Tgp chi Khoa hpc va Phat trien 2012 Tgp 10, so 3:494-502 www.hua.edu.vn MOT SO KET QUA NGHIEN CQU T H I I T KE HE THONG THIET Bj SAY VAI QUA THEO PHUf0NG PHAP PHOI HOP DOI LUU VA BlTC XA NHIET Iran Nhir Khuygn*, Ph^m Dire Nghia, Ho^ng Xuan Anh, Ng6 Thi Hi^n, Le Huy Thirffng, Trirong Thi Toin Khoa CoDi§n, Truong Dai hQC Nong nghiep Hd Ngi Email: trannhukhuyen@yahoo.com Ngay giri bai: 04.04.2012 Ngay chip nhan: 14.06.2012 TOM TAT Hp thong thiet bi say vai qua theo phuong phap phoi hpp doi luu va buc xg nhipt SV-1,0 dup'c thiet ke va che tgo tgi Bp mon Thiet bj bao quan vS che bien ndng san khoa Cff Dipn trudng Dpi hpc Ndng nghiep Ha Ndi Day la hp thdng thiet bj say co cau lao dan gian, thuc hipn cap nhipt cho vat lipu say theo phuang phap phdi hp^p doi luu va buc xg nen da nang cao hipu qua truyen nhipt cho vpt lipu say Ket qua thi nghipm da xac djnh dupc mi>c dO anh hu'dng cua nhipt dp vS toe dp ddng sly mgt dp vgt lipu budng say den dp kho khdng deu cua san pham say, diem tdng hpp chat lupng san pham s l y vS chi phi nhien lipu rieng So vdi mpt so hp thdng say thdng dpng san xuat he thong say SV-1,0 cd uu di\em: thdi gian say 70.5h chi bing 55,7% so vdi Id say thu cong, bang 94% so vdi thiet bj say cai tien; dg khfl khdng deu cua san phim say la 2.1% giam 2,2% so vdi Id say thu cong va 1,6% so vdi thiet bj say cai tien; chi phi nhien lipu rieng la 0,45kg than/kg SPK bing 46.2% so voi Id say thu cdng va 74,0% so vdi thiet bi say cai tien vai qua khd chat lu'p'ng tot, hinh dang va mau sac dpp Tu khda: Buc xa nhipt, chi phi nhien lipu rieng, doi luu, say vai qua Research Results on Designing Drying System for Litchi Using Combined Thermal Convection and Radiation Method ABSTRACT Equipment system SV-1.0 for drying litchi by combining convection and radiation method has been designed and manufactured at Department of Agricultural products Processing and Storage, Faculty of Engineering, Hanoi University of Agriculture, This drying system has simple structure and the heat are supplied by combining thermal convection and radiation method As a result, heat transfer effect was improved The effect of temperature, drying air velocity, density of material in drying chamber on drying material heterogeneity of dried product and specific fuel consumption was identified In comparison with common drying systems being used, the drying system SV-1.0 has several advantages: drying time was reduced (70.5 hours), equal to 55.7% of manual drying ovens and 94% of improved drying equipmen The heterogeneity of dned product is 2.1%, reduced by 2% in companson with manual drying oven and by 1.6% with the improved drying equipment Specific fuel consumption is 0.45kg of coal for 1kg of dried product, equal lo 46.1% of manual drying oven and 74% of the improved drying equipment The dried litchi product has good quality with nice shape and colour Keywords: Drying system for litchi, specific fuel consumption, radiation methed, thermal convection Tran Nhu- Khuyen, Phgm Due NghTa, Hoang Xuan Anh, Ngo Thi Hien, Le Huy Thuong TnfO'ng Thi Toan DAT VAN DE Vai thieu la loai cay an qua quy c6 gia tri