Heat transfer enhancement in dense suspensions of agitated solids. Part I: Theory

We predict heat transfer enhancement through dense homogeneous suspensions of agitated solids in conductive fluids by coupling the fluid and solid phases through a volumetric source term. The enhancement is governed by a Damköhler number demarcating an “exchange limit” where the source term dominates, and a “diffusion limit” set by the ability of agitated particles to self-diffuse. We point out effects of particle ordering on mixture conductivity and volumetric heat exchange rate, carry out thermal simulations to justify the form of these terms, and model further enhancements from gas velocity fluctuations induced by solids of high agitation.