NGHIEN cuu-TRAOD(!)l NGHIEN CLPU XAC OjNH QUY LUAT T A NHIET TRONG XY LANH DONG CO RESEARCH AND DETERMINATION OF HEAT RELEASE RULE OF ENGINE CYLINDER Nguyen Tien Han Trudng Dai hgc Cong nghiep Ha Ndi TOM TAT Viic xdc dinh quy lugt tda nhiet cua nhien lieu d qud trinh chdy cua dong ca ddt Id rdt cdn thiet vd khdng thi thiiu dugc ddi vai cdc nghien eieu md hinh hda chu trinh cdng tdc ctia dgng ca vd nghien cuu hodn thi^n qud trinh chdy Tuy nhiin, viec xdc dinh true tiep quy lugt ndy bdng thi^c nghiem Id mdt viic ldm rdt khd khdn Bdi bdo ndy neu len phuang phdp xdc dinh guy ludt Ida nhiet cua nhien lieu xy lanh dgng ca dua trin phdn tich diin bien thay ddi ndng luang chdy xy lanh ddng ca Tir khoa: Quy lugt tda nhiet, Qud trinh chdy cua dgng ca; Ap sudt the ABSTRACT The detetmination of heat release rule of fuel in engine cylinder is very important to study the model of thermodynamic cycle and the improvement of combustion process ofthe engine However, the direct experimental determination of this rule is very difficult This article describes a method for determination of heat release rule of fuel in engine cylinder based on the analysis of changed process of combustion energy in engine cylinder Keywords: Heat release rule, the combustion process of engine, cylinder pressure DAT VAN DE Qua trinh tda nhiet xy lanh dpng ca CO quy luat giong nhu quy luat ciia ap suat the Quy luat thay doi theo goc quay true khuyu va phan anh day dii cac ylu t l lien quan dgn chu trinh cdng tac ciia dpng ca nhu dac diem qua trinh chay ciia nhign lieu, cdng cua chu trinh, su traa ddi nhiet ciia mdi chat, ton that qua trinh thay ddi dpng ca, v.v Do do, viec nghign ciru dae diem bien thign ap suat the co vai trd dac biet quan trpng nghign ciiu hoan thien va phat trien dpng co ISSN 0866 - 7056 TAP CHi CO KHI VIET NAM, Sd nam 2017 www.cokhivietnam.vn Co nhieu cdng trinh nghien eim lien NGHIEN CUU-TRAO D | quan den van dl nay, ca bang phuong phap md hinh hda va bang thuc nghiem Cac cdng trinh nghien eiiu md hinh hda kha da dang nhu tinh toan ap suat xy lanh ddng ca bang thuat toan Levenberg-Marquardt [1] de phan tich dac tinh Iam viee cua dpng ca, nghien ciiu qua trinh nhiet dgng cua moi chit xy lanh dgng ca giai doan khdi dpng lanh va ehay am may bang phuang phap md hinh hoa [2], qua xac dinh su bign thign ap suat va nhiet dp the xy lanh Iam ca sd dg nghien ciiu su hinh va dac diem phat thai NOx dpng ca [3] Lfu diem cua md hmh hda la cd the de dang nghien ciru sir anh hudng cua mdt thdng sd bat ky den dac diem dien bign cua ap suat chay xy lanh dgng ca nhu nghign ciru anh hudng cua tdc ddng ca den su thay doi ap suat thg giiia cac chu trinh [4], Hay nghign eim mdi lign he giii'a dao ddng, rung ddng va tdc dp dpng ca vdi dac diem thay doi ap suat the xy lanh [5] Tuy nhign, phuang phap mo hinh hda nghign ciiu qua trinh nhiet ddng ddng co thucmg phai sir dung cac