  In dense systems composed of numerous nanoparticles, direct simulations of
near-field radiative heat transfer (NFRHT) require considerable computational
resources. NFRHT for the simple one-dimensional nanoparticle chains embedded in
a non-absorbing host medium is investigated from the point of view of the
continuum by means of an approach combining the many-body radiative heat
transfer theory and the Fourier law. Effects of the phase change of the
insulator-metal transition material (VO$_2$), the complex many-body interaction
(MBI) and the host medium relative permittivity on the characteristic effective
thermal conductivity (ETC) are analyzed. The ETC for VO$_2$ nanoparticle chains
below the transition temperature can be as high as 50 times of that above the
transition temperature due to the phase change effect. The strong coupling in
the insulator-phase VO$_2$ nanoparticle chain accounts for its high ETC as
compared to the low ETC for the chain at the metallic phase, where there is a
mismatch between the characteristic thermal frequency and resonance frequency.
The strong MBI is in favor of the ETC. For SiC nanoparticle chains, the MBI
even can double the ETC as compared to those without considering the MBI
effect. For the dense chains, a strong MBI enhances the ETC due to the strong
inter-particles couplings. When the chains go more and more dilute, the MBI can
be neglected safely due to negligible couplings. The host medium relative
permittivity significantly affects the inter-particles couplings, which
accounts for the permittivity-dependent ETC for the VO$_2$ nanoparticle chains.
