NGHIEN cuu-TRAO eoi NGHIEN CLFU QUA TRINH TRAO D | NHIET VA OANH GIA HIEU QUA BAT CHE N A N G XE CON KHI D NGOAI T R Q I THE HEAT EXCHANGE STUDY AND EFFECTIVE EVALUATION OF COVER CAR WHEN THE CAR IS RADIATED SUN Nguyln The Lmrag Trudng Dai hpc Bach Khoa Ha Ngi TOM TAT Khi to ngodi trai md khong co thiet bi bdo ve ldm cho nhiet xe tdng cao, ldm tdng khd ndng ldo hoa cdc chi tiet, gdy nguy hgi cho nguai vd ldm tdng nguy ca chdy no tren xe Nghien cicu ndy se se tinh todn trao doi nhiet xe vd vd ddnh gid hieu qud bgt che ndng xe ngodi trai Nhirng kit qud nghien ciru chi rdng, nhiet xe cao nhdt Id 66,7°C xe ngodi trai md khong co bgt che ndng, su dting bgt mol lap vd ba lop, nhiet cao nhdt xe idn lu0 Id 52,9°C vd 49,3''C Ket qud tinh todn cQng chi rdng, gud trinh trao doi nhiet chu yeu xdy a be mat kinh truac vd sau, trung binh dung bgt mot lop vd ba lap tong luang nhiet tod vdo xe trung binh gidm ldn luat Id 38,9% vd 65, l%so vai khong su dung bat Tir khoa: Biec xg, mat trai, bgt che ndng, oto, trao doi nhiet ABSTRACT When vehicle is parked in the open air without the sunscreen; the temperature inside the car is much higher than the environmental temperature High temperature will accelerate the auto parts, interior aging and damage This research will calculate the heat exchanges of car and evaluate effective cover car when the car is radiated the sun, the results showed that, the highest temperature inside car was 66, ?"€ without car cover, in case of using one layer and there layers car covers, the highest temperature inside car were respectively 52.9°C and 49.3"C The results also showed that, the heat exchanges were more effective on before and after of car glass surface, the average heat total was transmitted from radiation ofthe sun to inside car when using one layer and there layers car cover decreased respectively 38.9 % and 65.1% compared to no car cover Keywords: Sun, radiation, cover car, heat exchange, car ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, Sl nam 2017 www.cokhivietn am NGHIEN CLTU-TRAO D O I DAT VAN DE Trong nhiing nang nong, xe bi phoi ngoai trdi co nhiet cao co thg gay bong, nggt ngat, anh hudng xau dgn nao bp, tham chi gay tu vong Chat benzen co nhigu tren be mat nhua ciia bang dieu khien, npi that xe, ghe ngoi, ong dan khi, co the gay hai cho than, gan, dan den cac benh bach cau, ung thu 50mg la miic benzen cho phep, nhien, dong kin Clia, mirc benzen len den 400-800 mg, cao hem lan miic cho phep Dac biet, dau xe dudi nang he (khoang 40°C), lugng benzen co thg dat 2.000 - 4.000 mg, vo cimg nguy hai Ngudi thudng xuyen ngoi xe kin nang ndng de tich tu chat dpc va mic benh Do xe dudi nang gat va nhiet dp cao thdi gian dai anh hudng it nhigu dgn be mat son, tac dpng true tigp den ngoai that va ngi that, ldp son nhanh xuong cap, cac chi tiet nhua, da va go trang tri ben giam tudi thp va lao hoa chiu tac dgng ciia hai nong Ngoai ra, xe ngoai trdi dudi nang gat, nhiet dp ciia nhung vat dl chay no dg xe nhu bat lira, Ion nudc nggt hay binh ciiu hoa mini tang cao gay mdi nguy hiem chay no trenxe [1] De khac phuc tinh trang tren, nhieu giai phap da dugc dua nhu dd xe dudi bdng