Heat transfer to packed and stirred beds from the surface of immersed bodies

Abstract The heat transfer between packed and stirred beds and immersed surfaces is controlled by the contact resistance at the surface followed by the heat penetration resistance of the bulk. Both resistances can be predicted from model equations with sufficient accuracy. The contact resistance and the bulk penetration resistance for packed beds follow from physical properties, while the prediction of the bulk penetration resistance for stirred beds requires the introduction of an empirical parameter, the so-called mixing number in order to describe the random particle motion. The mixing number was found to lie between 2 and 25, depending on the design of the stirrer.