The dependence (i) must be regarded as a first approximation, which could be useful in practice, but does not pretend to give a complete description of the physics of the process, which is based on the interaction of detonation, shock, and unloading waves in the PE and the materials of the body and casing of the explosive. We believe that the significant difference in the value of ~max for an open charge initiated by the method studied (~max = 1.3r) from the value obtained in [3, 4] ~max = (4.5-7)r with initiation of an open charge in the direction of acceleration of the plate can be largely explained by the different orientation of the wave interactions. It should also be noted that the density of the explosive with a specific composition affects ~max, unlike the result of [4] where it was found that ~max is independent of the density of the explosive based on experiments with different compositions, which have the maximum practically achievable density. It would be interesting to verify experimentally the applicability of the formula (i) in a wider range of the factors studied. In conclusion,

I thank A. M. Kalugin for assistance

in performing the experiments.

LITERATURE CITED 1,

2. 3. 4. 5.

A. V. K. M. US

G. Ivanov and G. Ya. Karpenko, Fiz. Goreniya Vzryva, 16, No. 2, 84 (1980). A. Ogorodnikov, S. Yu. Pinchuk, et al., Fiz. Goreniya Vzryva, 17, No. i, 133 (1981). P. Stanyukovich (ed.), The Physics of Explosions [in Russian], Nauka, Moscow (1975). A. Cook, The Science of High Explosives, New York (1957). Patent No. 3430563, cl. 102-22 (1969).

SHOCK DEGASSING AS A METHOD FOR INCREASING PROCESS EFFICIENCY B. E. Gutman

UDC 678.019.36

Thermodynamic calculations for the system C - H - S [i] showed that in the case C/H = 1/2 the chemical efficiency of the reaction, defined as the ratio of the enthalpies of C2H 2, C2H~, and C~H~ at standard temperature to the enthalpy at the temperature corresponding to minimum energy consumption (T = 1850 K), reaches the value n = 60% (Fig. i). In plasma chemical processes ~ ~ 20-30%, so that it is of definite interest to raise it to the level permitted by thermodynamics. To solve this problem a neodymium laser with an average radiation energy of 5 J per pulse, operating in the infrared range at a wavelength of % = 1060 nm with power densities of SQ = I011-i012 W/m 2 and pulse duration 9 = 10-2-10 -~ sec, was employed as a pulsed source of radiation. Petroleum resin with a molecular mass of I000 was used as the starting material; its elemental (mass) composition was as follows: C - 82.1%, H - 11.2%, N - 1.2%, S - 3.5%, O - 2%. The duration of the radiation pulse was regulated by changing the inductance in the circuit powering the flashlamp. A microcalorimeter based on an operational amplifier was developed for measuring the radiation energy E expended on the reaction and for determining q. The laser-chemical reactor with the microcalorimeter consisted of control and experimental chambers. The resin was placed into the experimental chamber. To make sure that the chambers were hermetically sealed and to minimize the radiation losses one wall was made of glass whose long-wavelength transmission limit % = 2700 nm. The hydrocarbons in the gas phase of the products of interaction of radiation and resin were analyzed by the methods of gas-adsorption chromatography. The times t of the chemical reactions forming C2H 2, C~H 4 were found by solving the equations of chemical kinetics and hydrodynamics taking energy losses into account [2]. Figure 2 shows the change in the mass yield of the products of pyrolysis c i, the temperature T, and the velocity of the plasma jet v as a function of the coordinate z or the time t neglecting (i) and taking into account (2) the energy losses. The data presented show that when the energy losses are taken into account for t > 10 -4 sec the concentration of C2H 2, C2H 4 corresponds to the level at thermodynamic equilibrium. Since t < 9 < rex (tex is the expansion time of the gas cloud), in this experiment the condition for thermodynamic equilibrium corresponds to t < tex.

Dushanbe. Translated from Fizika Goreniya i Vzryva, Vol. 25, No. 2, pp. 142-144, MarchApril, 1989. Original article submitted January 29, 1987; revision submitted May 26, 1987.

260

0010-5082/89/2502-0260512.50

9 1989 Plenum Publishing Corporation

u,in/sec

T~K

T

2900 ~ 400t 4 laoo

-

4 320-

! 7000 ~ 240-

H2.