kinh te va dinh dudng cao, dUdc coi la vua trai cay d cac nUdc nhiet ddi nudc ta cay vai ditdc coi la cay chu IiJc vudn, dien tich va san lUdng vai qua khdng ngiing tang len Dac diem ciia vai qua la thdi gian thu hoach rat ngSn (35 - 40 ngay), lai rat de h\I hdng bdi thdi tiet ning ndng, mUa nhieu vu thu hoach tieu thu khdng kip nen vai qua thiJdng dUdc sd'y khd de keo dai thdi han bao quan Mat khac, vai qua khd hien dang diidc coi nhiJ la san pham thay the' cho vai qua tifdi trai vu c6 hifdng vi thdm ngon dac trKng, vdy nhu cau tieu thu loai vai qua kho lien tuc tang tren thi tritdng qu6'c te' (Nguyen Manh Dung, 2001; Hoang Quang Sang, 2010) De nang cao chd't lUdng vai qua kh6 xuat khau, mpt s6' cd sd san xuat, cac vien, tnidng dai hpc da nghien ciiu thiet ke che tao thie't bi say vai qua va da gop phan nang cao chat lUdng san pham nhif: thiet bi sa'y vai qua cai tien SVQ-1 cua Trifdng Dai hpc Ndng nghiep Ha Npi, diing tac nhan sS'y la khdi 16 (cd ldp them bd phan lpc bui va xb ly khdi), thie't bi say SRQ-12 cua Vien Cd Dien nong nghiep va Cong nghe sau thu hoach dung tac nhan say la khdng difdc dd't ndng qua calorife kie'u khi- khoi, (Pham Thi Minh Hue, Tran Nhif Khuyen, 2010) Tuy nhien, nhieu ban che' nhif: chat lUdng san pham khdng on dinh, chi phi nhien lieu, chi phi dau tif mua sSm thie't bi, chi phi cho viec bao tri va siia chiia Idn nen cac cd sd san xuat khd chap nhan Thuc te hien nay, phan Idn vai qua vin difdc lam khd hang tram Id say thii cdng diing triic tie'p khdi 16 lam tac nhan say nen nhieu me say cd chat liidng rat k6m, khong tieu thu dddc va nhieu Id hang xuat khau khong dat tieu chu^n chat liidng phai tra ve hoac chiu chap nhan gia ban tha'p gay thiet hai Idn cho ngifdi san xua't Vi vay viec nghien ciiu thie't ke' cai tie'n thie't bi say vai qua nh&m tao san pham say cd chat lifdng cao, cau tao dOn gian gia ha, giam chi phi cho qua trinh say de cd the trien khai ap dung rpng rai san xuat la van de rat cap thie't Dudi day trinh bay mpt so' ke't qua cdu thiet ke' he tho'ng thie't bi say vai qua theo phupng phap phdi hdp doi lilu va bdc xa nhiet VAT LIEU VA PHUONG P H A P 2.1 Vat lieu nghiSn ciJfu Vai qua d Luc Ngan tinh Bac Giang c6 difdng kinh trung binh 1,8 -2,5cm, chieu dai trung binh 3,2-3,8 cm, khdi lifdng trung binh 22 -25g Thanh phdn hoa hpc ciia vai qua tUdi difdc Vien Nghien ciiu Rau qua phan tich nam 2011 gom: ham lifdng nudc 81,65%, ham lifdng difdng tdng s6' 75,96%, ham lifdng acid 1,54%, ham lifdng vitamin C 68,99mg/100g Mat dp vai qua xe'p budng say 120-200kg/m^, tifdng difdng vdi khoi lUdng 0,723 - l,205ta'n Vai qua difdc budc tifng chum tii cd khoi lUdng trung binh 2,5 kg, dUdng kinh trung binh 18 - 2Gcm va difdc treo tren cac treo tiing hang, khoang cac giu!a cac hang c6 the thay doi difdc theo tiing me say 2.2 Phiitfng p h a p nghien cufu Ap dung phifdng phap nghien ciiu thuc nghiem ddn ye'u td de nghien ciiu anh hifdng rieng cua mpt sd' thong so': nhiet dp ddng say T ("C), td'c chuyen dpng ciia dong say v (m/s) va mat dp vat li^u budng say M (kg/m^ de'n dp kho khdng deu cua san pham say K (%), diem tong hdp chat liidng san ph&m