Fuels for High Compression
Engines A Preliminary Study of t h e Selective Blending of Gasoline Distillates from PrescntDay Refining Processes I\. C. O F F L T T , J. E. TAYLOR, AND G. B. SWART%, Jtc. Ciilf
Reseurrh & Drcelopment C o m p a n y , P i t t s b u r g h , I'u.
T h e automotive and petroleum industries should d e l elop engines and fuels simultaneously in order t h a t the engines and fuels are properly matched, and any upgrading of t h e fuel antiknock quality requirements of automotive engines should be established sufficiently ahead of the engine production t h a t the refiner can develop techniques to economically produce satisfactor>-fuels. Recently it has been shown t h a t t h e mechanical barriers to highcompression ratio can be controlled by proper attention to mechanical design. Consequently, i t can be, anticipated t h a t a n upward trend i n compression ratio will be established as soon as new techniques are developed to economically produce motor fuels of sufficiently high
SI: of tli(%moat significant trends in t h r dcsign of automotive: rnginw in the past has been toward steadily increasing compression ratios. K h e n the surcessful operation of a 12.5 t o 1 comprrssion ratio, experimental engine was announced ( J ) in the spring of 1047, i t became evident t h a t t h r merhanirnl barriers t o the production of high compression cmgines could be controlled by proper attention t o mechanical drsign. Fueling these engines, however, is a problem still to he solved. Since the development of improved motor fuels must proceed simultantmAy with advances in engine design if tht, cnginrs arc to run satisfactorily, the petroleum industry should investigate in advance the characteristics of high compression engines, together with their fuel requirements. Allthougha large amount of information has been accumulatccl over a period of yrars concrrning the behavior of various refiner!, distillatci and gasoline components in present-day autornotivc cnginecl, there is no reason to h l i e v e t h a t all of the previously csstablishrd relations will apply t o newly designed high compression engines. .lwordingly, t o establish fully the perfoi,m:inw c.li:iracteristics and fuel-enginr rrlations for high compression cmgines, a similar large volume nf experimental ~ o r in k numerous luhoratories throughout t h r prtroleuni industr>- will probably Iic nerrs,viry. .l comprehensive program dcsignrd t o make possible thc rfficient utilizatitrn of prt.sent-d:iy refinrry distillates i n the new fur1 c~nginrsmust iiii~ludc: (1) :t ronip:iri~on of hydroc~arl)oi~ typrs in :ill portions of the furl; ( 2 ) :I ronip:irison of distill:rtw from v:trious refining pi'ocmsrs oprrating with R \vide v:iriet!- of charge stocks and operating conditions; and ( 3 ) a comparison o f diffrrent methods of blending furls from the available refiner!. mmponrrits. If ail? of the principles of fuel pPrforniance prrvioudy discovered for convcntional :tutoniotive enginrs are f'nuncl t o apply, thfx task may h r consitlrrahly reduced. .k small nunibrr of saniplrs h a w been tested in specifirally tiwigned rxperiniental, high rompres,cion engines as the beginning of the estcnsivr invristigation aimed a t determining t h e best nirthods for produring fuels for futurc: high compression engines.
octane number to permit satisfactory operation o f sucll engines. Because conventional engines with stepped-lip compression ratios do not rate fuels t h e same as specilically designed high compression engines, test data must be obtained on the newly designed engines. The data presented in this paper summarize t h e road antiknocli performance of several selectively blended gasoline clistillates from operating refinery processes in specially designed engines of 8 to l, 10 to l, and 12.5 to l compression ratio. Since t h e hydrocarbon-type composition tius h e e n shown to affect t h e road performance of motor fiiels, a complete hydrocarbon analysis is shown for the fuels rated.
