Thermoemissional charging of a spherical sedimentary particle

J. Aerosol SeL, Vol. 26. Suppl 1, pp. $321-S322, 1995 Elsevier Science Ltd Printed in Great Britain 0021-8502/95 $9.50 + 0.00

"~ D e r " a m o n

IHERMOEMISSIONAL CHARGING OF A SPHERICAL SEDINENIARY PARIICLE 5uslov A.~., Lyalin L.A., Semionov K . I . I n s t i t u t e for Combustion ano Non-lraOitional lechnologies of OOessa State University,Ukraine,27OlOO,OOessa,Pyotr

Velikiy Str.2

KEYWORD5 thermoemission,condenseO

dispersed phase,particle,electron

flow

An investigation

of thermoemissienal

charging of a spherical seoi

mentary particle

in the air under the atmosphere pressure has been

OescribeO in the presented paper. In the first

part

of

t h e work we s t u d i e d

with condensed dispersed phase. s p h e r e methoO.

concentric

,ituateo

face,

where I

is

at

a mean v a l u e

an e l e c t r o n

- ~e.

ihe

not

A particle

was surrounOeo w i t h

a oistaoce of

fro,

an oxygen i o n

free

that

of

face

and by t h e b o u n d a r y s p h e r e was named a k i n e t i c

track zone.

this kinetic zone not interacting with one another,

-toiano sur-

he have

move inside

coiiioing only

at the boundary sphere surface anO with the particles' electrons'

a

its

space bounded by t h e p a r t i c i e s '

supposed that electrons and negative ions of oxygen O

lhe elastic

surrounOeO

In describing the process we have

used t h e b o u n d a r y sphere

particles

surface.

scat lerin~ ol the fIow emitteO from the

heated surface of a particle by nitrogen molecules was also taken into consiOeration, the eIectrostatic

lhe diffusion probiem ol a charge transfer

in

lielo of the particle has been solved beyond the

limits of the boundary sphere.

Accounting lot the non-interrupteO

flew ol the charge through the boundary sphere we have received an exact e~uatiorl for thermoemissional mentary particle. thermoemission

charging ol a spherical seci-

]his equation defines the Oepenoancy ol electrons

flow ~rom the particIes'

surlace on the values oI

their char§e and temperature. Comparing the designed anO experimental investigation ticles

oI eIectrons'

( r= 75 mkm ) u n O e r

satislactory

results rec~iveo ou~ing the

thermoemission

irom Cu~O spherical par-

the atmosphere air pressure provided a

correspondence. $321

S322

A.V. SusLov et al.

The second goal o f t h i s paper was t o p r e s e n t the r e s u l t s of the t h e o r e t i c a l i n v e s t i g a t i o n of the process of t h e r m o e m i s s i o n a l c h a r g ing of a spherical metal particle in the air, when it is surrounOeO by the condensed OisperseO phase. We have obtained an equation for thermoemissional charging of a lone metal particle. It defines the Oepenoancy of the value of the thermoemission fiow of electrons from the particle on the vaiues of their charge and temperature. When deriving this equation we also used the boundary sphere method. We aiso took into account the formation of negative oxygen ions 0

in the air surrounding the particIes anO the partial elast-

ic scattering of electrons' fIow (emitteO by the particles' surface) by nitrogen moiecules. 5asing on the charge equiIibrtum of the conOenseO phase lone particle with the electrons' voIume charge we obtained the vaIue of the eiectrons' volume concentration (ions ot 0 )anO

the mean vaIue of a condensed phase particle charge. We

have also receiveo the condition for an equilibrium ot a metal particie charge with a conOenseo phase voiume c~arge. It has been shown that under certain conOitions, when the exit work from the surface of a conOenseO phase particle is less than the exit work from a large metai particle surface, then a large metal particie can attain an equilibrium negative charge. the comparison of the experimental and Oesigned resuits of the electrons' thermoemission from iarge spherical copper parricide ( r= log mkm) when they are surrounded by the condensed disperseO phase consisting from CuB and CuzO particIes,>,yieloeO a satisfactory c o r r e s p o n d e n c e .