Interaction of heat transfer, drying and thermochemical processes in a hearth furnace floor
C3 delivers experimental data sets which allow to verify DEM/CFD simulations and is, therefore, a key element in the CRC/TRR’s validation strategy. Two test rigs are used, a generic grate system and a generic hearth furnace configuration.
The grate system provides a comprehensive data for particle mechanics and convective heat transfer for polydisperse moving granular assemblies with gas flow. The particle bed is agitated by moving grate bars which allow for different bar moving modes. Mixing and segregation can be studied through optically transparent test rig side walls. The moving granular assembly is exposed to a passing flow of hot air. Particle temperatures are obtained by infrared camera recording. Spherical particles and particles of complex shape (dodecahedron) made of plastics were used as granular material. In addition, the test rig serves as a test bed for measurement of particle trajectories by Positron Emission Particle Tracking (project C1) and Radar Wave based tracking (project B1).
In the hearth furnace configuration, particles located on the circular furnace floor are agitated by a rotating rabble arm which is equipped with mixing blades. The furnace floor is heated electrically which allows to study contact heat transfer. In addition, the particle assembly can be can be exposed to radiative heat input. Experiments with spherical particles made of plastics and and aluminium have been carried out for monodisperse and polydisperse assemblies. Also here, particle temperature and particle trajectories were determined. Silica gel and beech wood particles will be used for drying experiments. Pyrolysis of beech wood will be examined in funding period 2.
In addition, contact force parameters are determined in C3 as an input parameter for DEM/CFD simulations in project C7.