NGHIEN CU'U - TRAO D O I c a s d LY THUYET CAl TliN TANG AP TREN DONG CQ XE MAY S(y DUNG NHIEN LI$U KHi CHUYEN D | TIJ DONG CaXANG DANG LU'U HANH THEORETICAL CALCULATION FOR SUPERCHARGING IN MOTORBIKE ENGINE FUELED WITH LIQUEFIED PETROLEUM GAS CONVERTED FROM CURRENTLY USED GASOLINE ENGINE Nguyln Tien Han Khoa Cdng nghe td, Trudug Dai hoc Cdng nghiep Ha Npi TOM TAT Bdi bdo trinh bdy nghiin ciru mo phong lua chgn ty so tdng dp trin dgng ca xe mdy su dung nhiin lieu chuyin doi tir dgng caxdng dang luu hdnh tgi Viit Nam Gidi phdp cdi thien tinh ndng ldm viic cua dgngca Id ldm tdng lugmg moi chdt ngp m&i vdo xy lanh moi chu trinh di ndng cao cong sudt cua dgng ca su dung nhiin liiu bdng cdch sir mdy nen tdng dp Cdn cu vdo each thirc hinh thdnh hon hap cua dgngca chdy cuang birc vd ddc tinh cua logi nhiin lieu sir dung di tinh todn sa bg ty so tdng dp cdn thiet dgng ca su dung nhien lieu LPG di ddm bdo tinh ndng ky thudt tri nhu doi v&i truang hcrp sir dung xdng Nghien cim mo phong dug'c thuc Men tren phdn mim A VL-Boost di ddnh gid tinh ky thugt cua dgng ca tdng dp, vcri cdc ty so tdng dp khdc Ket qud nghien cuu mo phong cho thdy, chuyin doi dgng ca xdng sang nhiin liiu_ khi, cong sudt vd mdmen cua dgng ca gidm khodng 20%, dnh hu&ng cua hiin tugng chiem cho cua nhiin lieu khi, tir ldm gidm lugng hon hgp ngp vdo dgng ca Tuy nhien, v&i viec tdng lugng moi chdt ngp m&i bdng mdy nen tang dp, tinh ndng ky thugt cua dgng ca dd dugc cdi thien ddng ke V&i ty so tdng dp 1,2 thi cong sudt cua dgng ca su dung nhien lieu sau tdng dp cdi thiin vd tri nhu tru&ng hap su dung nhien lieu xdng truyen thong Tu Ithoa: Khi thiin nhien; Khi hoa long; Tdng dp dgng ca ABSTRACT This paper presents a simulation study for determination pressure ratio in motorbike engine fueled with liquefied petroleum gas converted from currently used gasoline engine in Viet Nam In this study, a solutionfor improving the performance characteristics ofthe engine fueled with LPG is increasing the air and fuel mixture into cyclinderfor improvement of brake power by supercharging According to mixti^reformation mechanism of spark ignition engine and properties of fuels, a theory calculation of pressure ratio was conducted for maintane performance characteristic ofthe engine Simulation study is conducted by A VL Boost software to evaluate the performance characteristics ofthe engine with different pressure ratio values The results show that when the engine fueled with liquefied petroleum gas, the brake power decreases about 20% incomparison to that of gasoline because ofthe occupation of liquefied petroleum gas in intake manifold that make the reducement in mass of charged mixture into the engine However, the increasement of mass of charged mixture by supercharging, performance characteristics ofthe engine improve considerably By supercharging with pressure ratio up to 1.2, the brake power of engine fueled with LPG improves and mantane as fueled with conventional gasoline Keywords: Natural gas, liquefied petroleum gas, supercharging ISSN 0866 - 7056 TAP CHf CO KHf VlfiT NAM, Sd nam 2017 www.rnkhiviptnam.vn NGHIEN CU'U-TRAODOI GIOI THIEU CHUNG Ngdy nay, cung vdi su phdt tridn manh cua cdng nghiep la su gia tang nhanh chdng cua cac phucmg tidn giao thdng van tdi, cdc thidt bi ddng luc