In this study, the effects of gas and slurry phase velocity, particle size, and slurry viscosity on phase holdups and heat transfer coefficients in two- and three-phase slurry fluidized beds have been determined. It is shown that heat transfer coefficients in two- and three-phase slurry-fluidized beds can be successfully estimated from the knowledge of liquid or slurry properties and energy input rate in the given system based on the surface renewal model with isotropic turbulence theory.