.Ut liough most of the experimental fucls contained gasoliiiw 01' frwtions of distillates from sonie of t h e present commcrc~i:rl opwating processes, some of the fuel romponents were not norm:il rrfinery stocks available for production nf motor gasolinrs. Thtw fuels mere made b y suitable cutting and rross-Iilrntliiig :iricl were intended t o cover a range of hydrocarbon types 1 ~ i I t l i in the total fuel and in the various portions of the gasoline I)oiling range. S o attempt has been made a t this time to rrl:itc thcb percentage of the various fuel components t o refinery >.icd(ls. The fourteen fuels on n-hich octane number dxta are :iv:Lil:ililia :ire ,shown in Table I. These include three f w l s prrpared from commercial gasolines. Two commercial fuels wJre hlended to a r w w r c h octane number of approximately 93 by t h r addition of trtr:~rtliyllenti, :is this was the probablc requiremciit for protluc,tinn engines of the new design. Ono of thrse f i i ~ l qWIS cwt t o :in cnd point of 323" F. t o eliminate the variable of vol:rtility in rvaluuting road antiknock quality. TIE remaininfi c'lrvoii furls were prepared from t h e initial I)oiliiig point t i r 200" 1.'. fr:Lction and the 200" to 325' F. fr:ic+iori of t,hrw r i h c r y yasolilies anti tFvo :idditional distillates selected to supply high concrntrntions of particular liydrocsarbon types. Thr refinery gasolines included a mid-continent straight-run gasoline, a distillate from fluid catalytic cracking of heavy mstern Venezuelu gas oil, and a distillate from polyforming of e a s t i m Vcric~zuc~l:~ naphtha. T h e two special distillates consistcvl of :in ariini:Lti(: roncentrate and a mixture of alkylate and other light i ~ ( i ~ ) : i r : i f f i i i - . Seven of the eleven fuels blended from these (listill:tt(~~ wcr(~ 1r:ided to a research octane number of 93; one h a d :t rcw:ii,c*li rating of 93 unleaded; the other three were mndc to still higher wsmrch ratings to satisfy t h r 10 t,o 1 arid 12.5 t o 1 conipr(wion r:itio rngines. Each of these cl(ww fuels ~ X Psufic~ic~iitly Io\v iir enti point that volatility waw n u t 3 v a r i a b l ~in~ dvt vrminiug t Iw road octane numbers. plinrs : t r r ~ l Hydrocarbon analyses of cwrh n i t h r e~nnii~i( refinery tlistillatrs w+rr detrrmined hy ni:iking a 35-plnte prccision fr:ictionation of the total fucsl and :rn:tlyziiig the: narrow ( 2 t o 2.5 volume yo)cuts for the various hydrocurbon types.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 41, No. 10
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
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I ~iuiini:irizoclr o d octane numbers of the same fuels as detcrniinrtl i n conventional cars which were modified to higher comIirrssion ratio. Thrse rxtings are also averages of several deteriiiiti~itions. .\ti attempt t o f o r m u h t e definite conclusions bused on data f i , i t m only fourteen fuels, the majority of which were leaded t o ! I 3 rrsrarch octane number, is very difficult. However, the i,i~sultsare significant in that they are derived from testing in specially designed high compression engines, :ind several trends i l l fuel and engine I ~ h a v i o rare rvident. T h e road octane n u i i i l ~ i ~ rof, - the fuels slio\vcxl :t tiend t o bccome higher as thc coinprcssion ratio n'as inereused in the new high comprc,qsioii, rsperinirrital cfinyines. Figure I illustrates
