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62-1037

CM

REOULAHITIES OBSEHVED IN MIXTOHBS OF LIQUID FDEL DUHIWJ IQIITIOH

*

V. I. Blinov

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1 '

lfTD'TT*62.io57yi^4

UNEDITED ROUGH DRAFT TRANSLATION

RWHJURITIfcj CBä&RVU Ui MIXTURLä GI U^ID 1U£L DURIMJ IGNITION

Byi T. I. BlinoT

&Q«liah Pagasi 6

Sourcai lüzbaQarno-Fizlobaakiy ihurnal, Vol. 4» No. 2, 1961, pp. 95-98

üöV/lTO-61-4-2-10/18

THIS THAWLATIOH It A MMWTIPH OF THf ORIOI- KAL FOMKM« TEXT WITHOUT ANT ANALYTICAL Off IMTOfflAL COMMNT. ITATIMINTt 0« TNfORIES AOVOCATIOOffWPUiOAWTMO»! OFTHf MMIRCf AND 00 NOT NeCEtURILY RCPLtCT TNE fOMTION OR OfflMON Of TNI FORSION TECNNOLOOV IN- VtlMNt

FTP-TT* 62.1037 A^^A

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niEPARiO RTi

TRANSLATION tiRTICil iRANCN PORliON TECNNOLOOT OIViMON WP^Pl, OH«.

HaGLURITlAJ OikiihViiD II« >JXIliUk} Q£ LI*üIfi

WML WBIiiQ IGNITION

T. I. BliLOT

1. Th« ignition ttn^oratur« of a liquid is th« lowest tsopsratur« for this

liquid at which tb« «margiat flsua will aot be •xtinguitbed,

!*• showed [Ij that in the case of the ignitioa of indiTidual liquids iu e

cylindrical tube

where £ is the saturated-vapor pressure at ignitioa temperature; p is the atmospberio

preesurei ^ is the distance of the surface of the liquid from the edge of the tube)

/) 7.'. lo' A:,/'/„ .',7i , ß^ la the diffusiTity of vapor at 0oCj T. is the ignition

temperature in \; ß is the uui&ber of moles of oxygen required for the oombusticD

of one mole of vapor; K is the number of moles of oxygen entering the flam« in 1

see; B is the uniTersal gas constant.

P. 0. Ipatov showed [ij that relation (l) holds true for binary mixturos of

liquids if we put

where jt and y^ are *"• ^d* fractions in the vapor phase of the mixture canponentt. P. G. IpatoT found the empirical dependeoees of the ignition temperature on the

compoaitiou of ideal and noaideal binary mixturea of liquid, but did not explain

F[D-Tr-62-1037/l*2t4 -1-

%

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thata dependences. In this paper, we attaupt to explain the basic regularities in

the rariation of the ignition temperature with rariation in the composition of

mixtures of liquid fuels.

2. It follows fron (l) that the ignition temperature of a specific liquid and

of mixtures of liquids is e^ual to the temperature at which the saturated Topor

pressure £ is equal to 1—exp (—bh),

Since the value of K may be considered the same for various materials, given an

invariable radius of the tube and an invariable concentration of oxygen in the

atidosphere, when p * const for mixtures of liquids, the ignition tei^peratures of

whicn do not greatl/ differ, we may assume that

then

If Dfl changes slightly with a change in the composition of the mixtures, than

at the given value of 4 for a mixture of the given two components p« const. In this

case the dependence of the ignition temperature ^.(0C) on the composition of the

liquid sod the vapor phase is graphically represented by curves which coincide with

the curves which give the relation between the boiling temperature 4. end the cco-

position of the phases at constant pressure, determined by relation (l).

It is clear that the curves of 4.(x} and *.(>•)• when fe is variable will differ

from 9Ax) and tfv(y) at constant pressure, but the character of the curves 9. and DO 1

#. will be the same. Thus, in the case of nonideal mixtures, with a maximum on

the pressure curve tnere should be a minimum on curves ^(x) end ^(y), while the

ignition temperature of the mixtures is lower than the ignition temperature of the

mixture components. These curves were obtained by P. C. Ipatov in a study of the

* x and y are the mcle fractions of a component in solution and it. the vapor

FTD-TT-6t-li^7/l*^4

phase.

1

mm

followiLg ailxtur««! dth«nol ♦ b«nzea« (••• Tig, l), «thanol ♦ tolura«, Mthanol ♦

♦ btnztM»

for BlxturM with • nlniauB on th«

pr«8»urt ourres, th« d«p«ad«M« of 4L

on 2 •o0 1 •bould b« r«pr«Mnt«d by eurrtt

with maxima. Th« addition of on« oon-

pon«nt to «Bother in this e«a« should l«ad

to th« formation of mixture«, th« ignition

t«inperature« of which ar« higher than

9. of th« pur« component«, Th« minima

and maxim« on th« ignition curve« should

corroapond to th« azeotropic m«««ur««.