say Q (d) va chi phi nhien lieu rieng N, (kg than/kg SPK) Cac thong so' nghien cdu cua thie't hi say difdc xac dinh nhif sau: Thiet ke hp thong thiet bj say vai qua - Nhiet dp ddng say dupc xac dinh bang thiet bi dien tb hien sd ma hieu SGK-MF-904 (Hong Kong), khoang am 40''Cden200''C, saisd±0,5''C - Chi phi nhien lieu difdc xac dinh bang ty sd' giiia lifdng nhien lieu tieu thu cho mpt me say vdi lifdng san ph&m khd thu difdc sau say - Td'c dp chuyen dong cua ddng say difdc xac dinh bing may td'c dp gio dien tii hien so', ma hieu AR 863 (hang SMART SENSOR Hong K6ng), khoang 0-25m/s, sai so'3% - Thdi gian sd'y la khoang thdi gian thiic hien mot me difdc tinh tit thdi diem bat diu say cho de'n vai qua dat dp am 20% va difdc xac dinh bang ddng hd thdi gian thdng dung - Mat dp v&t lieu buong SEty diidc xac dinh bang ty so' giO khoi lUdng vai qua xe'p budng say vdi the tich budng say - Ham lifdng dUdng tong s6' va ham lifdng vitamin C difdc xac dinh bang phifdng phap sac ky tai Vien Nghien cdu Rau qua De tie'n hanh nghien cifu thuc nghiem ddn ye'u to", cac thi nghiem difdc bd tri nhU sau: thi nghiem xac dinh anh hudng cua nhiet dp say vdi cac mile: 60; 65; 70; 75; SO^C, thi nghiem xac dinh anh hifdng cua tac nhan say vdi cac mdc: 0,4; 0,6; 0,8; 1,0; l,2m/s va thi nghiem xac dinh anh hudng cua mdt dp vat lieu sa'y vdi cac miic: 120; 140; 160; 180; 20Dkg/m^ - Dp am cua san pham say difdc xac dinh bang may Data Holp MC-7805 (Trung Qud'c), khoang tif - 50 %, sai so' i 0,1 % Day la loai thie't bi hien dai, cd dau cam bien nhiet dp va dp dm difdc cam sau vao khdi vat lieu cin va nhiet dp va dp am ciia vat lieu budng say dupc hien thi s6' len man hinh ciia thie't bi dat b ngoai buong say - Dp kho khong deu cua san pham say difdc xac dinh theo hd sd' bie'n dgng ciia cac mau san pham say d cac vi tri khac budng say va dupc tinh theo cong thiic: K= -100% (1) o- lech chuan difdc xac dinh: Z(w,-w.) (2) Mau phan tich chat lifdng san pham sa'y (dp khd khong deu ciia san ph^m say, ham lifdng difdng, vitamin C) co kho'i lifdng 190-200g (khoang 30-32 qua vai kho) dUdc la'y tii mdu h6n hdp cd kh6i lifdng khoang 3kg (tdp hdp ciia 15 mSu diem cl tang, mdi tang diem), sau tien hanh giam khdi lifdng bang phifdng phap chia cheo, ham lifdng difdng tong so' va ham lUdng vitamin C difdc xac dinh bang sdc ky tren thie't hi chuyen dung W, - dp am cua mau vai qua phan tich, %, KET QUA VA THAO LUAN W„ - dp am qui dinh doi vdi vai qua sau 3.1 K^t qua nghien ciifu thiet ke hg thong thiet bi say s^'y, % n- so' lifdng mau phan tich Diem tong hdp chat lUdng san phara difdc xac dinh bang phifdng phap cam quan theo TCVN 3215-79 He tho'ng sa'y vai qua (ky hieu SV-1,0) difdc thie't ke' va che' tao tai Bp mon Thiet bi bao quan va ehd' bie'n ndng san khoa Cd Dien tnfdng Dai hpc Ndng nghiep Ha N6i TrIn Nhu- Khuyen, Phgm Due NghTa, Hoang Xuan Anh Ngd Thj Hien, Le Huy Thuang, Truong Thj Toan reY~ i \ s ; "N ^ ' \ i 6 \1 WsT %7 H i n h Sc* h e tho'ng thiet b; say vai qua SV-1,0 1- Buong eay; 2- Thanh treo vait heu say; 3- Khung il6 treo vat heu say, 4- Ong phan phoi khf, 5- Quat; 6- Buong hoa tron khi; 7- Bp