Study of heat transfer under RF heating in a micro trickle-bed reactor.

Understanding of the principles of coupling of electromagnetic (EM) energy with the absorbing materials is of primary importance for the design of new functional materials as well as proper design of the corresponding reaction equipment. The heating effects of magnetic nanoparticles submitted to AC magnetic fields are due to several types of loss processes (hysteresis losses, Neel and Brown relaxation), the relative contributions of which depend strongly on particle size and surrounding medium. Hysteresis losses of selected magnetic materials are investigated with a superconducting quantum interference device (SQUID magnetometer). The analysis of temperature dependences of coercivity (or coercive force) and saturation magnetisation allows us to predict a heat evolution function, which is further used in equipment design.
The spatial distribution of EM energy, i.e. the EM field, is directly linked with the uniformity of reactor performance, especially when dealing with assemblies. Thus, this issue is directly related with the scaling-out of a single channel reactor and the suitability of the approach investigated here for chemical production. For reactors with large axial dimensions, i.e. straight or coiled tubes, the EM field configuration may also correlate with the reactor length, i.e. with the residence time scale of the chemical reaction. Therefore, optimum positioning of the channel with respect to the field and optimum channel shape (circular, square etc.) is of importance.
In this project a model for description of the spacial distribution of electromagnetic field in a EM coil is developed. Anisotropy of the EM field is artificially created by modifying the applicator. Experiments are carried out with single capillary located in various positions with respect to the EM field, in order to quantify the effect of mutual positioning on the energy uptake by the reacting system and to compare the performance of RF heating with conventional heating.