ham kinh nghiem bigu dign toe dp chay ciia nhign lieu ma cac ham thudng kho xac dinh chinh xac bang thirc nghiem ngn cac quy luat thay doi ap suat tinh toan dugc bang md hinh hda thucmg mang tinh gan diing De nang cao chinh xac ket qua tinh toan bang md hinh boa doi hoi phai xae dinh dupe quy luat tda nhiet hay tdc dpc chay cua nhign lieu mgt each dan gian va tin c|y bang thuc nghiem Cac cdng trinh nghien ciiu thuc nghiem da thuc hien thudng tap trung phan tich danh gia chu trinh cong tac va dac digm Iam viec Clia dpng ca dua tren thi bien thign ap suat thg dugc nhu phan tich qua trinh chay va su biln dgng ap suat giua cac ehu trinh dudi cac dilu kien lam viec khac cua dpng ca [6], hay xac dinh goc phun sdm toi uu d cac chl dp lam viec khae [7], xac dinh ty le nhign lieu, khdng ciia hdn hgp xy lanh dpng co [8, 9] va nghien cihi dac diem qua trinh chay va dac tinh dpng ca sir dung nhign lieu hydro [10] Bai bao trinh bay phucmg phap xac dinh quy luat toa nhiet dua trgn phan tich dien bien thay doi ap suat thg xy lanh va nguygn Iy thir nhat ciia nhiet ddng hpc de lam co sd eho viec nghign ciiu tigp hoan thien qua trinh chay va nang cao hieu suat cita ddng co C O SOf LY THUYET XAC DINH QUY LUAT TOA NHIET VA C H A Y CUA NHIEN LIEU De tinh toan toe dp toa nhiet hay toe d6 chay cua nhien lieu tai cac thdi digm chu trinh cong tac cua dpng ca dua ugn phan tich thi ap suat p=f(a) mdt each dan gian nhung van dam bao dp chinh xac can thigt ed thg dua tren mo hinh nhiet ddng mpt vimg Trong mo hinh nay, nhiet dp xylanh dugc coi la nhu tai mgi digm Vigt phucmg trinh nhiet dpng thli nhat cho moi chat xy lanh ta co dQ^dU + pdV + dQ^+Y,h.dm^ (1) Trong do: dQ: Nhiet Iugng da nhien lieu chay dU: Bien thign ndi nang pdV: Cong lam dich chuyen piston dQ^: Nhiet lugng truygn cho xy lanh h^ va dm_ la entanpi va khoi Iugng ciia vao hoac khoi buong chay Ta co: dU-d{rmi)=mjdu+Ujdm-m(;dT-udrTj^ (2) (3) dQ„ = A}i^{T'T,)dt=-A.h^(T-TJ.da h' va dm la entanpi va khoi lugng Cr ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, Sd nam 2017 www.cokhivietnam.vn NGHIEN cuu-TRAO DOI Ipt kdi buong ehay, h^: He so truyen nhiet tir the c6 nhiet dp T buong chay cd nhiet T^, dien tich truyen nhiet bic thdi A co: Van toe goc true khuyu, rad/s Su dung phuang trinh trang thai li tudng pV=mRT, vi phan hai vg va thl mdT vao phuang trinh (2) rdi thl vao phuong trinh (I), chu y tinh chat nhiet ddng cua Ii tudng R=Cp - Cv va k=Cp/Cv ta co: dt k-l^ dl k-l dt^ {h-u + c, T)dm^ + A.h,(T-TJ (4) Nhu vay, dugc fri so va bien thien ap suat theo gdc quay true khuyu ta co thg tinh toan dugc tdc toa nhiet cua nhign lieu, hoac Iugng nhiet toa ciia nhien lieu chay xy lanh d cac thdi diem hoac cac vi tri gdc quay true khuyu Ddi vdi dpng ca diesel, ta ggi Q =QQ^ la nhiet cua nhign lieu chay tda sau da trir di phan nhiet truyen cho buIng chay 0^^ Bd qua anh hudng cua khe ke giiia piston-xy lanh (tire la khong kg dgn hien tugng nen va thoat khoi cac khe ke) va bd qua enthanpi cua nhign lieu phun vao (tiic la "^h^m^ =h^ m^ =0, h^ mAk enthanpi va khoi Iugng nhien lieu phun vao) Phuang trinh (4) dugc viet thanh: dQ„ dt - dV p h V-^ (5) k-\ dt k-l dt Bien dpi (5) tlieo goc quay true khuyu; * l ^ = J _ dV da da'dt k-l''da'dt* k dV — p— + da k-\ da k-\ ^ k-\ ^^dp V -^ da dp da da'dt (6) Dat tc-V da k-\ da ISSN 0866 - 7056 TAP CHi CO KHi V I £ T NAM, So nam www.cokhivietnam.vn -^ Co the dg dang tinh dugc theo cac thong sd hinh hpc ciia dpng ca, ap suat p dugc tir ket qua thi nghiem img vdi cac gia tri a Nhu vay, ta cho a di tii ^ 720" ta se tinh dugc ket quaYj.De tinh Yj,ta da bilt quy luat ciia V^f(a) theo quan he hinh hgc, chua bilt dugc quy luat ham sd cita ap suat p=f(a) ma chi biet dugc eac gia tri ap suat tai cac diem do, vi vay ta su dung phuang phap tinh gan diing dao ham: dp_^^f{a+h)-fia) da >^ (a + h)-a ^dp _f(a + h)-f(a)J^p da (a + h)-a Aa Trong do: a la gdc quay true khuyu; h la so gia cua doi so a, chpn h=Aa=a -a, -0,5" (7) Sau giai dugc Yj va Y^, cpng lai se dugc gia tri quy luat toa nhiet — ^ theo da goc quay true khuyu, (d day tac gia diing MATLAB de giai phuang trinh (6), kit qua xuat d dang bang va dl thi) D l dem gian tinh toan, ta chi xac dinh quy luat chay tir phun nhign lieu cp^ =22° din md sdm xuppap thai cp^ =40" Nhu vay, quy luat chay dugc xac dinh khoang a= 338^500" goc quay true khuyu De tinh nhiet tda qua trinh chay_^, ta xae dmh lugng nhiet huyin cho da buong chay - ^ theo cong thiic (3) He da so truyen nhiet cd thg dugc xac dinh theo cong thlic thuc nghiem ciia Woschini h, =S,26 J)-'\pM'f''l-°-^ ,Wlm^X (8) 2017 NGHIEN CU'U-TRAO DOI Ngu gia thigt lugng nhiet toa ty Ie vdi Iupng nhien lieu da chay, ta xac dinh dugc ty le nhign lieu da chay x theo gdc quay tnic D: Duong klnli xylanh, m p: Ap suat th6, kPa T: Nhiet dp thi, K khuyu nhu sau: v - MJC,.c ' +C,-^^.V(p- p.) p.y (12) (5) p , V , T la ap suat, thg tich va nhiet ciia xy lanh tai mdt thdi diem nao dd, thudng chgn la cuoi ki nap (trong phan nay, dg dan gian chpn p^=lbar, T^ =298K; p, V la ap suat va the tich xylanh tai mpt thdi diem xet; p^ la ap suat xylanh (xae dinh d cimg vi tri gdc quay true khuyu vdi p) dpng ca dugc keo khong no d cimg dieu kien Iam viec Trong dd: Q la nhiet Iupng nhign lieu chay smh tir thdi digm bat dau chay den thdi digm i dang xet SQ la tdng Iugng nhiet toa dot chay tdng sd nhien lieu dua vao xylanh dpng CO mdt chu uinh cong tac XAY DlHVG MO HINH VA TINH TOAN QUA TRINH CHAY DONG C O XANG 3.1 Xay dyng mo hinh Q hanh trinh hiit thai: Q - , + , ^ De khao sat qui luat tda nhiet tac gia su dung dpng ca 13 SOHC dpng ca cd cac thong so ky thuat nhu d bang I Ci hanh trinh khac: C, ^ 2,28+ 0,308— c„ Bdng Thdng so ky thudt dgng ca xe Matiz c : Tdc dp trung binh cua piston; v, = — ^ , vdi (Wp la tie dp xoay ldc xylanh, chgn CO ^20m/s Khi ehua cd su chay nhien lieu, C^ -0^ chay nhien lieu C, =3,24.I0-\ Dien tich tuc thdi A dugc xac dinh gan dung theo cac thong sd hinh hgc cua xylanh dpng ca nhu sau TT Thong so ky thuat Gia tri Donvi Dung tich cong tac 0,796 lit Ty so nen 9,3 Cong suat N^^^ 37,5 kW So vong quay n^N 6000 v/ph 68,6 Nm So vong quay n^M 4600 v/ph Goc danh lira som 10 dp Goc mcr sctm, dong muon xupap nap 10; 70 dp Goc mo som, dong muon xupap xa 70; 10 dp ^^2^+sD.-ra-cosa)+-(l-cos2a)] 4 (10) Sau tinh toan dugc Iugng nhiet truyln cho vach xylanh bang each giai phuang trinh vi phan (3) ta tinh dugc nhiet Iugng nhien lieu toa dQ^dQ^^dQ^ da da da (11) Mo men M Mo hinh dpng ca 13 SOHC xay dtmg bing phan mem AVL Boost nhu hinh 3.6 ISSN 0866 - 7056 TAP CHi CO KHi VI$T NAM, So nam 2017 www.cokhivietnain.vn a= NGHIEN CLFU-TRAOD6I Kgt qua tinh toan tdc ehay d m6i vi tri gdc quay true khuyu theo phuang phap trinh bay d trgn d chg dp toan tai dudi cac t6c dp vdng quay khac ciia dpng co duoc bigu dien bang thi tren Hinh Hinh Md hinh dong ca nhiit 13 SOHC Mo hinh ddng ca su dung md hinh chay Fractal; md hinh truyen nhien Woschni 1978; md hinh nap, thai; md hinh thai Sau thigt lap va tien hanh chay mo hinh d dac tinh ngoai Ket qua md phong cho thay su sai khac giiia ly thuyet va kgt qua thuc nghiem la khdng ldn Do do, mo hinh mo phdng ddng ca 13 SOHC la dang tin cay va co the dimg dg tinh toan cac thong sd khac cita ddng ca Hinh 3, la thi bieu diln tdc d6 toa nhiet — cua nhign lieu qua trinh chay theo goc quay true khuyu Phan tich eac d6 thi nay, ta thay rang ban dau toe dp toa nhigt tang lgn rat nhanh (dd thj co ddc Idn) va dat gia tri cue dai d lan can 375° goc quay true khuyu Toe toa nhiet tang nhanh iing vdi giai doan chay ehinh cua dpng co xang, dieu phu hgp vdi ly thuygt Sau -^ dat gia tri circ dai, tdc dp toa nhiet giam cran Iuc too dp chay da giam, nong san vat chay xylanh tang len, ndng dp oxy giam, piston dang di xuong digm chet dudi Iam cho thg tich tang lgn, ap suat va nhiet dp xy lanh ciing giam Day la giai doan ling vdi thcri ky chay rot ciia nhien lieu xy lanh dgng ea 3.2 Danh gia ket qua Hinh 2, gidi thieu thi khai trien ap suat theo gdc quay true khuyu ciia cac xy lanh tai 100% tai d toe dp ddng ca 6000vg/ph Gia tri p^^ dat tai 10" sau digm chet tren va p^^ giiia cac xy lanh khac anh hudng cua sdng ap suat trgn dudng nap Iam cho he so nap khac Hinh Tdc tod nhiit chgy a 100% tdi Hinh Bd thi khai tnin dp sudt theo gdc quay true khuyu Khi tdc ddng co tang lgn thl vi tri gdc quay true khuyu img vdi — co xu hudng dieh chuyen sang ben phai Dieu cho thay tang toe ddng ea, goc quay true khuyu ung vdi qua trinh chay tang len, chay se keo dai trgn dudng gian nd Uong thdi gian chay thue lai giam xuong ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, S6 nam 2017 www.cokhivietnam.vn NGHIEN CU'U-TRAO D | Dua vao cac dd thi ta thSy ring, ciing mdt chg