ph|in trao nhi^t ki^u onf 8- Buong dot; 9- Bp phSn trao doi nhiet hitc xa dang tam; 10- Lo dot than; 11-Bp phan dieu khien nhiet say; 12- Bo phan lpc khoi; 13- Ong dan khoi Day la he thd'ng sd'y sii dung phifdng thiic cap nhiet phoi hpp dd'i Iifu va bdc xa nhi§t, c6 nang sua't 1,0 tan/me Sd nguyen ly cau tao ciia he thd'ng sa'y difdc the hien tren hinh Thie't bi sdy SV-1,0 gdm phan chinh: budng say Id dd't than, thie't hi trao ddi nhiet (calorifer) va bd phdn dieu khien nhiet dp tii dpng: - Budng sa'y c6 dang hinh hop chii nhat, ben c6 gia lap gian d'ng de dd cac treo vat lieu say Trong budng sd'y co tang va m6i ting c6 lap treo, khoang each giiia cac tang va khoang each gifla cac treo co the dieu chinh dUdc, - Ld do't than cd dang hinh tru, difdc dat b buong, cd quat Id de diin khien qua trinh chay Thie't bitrao doi nhiet gom cd: bp phan trao dd'i nhiet biic xa dang ta'm va bp phan trao doi nhiet kieu d'ng xoan, cd nhiem vu ca'p nhiet (gian tie'p) cho vat lieu buong sa'y - Bd phan dieu khien nhiet dp say gom cd thie't bi dieu khien lien he vdi cac cam bie'n nhiet dildc dat b budng sa'y va budng dd't de dieu khien to'c dp cua quat Id, dieu khien van la cua buong hoa tron khi, nhd dd c6 the dieu khien dtfdc nhiet dp budng sa'y difdc nhiet dp ta'm gia nhiet bifc xa va nhi^t dp buong sa'y He tho'ng sa'y SV-1,0 vdi ke't ca'u nhu tren nham dat difdc cac ifu diem: Sfl dung khdng difdc do't ndng gian tie'p lam tac nhan sa'y nen da tao san pham sa'y "sach" khdng bi nhiem ban bdi muoi than hay cac dpc san pham chay tao - Thie't bi sa'y c6 ket cd'u ddn gian nhifng hieu qua truyen nhiet ra't cao, phdi hdp difdc phUdng thiic truyen nhiet la d6l lifu va biic xa nhiet, dd nhiet biic xa tfl thie't bi trao dd'i nhiet dang ta'm da gop phan lam cho nhiet budng sa'y luon ddng deu theo tiet dien ngang cua budng say Thiet ke hp thdng thiet bj say vai qua - Lo dd't va thiet bi trao ddi nhiet dupe dat d ben budng sa'y nen giam difdc tdn that nhiet moi trUdng, nhd dd da tiet kiem difdc nhien lieu Hdn niia cac thie't hi trao do'i nhiet khdng bi do't ndng tnic tie'p bang ngpn Ida cua 16 dot than nen dp ben se keo dai hdn nhieu so vdi thie't bi trao ddi nhiet dang 6'ng chum - Do ke't ca'u budng sa'y vai qua treo nen cd Uu diem hdn han so vdi buong sa'y vai qua bet la: sd IiJdng vai difa vao budng sa'y c6 the Idn hpn tfl 3-4 lln; kha nang thdng thoang budng sa'y t6't hdn nen dp khdng deu ciia vai qua tha'p hdn; vai qua khdng bi de nen, chen ep Ian nen khong hi bep, meo, niit nhd dd lam tang gia tri cam quan cho san pham sd'y; khdng to'n nhan cdng de dao qua qua trinh sa'y nen giam dUdc ap lute ve ngudn lao ddng thdi vu thu hoach cang thang 3.2 Khao sat anh hufcfng cua mot so' thong so' den qua trinh say 3.2.1 Anh hudng nhift dg dong say T fC) K (%) Die'u kien thi nghiem: To'c dp dong say v = 0,8 m/s, mat dp vat lidu budng sa'y M = 160kg/m^ Ke't qua thi nghiera dUdc the hien tren dd thi hinh Tren thi hinh ta tha'y, nhiet dp ddng sa'y tang, td'c dp b6'c hdi am tang, thdi gian say giam do chi phi nhien lieu rieng giam, dp khd kh6ng deu va diem tdng hdp cha't lifdng san pha'm sd'y cd xu hudng