trang bi ddng co ddt (DCDT) Tir dd, nhu cdu sir dung nhidn li^u cang cang trd nen cdp thidt, ddc bidt la nhidn lieu hda thach truyen thdng xang vd ddu diesel Nhu cdu sir dung nhien lieu tang, gay nguy CO can kiet nhanh ngudn nhidn lieu truyen thdng Them nua, tieu thu ngudn nhien lieu hda thach truydn thdng se thdi mdi trudng mdt lupng Ion cac chat ddc hai Dieu ddn ddn nhiing tac ddng xdu ddn mdi trudng sinh thai, bien ddi hdu, trdi dat ndng len vd hien tupng bang tan d hai dia cue va dac biet anh hudng xau den siic khoe ngudi Viet Nam la nudc dang phat trien nen ciing khdng ndm ngoai quy ludt phat trien chung cua thd gidi Tinh trang thieu nhien lieu va d nhiem mdi trudfng thai ddng ca dang d muc bao ddng Do dd, van de dat la cdn nghidn cuu va sir dung cac loai nhien lieu thay the co mnrc dp phdt thai ddc hai thdp de mdt mat giam d nhiem mdi trudng Mat khac cd thd bu ddp mpt phdn nhu cdu su dung nhien lieu truyen thdng Cdc loai nhien lieu thay the dupc uu tien sir dung la cdc loai nhien lieu sach (phat thai ddc hai thap), trir lupng ldn, gia re va cd the sir dung dd dang tren ddng CO truyen thdng ma khdng can thay ddi nhidu ve ket cdu Cd the kd den mdt sd loai nhien lieu nhu hydro, ddu md hda long, thien nhien, sinh khdi Trong sd do, ddu md hda Idng LPG Id loai nhien lieu hda thach thdng dyng va thdn thidn vdi mdi trudtig vi LPG cd san pham chdy than thien vdi mdi trudtig va cd nang suat tda nhiet cao Nhien lieu LPG cd dac diem chay gdn tuong tu nhien lieu xang, cd kha nang hda trdn tdt voi khdng va cd tri sd Octane cao ban xang ndn rat thich Ipp ldm nhien lieu cho ddng co ddt danh lira cuong buc Do vdy, dac diem ket cdu chung cda ddng co LPG ddt chdy cuong biic hoan toan tuong tir ddng co xang vd chi khdc d he thdng cung cdp nhien lieu vd tao hdn hop Vdi viec cd sd lupng xe mdy ldn dang luu hanh, thl vide nghidn ciiu chuyen ddi ddng CO truyen thdng sang su dung LPG se cd y nghTa thuc tien cao Tuy nhidn, LPG dupc cung cap d dang nen chuyen ddi ddng CO xang sang sir dung LPG theo phuong phdp thdng dung cdp nhien lieu vao dudng nap, LPG se chiem chd cua khdng nap hon so vdi nhien lieu long nen cdng sudt ddng co giam Vi vdy, viec nghien ctiu co sd khoa hpc sir dung LPG tren ddng co xang hien hanh va cdc nhan td anh huong de tim bien phap ndng cao hieu qua su dung LPG de khac phuc mdt phdn su suy gidm cdng suat va cai thien tieu hao nhien lieu vd phat thdi cua ddng co chuyen sang su dung LPG la rat can thiet Khi nghien ciiu chuyen ddi ddng co xang sang sii diong nhidn lieu khi, Tahir vd cdng su [1] da chi rang, vdi phuang phap cap nhidn lieu vao dudng dng nap, cdng sudt ddng ca giam 18,5% so vai su dung xang d cimg che dp tai va tdc dp lupmg nap giam den 14,5% vi bi nhien lieu chiem chd Mdt ly khac nua cd the la tdc dp chdy ciia nhien lieu nhd ban so vdi xang [2] gdc danh lu'a som van giii nguyen Ichdng dupc dieu chinh cho phu hop vai nhidn lieu khi, lam giam chat lupng qua trinh chay Chinh vi vay, nghien ciiu chuyen ddi ddng ca xang sang sir dung nhien lieu khi, cac nha nghien ciiu da chi rang, dpng co chay nen dupc thiet ke tang ty sd nen cua ddng co va thay ddi gdc danh lua sdm theo hudng tang mpt chut so vdi ddng ca chay xang de tang hieu sudt, cdng sudt vd gidm sudt tieu hao nhien li^u Ngoai ra, dd tang cdng sudt cho ddng ca chuydn