Interaction of heat transfer, drying and thermochemical processes in a hearth furnace floor
C3 will deliver unique data sets which allow to verify DEM/CFD simulations. Funding period 1 will concentrate on particle mechanics, heat transfer (convection, radiation, contact heat transfer) and drying of polydisperse spherical particles. In the following periods, the experiment will be extended to chemical reaction, namely pyrolysis, of non-spherical particles with anisotropic properties (wood). In funding period (FP) 1, two test rigs will be used, an existing generic grate system and a newly developed generic hearth furnace configuration.
The grate system will be used to supplement an already existing data set for particle mechanics, heat transfer and drying of monodisperse particle assemblies by a corresponding data set for polydisperse packings. This will lead to the most comprehensive data set available for the validation of DEM/CFD simulations of thermally thick particles which underlie a polydisperse particle size distribution in a system dominated by convection.
The hearth furnace configuration has the great advantage that it allows to examine further phenomena, i.e. the combination of the effects of convective, radiative and conductive heat transfer in one test rig with good optical access to particle motion. Therefore, it will be introduced in FP1 as the future test bed for C3. The hearth furnace configuration in C3 represents one of the two system experiments (together with C2) which will accompany BULK-REACTION over the three funding periods, and, therefore, is a key element in the CRC/TRR’s validation strategy.
Experiments with spherical polyoxymethylene (POM), silica gel, beech wood, aluminium (5-20 mm) and glass particles (1 mm) will be carried out for monodisperse and polydisperse assemblies. The silica gel and beech wood particles are humidified for drying experiments in a climate cabinet. Particle trajectories, particle velocity (Particle Tracking Velocimetry, PTV), particle surface temperature (IR camera) and humidity (moisture indicator) will be measured. Mass loss rate due to drying will be determined by measuring air mass flow and gas phase humidity by capacitive sensors. Finally, contact force parameters are determined as an input parameter for DEM/CFD simulations in project C7.