  We perform experimental study of turbulent transport of nanoparticles in
convective turbulence with the Rayleigh number $\sim 10^8$ in the air flow. We
measure temperature field in many locations by a temperature probe equipped
with 11 E-thermocouples. Nanoparticles of the size $\sim 70$ nm in diameter are
produced by Advanced Electrospray Aerosol Generator. To determine the number
density of nanoparticles, we use Condensation Particle Counter. We demonstrate
that the joint action of turbulent effects (which are important in the core
flow) and molecular effects (which are essential near the boundaries of the
chamber) results in an effective accumulation of nanoparticles at the cold wall
of the chamber. The turbulent effects are characterised by turbulent diffusion
and turbulent thermal diffusion of nanoparticles, while the molecular effects
are described by the Brownian diffusion and thermophoresis, as well as the
adhesion of nanoparticles at the cold wall of the chamber. In different
experiments in convective turbulence in a chamber with the temperature
difference $\Delta T$ between the bottom and top walls varying between $\Delta
T= 29$ K to $\Delta T= 61$ K, we find that the mean number density of
nanoparticles decreases exponentially in time. For instance, the characteristic
decay time of the mean number density of nanoparticles varies from 12.8 min for
$\Delta T= 61$ K to 24 min for $\Delta T= 29$ K. For better understanding of
experimental results, we perform one-dimensional mean-field numerical
simulations of the evolution of the mean number density of nanoparticles for
conditions pertinent to the laboratory experiments. The obtained numerical
results are in a good agreement with the experimental results.
