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.     

Radiowellenunterstützte thermische Behandlung als neue Technologie zur Trocknung und Dekontamination von Bauteilen

Direct dielectric heating using radio waves, i. e., electromagnetic waves in the high‐frequency range, was successfully tested for the application in the field of building redevelopment. It could be shown that this method can be utilized to homogeneously and efficiently heat various materials such as sandstone and fibre concrete in a controlled manner. Final temperatures of more than 100 °C can be achieved. This allows drying of building materials without disturbance of the structure. By placing formed structures in a packed bed of an appropriate material, this method can also be applied for the preservation of cultural goods, for example for drying sculptures.     

Chemikalienfreie Bekämpfung von Holzschädlingen durch dielektrische Erwärmung mit Radiowellen und Mikrowellen

Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase.     

Dielektrische Erwärmung von Zeolithen mittels Radiowellen – Selektivität,thermo‐chromatographischer Puls und Trocknen mit Wasser

Dielectric heating with radio‐frequency energy can be applied for a wide spectrum of dry or moist zeolites. It is possible to homogeneously heat packed beds in technical scale. The energy absorption strongly varies with the zeolite type enabling selective heating of layered arrangements containing different zeolites. The specific effect of water interacting with the structural cations allows establishing pronounced temperature gradients within a packed bed with varying water content. For distinct materials such as zeolite NaY, a coupled water‐temperature pulse moving through the packed bed can be established. Potential applications for such a so‐called thermo‐chromatographic pulse range from adsorptive catalytic off‐gas cleaning to thermal regeneration of zeolites in the context of gas drying.