Xác định tải trọng trong thiết kế cơ khí hệ thống năng lượng mặt trời tự xoay

NGHIEN C U U - T R A G D P I XfiC DINH Tfll TRONQ TRONG THIET KE CO KHI HE THONG NfiNG LtfOfNG M^T T R O I TCT XOfiY Nguyen Van D^\ Hoang Tiln Dat', L^ Duy Hdi^ Nguyin Hodng GiangS Van Cdng Bich' 'TrUdng Dai hpc Ky thuat Cdng nghiep, Dai hpc Thai Nguyen ^Trudng Cao ding Kinh te Ky thuat, Dai hgc Thai Nguyen, 'TrUdng Cao dang Cdng nghi?p Hue T6M TAT Bdi bdo ndy trinh bdy cdch xdc dinh tdi trgng cho bdi todn thiet keket cau cd cua he thong ddn ndng lUdng mat trdi tU xoay theo hUdng tia sdng Mo men cdn thiet dexoay ddn dUdc xdc dinh de thdng sdc } qudn tinh, mo men ma sdt vd mo men cdn cua gid Md hinh tinh todn dUdc xdy dUng nham tinh todn cong suat cdn thiet dexoay ddn tiiy thugc cong suat phdt dien yiu cau Mo hinh co thesddun^ de tinh todn thiet kecdc he thong ndng lUdng mat trdi tU xoay khdc nhU bi'p ndu dn ndng lUdng mat trdi, dgng cd ndng lUdng mat trdi cdn xoay theo hUdng tia sdng ABSTRACT This paper presents a method to determine loads for mechanical design of solar trackers Moment needed to operate the system following the sun is calculated from inertial, frictional moments and wind load acting on the moving parts A calculation model was built to determine the power needed to operate the moving parts based on required output powers The model can be used to design mechanical structures of solar systems such as solar cells, solar cookers and solar dish engines tracking the sun path TU khda: Ndng lUdng tdi tao, dgng lUc hgc, tdi trgng, truyen ddn cd E TAP CHi CO KHi VIET NAM • Sd (Thdng nam 2012) NGHIEN CUfU-TRAOeOl GlCfl THifiU mat phang chda quy dao quay cua nd quanh mat trdi Thdi gian chieu sang vd sU hinh thdnh cac Khai thac nang lugng tdi tao dang la mda nam Id ket qua chuyen ddng tU xoay van de dUpc quan tam nghien cdu vd ang dpng, vd chuyen dpng quay cua trdi dat quanh mat trdi nham dap dng yeu cau nang lUpng cang cao (Hinh 1) cua ngUdi, yeu cau giam thieu d nhi^m mdi trudng va giai quyet khd khan ve khd nang ddp ang cua nang lUpng truyen thdng Cac nghien cUu da cho thay, chi can thu lai 10% nang lUpng mat trdi chieu tren dien tich 0,16% be mat trdi dat, da cd the cung cap 20 TW nang lUpng, gap ddi nang lUpng cd dUgc ta dot nhien li?u hda thach truyen thdng [1] Nang lUpng mat trdi dang dUpc nghien cUu, khai thac bdng each bien ddi sang nang lUpng dien (pin mat trdi, ddng ca mat trdi), sa dung phan nhiet nang cua dnh ndng (bep nau ] linh 1: (~litivOii JOIIL; CLia Irai dat va cac miia Iroiig nam mat trdi, binh nUdc ndng) Xoay he thdng ludn hudng ve phia mat trdi Id mdt cdch tiep can don gidn de nang cao hieu qud sa dung, thu hoi nhanh ,iii\ ili'iiii,ilt|Mi ;i vdn dSu tu cho cac he thdng khai thac nang lugng mat trdi [ -6] Hang tram nghien cdu va ang dung da trien khai vdi muc dich xoay he thdng thu nang lugng theo hudng mat trdi [1] Tuy vay, cho den nay, van chUa cd tdi lieu ndo trinh bdy ve tinh toan thiet