Simulação numérica e otimização do processo de produção de pigmentos cerâmicos com recurso a micro-ondas

Pedro André Varela Ramos

Key information

Authors:

Pedro André Varela Ramos (Pedro André Varela Ramos)

Supervisors:

José Carlos Fernandes Pereira (José Carlos Fernandes Pereira); Duarte Manuel Salvador Freire Silva de Albuquerque (Duarte Manuel Salvador Freire Silva de Albuquerque)

Published in

02/05/2021

Abstract

Ceramic pigments are widely used to give colouration in several industries. The high temperatures that characterize pigment formation make this sector a very energy intensive one, contributing to green-house gas emissions if conventional heating is used. The aim of this Thesis is to access the possibility of producing ceramic pigments using electromagnetic heating and contribute to a high efficiency process that allows pigment production using microwaves while avoiding temperature related problems such as hot-spots and thermal-runaway. In this study, the continuous microwave production of pigments was modelled using COMSOL Multiphysics together with a controller developed in MATLAB to automatically manage the input power and cavity impedance. A single-mode cavity operating at 2.45 GHz, together with a rectangular waveguide, was used. A chemical model using experimental data was developed using a model-fitting approach to predict chemical conversion with time. Mathematical model includes two-way coupling between Maxwell’s equations and energy equation as well as between thermal and chemical interfaces. A parametric study including variation in velocity and convection coefficient was also performed to access the impact of these variables in the process efficiency. To show the influence of physical properties in the heating mechanism two pigments were used in the simulations. Solution Verification was performed to sustain results reliability.