 0,968).

Hinh 11. Quan h^Ar -T -h

Hinh 12. Quan hd Ar -1 - h

3.3. K it qui xiy dung v i giii bii toin tdi uu

Chi tidu toi uu vd ham lupng xynarin la ham lupng dat cao nhit, chi tidu tdi uu vd sai ldch Im dp giua 16p trdn va lop dudi la sai ldch nho nhat, chi tidu tdi uu vd chi phi tidu thu didn ning ridng dd sly la chi phi tidu thu didn ning thip nhit. Nhu v|ky, chi tidu tdi uu chung la ham lupng xynarin cao nhit vdi sai ldch vd am do giua lop trdn v i ldp dudi \k nho nhit v i muc tidu thu didn ning ridng II thip nhit Thong sd tdi uu la gia tri cic thong sd dam bio chi sd tdi uu tuong ung.

Nhu vay, xuit phit tu muc dich nghidn cuu, bii toin tdi uu dupe lap trdn co sdr ba him Cy, W v i Ar die trung cho ba chi tidu nghidn cuu:

- Ham muc tidu: Cy - » max, W -> min v i Ar -> min.

- Ham didu kidn: 1,682 > T*, hj, t* > -1,682.

Kdt qui giai bii toin tdi uu da muc tidu da xac dinh duoc cic thong sd tdi uu va chi tidu tdi uu nhu sau:

+ Thong sd tdi uu: nhidt do sly: 44,6°C, bd diy 16p vat lidu sly: 0,6 m, thoi gian dao chidu tic nhan say: 5,7 h.

+ Chi tidu tdi uu: ham lupng xynarin dat 0,0354 mg/g, sai ldch am do giua ldp trdn v i ldp dudi l i 1,32% v i chi phi didn ning ridng cho qui trinh sly 1,603 kWh/kg.

3-4. Kdt qui xiy dyng phuong trinh giim Im theo thdi gian sly

Tu kdt qua xac d|nh chd do sly tdi uu, nghidn ciiu d i tidn hinh thuc nghidm sly bong atisd tai chd do sly niy. Qui trinh giam Im cua bdng atisd dupe trinh biy trdn hinh 13. Su khic bidt v i Im dd giua ldp trdn v i ldp dudi cua bong atisd trong budng sly ngiy cang ting theo thdi gian sly, tuy nhidn tai thdi didm dao chiiu tic nhin sly thi sijr sai khap niy g j ^

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dang ke. Kert qua thi nghidm da xac dinh duoc toe do giam am trung binh cua qua tnnh say la 8,2%/h.

Ilirti gian s/fy (h )

Hinh 13. Qui trinh giim Im cua bdng atisd thii lit trong qui trinh siy

Kdt qua xay dung phuong tnnh du doan su giam am cua bong atiso trong qua trinh say:

W = 83,5222 - 23,5236.t + 2,673-t2 - 0,108-t3Phuong trinh bieu thi moi quan hd giua thdi gian

say (t) va am do bdng atiso (W) cd dang da thuc bac ba voi he so tuong quan giua gia tri thuc nghiem va gia tri tien doan R2 = 0,993.

4 .K FT U M NMd hinh may say bdng atiso thai lat theo nguydn

ly say bom nhiet, cd dao chieu tac nhan say, nang suat 20 kg/me da duoc thidt kd che tao. Ket qua nghien cuu da xac dinh duoc mdi quan he giua che do say nhu nhiet do say, thdi gian dao chieu tac nhan say va be day ldp vat lieu say den cac chi tieu kinh td ky thuat cua qua trinh say bdng atiso thai lat

Vdi yeu cau chat luong bdng atiso sau khi say la

kdt qua nghidn cuu da xac dinh dugc chd d -ay tdi uu cho qua tnnh say bong atisd: chi tidu toi uu cho qua tnnh say Cym„ = 0,0354 mg/g, WEa. = 1,32%, A r^ = 1,603 kWh/kg tai nhidt do say 44.6"C, thdi gian dao chieu tac nhan say la 5,7 gio va bd day ldp bdng atiso trong buong say la 0,6 m.

Phuong trinh du doan qua tnnh giam am cua bdng atiso theo thdi gian siy da dugc xac dinh, phuong trinh 6 dang da thuc bac ba vdi hd sd tuong quan rat cao, dieu nay cho thay su chinh xac cua md hinh.

Ket qua danh gia bang cam quan va xet nghidm ham luong duoc hpc cua bdng atisd sau khi say da cho thay chat lugng bdng dupe cai thidn rat dang kd vd mau sac, mui vj, ham lupng duoc hpc... so vdi cac phuong phap phoi say hidn dang dugc sir dung.

TAI L E I THAM lOtAO1. Alves-Filho O., Stommen I., 1996. Application

of heat pump in drying of biomaterials. Dry Technol. 14:2061-90.

2. Nguydn Nhat Ld, 2001. Tdi uu hda ung dung. Nha xuat ban Khoa hpc va Ky thuat

3. Nguydn Van May, 2002. Ky thuat say ndng san thuc pham. NXB Khoa hpc va Ky thuat Ha Noi.

4. Tran Van Phu, 2001. Tinh toan va thiet kd hd thong say. Nha xuat ban Giio due.

5. Phan Hidu Hidn, 2001. Phuong phap bd tri thi nghidm va xu ly sd lidu. Nha xuat ban Ndng nghidp TP.HCM.cao nhat va chi phi cho qua trinh say la thap nhap,

STUDY ON DESIGN AND EXPERIMENTAL DETERMINATION OF ARTICHOKE FLOWERS DRYING REGIME

Nguyen Hay, Le Anh Due, Pham CanSummary

This study was performed to calculate, design and determine the effects of drying parameters on technical and economic norms, and determine optimal drying condition for sliced artichoke flowers based on a heat pump dryer, re-circulating and reversible airflow, with capacity of 20 kg/batch. The experimental results determined related equations of influence of drying air temperature, thickness of artichoke layer and appropriate timing for the air reversal on cynarin contents of dried artichoke (Cy), moisture content difference of artichokes after drying (W) and specific energy consumption for drying process (Ar). Result of solving optimal problem determined optimal drying regime of the artichoke dryer such as: optimal norms for drying process: Cym„ = 0.0354 mg/g, W,,,,,, = 1.32%, Armm = 1.603 kWh/kg at drying air temperature T = 44.6°C, thickness of artichoke layer in drying chamber h = 0.6 m, and appropriate timing for the air reversal t = 5.7 h. Predicted equation moiture content W (%) of artichoke versus drying time (t) in the drying process was determined: W = 83.5222 - 23.5236*t + 2.673*t2 - O.lOSxt3; (R2 = 0.993). The experiment results shown that the drying time is short, cynarin contents, colors and flavors of the artichoke flowers after drying are better than the control artichoke samples.Keywords: Artichoke, cynarin, heat pump dryer, specifc energy consumption.Ngudi phan bidn: GS. TSKH. Pham Van Lang Ngiy nhin bii: 25/11/2013 Ngiy thong qua phin bidn: 27/12/2013 Ngiy duydt ding: 03/01/2014

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