ke ca cho he thong nang lUpng mat trdi tu xoay Mdt vai cdng bd [2-4] da gidi thieu ket cau cd nhUng chi cd tinh chat nguyen ly; cac thdng so dugc chpn chUa dUa tren tinh todn theo tai trpng, vay khd cd khd nang dp dung cho cdc trudng hpp thiet ke khdc Hinh 2: Chuyen dpng tUOng ddi cua mat trdi so vdi diem tren mat dat Bdi bao ndy trinh bay md hinh tinh todn Trong khodng thdi gian chieu sdng mdi tdi trpng phuc vu cho thi^t ke be thdng ca cho ddn nang luang mat trdi tU xoay Cdng suat xoay ngdy, mat trdi chuyen ddng tUOng ddi so vdi diem dan duoc xac dinh dUa tren khdi lUflng, quan tinh, dat he thdng thu nang lUpng theo mpt quy dao ta ma sat cua he thdng va lUc cdn gid Cdc thdng sd Ddng sang Tdy (chuyin ddng quay theo gid) Mat I ndy dugc tinh todn nhU cdc hdm phu thudc cdng phang chda quy dao chuyen ddng ndy caa mat suat mong mudn cua he thdng Md hinh todn hpc trdi cung dich chuyen tUOng doi giCa cdc ngdy • dupc xdy dung cd the ap dung cho nhieu dang ket nam (chuyin ddng theo ngdy - xem minh cau khdc nhU ddn pin mat trdi (Solar photo- hpa tren hinh 2) vohaic cells), Up nau (solar cooking) hay dia thu '' nhiet cho dpng cO mat trdi (Solar disc) BAI TOAN THIET KE 2.1 Cac nguy&n tac xoay dan True tu xoay cua trai dat nghieng 23^27' so vdi Cac he thdng bam theo quy dao mat trdi (Solar tracking) thUdng dUOc thiet ke dUa tren nguyen tac phdi hpp giCa hai sd chuyen ddng quay quanh true X, Y va Z nhU minh hpa tren hinh TAP CHi CO KHi VI£T NAM V Sd (Thang nam 2012) NGHIEN CUfU-TRAODOl 2.2 Bdi toan c^n gidi quy^t Bdi toan dat Id ta cdc thdng sd kich thudc vd khdi lUpng bp phan thu ndng lUpng (da xdc djnh theo yeu cau cdng suat cua h^ thdng, ching ban, dien tich cdc tdm pin, kich thUdc gUpng pa-ra-bdn thu nhi?t ), can xdc dinh tdi trpng dat Ien h? thdng Xdc djnh dUgc tdi trgng se la ca sd de tinh todn chgn d^ng cO di^n vd cdc thdng s6 kit cdu ca de ddm bdo ddn boat ddng dn dinh vd dd ben Md men cdn xoay ddn cd the xdc djnh ta thdnh phan: M^^=M^+M„ +M^_^ (1) Trong dd, M , M va M Ian lupt Id md D ' e' ms glo Fif- • ^ ^ T men cdn dan dat lech tam so vdi trpc xoay Hinh 4: Momen l^ch tam (hinh 4), md men can ma sdt tren true xoay vd md men can cua gid tac ddng Ien he thdng Nhu minh hpa tren hinh 4, ca kh xoay ddn cd khdi lUpng dugc phan bd deu hai ben trui xoay (Fj=F2=F), nhUng trpng tam dan led so vdi tdm xoay mdt khoang e, van gay nen mO momen l^ch tam \t^ = /^(Z, -A) = F.e.sma Momen cd gia tri Idn nhat a = ± 90", nghii Id, ddn vudng gdc vdi phuang nam ngang T?i thdi diem khdi dpng, md men khd ddng cdn can thdng sac i (qudn tinh) cua cac do; tupng xoay, tac la: A^™ :M+M, +M, +M„, (2) CAC CO Sd TiNH TOAN Cac phan momen can xoay dan dugc tinh toan nhU dUdi day 3.1 Momen can Ifch tam Hinh 3: Cac true xoay dan vd cac thdnh phSn tai trgng [8] TAP CHi CO KHi V I £ T NA M •!• Cdc he thdng thu nang lUpng mat trdi thudng cd khdi lUpng kha Idn Khdi lUpng naf neu l?ch tam xoay se gay md men cdn xoay rat dang ke Gpi khoi lU