be solved at the level of the State Commission on Science and Technology, Gosplan, State Standards, and the State Board of Construction. It is, however, possible at present to use it effectively in the operation of actual enterprises of any branch of industry in the national economy as is confirmed by practical experience.

LITERATURE CITED

i. V. I. Radin, "Everything begins with design," EKO, No. 6, 92-100 (1985). 2. B. I. Kudrin, "Scientific and technical progress in costing," EKO, No, 8, 25-28 (1980), 3. V. V. Fufaev, "Optimization of the structure of electrica! equipment planned or already

in use," in: The Scientific Proceedings of the Moscow Energy Institute [in Russian], No, 90, Moscow (1986), pp. 31-40.

4. B. I. Kudrin, The Identification and Description of Electrical Costing, Electromechanics [in Russian], No. 7, Izv. Vyssh. Uchebn. Zaved. SSSR (1985), pp, 49-54,

CHOICE OF AN ELECTRIC MOTOR FOR THE FAN DRIVE OF

GLASS QUENCHING EQUIPMENT

A. I. Shutov UDC 666,1,038

The main task when choosing an electric motor for the drive to the fan for the supply of air to the grid of glass-quenching equipment is to define its power.

An analysis of the design of a range of equipment at plants has shown that in most cases they use an electric motor of a higher power than necessary. The choice of the power of the drive is not always related to the glass-quenching process itself nor with the design of the grid that is used.

The aim of the present study was to find the optimal power for the drive. A typical sys- tem for organizing the air supply to the quenching grid is shown in Fig, I, The fan (3) is brought into action by the electric motor (I) via the mechanical drive (2) and creates an excess air pressure which after passing through the air-lead system (4) arrives at the quench- ing grid (5) and is directed via the nozzles on to the surface of the heated glass.

The power of the air jets which cools the glass is

P = O~gp/p, (i)

where G is the mass consumption of air used per unit area of the grid; F$ is the surface area of the grid; and p, 0 is the pressure and density respectively, of the alr,

The immediate values of G and p can be defined as the minimally required value of the co- efficient ~ of heat transmission for quenching glass of a specified thickness: the specifica- tion values of a have already been published in [i].

According to Gardon [2],

ReO.6~s. = 0286-- (2) X

where k is the thermal conductivity of the air; x is the interval between nozzles; Re is Reynolds number; and

G~ Re = 8.45 - - ( 3 )

-ZDIL

where Z is the distance from the nozzle to the cooled suface; D is the diameter of the nozzle: and ~ is the dynamic viscosity of the glass.

I. A. Grishmanov All-Union Technological Institute of Glass >~chinery. Translated from Steklo i Keramika, No. 9, pp. 14-15, September, 1987.

0361-7610/87/0910-0379512.50 �9 1988 Plenum Publishing Corporation 379

r ]/ * i !

uuu'uuuuuu

r 2 ' ~ .~ ~3

Fig. I. Air-supply to the grid of the quenching equipment,

Solving Eqs. (2) and (3) simultaneously relative to G and substituting the results in Eq. (i), we obtain

(~)1.6 pFp ZD tt (4) P = 0.877 x 1. 4 p

With specified design parameters for the grid, the value of P is determined by the coeffi- cient of heat transmission which, in turn, depends on the conditions used for quenching glass of a specified thickness.

Let us call the term P the "useful" or effective power. The difference between Pe,m (the power of the electric motor) and P compensates for unavoidable losses~ mechanical (in the drive from the electric motor to the fan) because of the imperfect working of the fan; in the air feeds (as a result of the friction in the places where there is resistance), The addition of the coefficients of useful action to Eq. (4) will make it possible to allow for these losses.

The efficiency of the fan drive is

Wd~ Pf/Pe.m.

where Pf is the power transmitted to the fan,

The efficiency of the fan

~f= ~ut/Pf,

where Pout is the power of the air jet at the outlet from the fan,

The efficiency of the air lines is

a. ~ P ' P~

Allowing for these terms,

P = Pe.m.~dr~f ~ a. s

consequently

P e.m.

