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Projeto de investigação
Development of an Efficient Microwave System for Material Transformation in energy INtensive processes for an improved Yield
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Enhancing the efficiency of Brown 24 pigment production through continuous microwave heating in conveyor belt and rotary kiln systems
Publication . Ramos, Pedro A.V.; Albuquerque, Duarte M.S.; Pereira, José C.F.; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; DEMI - Departamento de Engenharia Mecânica e Industrial; Faculdade de Ciências e Tecnologia (FCT); Elsevier Science B.V., Amsterdam.
In energy intensive industries, the continuous production with microwave technology presents several challenges in achieving high energy efficiency and heating uniformity. In the ceramic pigments sector, the Brown 24 is the ideal candidate for this study due to its susceptibility to thermal runaways and its high temperature to reach total conversion, higher than 1000 K. By another hand, most literature related to this field focus on static systems while ignoring the continuous ones which are required by the industry. A coupled model that integrates thermal, electromagnetic and chemical phenomena within an energy system was implemented in COMSOL Multiphysics. Additionally, a MATLAB controller was employed to dynamically adjust the cavity length through a moving plunger, which maximizes the electrical efficiency. The required power is also managed to guarantee a total chemical conversion of the material. The proposed optimization methodology reduces computational costs, and it is applicable to any continuous microwave system processing moving solid materials. In this work, two microwave configurations were optimized. The first one, based on a conveyor belt, achieved a global efficiency close to 70%. While the second one, based on a rotary kiln, achieved a global efficiency of 85% and a production rate of 4.66 kg/h, significantly outperforming a previous study by factors of 1.57 and 2.06, respectively. These findings show the potential for substantial improvements in continuous microwave systems.
Modelling and energy efficiency analysis of the microwave continuous processing of limestone
Publication . Gonçalves, Sofia N.; Albuquerque, Duarte M.S.; Pereira, José C.F.; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; Faculdade de Ciências e Tecnologia (FCT); Elsevier
Our numerical investigation is oriented to the energy efficiency of the microwave heating technology for the continuous production of cement clinker. Simulations of the novel microwave continuous processing of limestone are performed using the COMSOL Multiphysics® Software. The proposed mathematical model couples Maxwell's equations with energy and chemical equations, and numerical verification and validation are undertaken to support the accuracy of the results in this work. This approach includes automatic control actions regulating energy input and cavity impedance. A rectangular waveguide, operating as a single-mode cavity at 2.45 GHz, is utilized. The impact of various fill ratios of material on the system's efficiency unveiled an intriguing heat transfer mechanism responsible for optimal operational conditions, with microwave efficiency up to 75% and thermal efficiency exceeding 90%. Notably, the potential of microwave technology in reducing greenhouse gas emissions is contingent upon establishing clean energy sources for electricity production.
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Entidade financiadora
European Commission
Programa de financiamento
H2020
Número da atribuição
820783