Jsir 62(1-2) 20-24.pdf

Journal of Scientilic & Industri al Research 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 Kalyan Kumar Das Department o f Mechani cal Engineering, Jadavpur Universi ty, Kolkata 700032, Indi a The rap id depletion of petrol eum fu el, and ever ri sing costs have forced engineers to search for altern ative fuels for the use in IC engines, With an abund ant sup ply 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 reli eving the fu el crisis worldover as a future source o f energy a,; well as cleaner fuel. Full replacement of petrol in J::etrol engine with CNG is not a problem but in the case of diesel engine it gives various prob lems in operat ion and hence ex tens ive research wo rk is necessary in this lield for full replace ment of di esel with CNG. Ir. thi s paper, SOllle resea rch wo rk on the use of CNG in C I and S I engines at national and intern at ional scenarios have been reported.

Introduction

GlobJI petrol eum depos its will get depleted with in th e nex t 100 and resea rch on alternati ve fu el powered car is on, in earnest. Experts have been predi cting th e use of altern ative fu el for ve hi c les for decades. With detori oratin g o il polluti on and ri sing oil prices , it is natural th at there wou ld be fo cused th inking on producing chea p environmental-friend ly alternati ve fuel. There are plenty of alternative sourccs of energy to foss il fuels. Hydrogen, comp ressed natural gas (CNG), alcoho l, bi ogas, produce r gas, liq ue fied petro leu m gas (LPG) and a host of vegetable oils are being tri ed allove r the wo rl d as substitutes to conventi onal pet r01 eum based ru c \ ~ . T he biogas and prod ucer gas are low energy conte nt pe r uni t mass. Mo reover, storage probl em is th ere wit h these fuels. Alco hol has poo r energy co ntcnt pe r unit mass. T hese fuels ha ve also low cetane numbe rs. As alco ho l fue ls do not read il y co mbust in C I engines, thi s limits th e sub stitutes fo r l hi gh co mpress ion ignttt on engines . The mall1 co nstraint of using vegeta ble oil s as fu el is th eir hi gh cost. CNG occupi es a very prominent place, primaril y because of its tec hn o economtc evaluation characteri sti cs and environmental benefits (Table I). The use of CNG as an engine fu el, fortun ately, does not ca ll for radi ca l changes in engine des ign. ;, Emeritus Professor. AICTE, Jadavp ur University, Ko lk ata, and Indi ,1Il Insti tu te ofTechnoiogy, Kharagpur, India

The properti es of natural gas, whi ch make it a better alternative fu el for IC engines are; (i)

Because of its gaseous state it defus es rap id ly in air fu el mixin g at lower inl et temperature than is poss ible with eith r gasoline or di esel. This leads to easi er startin g, more rel iable idling, smooth er accelerati on and more co mplete and e ffi c ient burning with less unburn ed hydrocarbons prese nt In th e exhaust.

(ii)

The hi gher igniti on tempera ture of gas compared with petrol eum based fuels leads to reduced au to igniti on de lay. Due to thi s higher ignition temperature, C NG is less haza rd ous than any petroleum based fu e ls .

(ii i) T he hi gher oc tan e rating of 120 for natural gas (NG ) co mpared with 87 for gaso line allows a hi gher co mpressi on rati o (C R) or 15:6: I and , consequentl y, more effici ent fu el co nsumption . Due to its higher CR, C I engines can also use CNG a ~ a fu el. But since cetan e rati ng of CNG is poo r it ca nn ot replace diese l totally like gaso line. (iv) Maintenance costs for gas are lower th an that of gasoline or di esel engines, beca use gaseous fue ls burn c lea n without ca rbon depos its. Furthermore, in gas engines the fuel

21

GHOSH el al.: APPLI C ATION OF CNG IN TRAN SPORTATION SECTOR

T able 1- Physico - chemica l properti es of C NG and gasoline NG

Properties

M eth ane 82.2 per ce nt Eth ane 6. 1 Propane 2.4 Isobutane 1.0 N-but ane, Isopcn tane 0.4 Nitrogen 7.7 Carbondi oxide and oxygen 0.2

Co mposition

2

j,

Stoic hi ometri c AJF rati o

3

Lo we r calorifi c va lue MJ / kg

4

Ign iti on temperature

Gasolinc

17

14. 6

44.24

43

649-72I"C

n i 'c

120

87

)

Ouan e no.

6

Adiabati c Il ame temperature

2 148 K

2470 K

7

Minimum energ y required for ignition

0.29 MJ

0.24 MJ

g

Volumetri c efficienc y

Le s ~

M ore

<)

H UCR

12.2

s .)