ddi sang sii dung nhien lieu khi, ta cd thd su ISSN 0866 - 7056 TAP CHf CO KHf VlfiT NAM, Sd nam 2017 www.eolihivietnam.vn NGHIEN C U ' U - T R A O D I dung phucmg phap tang luong nhien lieu nap vao frong xylanh d mdi chu trinh Bien phap Sli dung may tang dp cung da dupc dk cap den nghien ciiu cua tdc gia FathoUah Ommi vacong su [3], cua ddng co Kdt qua nghien ciiu cho thay, tang ap voi ty 1,2 giup tang dang ke he sd nap cua ddng ca, tii cdi thien tinh nang ky thudt cua ddng co sir dyng nhien lieu de thay the cho nhien lieu xang tmyen thdng Trong nghien ciiu ndy, nhdm tac gid tidn hanh tinh toan ddnh gia miic dp thay ddi cdng suat cua ddng co chuyen tit sir dung xang sang sir dung LPG theo phuong phdp cung cap nhidn Iidu vdo dudng nap Trdn ca sd cd the uoc luang sa bd miic dp tang ap cdn thidt de ddng co su dung LPG vdn cd the tri dupc cdng suat nhu su dung nhien lieu xang Qua trinh nghien ciiu md phdng dupc thyc hidn trdn phan mem AVL Boost vdi cac ty sd tang dp khac de tir dua dupc lua chpn phii hpp tri dupc tinh nang ky thuat NOI DUNG NGHIEN CUtJ 2.1 D6i tuong nghidn cihi Ddi tupng nghien la ddng co mdt xylanh sir dung he thdng nhien lieu phun xdng dien tu tren dudng nap Ddng ca dupc ldp tren xe mdy Honda SCR, la loai xe trang duoc sii dung khd phd bien hidn tai Viet Nam Mpt sd thdng sd ky thudt ca bdn cua ddng ca duac the hien Bang Bdng Cdc thong so ca bdn cua dpng ca- TT Thong s6 Loai dpng ca Dung tich Duong kinli xylanh Hanh trinh piston Ti so nen Cong suat toi da Momen xoan toi da He th6ng nhien lieu 2.2 Nghi&n cihi m6 phong fren phan mem AVL Boost 2.2.1 Xay ditng md hinh Gia trj/dffn vi Honda SCR 108 cm> 50 mm 55 mm 11:1 6,5 kW/7500 v/ph 9,1 Nm/5500 v/ph Phun xang dien tiir hieu chinh tir mo hinh nguyen ban bang each b6 sung them phan tu may nen co nhu tren Hinh 2.2 +-tH- Trong nghien ciiu nay, mo hinh mo phong dpng CO duac xay dimg tren phan mem AVL-Boost Mo hinh dpng co nguyen ban diroc xay dung dua tren co so dac di6m Icet cSu dgng co thuc ik, cac s6 lieu dac va cac tai lieu lien quan dSn dpng co nhu the hien tren Hinh 2.1 Mo hinh dong co tang ap thi dupc -+- *^ •X-H Hinh 2.1 Mo hinh dong ca nguyen bdn ISSN 0866-7056 TAP CHl CO K H J V £ T NAIM, S6 nam 2017 w w w r n k h i vi ptn » m _ V n NGHIEN CU'U-TRAODOI T iK.f ' T > ^ < " ^ r ^ ^ ' 2.2.3 Co s& ly thuyit xac dinh ^ so tang dp cho dpng ca Hinh 2.2 Mo hinh dpng ca co ldng dp Khi cung cdp nhien lieu LPG vao dudng n^ip thi lupng khdng nap se bi suy gidm anh hudng chiem chd cua nhien lieu Vd mat ly thuyet, gpi V^^ la the tich khdng nap trudng hpp ddng co su dung nhien lieu xang, vdi gid thiet ty le hda trdn khdng khi/nhien lieu dat gia tri ly thuyet X =1 hay: 2.2.2 Banh gid dg tin cay cua mo hinh Dp tin cdy cua md hinh nguyen ban dupc danh gid tren co sd so sanh giiia ket qud cdng sudt va md men giira md phdng vd thi nghiem nhu thd hidn tren Hinh 2.3 Ket qud cho thdy, dudng dac tinh cdng suat giiia md phdng va thi nghiem la kha tuong ddng Sai lech ldn nhdt Id khdng qua 5% Sai lech cd the mdt sd gia thiet cda qua trinh md phdng chua thuc su phu hpp vdi thi nghiem Tuy nhien, vdi sai sd nhd ban 5% da cd the dam bdo duoc dp tin cay ciia md hinh nguyen ban Tren co sd cd the sir dung md hinh ndy de tidn hdnh nghien ciiu md phdng su dung nhien lieu cirng nhu tang ap tren ddng co (I).