Surface Contact—Its Significance for Multiphase Heat Transfer: Diverse Examples

Abstract

The nature and dynamics of surface contacts often govern heat transfer in multiphase systems. Physical scale, time scale, and intermolecular forces all affect basic mechanisms of transport between the multiphase medium and a submerged surface. Parameters in one or more of these domains can be the determining factor for transfer rate and efficiency, depending on the specific application. Research results for systems as diverse as fluidized particles and condensing liquids are examined to illustrate this significance. Specifically, it is shown that for heat transfer to/from surfaces submerged in bubbling fluidized beds, parameters in time domain are most important. In the case of condensation, it is shown that substantial enhancement of heat transfer coefficient can be obtained by controlling parameters in the domain of surface free energies.