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this poiiit I)\, coni~)ui~iiig the ionti ratiiigs of tlict ~ i i c ~ \l \si t l i t Iil,ii, 1:ibor:ttory ixtings. T h e lower curve in the figriiv i ~ o n i p : u wt l i t , road rating at 1200 r.p.m. with t h e research ixtitig I)y ploltiiie the average difference in these values for all of thia furls. T I i t , research rating wa,5 fair]>-closr to the road rxting a t this sprivl, being somenhat higher at 8 to 1 and somewh:tt lontsr at 10 1 1 ) I and 12.3 t o I compression ratio. ;\t 2800 r.j),ni,, whcrc 1111. motor octaric riumbcr is genct~allyconsiderrtl t o cwrrc~lnteclosvl~. with the roatl octane number i n present-da>, c,ngiiicxs, the uppc'r' curve shon-s t h a t the ro:itl riiting cscmd(~t1t h c b motor rtiting : i t S to 1 comprc~ssionr:itio Iiy four nunitxr.;, :iii11 with iticrcasin:: n i e greatcr. compression miio tlic tleviatioii I ~ i ~ ~ aniuc.li Another iiiiportant ti,rwtl i l o t c d i i i i~rg:iitlt ( J the effect of coiiipression ratio o n the m t i l rating of f u c ~ lin ~ high conipressioii engines n'as that the slope of t h e r0:iil octane number agniircl speed curve was reduced as the coniprcwion ratio n-as incrr:im I . Table 1- s h o w the slope, v h i r h has I ~ c r ntlrfirietl as thc. I Y I ; I ( I r:it)ing a t 1200 r.p.m. minus the road rating :it 2800 r.li.ni., f r i i , c w h fuel a t the various compres,sioii ixtios. 11 is eviclciif t l l r i l increasing comprcssion ratio tlccreiiscd the slopi: of the raiiri:: curvr for. :t givoi f u i t l . :is :t f i i i ~ t l i i ~illiisii~:iti(iii i~ r i f this I m i n t ,
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EXPERIMENTAL CARS OF HIGH CClMPRESSiON DESIGN
UP CONVENTIONAL CARS
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RATIO
FiFiirr 1. Effect of Increasing Compresiiiiti Katio on Road Octane R n f i n p
7
8
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COMPRESSION RATIO
Figure 2.
Effect of Increasing CompresGiiii Octant-Sped V t i n
, tended t o c:inwl the advantage of t h c 1;irg~. ;miourit of light olefins in furl 8. Thc. ro:ctl ort:iric iiunihcr-speed curvcs for these fuels :LIT :ilniost identical, with only a slight tentlc,ric*J-to tlivt,rye as compression ratio is incri. their principal difference :ippenrs t o tw i i i 1 1 i ~ tetr:ic~thylleadrtquircnient to reach the s:iniib i~cscnrc~h rating. Fuel 1, n.hit:h a a s tllc hsc: fuel froni n.hich fuels 8 and 33 were preparc.tl, is included in the figure for cuniparative purposes. Fuels 31 arid 32 stin\\- the effect of increasing volntility. Fuel 32 was prepareil b y thr: removal of 10 volumt: 70from the heivy end of fuel 31 b y distillation; this 1ow-erc:tl tlir .i,S.T,lI. 0070 evaporated teniperaturc froiir 330" to 286" 17. Although this niethotl of chnriging volatility resulted in :t 1osh of mimatics and :t gain in the perceritagc of oltsfitis, paraffins, and naplithenes, therc \V.L< littlc change in the road antiknock q~.i:ii!~y,;IS shon-ri in Figure 6. Honever, the test car driver clr:trly observed t h a t the less volatile fuels (31 and 31) caused a loss in performance other t h m octanewise, although this was not measured quantitatively. T h e r e n i a i n i 11g twelve fuels were all of high volatility in order t h a t t,his effect could be eliminated.