ram, sii dung cac bat chong nang, phim chdng ndng, migng dinh phan quang Phuang phap mang lai hieu qua va dugc sir dung phd biln la bat chong nang bang vai phan quang [2] Hien nay, chua co cdng trinh nghien ciiu nao dugc cong bo vg qua trinh trao dli nhiet cua xe va danh gia hieu qua chong ndng cua bat xe dd ngoai trdi Trong nghien ciiu se nghien ciiu xay dung md hinh tinh toan qua trinh trao doi nhiet xe va danh gia hieu qua chlng ndng Clia bat xe ngoai trdi XAY DUTVG M HINH TINH TOAN QUA TRINH TRAO DOI NHIET XE CON KHI DO NGOAI TROfI 2.1 Doi tuong nghiSn cihi Trong nghien ciiu nay, tac gia lira chpn xe Ford Laser 1.8L lam doi tugng nghieu cim qua trinh trao ddi nhiet ciing nhu hieu qua che nang cua bat che nang, thong so kich thudc ca ban ciia xe nhu sau: Chieu dai: 4,47 (m), chigu rpng 1,705 (m), chieu cao 1,43 (m), chieu dai ca sd 2,610 (m) 2.2 XSy dung md hinh tinh toan qua trinh trao d6i nhigt xe ngoai trM khong co bat Mo hinh tinh toan qua trinh trao doi nhiet ciia xe ngoai trdi trudng hop cd bat va khong cd bat dugc thuc hien nhu sau: Qj- Nhi^t toa vao xe qua cra kinh trudc (phia Dong): Q,-Nhi$t toa vdoxe qua aa kinh sau (phia Toy); Qf Nhiit toa vao xe qua a a kinh ben Irai (phia Bac), Qf Nhi?t toa vao xe qua c'ca kinh ben phai (phia Nam) Qf Nhi0t toa vdo xe qua r Qf Nhiet toa vao xe qua mat ben Irai (phia Bac); Qf Nhiet toa vao xe qua mat ben phat (phia Nam) Hinh I Mo hinh tinh todn trao doi nhiet Biic xa mat trdi chigu xuong be mat xe theo nhieu phuang khac vdi cudng dp ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, Sd nam 2017 www.cokhivietnam.vn NGHIEN ClJU-TRAO 06l khac Nang lugng tan xa theo cac hudng Ddng - Tay - Nam - Bac va Idn nhat chu ygu theo hudng Ddng-Tay [3], vi vay, nghien ciiu nay, hudng dd xe dugc chpn theo hudng Dong - Tay Hinh 1, chi md hinh tinh toan qua trinh trao ddi nhiet to ngoai trdi theo hudng Ddng-Tay Hinh 1, chi rang, be mat xe chu yeu gdm hai dang la be mat kinh va bg mat thep co gan ni hoac bdng dg each nhiet, each am, qua trinh trao ddi nhiet xe la qua trinh trao ddi nhiet phiic tap, bao gdm biic xa nhiet tir mat trdi lgn be mat xe va vao xe, qua trinh truyen nhiet tir be mat xe vao xe Dg tang dp chinh xac qua trinh tinh toan trao doi nhiet, xe se dugc chia nhieu be mat, bao gdm be mat kinh va bg mat thep, bg mat kinh bao gdm be mat kinh trudc Q , kinh sau Q , kinh bgn trai Q, va ben phai Q^ (hinh I) Be mat vd thep bao gdm phan bg mat vo thep tren ndc xe Q^, be mat vo thep bgn canh bgn trai Q^ va ben phai Q, (hinh 1) Khi xe ngoai trdi, ddng co dot khdng Iam viec, vi vay trao ddi nhiet tir ddng ca vdi khoang xe khdng dang ke, tuong tu nhiet biic xa tir mat dudng vao gam xe cung khdng dang kg, nghign ciiu se bo qua qua trinh trao ddi nhiet cua dpng ca va mat dudng vao khoang xe So lieu cong bo quy chuan xay dung Viet Nam, 2008 [1] chi cudng biic xa mat trdi theo cac hudng, theo thdi gian va theo cac thang nam ciia Ha Ndi, kgt qua cho thay cudng dp biic xa ldn nhat vao thang 7, so lieu cudng dp biic xa nhiet trung binh cua thang dugc chi bang J / Birc xg nhiet trung binh thdng theo cdc hu&ng (W/m^) vd cdc gid ngdy: Hirong Bac Nam Dong Tay Ngang 10 150.4 146.4 