Open Access

ARTICLE

DEVELOPMENT OF A 10 KW MICROWAVE APPLICATOR FOR THERMAL CRACKING OF LIGNITE BRIQUETTES

Benjamin Lepers^a,∗, Thomas Seitz^a, Guido Link^a, John Jelonnek^a,b, Mark Zink^c

a Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology (IHM), Eggenstein Leopoldshafen, 76344, Germany
b Karlsruhe Institute of Technology, Institute for Highfrequency Techniques and Electronic (IHE), Karlsruhe, 71131, Germany
c TU Bergakademie Freiberg, Institute of Energy Process Engineering and Chemical Engineering (IEC), Fuchsmuehlenweg 9, 09599 Freiberg, Germany

* Corresponding Author: Email:

Frontiers in Heat and Mass Transfer 2015, 6, 1-6. https://doi.org/10.5098/hmt.6.20

Abstract

A compact 10 kW microwave applicator operating at 2.45 GHz for fast volumetric heating and thermal cracking of lignite briquettes has been successfully designed and tested. In this paper, the applicator design and construction are presented together with a sequentially coupled electromagnetic, thermal-fluid and mechanical Comsol model. In a first step, this model allows us to calculate the power density inside the lignite material and the temperature distribution in the applicator for different water flow rates. In a second step, the total stress due to the thermal dilatation, the internal pressure inside the ceramic and the contact pressure from the seals at both ends of the ceramic can be computed. In addition, preliminary experimental results are given and showed a significant mechanical strength weakening of the briquettes with microwave heating.

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Keywords

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