10

Storage and handling

Dirtl cull

Ea~ i c r

II

Availabi lit y

Ab und anl

Limil cd

12

Rcnc wabilil y

(v)

Rcnewab le and can be ob tain ed from ~e lVage and biomas s. shale oil and olher sou rce

N OI

rcnewahle

does not mix up with th e lubri ca nt s to dilute it or red uce its viscos it y so that lubrica nt co nsumpti on is lower in gas engine than th at in gasolin e/di ese l engines.

elect roni c control ,' .-l The cho ice betwee n mec han ical and electroni c kit would depend up on th e cost of kit , ease of conversi on, ease of maintenance and type of appli cati on.

Opt imi sed natural gas ve hic les are expected to produce mu ch less carbon monox ide nearzero reac ti vit y of meth ane, natural gas vehicl es may cause less ozone form ati on tha n gaso line/d iese l ve hi cles.

Ex perimental in vesti gati ons, re latin g to th e utilisation of CNG in on automotive passe nge r ca r were ca rri ed out by Nagraj et (l1'- In vesti gati ons "vere carri ed out for: (a) Gaso line ope ration , b) CNG with a standard kit , (c) CNG with th e kit tu ned fo r max imum power, (d) CNG with the kit tu ned for lower e mi ss ions. The studi es indi cated that th e performance of the CNG kit with standard se tting was fo und to be lowe r than gasolin e operation . It was observed th at if this kit was tun ed furth er, improve ment in bra ke powe r co uld be achi eved. Und er these co nditi ons th e BSEC and e missi ons were noticed to be lower than gaso line ve rsi on.

Review of Current Status of Technology CO // l'eJ's i o // Kifs 2 The natural gas retrofit kits bas ica ll y co nsist of: (i) On board storage tank, (ii ) ri lling val ve, (iii ) Press ure regulator, (iv) Pressure gauge, (v) Load and speed dependent regul ators , (vi) Gas air mi xer, (vii ) Shut off and Co nt ro l va lves, (viii ) Low and hi gh pressure tubing and fittin gs. Most kits arc mechani ca l in operati on and are designed typ ica ll y for use as a 'Seco nd-fuel System' . Kit s with electro ni c control, based on engine pe rformance map systems have also bee n developed. Kits and engine deve lopments are also under way whi ch ca n tak e ca re of va riati ons in gas co mp os iti ons and maintain engine performan ce c lose to gaso line or di ese l through

Ex pe rime nts were carri ed out by Das and Redd /' in the Engines and Unco nve ntion al Fuels Laboratory at liT, De lhi in de velopin g a CNG fuell ed spark Igniti on Engine . Res ults of th e work have shown th at maximum le vel of ca rbon monoxid e NO, e miss ion emissi ons was 0.325 pe r cent, co ncentrati ons ac hi eve th e peak valu e around anequi va lence rat io of 1.1 , whereas if it reduces th e

22

J SCII NDRES VOL61 JANUARY -FEBRUARY 2003

leaner and ri c he r mi xtures. Res ults of the work showed an improve me nt in the pe rfo rmance and e mi ss io n c harac te ri sti cs of the CNG fue ll ed e ngine, usin g a spec ia lly des igned Electro M ec hani ca l Fuel (EMF ,) sys te m. F le min g and Allsup7 ha ve carri ed out study of natural gas as low-po llution automotive fuel us ing a s in g le cy linde r, a multi cy linde r engine and six ve hi c les. Res ults showed that the light-l oad lean-limit mi sfire region o f natura l gas begins at an a ir fu e l ratio be tween 140-150 per cent of sto ic hiometri c. Changes in igniti on timin g, significantly influe nced e mi ss ion of nit rogen ox ides and hydroca rbon s but had littl e effect on CO e mi ss ion. Lowe r e mi ss io ns ca n be ac hi eved (by adju stment) with current des ign engines, but w ith heavy pe na lty to e ngine perfo rma nce. Emi ss io ns from vehi c les fu e led w ith natura l gas are virtuall y unaffec ted between 20-100°F. Natura l gas ex hau st is estimated to be 22 pe r cent-2S pe r cent as reacti ve as gaso lin e ex haust. x