In thoö« c«s«s where the mixture« «re ideal or eloa« to id««!, th« d«p«nd«no«a

d (x) and 9Ay) ahould b« r«pr«s«nt«d by monotonic curr«« clo«« to th« corresponding

Fig. 1* Th« d«p«nd«no« of th« ignition t«mp«r«tur« on th« com« position of mlxtur«« of «thanol and benzan«.

boiling cunra«, wnicn is also confirmed in th« work of Ipator [2].

In the work of Ipato» [2j it was found that for ideal mixture« of tolu«n« and

benzene, «.(y) is represented by s straight lin«. Thi« i« «asy to explain in th«

following w«y. For ideal mixture«

/' = P)o ■ (/'-•o - PuJx: ■

1+0 -Dy ■'I. (4)

wh«r« plr. and V^K* tne »aturatad T«por pressure«of t^ pure components at th«

ignition t«inp«r«ture of the mixture; x. and y2 ar« th« mole freotions of the second

ooopooent in the «olutioa and in the vapor phase.

If the yalue of fc. for tne giTen mixtures changes only slightly when x, changes and

if ^ ia conatant, the preaaure £ will be constant for all practicnl purpoa««; let

us designate this ralue of £ M p'. Then froa (4; we find that

1

ITD-IT-62-lC37/l*2*4

•' PJO = p' [1 ♦ (e'-l^].

->

(3)

Lit us now dMignat« tbt ignition t«q>«ratures of the adxtur« and of the second

oonponent es T end T0 measured in 0K. Let T —T0 * • and •/t0 « 1. Now we may

aasuae that

1

r.ji+—)

Since the saturated rapcar preesure is determined by the reletion p « ae

where (I is the moler heet of vaporizetion

-k-

pJ0 = a exp - Q RTt

a tfxp 0 ^H

p-"p(wH)'P!"('-we) RTt RTt

el. («)

where ppf. is th« saturated vapor preesure of the second eou.pon«nt of the Bixture at

ignition temperature T2.

Since the value of a* changes slightly with temperature, it follows from (3) end

(6) that

a B

where e, end a ere constant; * and d,f the ignition temper a tuxes of the mixture

end the eeooud component.

Taking into consideration the fact that 9 « A- when y2 - 1 ami * a fl. (fc is

the ignition temperature of the firat oenponent), when y » 0, we will have

^-•i-(»i-^ft. (7)

Reletion (7) agrees with the enpirical fonoula found b> P. G. Ipatov,

% The loweat temperature of a liquid at vhich its vapor ferns with air a

mixture which ignites in the presence of an ignition source is called the flaah-

The flash-point 4L is closely related tc the low point of a liquid,

concentration limit of ihu ignition of a mixture of vapor aau air. This relation

may be determined In the following way. The ignition limit

ITO-TT-62-107/l*2*4

mfmm

T r

\ FIRST Mf

V -X-V 100=- Pl

% + A • ICO.

wh«r« VT and ^ are the roluau and pT and pt are the partial praaauraa of rapor aad

air ia a mixtura. Sine« p ♦ p » p , whan p » 760 no

P - 7,6 ft. (8)

ÄTidantly, in formula (8) £ equals the saturated vapor pressure at the flash point.

äince the flash point *•

close to the ignition temperature, we may

use the above relations for the determina-

tion of the limit of £, from (l) and (5)

when 4 is constant and the value of ££ is

small

Fig. 2. iJependence of the ignition limit on the Conposition of the Bearing in mind the fact that the valuea of mixtures» 1, 2, and 3 are the raaulta of tests [j)J for mixtures, 4^ relationa (6; and (9) are siaiilar, wa respectively, of benzene with toluene, ethanol witu Lenzene, and may write acetone with benzene. The solid liL.es were calculated frooi fornule (10). The value of i, is taken as the seuii« for all mixtures} the value D -was calculated frexn for- nule (27, i.are the mole fraotiona (10) satiafactorily describes the given

k ■-- B/D}, B^cousi. r^j

Zt can be seen from fig. 2 that formula

of benzane in tne vapor phase. data.

In conclusion, It anould be noted that the ignition limit of Mxturee is frequently

determined b. the L. Chfftelier principle. This principle.wnicn U an application of

the ttnylMMBl principie tc wixPU* of ii^ui. fuel., Fu*a TtBvliB cloae t# thoae

of the teats in a number of cases. If a. use it, ve would need aix empirical con-

stants for the given data In Fig. ., whil« Mn M uae relatlor. (1C, we need only

one constant dotermined froa 6Xi.äi iaient.

Fn/-rr-öt-ic^/itt.+4 "3"

F/RS: 1, f. I. Blinov. DIN SSSR, Vol. 32, 9, 1946.

2. f. G. IpatOT. lafomation Sympoaium of TaNIIPO,* 1932,

3* F. S« Ipatov. morks of the Leningrad Institute of Aviation Inatrument Deaign, Sio, 1, 1934.

4« Lu-iÄli» ixplosiona and Combustion in Gases. Inostrannaya Literature, Moscow, 1932.

* Central fire Protection Scientific Research Institute

Institute of Aviation Instrument Design, Leningrad

Sutanitted July 1, i960

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