3D Self-heating numerical simulation of municipal waste material in a biodrier

The self-heating of municipal waste material (MWM) in an experimental bio-drying reactor was simulated by the finite volume method in order to describe the physical processes inside the reactor. The three-dimensional mathematical model includes the unsteady solution of turbulent flow field inside the reactor, the energy transport in the flow and the ensuing heat and mass transfer by convection over the MWM. Turbulent treatment is done with the k-ɛ model. The MWM is treated as a porous medium and the oxygen depletion and heat generation produced by the aerobic bacteria and chemical oxidation are also included. The validation of the mathematical model was realized by comparing experimental and numerical results which show good agreement. In order to improve the efficiency of the reactor, the air inlet and outlet position were changed which allowed to observe the variation of the turbulence parameters in the reactor and over the MWM surface. The mathematical model and the numerical simulation allow to predict the performance of an experimental bio-drying reactor and shed light over some criteria that can be explored in order to improve the bio-dryer and to increase the efficiency of the process.