185.7 137.4 155 11 158 157 174.3 148.1 159.5 12 160.6 161.3 160.9 160.9 160.9 Gifr mat trfri (h) 14 13 158 150.4 157.5 146.4 137.4 148.1 174.3 185.7 159.5 155 15 137.9 128.6 122.2 190.8 144.9 16 120.2 105 101.5 183.4 127.5 Theo hinh I, tdng nhiet tda vao xe dugc tinh nhu sau: I : Q = Q , + Q , + Q3 + Q , + Q3 + Q3 + Q , + Q , ( W ) (1) Trong dd: Nhiet tda vao xe chia lam hai phan, qua vo va qua cira kinh, sau day se trinh bay chi tilt each tinh hai phan tren - Nhiet toa vao xe qua cua kinh bao gdm biic xa va truyen nhiet qua vach phang, dudi day (a cong thlic xac dinh nhiet tda vao xe qua cira kinh: = ZQj^^, + IQ„^_(i=l*4) (2) Trong do, nhiet toa birc xa mat trdi qua cac ciia kinh dugc tinh theo cdng thiic sau [4]: ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, So nam 2017 www.cokhivietn am cr NGHIEN CO'U-TRAOD6I (3) Q , , ^T,.T,.T,.T y.q.F ^^bxki ' ' I Cidd: T|^0,9: He sd suit cua kinh; Tj=0,8: He sl bSn mat kinh; T3=0,75: He sd che khuat ciia khung; T^=0,65: He so tan xa che chan; 7=0,9: He so xuyen qua ciia kinh; q: Biic xa mat trdi di den be mat kinh; F^: Dien tich bl mat kinh thii i (i=l-4) Truyen nhiet qua cac cira kinh xac dinh theo cdng thiic sau [5]: =k, F At (4) k^i He sd truygn nhiet ciia kinh, vdi kinh xe cd chilu day mm, tir tinh dugc k^ = 11,162 (W/m^K) At: Do chenh lech nhiet giiia xe va ngoai xe qua cac cira kinh; F|=l,26 (m^): Dien tich kinh trudc xe; Fj=0,89 (m^): Dien tich kinh sau xe; F3=^F^=0,5 (m^): Dien tich kinh ben ciia xe - Nhigt toa vao xe qua vd xe dupc tinh theo cdng thiic sau: Qv^Qv5+Qv6+Qv7 = 2Qv, (i^5^7) (5) Q^=k.F^.A„ (6) k: He so truyen nhiet cua vo xe: L ^ ^ a =20 (W/m^K): He so tda nhiet Ui ben ngoai dgn bg mat vd xe; 0^=30 (W/m-.K): He sd tda nhiet bgn bg mat ldp ni vao xe; 0i=3 (mm): Chigu day vd xe; ^15 (mm): Chigu day ldp ni each nhiet; =58 (W/m.K): He sl din nhiet Clia thep; =0,032 (W/m.K): Hg s6 din nhiet ciia ni; 1,811 (W/m^K) : Dp chgnh lech nhiet dp giua va ngoai qua noc xe; : Dp chenh lech nhiet dp giua va ngoai mat bgn xe phia trai; ,: Dp chgnh lech nhiet giua va ngo^ qua mat bgn xe phia phai; =1,56(m^): Dien tich ndc xe; =F =1,095 (m^): Dien tich mat bgn cua xe Thay cac thdng sd tinh toan dugc o cong thlic (2) va (5) vao (1) ta se xac dinh dugrc tong nhiet vao xe 2.3 Xay diimg mo hinh tinh toan qua trinh trao d6i nhift xe dS ngoai troi co bat mot Idp va ba lop Khi dung bat che nSng mpt ldp, anh sang mat trdi se chieu true tigp len Idp vai Tinh toan qua trinh biic xa nhiet lgn vai, sau nhiet se truyen tii bat len vd xe, vi vay qua trinh la qua trinh trao doi nhiet vao xe la qua truygn nhiet qua vach phang nhigu ldp, qua trinh tinh toan ciing hrong Ur nhu tren, d day chieu day ldp vai la 0,5mm, he sd din nhiet cua vai 0,06 (W/m.K) [2] Trong trudng hpp dung bat lap, ngoai hai ldp vai d trgn, tren bat ba ldp bo tri them ldp cao su luu hda de each nhiet, thong sd cua ldp cao su luu hda nhu sau: Chieu day tim cao su luu hoa mm, he sd dan nhiet cua cao su luu hda 0,034 (W/m.K) [6] KET QUA TINH TOAN QUA TRINH TRAO DOI NHlfiT VA DANH GIA HIEU QUA CUA BAT CHE NANG De tinh toan tdng nhiet Iugng mat trdi toa vao xe cac trudng hgp khong CO bat, CO bat mdt ldp