Paul et at. have condu cted ex pe rime nt s on a co mmerc ia l, four stroke, s ix-cy linde rs water-coo led , direct inj ection Tata di ese l engine usin g thi s du e l fu e l. The maximum pe rcentage re pl aceme nt of diese l with CNG has been fo und to be 69.4 pe r cent at an optimum speed of 1900 rpm. The bra ke th e rmal e ffi c ie ncy of thi s eng ine when run with dual fu e l is comparabl y at differe nt speeds a nd load s w ith that if the eng ine when run with di ese l o nly . Das and Ghosh C) made co mpa rati ve studi es of gaso lin e a nd CNG as fuel for spark ignition e ngine. In thi s paper, different pe rformance pa ra mete rs, suc h as effic iency, spec ifi c fuel consumption. The presence of CO and NO, in th e exhau st of SI e ngine run wit.h CNG as fuel have been measured and plotted as a function of air index at differe nt runnin g conditi ons. Th e CNG fu e led engine showed improved effi c ie ncy by 3-5 pe r cent dependin g on the compress ion ratio and a ir index, e mit s less CO but 51ightl y high e r amount of NO,. Das and Ghosh' o have carried out ex pe riments o n the di ese l version of Richard s va riable Co mme rc ia l e ngine and a commercial Tata di ese l e ngine to study the pe rfo rmance and e mi ss ion c haracte ri stic s, pe rce ntage redu c tion o f di ese l with CNG. It was o bserved th at the dual fuel operation produced less a mount of nitroge n oxides durin g AlF o perati o n but slightly more CO than diese l fuel ope rati o n.

At present, in India th e c iti es lik e Delhi , Mumbai , Vadodara and Surat vehicl es are o perat in g on CNG in a large sca le. M o re than 30,000 vehi c les are runnin g o n CNG in New Delhi a nd ! 0,000 buses would be conve rted to CNG by Oc to be r e nd . Most ene rgy ex pe rts agree th at it is not on l/ CNG but severa l other steps like phasin g out of o ld vehicles a nd reducing sulphur content in th e fuel ca n contribute to reducin g a ir polluti o n. A comb inati o n of CNG with other a lte rn ative fuels could a lso be used to redu ce air po lluti o n. On th e g lobal scene, CNG is po pula r in poc kets and th at too o nl y where e ithe r the government or the judiciary have push ed it. From th e hea lth and safety point of view , C NG is as good as , o r even be tte r than petro l and oth er alternative fuels. C hi cago has about 30 pe r ce nt of its publi c tran spo rt be in g o pe rated o n CNG and it is as low as 5 pe rcent in New York , and 2 pe r cent in Pari s. In case of the Middle East countries, they prefer to flare up the gas in stead of c han g in g the ir entire fleet to CNG . The fu e l is li g hte r th an air hence in the event of a lea k, it will ri se and di spe rse in the atmosphere and ne ithe r form puddl es (as in th e case of petrol ) nor w ill it spread (as in LPG). The igniti on te mperature of natural gas is muc h hi g he r than pe tro l, ma kin g il more difficult to ig nite.

Future Projections CNG is go ing to playa vital rol e in re li ev ing the fu e l c ri sis worldove r as a future source o f e ne rgy as we ll as a cleaner fu e l. India has ta ke n up the c hall e nge and conve rtin g most of its ve hic les to run on CNG. In Indi a, two-wh ee le rs are popul a r because of its low cost ope ration inc luding suppl y of fu e l. Many manufacture rs are in the process of converting ex istin g petro l and di ese l ope rated two-whee lers petrol and di esel to CNG operation . The full replacement of petrol in a pe tro l engine w ith CNG is not a probl e m but full repl acement of d iese l in a di ese l e ngine possess a lot of problems because of the low cetane number of di ese l. A s per Indian context, auto mobil e manufacturers are loo kin g forward fo r the complete rep laceme nt of diese l with CNG, demanding an extens ive research work in the use of CNG in the di ese l e ng ine.

GHOSH et al.: APPLICATION OF CNG IN TR AN SPORTATION SECTOR

Prof. Re ne at th e University o f Auc land , New Zeland. Prof. Bill at th e University of Allabama, USA Prof. L.M . Das at lIT De lhi , India . Prof. B.B . Gho sh at lIT Kharag pur, Indi a Prof. H.B . M athur at lIT De lhi , Indi a Prof. Probir Kr. Bose, at Jadavpur Univers ity, Jadavpur, India .

Conclusions Going throug h the researc h work carried out by researc hers at national and inte rnational leve l the following fac ts have corne to li g ht : (i)

The ex istin g SI e ng ines can be ope rated with 100 pe r cent substitution o f CNG in place of petro l.

(ii )

It is diffi cult to ope rate the CI e ng ines with the substituti o n of 100 per cent CNG in place of di ese l. Howeve r, hi ghe r percentage of substitution of CNG is poss ibl e at the o pe rati o n of hi g h loads.

