JSIR 62(1-2) 20-24
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Journal of Scientilic & In du stri al Resea rch Vo l. 62, Janu ary-February 2003, pp 20-24 Application of CNG in Transportation Sector - A Review of the Current Status of Technology and Future Projections B B Ghos h"', P K Bose, Ranajit Kumar Chakrabarti and Ka ly an Kumar Das Depa rt me nt o f Mecha ni ca l Enginee rin g, Jadavpur Universi ty, Kolkata 700032, Indi a The rap id depletion of petrol eum fu el, and ever ri sin g costs have for ced engin ee rs to sea rch for a lt e rn ative fuels for th e use in IC engin es, With an abundant supply and cleaner ex haust, CNG has great potential as a subst itute of petrolt:u m fu els. CNG can also play vit al ro le in re li ev in g th e fu el crisis worldover as a future source of energy a,; we ll as clea ner fuel. Full replacement of petrol in J::e trol engin e with CNG is not a problem but in th e case of di esel engine it gives various problems in operat ion and hen ce ex tens ive research wo rk is necessary in this lield for full rep lace me nt of di esel with CNG. Ir. thi s paper, SOl lle resea rch wo rk on th e use of CNG in C I a nd S I engin es at nati o nal and int ern at ional scenarios have been reported. Introduction GlobJI petroleum depos its w ill get de pl eted with in th e nex t 100 a nd research on a lt ernati ve fu el powered car is on, in earnest. Experts have been predi cting th e use of alte rn ative fu el for ve hi c les for decades. With detori orating o il polluti on and ri s in g o il prices, it is natural th at th ere wou ld be fo cused th inking on producing cheap environme nt al-friend ly a lt ernati ve fuel. There are pl e nt y of a lt ernative sourccs of energy to foss il fuels. Hydrogen, comp ressed natural gas (CNG), alcoho l, bi ogas, producer gas, liq ue fied petro leu m gas (LPG) a nd a host of vegetable o ils are being tri ed allove r the wo rl d as substitutes to conventi o nal pet r01 e um based The biogas and producer gas are low energy conte nt per uni t mass. Moreover, storage problem is th ere wit h these fuels. Alco hol ha s poor energy contcnt per u nit mas s. These fue ls ha ve also low cetane numbers. As alcohol fuels do not re ad il y combust in C I eng in es, thi s limits th e s ub stitutes fo r hi gh compress ion ignttt on eng in es l . Th e ma ll1 co nstraint of us in g vegeta bl e o il s as fu el is th e ir hi gh cost. CNG occupies a ve ry promine nt place, primaril y because of its tec hn o economtc evaluation c ha ra cte ri sti cs and environme nt al benefits (Table I). The use of CNG as an eng in e fu el, fortun ately, does not ca ll for radi cal changes in eng in e design. ;, Emeritus Prof es sor. AICT E, Jad avp ur University, Ko lk ata, and In di , 1Il Insti tu te ofTechnoiogy, Kharagpur, In dia The prope rti es of natural gas, whi ch make it a be tt er a lt ernative fu el for IC engines are; (i) Because of it s gaseous state it de fus es rap id ly in air fu el mixing at lower inl et te mp erature than is po ss ibl e with eith r gasoline or di ese l. This leads to ea si er starting, more rel iable idlin g, smoo th er acceleration and more complete and e ffi c ie nt burning with les s unburned hydrocarbons prese nt In th e exhaust. (ii) The hi gher ig niti on temperature of gas compared with petroleum based fuels leads to reduced au to igniti on de lay. Due to t hi s higher ignition temperature, C NG is less haza rd ous than any petroleum based fu e ls . ( ii i) T he hi gher octane rating of 120 for natural g as ( NG ) compared with 87 for gaso line allows a hi gher compression ratio (CR) or 15:6: I a nd , co ns equentl y, mo re e ffici e nt fu el consumption . Du e to it s higher CR, CI eng in es can also use CNG a fu e l. But s in ce cetane rati ng of CNG is poor it ca nn ot replace diesel totally like gaso lin e. (iv) Maintenance costs for gas are lower th an that of gasoline or di esel eng in es, because gaseo us fue ls burn c lea n without ca rb on depos it s. Furthermore, in gas eng in es th e fuel