va bat ba ldp, cin thigt ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, Sd nam 2017 www.cokhivietnam.vn NGHIEN CU'U - TRAO D I phai xac dinh nhiet dp moi trudng va nhiet dp xe trudng hgp khdng cd bat, cd bat mgt ldp va ba ldp 3.1 Thuc nghigm xac dfnh nhiet mdi tru'dng va nhiet xe dd ngoai trdi Hinh Thir nghiem lai bdi gih xe Trdn Dgi Nghia, Hat Bd Trimg, Hd Noi, thdng 7/2016 thuc, chu ky lly mlu 60ms, phan mgm ghi dii lieu la ciia hang Hanyoung di theo thiet bi Hinh 2, chi hinh anh thuc nghiem nhiet xe su dung bat mgt ldp, thdi gian thue nghiem tir lOh dgn I6h, thuc hien tai ba thdi diem cd nang khac la thdi digm dau, giiia va cuoi cua thang 7/2016 Hinh 3, chi kgt qua nhiet dp trung binh xe tai ba thdi digm khac tchi xe dd ngoai trdi khdng cd bat, cd bat mpt ldp va bat ba ldp Ket qua chi rang, vao thang 7, nhigt dp moi tnrdng trung binh theo cac gid thap nhat la 38,1''C tai thdi diem lOh va cao nhat la 40,4°C tai I4h Ket qua tren hinh ciing cho thay nhiet dp xe khdng cd bat tang cao, cao nhat la 66,6''C tai 12h, sir dung bat mgt Idp va bat ba Idp nhiet dp cao nhat giam xuing 52,8''C va 49,3''C 3.2 Kit qua tinh toan qua trinh trao dot nhi^t va danh gia hieu qua ciia bat che nang De tinh tdng nhiet tda vao xe qua trinh trao ddi nhiet, dau tign ta xac dinh nhiet dp be mat ben ngoai xe tai cac be mat trao doi nhiet Theo cong thiic ve qua trinh trao doi nhiet phiic tap [5] ta co: Nhiet be mat i (1=1-^7): Hinh Do thi nhi^t moi tru&ng vd nhi^t dg Irong xe tru&ng hap co bat vd khong CO bgt T^i = *|(tf + ) ^ + ^ - 273 (T) (7) Trong do: D I thuc hien nhiet dp xe va moi trudng, tac gia da sii dung cam bign PtI 00 vdi cac thong s l nhu sau: Dai -50~200''C, sai sd nhi?t dp 0,1% toan giai Bd digu khien nhigt dp Hanyoung HX7, chinh xac 0,5%, bp digu khien cd kgt noi RS485 ket ndi vdi may tinh de ghi dii lieu nhiet theo thdi gian e^: He so hap thu biic xa cua vat lieu tai be mat i, tnrdng hgp khong co bat, anh nang mat trdi chigu true tigp xuong be mat thep va kinh, vi vay he so hap thu biic xa ciia thep va kinh chgn lan lugt la 0,6 va 0,44 Ddi vdi trudng hgp sir dung bat, liic anh sang CP ISSN 0866 - 7056 TAP CHi CO KHi V I £ T NAM, So nam www.cokhivietnam.vn 2017 NGHIEN cuu-TRAO 06l mat trdi chilu true tigp lgn vai bat, he sd hap thu biic xa cua vai chpn la 0,8 tf Nhiet dp moi trudng ben ngoai xe q (W/m-): Cudng biic xa mat trdi chigu len bg mat trao doi nhiet C„=5,67 (W/m^.K"): He so biic xa ciia vat den tuygt ddi Thay cac gia tri tren vao cong thiic 7, ta se tinh toan dupc nhiet tai cac be mat trao doi nhiet Hinh 4, chi nhiet cac bg mat trao ddi tuang img tir be mat Q^ den Q^ tnrcmg hgp khong cd bat che nang, ket qua cho thay nhiet dg be mat Q, (T^.^) cd xu hudng giam dan tir 87,1''C den 67,8°C, dieu cudng birc xa cua hudng Dong giam dan thdi gian tir lOh dgn 16h (bang 1) Doi vdi cac be mat trao ddi nhiet khac, cudng dp biic xa nhiet tang dan tir lOh den 12h sau giam dan, digu dan tdi nhiet cac be mat Q, (TJ, Q, (T^3), Q, (TJ, Q, (TJ, Q^, (T^^) ban dau tang dan dgn gia trj Idn nhat sau giam dan, kgt qua ciing chi rang, nhiet dp cao nhat tai cac bg mat Q^, Q3, Q^, Q^, Q^ va Q,lln lugt la 89,0"C, , ^ , 82,9