-', ^ !Gx^ ^ = 14,7 (1) Khi ddng co lam viec vdi nhien lieu LPG, lupng khdng nap chiem the tich la V^^, p^ va lucmg nhien Iidu LPG chiem the tich kkLPG 14V,„ , dd ta cd: =1 , Q ^ " ^ ^ ' * = , (2) '^LPG P LPG (3) Trong do: p^^ va p^^p^ la khdi luong rieng cua khdng va LPG duac tinh theo dieu kien dp sudt va nhiet dp dudng nap Vai gid thiet p - , a t = 9xlO*Pafhayp =0,9x760 = 684 mmHg) va nhiet dp dudng nap t =20°C (293K) He sd (A/F)LPG = VomC^^.{M^) C^B.^ + %mC,H,^.(A/F)C^H„ Khoi luong rieng cua khdng d dieu kien dp sudt nhiet tren dudng nap dupc xdc dinh theo cdng thuc: U39.;7^ P,± = (l + 0,0036r^)Po -l,026itg/m' (4) Toed? (v/ph) Hinh 2.3 So sdnh cong sudt vd mo men giira mo phdng vd thinghiem Xac dinh mdt each gan dung p^p^, theo cdng thlic: ISSN 0866 - 7056 TAP CHi CO KHi VIET NAM, Sd nam 2017 www.coldiivietnam.vn NGHIEN CLTU-TRAO D C I ,PjdMiP nhieu hon = 0,56kg/m' (5) Theo cdng thiic tinh cdng sudt cd ich cua ddng CO [4]: Trong do: Mj^ •29, la khdi lupng mol cua khdng va M =51 la khdi lupng mol Clia LPG (d day coi M^p^ = {M„„,+ M ^ , , , / ) MQ Ket hpp cdc cdng thiic hi ddn thu dupc V, ~ ' Dieu cho thay, ve mat ly thuyet Sli dyng LPG thi lupng khdng nap gidm khoang 10% so vdi trudng hpp su dyng nhien lieu xang De danh gia miic dp thay ddi cdng sudt ciia ddng co su dung nhien lieu LPG, dya vao tdng nang lupng cung cdp cho ddng co Nang luang cung cdp cho ddng ca su dung nhien lieu xang: E^ =m^.LHV^ ^-^LHV^ (6) Nang lupng cung cdp cho ddng ca stt dyng nhien lieu LPG: ^LPG -~ miPT.^HVjp^^ ^LPC '"LPC -^ - 1•HVJJ,^ (7) 30r a Cho thdy cdng suat cd ich cua ddng co (Ne) ti le thudn vdi he sd nap (q^) va khdi lupng rieng cua nap mdi (P|) Theo cac nghien ciiu, sir dung nhien lieu LPG thay the Uen dpng CO xang, cdng sudt se giam khoang 15% Vi vay, dp suat mooi chdt nap mai ciing cdn tang them 15% de bu dap phan cdng sudt bi gidm Ci ddy, cd the coi mdt sd thdng sd nhu V|_,Ti^,Ti^,Q^, n, T, a, I va ri^la hdng sd tang dp hoac khdng tang dp vi cdc thdng sd ndy thay ddi rat it so vdi su thay ddi cua dp sudt mdi chat nap mdi, dd cdng sudt ciia ddng co phu thudc vdo su thay ddi cua khdi luang rieng nap mdi nhu the hien d phuong trinh 8: In "KM _ 2ih - "" = 1 /*rA "LPG (8) Trong do: N.^^ va N^^.^^ Id cdng sudt ddng CO LPG tang ap va khdng tang dp Cdn tang dp cho mdi chdt nap mdi de cdng suat ddng ca LPG tang dp bdng vdi cdng sudt ddng CO su dung xang (N^) Tuhaic6ngtfauc6va7thudugc:-^a0,85 (LVH^ = 44,000 kJ/kg va LVHLPG = (LVH„, „ + LVH^„ )/2=46,000 kJ/kg) Nhu vay, t6ng nang lugfng cung cip vao dong CO sir dung nhien lieu LPG giam khoang 15% so voi tnrcmg hop su dung nhien lieu xang Ngoai ra, neu dong co su dung LPG khong hieu chinh thong sd lam viec nhu goc danh liia som thi cong suit dSu co thS giam Tren ca sd do, ty sd tang dp dupc xac dinh theo phuang trinh 9: =?T„= • = (1,17^=1,24(9) Nhu vdy, de ddm bdo cdng suat ciia dpng CO su dyng LPG tri nhu ddi vdi trudng hap sir dung nhien lieu xang thi ty sd tang dp cua dpng co cdn dat khodng 1,24 ^ ISSN 0866 - 7056 TAP CHi CO KHl VIET NAM, Sd nam 2017 NGHIEN CU'U-TRAODG chpn ty so tang dp tren ddng co xe may su dyng nhien lieu hoan cai tir ddng ca xdng truyen thdng da dupc thuc hien, cac kdt qud chinh dupc tdm tdt nhu sau: —p-LFG-tait ip e I" -|» 10 :i ^ = - Khi sir dung nhien lieu dang LPG theo