(iii ) Th e C I e ng in es ca n be completely operated with C NG by co nve rtin g th e CI e ngin es to SI e ng in es, th o ug h it is no t eco no mi ca l. (iv) Th e na tural gas fro m th e source ca n be ava ilabl e in three forms suc h as Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG ), Liqu e fi ed Pe trol e um Gas (LPG ), out of th ese CNG appears to be econo mi ca l because of the following reaso ns: (a) Th e conve rs io n of NG to CNG need s a co mpressor.

(v ii ) ]t has been rea lised that CNG is a c lean fuel in compari son to petrol and di ese l as pe r th e e ngine ex haust e mi ss ion. (v iii) On th e whole on the bas is eng in e pe rfo rman ce and e mi ss ion s, in future the dedi cated CNG eng ines have to be des ig ned and manufactured . (ix) It is th e pro pe r time to go in for ded icated CNG e ng in es which can be o pe rated at hi g he r compression rati o in order of 14 to have very good e ng in e effi c ie ncy.

ex) As pe r th e safety po int of vie w th e operatio n o n CNG e ngines is mo re safe r bec ause of it s hi gh ig nition te mpe rature as co mpared to petro l a nd diese l. References DcLuchi A M. John ston R A & Spcrlin g D. M ethanol 1'.1' natllml gas I'echiclesn: a cOlllllarison. SAE Pape r No.

(b) Th e co nvers io n of NG to LNG needs cryogenic set up to maintain the NG at 40 DC which is un econo mi ca l. (c) LPG is th e byprodu c t o f c rude petrol eum. Durin g the process in g o f c rud e petro leum it becomes ex pens ive a nd ava il ab ilit y is als o limited. (v)

The co nvers io n of e xistin g S I and C I e ng ines needs kits th e manufacture o f w hi c h has been ve ry popular all over the world. It appears throu g h the Iite rature survey that th e devel o pment of kit s has a w ide sco pe re lated to th e pro pe r des ign and fa bri ca ti o n. As pe r the diffe re nt SI and C I eng in es ha vin g diffe re nt ho rse powers (hp ) th e ca reful des ig n and fabrication of C G kit s require prope r thou g ht. Thus th e des ign and fabri ca ti o n of CNG kits for diffe re nt capacity e ng ll1 es has bee n a c hall eng in g globa l issu e.

(v i) On th e basis of works carried out by Prof. Karim at Unive rsity of Calgary Ca nada . Prof. Evan at th e Uni vers it y of Colombia, Canad a.

23

88 1656. 198 8. 2

Singhal S, Sharma J & Ga ndhi K K. Strat cgy 1'01' use o r natural gas as a transport ation ru cl in In dia, PmI' TI \'e/jih Nllt Conj'l C t:ng COII/bllst liP. D eh radlln , 1<)<)2.

3

Kimb ara Y. Kat sum ata S. Iehimi ya T, Kan M & Kondo S Dcvclopment o r toyo to clectroni ca ll y co nt rollcd comp rcsscd natural gas vc hi clc. Con/, Pall Gaseons FilI' I Tran .I·I }()r!. 0 I August 1<)86, Va nco uvcr B C, Ca nada .

4

Su lli van 0 P J & Gctt cl L E, Elcctroni c du al-rucl diesel ('ontrol sys tc ms, Con/, Pal l Gas F llel s TraIlSI }(} I'/. 0 I Augu st 86, Vancou ver B C, Ca nada .

:)

Naga raj A Ramcsh. D S Kh atri & Gajcndra Bahu M K. Ascss mcnt o r thc pcr l
6

Das L M & Rcdd y Y V. Ex haus t cmi ss ion characteristics oj' a CNG-ruell cd cnginc. Proc Sixteenth Nut CrJllt' I C EI/ g

Un i vers itr . 2000.

Combllst . .fadm'lmr Unil 'ersitr , 2000 .

7

Flcming R D & All sup J R. Ellliss i on characteristics o/' I/at l/ ral gas as i n a ll/ol/ lOt i )'/' .fi{('I , SAE papcr No. 7 108JJ m 1<)7 1.

8

Paul G. Majumdar S & Ghosh B B. Use rl colllllr e.I'serl natllral gas il/ COIII/II('1'ci a l cO/llpression ignitiol/ (' I/g il/ e. Vol 73 , Thc Instituti on o r Enginee rs (India ), Seplcmhcr 1992.

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J SCIIND RES VOL 61 JANUARY-FEBR UARY 2003

Das R K & Ghosh F3 S, COIIII,arali ve sllldies ()fgaso line and cOIIII,re.l·sed natllral gas as .lile! for spark ignilion engines , Vol. 75 , Th e Instituti on or engineers (Indi a), November

10

Das R K & Ghosh B B, SOlli e Sl lIdies on Ih e {'({se (lj' CNG in research and cOllllllercial diesel engines, Vol. 76, Th e In stitution of Engineers (India), November 1995.