I

2

Oj,, , ~ , ' 2 2 --z.lO;~m 10-3 10-I 100 10~ t~ S e C

I

50 ~ ;. :C

~

'

5/10 C,,'H

3/70

)

~_

~

I

,10-4

b

a 037~E~ 3 J

-

2o--~ 0 -

~

}

10-e

Fig. 2

Fig. 1

-40

]

10-8

)

~ .... i Z2 ~'~"~'~-

2~ 1 ) " ~" 70 3~

sec

o

~~i-r-'----

2

.

-i Fig. 3 Unsaturated hydrocarbons can interact with molecular oxygen liberated in the process of "shock degassing" [3, 4], creating a detonation wave. Taking into account the power density of the laser pulse we shall estimate the velocity of the detonation [5] of the products in an air medium:

D

----[2

(7-~ -- t)

.% ],/3 --

PoJ

~2,6-I0 3 m/sec,

the enthalpy

22/37 H=

[ Soh2/3

(@_i)ij3(7@I) k-~o]

~0'4"I06 J-~---kg

and the mean-mass temperature, equal to 3.4.10 3 K (7 is the adiabatic index and P0 is the density). This estimate enables referencing to the data from the thermodynamic calculation and determining the composition of the products of "shock degassing" [6]. The expanding cloud of gaseous products contains 0.5 mole fractions of dissociated hydrogen and 10 -4 mole fractions of dissociated nitrogen and oxygen. For this reason the absorption by the glass cloud is insignificant. The process of shock expansion of the cloud is accompanied by infrared emission. The composition of the products corresponds to hightemperature thermodynamic equiiibrium. On expansion the temperature of the gaseous products drops, while t increases to tex. At t = tex it is no longer necessary to provide heat sinks, so that the stage of "quenching" of the reaction products is eliminated. Let us study the experimental dependences obtained: q(~) and D(E) [Fig. 3a and b: i) p = I0 ~ Pa, 2) in an oxygen medium; for Fig. 3a: 0.7 ~ E ~ 3 J], the degree of transformation of the starting material into gaseous products 6 and the energy expended on producing unsaturated hydrocarbons ~ versus T (Fig. 4), as well as the dependences S(E) and ~(E) (Fig. 5). 261

12

i%

70

'\

O

76

-

I i -i 4

-,,-.

!20

t~

J *

~0~ -40

4

-~0 ~ 2

7~2

7,7

o ~.1o ~, se~

Fig. 4

O

"1

2 2~ e , j Fig. 5

The negative values of q in an oxygen medium (see Fig. 3) are explained by the additional heat liberated in the reactor owing to oxidation. Comparison of the data presented in the figures shows that the process of impulsive pyrolysis is more sensitive to E than to ~. The low absolute values of ~ and ~ are explained by the comparatively low specific energy of irradiation of the starting material [i, 2]. The experimental data presented reflect the fact that the process is highly sensitive to the energy and duration of the irradiation pulse as well as the possibility of approaching the thermodynamically possible values of q with the "quenching" stage eliminated from the technological chain. Thus pulsed processes increase the efficiency of high-temperature conversion of hydrocarbons and are most acceptable from the viewpoint of producing highenthalpy gaseous media for some processes employed in high-temperature technology [7]. LITERATURE CITED I.

L.E.

Slyn'ko, B. E. Gutman, et al., Dokl. Akad. Nauk Tadzhik. SSR, 16, No. 12, 41

(1973). 2. 3. 4. 5. 6. 7.

262

F . B . Vurzel', B. E. Gutman, I. L. Epshtein, et al., Khim. Vys. Energ., 19, No. I, 55 (1975). M . V . Gerasimov, Pis'ma Akust. Zh., ~, No. 5, 36 (1979). M . V . Gerasimov and L. M. Mukhin, Lunar and Planetary Sci., 15, Lunar and Planetary Institute, Houston (1984). S . A . Ramsden and W. E. Davies, Phys. Rev, Lett., 13, 227 (1964). A . L . Suris, Thermodynamics of High-Temperature Processes [in Russian], Metallurgiya, Moscow (1985). B . E . Gutman, Svarochnoe Proizvod., No. 8, 36 (1986).