phuong phdp cung cdp nhien lieu vao dudng nap, tinh nang ky thudt cua ddng CO giam khoang 20% De ddm bao tinh nang ky thuat cua dpng ca sir dung LPG tuan^ duong vdi xdng thi cdn tang ap sudt mdi chat nap mdi vdi ty so 1,24 ^ l^ l''0 «0 450 Goc qiiay true kliii>ii (dQ) Hmh 3.3 So sdnh dp sudt xylanh cua dongcd d 7500v/ph sd dung nhien lieu xang va LPG Theo ket qua rad phdng dien bidn ap suat xylanh tai ty sd tang dp 1,2 nhu thd hien tren Hinh 3.3, dp sudt xylanh ddi vdi nhien heu xang la cao nhdt, tiep theo ddn tnrdng hpp sii dung nhien lieu LPG c6 tang ap va cudi cimg la sir dyng nhien lieu LPG khdng tang dp Ddi vdi trudng hop sir dung LPG, lupng nap vao xylanh bi giam vi hien tupng chiem chd ciia nhien lieu vdi khdng nap, vi vay ap sudt cd hai frudng hpp diing nhien lieu LPG deu giam di so vdi dung nhien lieu xang Ngoai ra, cdn cd the xet den dnh hudng cita ty sd nen va gdc danh lua chua duac thay ddi phu hop vdi nhien lieu LPG nen dp sudt xylanh ciing gidm so vdi dung nhien lieu xang Sau sir dung may nen tang dp, dp sudt xylanh da tang len rd ret so vdi trudng hpp khdng dung tang dp va dat khodng 90% so vdi dp sudt SIX dung nhien lieu xdng iVlay nen tang dp cling lam tang ap suat qua trinh nap nhien lieu Ket qua tren Hmh 3.3 cho thdy toan bd qua hinh nap, ap sudt xylanh da dupc tang len so vdi hai trudng hpp sir dyng nhien lieu xang va sir dyng LPG khdng cd tang dp Ty sd tang dp trung binh todn bd qua trinh nap la 1,23 - Theo ket qud md phdng tren phdn mem AVL Boost, thuc hien tang ap tdi ty sd tang dp 1,3 thi he sd nap cua dpng co cai thien 22,6% so vdi trudng hgp khdng tang dp vd 11,7% so vdi tnidng hpp sir dung nhien lieu xang truyen thdng LM cam on: Nhdm nghien ciiu chdn cam an Phdng Thi nghiem Ddng co Ddt trong, Vien Co Ddng luc, Trudng Dai hpc Bdch khoa Ha Npi da tao dieu kien thyc hien nghien ciiu nay.*;* Ngaynhanbai: 08/6/2017 Ngay phan bien: 18/6/2017 Tai lieu tham khao: KET LUAN [4] Nghien ciiu thih todn ly thuyet lua Musthafah Mohd, Tahir, et.al, (2015), Performance analysis of a spark ignition engine using compressed natural gas (CNG) as fiiel, Energy procedia 68, pp, 355-362 Varde K.S, Asar GM.M, (2001), Bum rates in natural-gas-ftieled single cylinder spark ignition engine, SAE Paper 2001-28-0023 FathoUah OMMI, Ehsan MOVAHEDNEJAD, Kouros NEKOFAR, (2013), Comparing performance characteristics of a gasonlme and CNG engines and increasmg volume efficiency and power using designed turbocharger comparing, ACTA Technica Corviniensis — Bulletin of Engineering, Tome VI (2013) Fascicule (April -June), ISSN 2067-3809 Vo NghTa, Le Anh Tuan; Tang dp dong ca dot trong, NXB Khoa hoc va Ky thuat, 2005 ISSN 0866 - 7056 TAP CHi CO KHI VIET NAM, Sd nam 2017 ... sir dung he thdng nhien lieu phun xdng dien tu tren dudng nap Ddng ca dupc ldp tren xe mdy Honda SCR, la loai xe trang duoc sii dung khd phd bien hidn tai Viet Nam Mpt sd thdng sd ky thudt ca bdn... tir ddng co xang vd chi khdc d he thdng cung cdp nhien lieu vd tao hdn hop Vdi viec cd sd lupng xe mdy ldn dang luu hanh, thl vide nghidn ciiu chuyen ddi ddng CO truyen thdng sang su dung LPG... 2017 www.cokhivietnam.vn NGHIEN cuu-TRAO DCI ^ —p-ianc —i^IJ>G chpn ty so tang dp tren ddng co xe may su dyng nhien lieu hoan cai tir ddng ca xdng truyen thdng da dupc thuc hien, cac kdt qud