1994,

A./ier being gradllated \\'ilh honollrs ill Mechanical Engineering .frolll GlasgoII' Universily in 1904, Prof 8 8 Ghosh j oilled Vickers E'ngin eering Ltd, England .for IIVO r ears 10 ha ve sOllie indllslrial e.r/'t'rimce. He also receil'('(l ARCST (Associale Melllher of Royal College of Science & Technology) Hons in Mechan ico l Engineering fm lll Slralhvcirde Universilv in 1964. He j oined Mechanical Engineerin g Deparllllenl o.f I I T. Khamglillr, India. He cOlllpleled his PhD and sen'ed I I T. Kharagpllr for 33 vears in leaching and research in Ih(' area o.f I C Eng ines. He gllided 60 B Tech, 40 M Tech and seven PhD Ih esis re!aled 10 I C Engines. He IJllblislll'd 60 nalional and Inlemalirmalpllhlicalionsandisa.fello\\.lII elllber oj. Inslillll eo.fEngineers (lndia). Lij.e lll elllher oj COlllhllslion /nslillll e, Inlemalional, Melllher(ASMC),Melllber(SAE). He hasll'onvariolls nalional and inlemalional{lll.ards.AII.res£.nl he is working as Vice-chair ( Malhs and Science ) in ElIslem SAE Seclion, India. I ({In lI'orking as {lfl l:'J}/erililS proj'essor (A ll India CO lln cil For Technical Edllcation) (II .Jadavpllr /JIII I'('f's i/r ({IIII Indian In Slilllle (~j'Techn o logv, Khargpllr afler relirelll elllfrolll 1fT, Kharagllllr, His dillies are related 10 re,l'earch in glliding PhD Iheses, coordinaling research projecls, ele.

PJ'()f P K 8 0SI' did his 8/~' in Mechanical Engin eering in Ihe yea r 1975frolll Ih e Regional En gineerin g College, Dllrgapllr and passed 0 111 lI'ilh Firsl Class (H(II/s.), He cOlllpleled MaSl er of F;ngineering. (ME) ill Me challical F;n gineer;'lIg / i'Oln .Jadm'lllIr Unil 'ersily in Ih e vea r 1978 and aim did his PhD in Engineering./imi/ Indian In Slillll£' oj' Teclu/Ologv, Bom!Jar in 1993. He has go lll/Ore Ihan 80 pllblications ill inlemational and nalionu/jollmuis (111(1 conj'e rence,I' 10 his ('{'edil (lnd has gllided 17 PhD sllIdenls lill n (}\I '. He is a II 11'111 her or 11/(/11.1' Ilm/('ssiollal hodies and Associations of En gineers and has also delil'ered leelllr('s ill variolls inslilllles (~j'diff'er('l/I ('ol(//Iri l's allm'er Ih(' I\·or/d. He is presenlil' Proj'l'ssor of Mechanical Enginl'ering in .Jadavp/(r Unil'ersil.", Kolka/(l,

~

r~!,~"

Shri R K Clwkra!Jarti gradllated in Me chanical /:.'ngineering Ivilh Firsl Class (1-lons ).fi'Olll .Jada l'llIIr Unil'ersilr ill 198 1. !-II' did Posl-Gradllalioll ill Mechanical engineerin g froll/ In dian In slil/(Ie of'Tec//I/Olo/?I·, Khamgp/(r in 1984, !-Ic has lI'orked ill II/(/n.\' Indllslries like Mil- Telco, .Jall/shedp/(r, Mil- Usha Telehoisl Ltd, Cu ic/(Ila and MilVOLTAS' Ltd. BOlllhav and Ca lclIlIlI. !-I(' jo ill al acar/l'lI/ie,I' in 1990 alld presenlll' is a Sl'nior Let'IWer, Mechanical Engin('c rin g IJeparlll/('I/l, .Jad(/\'llIIr Universil.\', Kolkata,

Kail'an KIIII/ar Das oiJlained his BE degree in Mechanical Engineering FOil/ Ihe Universi/r of' No rth Bengal Oil 1972, He is a cons/(Italll to va rio/(s Indllslries and ca /'lyin g 0 111 research work on allematil'e alllolllOhilejil!'1 ill Ihl' MI'c/wllicai Engin eering Dell(lr/lnelll or .Jadavp/(r Universil.\', In dia. !-Ie is a II/ell/ber (If IIISlillllion of En gineers, India and SAE Inlemalional, USA.