~dr~fDa.Z.

or in the evolved form

0.877 (~) Pe,m.-- ,]dr~f,a. Z. -~ • (5)

1,6pYplD ~ • x 1.4 p

The obtained expression makes it possible to start to make an objective choice of power for the electric motor on the basis of the quenching conditions and the actual parameters of

the quenching grid.

380

.An evaluation of the terms ndr, nf, and nc.l presents no particular difficulties since they are all in the reference books. Moreover, Eq. (5) makes it possible to mark out design measures on the use of a lower-powered drive by changing the parameters of the blowing grid,

For example, the grid on the LZAS line (for quenching automobile glass) has the follow- ing parameters: Z = 40 mm; D = i0 mm; and x = 37 mm. The total area of the surface of grat- ing space on both sides is Fg = 14.4 mm =. The specification value of ~ is 420 W/r [!],

The constants of the properties of the air under normal atmospheric conditions are known from [3]: k = 2.41"10 -= W/(m.K); ~ = 1.71"i0 -s Pa.sec; 0 = 1.3178 kg/m3; and the air pres- sure p = 3.8 kPa.

The efficiency at the planning stage can be taken as: ndr = 0.95, ~f = 0.75, and qa.~ = 0.85.

Substituting these values in Eq. (5) we obtain the value of Pe.m. " 250 kW which is the required minimal value for these particular conditions for quenching,

The results of the work can be used in the planning and modernization of a glass-quench- ing multi-purpose line in particular for automobile glass,

LITERATURE CITED

i. A. I. Shutov and I. P. Kazakova, "Optimization of the parameters of quenching grids," Steklo Keram., No. 9, 8-9, (1981).

2. R. Gordon and I. Cobonque, "Heat transfer of drafting air jets on a plane surface," international Heat Conference, Colorado (1961).

3. Physical Encyclopedic Dictionary [in Russian], Sovetskaya Entsiklopediya, Moscow (1983),

TIN OXIDE FILMS ON GLASSES OF VARIOUS COMPOSITION

O. P. Proshina, I. L. Nesterova, T. B. Fedorova, L. F. Komolova, and P. V. Kovtunenko

UDC 666,1.056

Thin tin-oxide films possess a unique combination of high transparency in the visible range of the spectrum, electric conductivity, chemical resistance, and good adhesion to glass, These properties ensure wide use of tin oxide films in electronics, radio technology, aviation, and other areas of technology.

The influence of glass composition on the properties of such coatings was established earlier [1-4]. An increase in the silica concentration in the glass improves the adhesion, electric conductivity, and the transparency of the films [i], The authors of [2-4] connect the change in the conducting properties of the films with the presence of alkaline components in the glasses and their diffusion into the tin-oxide layer,

The aim of the present work was to study the influence of the chemical composition of the glass on the composition of the Sn0= films. In order to explain the nature of the pro- cesses occurring during the heating of the film structures on the basis of tin oxide applied to quartz and glass of different compositions, a study was made of the high-temperature reac- tions of tin oxide and silica and glasses. We studied SnO= films on substrata made from dif- ferent glasses, compositions, and softening temperatures as shown in Table I [5], and also mixtures of SnO~ and milled glasses, powdered SnO= (chemical analysis purity), fused quartz (occular purity), tin monoxide (chemical purity), and silicon monoxide (special purity).

In order to explain the possibility of forming new phases during heating of the system containing tin oxides and silica, we used the methods of derivatography (DTA), x-ray phase analysis (RFA), x-ray photoelectronic spectroscopy (RF~S) and Auger-electron spectroscopy (OES). In carrying out the DTA studies on the "Derivatograf-1500" apparatus the heating-- cooling rate was 5~ For the RFA we used the URS-50 IM apparatus with monochromatic

D. I. Mendeleev Moscow Institute of Chemical Technology. Translated from Steklo i Keramika, No. 9, pp. 15-17, September, 1987.

0361-7610/87/0910-0381512.50 �9 1988 Plenum Publishing Corporation 381