Rapid Heating of Gas/Small-Particle Mixture

The concept of using a mixture of particles and air as a medium to absorb radiative energy has been proposed for various applications. In this paper, carbon particles mixed with gas form a medium that absorbs radiation from sources such as concentrated solar energy. A single-particle, two-temperature model is used to study the transient temperature of the particle/gas mixture as it undergoes aconstant pressure expansion process. The results indicate that for particles smaller than 1 um in diameter, the surrounding air can be heated as quickly as the particles, while for particles larger than 1 mm in diameter, the air temperature stays relatively unchanged and the particles are heated to a very high temperature. The effect of scattering from the particles is also examined, revealingthat such a contribution is insignificant for small particles.