While the Discrete Element Method (DEM) is expected to evaluate wet grinding performance of bead mills, the conventional DEM requires high computational cost because it has the limitation of the time step size for stable computation. In addition, the simulation of wet grinding process requires additional cost to consider the interaction between beads and fluids by using such as CFD-DEM coupling techniques. This study proposes an analysis system for evaluating wet grinding performance of bead mills with less computational cost. Our proposed system adopts the Impulse-Based DEM (IB-DEM) which can use large time step size, the wall model by using the Sign Distance Function (SDF) which flexibly represents complicated shape walls, and the simple modeling of fluid force which can reduce computational cost. We verify our proposed system by comparing the numerical results with experimental results of bead mills with different shapes of rotors.
For sustainable development, there is growing demand for waste biomass utilization. In order to meet such social needs, we have demonstrated “sewage sludge fuel production technology using carbonization furnace with an electrically heated screw conveyor” for the purpose of energy utilization of sewage sludge. And we have confirmed that the technology can produce sludge fuel with a stable calorific value and save energy. Based on the results of this demonstration, the technology was evaluated and authorized in “JS innovation program” by the Japan Sewage Works Agency.
Self-propagating high-temperature synthesis (SHS) is a promising technique for rapid synthesis of high-purity powder. It can be used to synthesize an objective material using heat generated by the reaction of raw materials, and the reaction proceeds spontaneously by supplying energy to initiate the reaction. Therefore, SHS method enables highly efficient energy utilization that makes maximum use of exothermic reactions between reactants or reactant-atmosphere, and it would contribute to the prevention of global warming and the reduction of carbon dioxide gas. The present review gives a brief description of SHS method, and introduces our results of combustion synthesis of Al4SiC4 and MgSiN2, in which high-purity powder could be synthesized at low pressure.
This paper introduces meso-scale structure synthesis on metal surfaces through reaction processes from raw metal powders. The mesostructures are applied to metal/polymer anchor joining. The first topic is the synthesis of Fe-based porous structure on Fe substrate through the combustion reaction of the Fe-Ti-B system. The structure could be controlled in view of the phase equilibria at the maximum temperature of the reaction. A Fe/epoxy resin joint via the porous structure exhibits high tensile strength in a direction perpendicular to the joint interface. The second topic is the fabrication of mesostructure protruded on an Al alloy surface by laser scanning on Al-Ti-C powders. The meso-structural morphology is related to the formation of TiC and Al3Ti phases, which can be understood based on the solidification sequence after the laser irradiation. An Al alloy/CFRTP joint via the mesostructure exhibits high joint strength compared with previously reported similar anchor joints.