Dw. Mackowski et al., EFFECT OF RADIATIVE HEAT-TRANSFER ON THE COAGULATION DYNAMICS OF COMBUSTION-GENERATED PARTICLES, Aerosol science and technology, 20(1), 1994, pp. 83-99
We examine the influences of radiation heat transfer on the size and n
umber density evolution of small coagulating particles. On a microscop
ic level, radiative emission and/or absorption by the particle will pe
rturb the ps temperature field adjacent to each particle. As a result
of thermophoretic particle transport, the nonequilibrium condition can
alter the collision rates with neighboring particles. A simplified an
alysis of the thermophoretic coagulation mechanism suggests that net r
adiative cooling of the particles can lead to an accelerated growth of
mum-sized particles, whereas net radiative heating can act to essenti
ally freeze coagulation rates. On the macroscopic level, the addition
or removal of heat in the ps through radiative absorption/emission by
the particle cloud can also significantly alter, through thermophoreti
c transport, the local particle number density. Under certain cases th
ese effects can augment the accelerated coagulation rates that occur u
nder radiative cooling conditions. We also examine the particular situ
ation of equilibrium between particle cloud radiative absorption and e
mission-which results in no net macroscopic effect on the gas. Under c
onditions where the spectral distribution of the incident radiation di
ffers from that of the emitted radiation, radiative equilibrium can le
ad to accelerated growth of certain particle sizes and retarded growth
of others. Using numerical solutions to the general dynamic equation
for particle growth, we demonstrate the possibility of using incident
radiation of controlled intensity and spectral distribution to narrow
the particle size distribution function of coagulating aerosols.