Effects of Granular Temperature on Inter-Phase Heat Transfer in Gas-Solid Flows

Direct numerical simulations with the immersed boundary-lattice Boltzmann method are used to investigate the effect of granular temperature on the heat transfer. The numerical method is validated first by comparing the simulation results for the heat conduction around a stationary particle immersed in stationary fluid with the analytical solution, then by comparing the results for forced convection around a single particle and around random arrays of spherical particles with empirical correlations published in literatures. To mimic the granular temperature of a typical gas-solid system, random velocities obeying the isotropic Maxwellian distribution are imposed to all particles in the computational domain. The simulation results show that the effect of granular temperature on the heat transfer is significant especially when the solid volume fraction and the particle Reynolds number are small. Based on the present results, a new term reflecting the effects of granular temperature and is added to the “static” Nusselt number correlation to formulate a new heat transfer correlation.