Microwave calorimeter for dielectric and thermal analysis of materials

• Published in: Energy (Oxford) 2023-01, Vol.263, p.125909, Article 125909
• Main Authors: Sánchez, Juan R., Gutiérrez-Cano, José D., Plaza-González, Pedro J., Penaranda-Foix, Felipe L., Catalá-Civera, José M.
• Format: Article
• Language: English
• Subjects: calorimeters; Calorimetry; ceramics; Dielectric properties; energy; heat; Microwave heating; microwave treatment; specific heat; temperature; Thermal analysis; Thermal properties
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2022.125909

A fast method for microwave processing and measurement of dielectric and thermal properties of materials as a function of temperature has been developed (MW-DETA). Unlike previous approaches, the method provides totally new quantitative measurements of the thermal parameters, which are fundamental for calculating the specific heat and in particular, the energy requirements of electrification of materials processing via microwave heating. The in-situ measurement of dielectric properties of the sample with temperature, together with the precise numerical modelling of the thermal process, provided the necessary information to quantify the thermal and microwave losses and, therefore, the precise amount of power delivered to the sample that is converted into heat. Compared to conventional calorimeters, microwave heating reduces the experimental time and improves the uniformity of heating, which leads to a fast and reliable method to determine the thermal properties of the material under test with different operation modes, either constant or variable heating rates. The functionality of the thermal parameters measurement system has been demonstrated by heating and measuring a ceramic sample of Macor up to 400 °C. Accuracy reached in the thermal process has been validated by comparison with a conventional DSC analysis. [Display omitted] •A novel fast microwave calorimeter with quantitative energy measurement is developed.•Energy consumption in the calorimeter including thermal and microwave losses is evaluated.•EM coupled with thermal simulation determines heat transfer and temperature distribution.•0D model accurately predicts temperature evolution and thermal parameters.•Comparison with DSC measurements validates the proposed microwave calorimetry method.