DBPapers
DOI: 10.5593/SGEM2014/B12/S2.101

SIMPLIFIED NUMERICAL MODEL OF THERMAL CONDUCTION AROUND THE GEOTHERMAL BOREHOLES AND ITS VERIFICATION BY PROGRAM FEFLOW

A. Leiter
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-08-7 / ISSN 1314-2704, June 19-25, 2014, Book 1, Vol. 2, 791-798 pp

ABSTRACT
One of exploitation methods of geothermal energy is the use of a grid of geothermal wells. The grid is to be used when the demanded power is high. The grid is characterized by its shape and dimensions. Compliance with the exact dimensions, however, is difficult. The real grid of geothermal wells usually has a distorted geometry. Boreholes are also often drilled with a deviation. This degrades thermal properties of such a system. This paper contains a simplified mathematical model used for studying the temperature field around the borehole. The model takes into consideration only heat conduction in a thin bordered plate and is based on a commonly known heat equation. Only the steady-state is considered. One reference and next six variants of borehole systems are solved by the model. The results show lowest thermal resistance of systems with larger numbers of boreholes placed evenly and worsening of the system parameters in cases of distorted geometry among the boreholes. Studied variants are verified by specialized software FEFLOW.

Keywords: geothermal borehole geometry, distortion of grid geometry, borehole deviation, numerical model of the borehole system.