Development And Modelling Of A Thermophotovoltaic System

Institut für Solare Energieversorgungstechnik Verein an der Universität Kassel e.V. Erneuerbare Energien und Energieeffizienz Renewable Energies and Energy Efficiency Band 8 / Vol. 8 Herausgegeben von / Edited by Prof. Dr.-Ing. Jürgen Schmid, Universität Kassel Giovanni Mattarolo Development and Modelling of a Thermophotovoltaic System This work has been accepted by the faculty of electrical engineering / computer science of the University of Kassel as a thesis for acquiring the academic degree of Doktor der Ingenieurwissenschaften (Dr.-Ing.). Supervisor: Co-Supervisor: Prof. Dr.-Ing. J. Schmid Prof. Dr.-Ing. P. Zacharias Defense day 29th November 2007 Bibliographic information published by Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at http://dnb.d-nb.de Zugl.: Kassel, Univ., Diss. 2007 ISBN: 978-3-89958-375-5 URN: urn:nbn:de:0002-3754 © 2007, kassel university press GmbH, Kassel www.upress.uni-kassel.de Cover layout: Grafik Design Jörg Batschi, Kassel Printed by: Unidruckerei, University of Kassel Printed in Germany A mamma e pap` a iii iv Abstract Thermophotovoltaic (TPV) generation of electricity is a technology based on the direct conversion of a radiation coming from a heat source into electric power by means of photovoltaic cells. TPV is a highly multidisciplinary technology, which involves and relates different research fields. Heat transfer via conduction, convection and radiation, chemical reaction and diffusion, generation, selection, transmission and absorption of radiation and photovoltaic effect are the different processes involved in the device to realize the energy conversion. Due to such a complexity, this technology has not yet reached a mature state: few TPV devices have been so far developed and brought successfully into operation and the highest system efficiency ever measured does not exceed 6.5%. However TPV generators could be soon competitive to other established electric generator technologies in the power range from some W to some kW. TPV, indeed, is a compact, reliable, quiet and safe technology with the potential for low cost and versatile fuel usage. The present PhD thesis describes the development and modelling of a small TPV gas-fuelled prototype based on GaSb cells. Purpose of the work is to realize the first ever TPV system which can be used as tester, working under different operating conditions with different combinations of cells and emitter materials. This would allow to get a better knowledge of the TPV technology and to develop optimization criteria for TPV systems. Besides the development of the prototype, another target of the work is to implement a theoretical simulation model of the TPV device and validate it, in order to realize a simulation tool which can be used for further analysis and optimization of the system. Several studies are already available in the literature, which deal with modelling of fuelled-TPV converters; however they are more focused on the spectral control and cell simulation and none of them takes into account the detailed modelling of the recuperative burner unit, which is indeed a key component where the heat is generated, converted into radiation by the emitter and partially recovered by the recuperative heat exchanger. The present work aims at developing a theoretical model of the whole TPV device: all the components and processes are considered, including also the combustion process and the heat transfer in the recuperator, as well as the reciprocal interactions between them. The thesis can be divided basically in two parts: the first one gives an overview of the TPV technology, while the second one describes the experimental and theoretical work