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
CAR C 10 I COMPRESSION RATIO
I
s
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100
CAR D I 2 5 I COMPRESSION RATIO
2365
the knock characteristics of various motor fuels in high conipression engines has been completed, it is believed that these limited data will contribute to the knowledge required for the economical production of satisfactory fuels for engines of advanced design. I t appears certain that fuel development programs should be carried out in engines of the specific design expected on the road, as antiknock ratings in stepped-up, conventional engines do not appear to be comparable. The road octane number of the motor fuels tested to date appears to incre:ise with in( compression ratio. This is particularly true a t high speeds, with the result that the octane number Lig:iinst spwtl curve for sensitive fuels tends to bcconic Hatter :IS compression ratio is increnscd. Several relations were similar to ttiosc. already noted froin previous octane number d:it:i obtained in prtwnt-clay cngiriw [ i f lower compression ratio. However, the corre1:ition b c t w w n research mcthocl octane numbers and loir- sped i,o:itl oc.t:uic, numbers in high compression c:ii's :ippenrq to I)e sigiiific*;iiitIy better than the correlation usu:ill>. detcrmincd using p r t w n t - ( h ~ ~ engines. ACKNOBLEDG3IEhT
0 FUEL 31
COMMERCIAL
GASOLINE
A
X FUEL 32
COMMERCIAL
GASOLINE
A CUT AT
800
1200
1600
2000
ENGINE SPEED
Figure 6.
325 OF
2400
2800
R PM
The authors are indehted t o the GcncrcLl 11otor.q Corpor:irion for making availnhle esperinientnl engine. of 8 t o 1 , 10 t o 1, and 12.3 to 1 compression ratio, for their kind c>oopcwtionn.hile rating the fuels, and for their consent to relts in their esperimental engines.
Road Octane >umber us. Engine Speed
Effect on road ratings of increu4ng volatilit? by undercutting
The only fuel which was completely different from the others in over-all composition was fuel 28, n n aviation stock consisting almost entirely of isop:ir:tffins. The road octane number-speed curve slopes upn-nrd rather than donnivard as for all of the other fuels. This type of rating would be expected from all previous work in lower compression engines. Although only a small portion of the program for evaluating
L1TER:ATURE CITED
(1) Am. Soc. Testing Materials, test proceduie D 484-40. ( 2 ) Francis, -4. IT..ISD.ESG. CHEM.,18, 821 (1926). (3) Groase, h. v , , and ivackher, I(. u., Isi). 1:s~.C H E M . , z'.s.\r.. ED., 11, 614 (1939). (4) Kettering, C . I?., S . A . E . Joicrnai, Qicavierly Trans., 1, GG9 (1947). (5) Petroleum Industry War C'ouncil. Tech. ;Idviaory Cornni., R e p t . HcAC-6. (6) Kagner, C. R.. lloss. IY.B., Henderson, I,. l l . , and Risk, T. f1.. Refiner .Vatzcral Gasolinf .l[.fr., 20, 436 f 1941). R E C E I V E )[arch D 8 . 1949.
Ternary System Diisopropyl Ether-Isopropyl Alcohol-Water at 25"C. F. J. FRERE I'ziblicker Industries, Znc., Z'hiladelphiu, P a . 3 f u t u a l sol~ihilityand tie line data on the s!stem diisopropyl ether-isoprop?l alcohol-water, determined during a general inicstigatioll of liquid-liquid extraction, are reported i n this paper.
I
x i t h freshly c:tlcincd lime, :tlttbr ivliich it \\-asfraction:ttcd on :t Podbielni:tk colunin; the ccJntcli,c u t \v:i* *eltIcted. Re:igcnt-gratle diisopropyl ethcr w ~ i hir:ictiori:itcd on :t l'ocibiclniak column; the centclr cut W:M w l w t c c l . 0rdin:iry distilled water \vas used.
S THE course of a rather general investigation on liquitl-
liquid estraction, mutual solubility and tie line data were required on the system diisopropl-l ether-isopropyl alcohol-water. .As far a s can be ascertained, this system has not been reported in the literature. Therefore these data were determined and arc reported in this paper. Re:tgent-grade isopropyl alcohol \vas reflusetl for several hours
3IUTUAL SOLUBILITY DATA
Known amounts of two components, isopropyl alcohol :ind diisopropyl ether or isopropJ-l alcohol and water, contained in a 100-ml. glass-stoppered volumetric flask, were mixed; quantities of the third component, water or diisopropyl ether, were ntldcd dropwise from a buret until the misturc became turbid :md re-
