Modellbasierte Untersuchung des Wärmeübergangs in einer induktiv beheizten Wirbelschicht

The aim of the presented study is to develop a new technology for a highly efficient heating of fluidized beds. The energy input in fluidized beds can be performed by convective indirect heating of the fluidizing medium, or by induction by means of electrically conductive inert particles (such as iron hollow balls), in which energy is transferred via an induction field. On the surface of these particles, the heat is released directly and without contact into the fluidized bed. The impact of parameters like bed mass, air velocity and supplied induction power on the inductive heating was systematically investigated. A simplified heat transfer model was developed. With this model a good agreement with the measured values for heating and cooling can be achieved.     

Bestimmung von Wärmeübergangskoeffizienten mit Hilfe des Wilson‐Plot‐Verfahrens

The heat transfer coefficient on the service side of a double‐pipe heat exchanger is determined with the Wilson‐plot method. Condensing hexanol vapor is used as heating medium and water in single phase counter current flow on the product side. In addition to the Wilson‐plot, two alternative methods are used for calculating the service side film heat transfer coefficient: the Nusselt theory for film condensation and the extraction from an overall heat transfer coefficient based on an energy balance and employing the Gnielinski equation for the tube side heat transfer. As the result, heat transfer coefficient can be calculated as a function of the transferred heat flux employing the Wilson‐plot.