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Transcript of JSIR 62(1-2) 20-24
Journal of Scientilic&Industri al Research Vol.62, January-February 2003,pp20-24 Application of CNG in Transportation Sector - AReview of theCurrent Status of Technology and Future Projections BB Ghos h"',PK Bose,RanajitKumar ChakrabartiandKalyanKumarDas Department of Mechani cal Engineering,JadavpurUniversi ty, Kolkata700032,Indi a The rapiddepletionof petrol eumfuel, andeverri sing costshaveforced engineers tosearchfor alt ernativefuelsfor the useinICengines,Withan abundantsupply andcleaner exhaust, CNGhasgreatpotential asasubst itut eof petrolt:um fu els. CNGcan alsoplayvit alroleinreli evingthefuelcrisisworldover asafuturesourceof energya,;wellascleanerfuel.Full replacementof petrolinJ::etrolenginewithCNGis nota probl em butinthe case of di esel engine itgivesvariousproblems in operat ionandhenceextens iveresearch workis necessaryinthi slieldforfullreplacementof di esel withCNG.Ir. thi spaper, SOllleresearch work on the useof CNGinCI andSI enginesatnati onalandint ernat ional scenarioshavebeenreport ed. Introduction GlobJIpetrol eumdepos itswillgetdepleted withinthenext100andresearchonalternati vefuel poweredcarison,inearnest.Expertshavebeen predi ctingtheuseof alternativefuelforvehi clesfor decades.Withdetori oratingoilpolluti onandri sing oilprices,itisnaturalthattherewou ldbefocused th inkingonproducingcheapenvironmental-friendly alternati vefuel.Therearepl entyofalternative sourccsofenergytofoss ilfuels.Hydrogen, compressednaturalgas(CNG),alcohol,bi ogas, producergas,liquefiedpetroleumgas(LPG)anda hostofvegetableoilsarebeingtri edalloverthe worl dassubstitutestoconventi onalpet r01eumbased r u c \ ~ Thebiogasandproducergasarelowenergy contentperuni tmass.Moreover,storageprobl emis therewit hthesefuels.Alcoholhaspoorenergy contcntperunitmass.Thesefuelshavealsolow cetanenumbers.Asalcoholfuelsdonotread il y combustinCI engines,thi slimitsthesubstitutesfor hi ghcompress ionignttt onenginesl.Themall1 constraintof usingvegetabl eoil sasfuel istheirhi gh cost.CNG occupi esavery prominentplace,primaril y becauseofitstechnoeconomtcevaluation characteri sti csandenvironmentalbenefits(Tabl eI). Theuseof CNGasanenginefuel,fortunately, doesnotca llforradi calchangesinenginedes ign. ;,EmeritusProfessor.AICTE,JadavpurUniversity, Kolkata,and Indi ,1IlInsti tuteofTechnoiogy,Kharagpur, India Theproperti esof naturalgas,whi chmakeitabetter alternativefuel forIC enginesare; (i)Because of its gaseous stateitdefusesrapidly inairfuelmixingatlowerinl ettemperature thanisposs ibl ewitheithrgasolineor di esel.Thisleadstoeasi erstarting,more rel iableidling,smootheraccelerati onand more complete andeffi cientburning withless unburnedhydrocarbonspresentInthe exhaust. (ii)Thehi gherigniti ontemperatureofgas comparedwithpetrol eumbasedfuelsleadsto reducedautoigniti ondelay.Duetothi s higherignitiontemperature,CNGisless hazardous than anypetroleumbasedfuels . (ii i)Thehi gheroctaneratingof120fornatural gas(NG)comparedwith87forgasoline allowsahi ghercompressi onrati o(CR)or 15:6: Iand,consequentl y,moreeffici entfuel consumption.DuetoitshigherCR,CI enginescan alsouse CNGa ~ afuel.Butsince cetanerati ngofCNGispooritcannot replace diesel totallylike gasoline. (iv)Maintenancecostsfor gas arelower thanthat ofgasolineordi eselengines,because gaseousfue lsburncleanwithoutcarbon depos its.Furthermore,ingasenginesthefuel j , GHOSH elal.:APPLI CATION OF CNGIN TRANSPORTATION SECTOR21 Tabl e1- Physico - chemi calproperti esof CNG andgasoline Properties Compositi on 2Stoichi ometri cAJFrati o 3Lower calorifi c value MJ/ kg 4I gniti on temperature )Ouane no. 6Adiabati cIl ame temperature 7Minimum energyrequiredfor ignition g Volumetri c efficiency