tang len Tuy nhien, ne'u tiep tuc tang nhiet dp dong kbi sa'y, tac dung cua nhiet lam cho be mat vo qua bi rdn va sit lai, ngan can qua trinh thoat am, vay thdi gian sa'y tang va chi phi nhien lieu tang len Dong thdi cung tac dung ciia nhiet dp cao, td'c dp caramon hda dUdng ciii vai xay nhanh hdn khien cho cui vai co mau nau den, vi dang, hdn niia hlen tifdng "soi" cui gay "viia" ciii cung de xay b nhiet dp cao lam cho vd qua de bi nflt, cui vai ma't deo dai, vi vay diem to'ng hdp chat lifdng cua san pham sa'y giam xu6'ng O nhiet dp 60-70"C, diem to'ng hdp chat lifdng san pham sa'y cao nha't va chi phi nhien lieu rieng tha'p nha't (d) 5.0 - • 20.0 4.0 •18.0 - 3.0 2.0 • Nr (kg than/ 1.2 1.0 16.0 • 0.8 • 14.0 • 0.6 10.0 0.2 1.0 • 60 65 70 75 Hinh Anh hufcfng cua nhiet dong say T ("€) Tran Nhu Khuyen, Phgm Ddc NghTa, Hoang Xuan Anh, Ngo Thj Hi^n, Le Huy Thu'o'ng, Tnjong Thi Toan 3.2.2 Anh hifdng say V (m/s) cua toe dong Dieu kien thi nghiem: Nhiet dong sa'y t = 70''C, to'c dp dong sa'y v= 0,8m/s Khi tang mat dp vat lieu budng sa'y thi kha nang lUu thong dong sd'y khd'i vai qua giam, t6'c dp thoat am cua vat lieu sa'y cham nen dp khd khong deu ciia vat lieu say tang, ddng thdi mau sac va miii vi ciia vai qua kem dong nha't, vi the' diem tdng hop cha't lifdng san pham sd'y giam Tuy nhien tang mat vdt lieu budng say thi nang sua't thie't bi sa'y tang nhifng chi phi nhien lieu cho qua trinh sa'y cung tang thdi gian say keo dai (Hinh 4) NgUdc lai, giam mat dp vat lieu buong sa'y, dp rdng cua khd'i qua Idn, td'c dp Iifu thdng dong sa'y qua khd'i vai qua va thoat ngoai tang, dd thai ngoai budng sa'y cd nhiet dp cao, gay hao to'n nhiet va tang chi phi nhien lieu CM phi nhien lieu rieng dat gia tri tha'p nhat flng vdi mat dp vdt lieu say M= 160kg/m^, Dieu kien thi nghiem: Nhiet dp sa'y T ~ 70"C, mat dp vat heu budng say M = 160kg/m^ Khi tang tdc dong say thi td'c dp thoat ^m tif vat lieu sa'y vao budng sa'y va tfl hudng sa'y ngoai difdc thiic hien nhanh hdn, d6 dp khd kh6ng ddng deu cua san pham sa'y giam xuo'ng, dong thdi diem tdng hdp cha't lUdng cua san pbim say tang len va dat tri sd' Idn nha't flng vdi t6'c dp dong kbi 0,6m/s Ne'u td'c dp ddng sa'y tie'p tuc tang, diem td'ng hdp cha't Iitdng san pham sa'y giam xud'ng Nguyen nhan la td'c dp thoat am ciia vat lieu d be" mat ngoai cua vd qua nhanh nhiing am ben chua kip khuyech tan be raat vo qua de bo'c hdi, tao nen sU chenh lech ap sud't gifla vd qua va ciii qua lam cho vo qua de bi ran niit, meo mo Mat khac td'c khdng sa'y qua nhanh, chifa kip truyen nhiet cho vat heu sa'y da bi d^y ngoai nen hieu sua't sii dung nhiet tha'p, chi phi nhien lieu tang nhanh (Hinh 3) 3.2.3 Anh hiidng cua mat vat buong say M(kg/m^) Tren dd thi cac hinh 2, 3, 4, ta cd the chpn dupc gia tri thicb hdp ciia cac ye'u td va flng vdi nbflng gia tri nay, cac chi tieu ve dp kho khong deu cua san pham say K, diem tdng hdp cha't lifdng san pham say Q lieu K (%) (d) (kg than/ 5.0 20.0 40 18-0 3.0 16.0 0.8 14.0 06 120 04 lU 0.6 0,8 1.0 12 Hinh Anh h i f ^ g cua toe dong say v (m/s) Thiet ke hp thong thiet bj say vai qua K %) 5.0 4.0 3.0 \ 2.0 ^ y" J\ X