dp tai, tang t6c dp ddng ca thi luc dau tdc dp chay nhign lieu tang len, tdc dp toa nhiet eung tang len Tdc chay nhien lieu tdt nhat ung vdi tde dp dpng co d 4.600 vdng/ph Sau do, t6c d6ng ca tang lgn thi tdc chay lai giam xudng Dieu cd the giai thich la toe dp ddng co nhd thi tang tdc dp ddng ca se lam tang xoay 16c buong chay va do chat lugng hoa trpn nhign lieu va khdng tdt hem se lam cho tdc dp chay tang lgn Tuy nhien, tdc dp ddng CO tang cao thi thdi gian thue iing vdi dp gde quay true khuyu giam di va qua trinh chay kep dai theo gdc quay true khuyu nen tdc dp chay theo gdc quay true khuyu giam di Tir eac kgt qua tinh toan cd thg xay dung dugc quan he giai tich ciia tdc dp chay theo gdc quay true khuyu ngu can Ngay nhan bai: 12/7/2017 Ngay phan bien: 20/7/2017 Tai lieu tham khao: [1] [2] [3] [4] [5] [6] KET LUAN Nhiet qua trinh chay va quy luat toa nhiet thay ddi cua no theo gdc quay true khuyu phan anh dSy dii cac yeu td lien quan den chu trinh cong tac cua dpng co, dac biet la dac diem qua trinh chay cua nhign lieu [7] [8] [9] [10] Bai baa da xay dung dugc phuang phap xac dinh quy luat chay ciia nhign lieu Ket qua cd y nghia quan trgng cho viec phan tich cac nhan td anh hudng dgn qua trinh chay dg nghign ciiu hoan thien va nang cao hieu qua qua trinh chay ciing nhu hieu suat ciia dpng ca *l* Shidfar and M A Garshasbi; Applied Mathematics & Computation, Vol 165, pp 163-170(2005) Hoang Dinh Long; Tap chi Khoa hpc & Cong nghe, s6 36+37 (2002) Hoang Dinh Long; The Proceedings ofthe International Conference on Automotive Technology, No.051 (ICAT 2002) Francis T Connolly and Andrew E Yagle; Mechanical Systems and Signal Processing, Vol 8, pp 1-19 (1994) Roger Jobnsson; Mechanical Systems and Signal Processing, Vol 20, pp 1923-1940 (2006) Asok K Sen, Rafal Longwic, Grzegorz Litak and Krzysztof Gorski; Mechanical Systems and Signal Processing, Vol 22, pp 362-373 (2008) Mam Yoon, Kangyoon Lee and Myoungho Sunwoo; Mechatronics, Vol 17, pp 469-479 (2007) Anders Tunestal; PhD thesis (2000) J.C Gilkey, J.D Powell; Stanford University (1985) Ali Mohammadi, Masahiro Shioji, Yasuyuki Nakai, Wataru Ishikura and Eizo Tabo; Intemational Joumal of Hydrogen Energy, Vol 32, pp 296-304 (2007) ISSN 0866 - 7056 TAP CHI CO KHi VIET NAM, Sd nam 2017 www.cokhivietnam.vn ... nhiet ddng mpt vimg Trong mo hinh nay, nhiet dp xylanh dugc coi la nhu tai mgi digm Vigt phucmg trinh nhiet dpng thli nhat cho moi chat xy lanh ta co dQ^dU + pdV + dQ^+Y,h.dm^ (1) Trong do: dQ: Nhiet... suat xy lanh ddng ca bang thuat toan Levenberg-Marquardt [1] de phan tich dac tinh Iam viee cua dpng ca, nghien ciiu qua trinh nhiet dgng cua moi chit xy lanh dgng ca giai doan khdi dpng lanh. .. dd, thudng chgn la cuoi ki nap (trong phan nay, dg dan gian chpn p^=lbar, T^ =298K; p, V la ap suat va the tich xylanh tai mpt thdi diem xet; p^ la ap suat xylanh (xae dinh d cimg vi tri gdc