Analysis of temperature variation in a geothermal borehole through TRT and cooling tests in the city of Talca, Chile
DOI:
https://doi.org/10.4067/S0718-28132020000100006%20Keywords:
Geothermal borehole, Temperature, Thermal conductivity, Borehole geothermal heat exchanger (BHE), Thermal response test (TRT), Cooling testAbstract
On the San Miguel campus of the Catholic University of Maule, in the city of Talca (Chile), the conductivity and thermal resistance of a geothermal borehole were analyzed through a thermal response test (TRT) based on initial ignoring time (IIT) for 3 different heat injection tests, resulting in the thermal conductivity of at least 1.6 Wm-1K-1 and a thermal resistance of 0.25 mKW-1 (most unfavorable values). Taking advantage of the heating process through the TRT, the cooling capacity of the vertical geothermal heat exchanger was analyzed from a theoretical and practical point of view. Temperature profiles were obtained along the borehole at different time intervals through a water pressure and temperature sensor, and in this way, an average temperature curve of the borehole until the equilibrium temperature was obtained. The latter was compared with the theoretical curve of the cooling process. The results indicate that the cooling curves obtained in a practical way are similar to the theoretical curves. Together with this, a value for the thermal conductivity of 2.35 Wm-1K-1 was obtained.
References
Carslaw, H.S. and Jaeger, J.C. (1959). Conduction of heat in solids. 2nd ed., Oxford University Press, Oxford, UK.
Castro, D., Pascual, P. y Indacoechea, I. (2012). Proyecto de aprovechamiento geotérmico de baja entalpía en edificio de usos múltiples. Parque Tecnológico. Tomo II: Campo de Sondas. Informe. Talca, Chile.
del Valle Fernández, P. (2012). Uso conjunto de diagrafías y TRT para la determinación de parámetros térmicos de un sondeo. Tesis de Máster en Ingeniería Energética, Universidad de Oviedo, España.
Ingersoll, L.R., Zobel, O.J. and Ingersoll, A.C. (1954). Heat conduction with engineering, geological, and other applications. University of Wisconsin Press, USA.
Jara Morales, L.S. y Martínez Martínez, M.V. (2016). Guía técnico-económica para la construcción de sistemas de climatización geotérmica aplicado a viviendas unifamiliares. Tesis de pregrado, Universidad Católica del Maule, Talca.
Lee, C., You, J. and Park, H. (2018). In-situ response test of various borehole depths and heat injection rates at standing column well geothermal heat exchanger systems. Energy and Buildings 172, 201–208.
Llopis Trillo, G. y Rodrigo Angulo, V. (2008). Guía de la energía geotérmica. Fundación de la Energía de la Comunidad de Madrid, España.
Mogensen, P. (1983). Fluid to duct wall heat transfer in duct system heat storages. Proceedings of the International Conference on Subsurface Heat Storage in Theory and Practice, Stockholm, Sweden, 652–657.
Monzó, P.M. (2011). Comparison of different Line Source Model approaches for analysis of thermal response Test in a U-pipe Borehole Heat Exchanger. MSc thesis, KTH School of Industrial Engineering and Management, Stockholm, Sweden .
Natural Resources Canada (2004). Heating and cooling with a heat pump (EnerGuide). Office of Energy Efficiency, Energy Publications, Canada.
Oyarce, C.N. (2018). Caracterización geotécnica de los suelos de fundación de la ciudad de Talca. Tesis de pregrado, Universidad Católica del Maule, Talca.
Sharqawy, M.H., Said, S.A., Mokheimer, E.M., Habib, M.A.,Badr, H.M. and Al-Shayea, N.A. (2009). First in situ determinationof the ground thermal conductivity for boreholeheat exchangerapplications in Saudi Arabia. Renewable Energy 34(10), 2218–2223.
VDI 4640 (2010). Thermische Nutzung des Untergrundes – Grundlagen, Genehmigungen, Umweltaspekte. Beuth Verlag, Berlin, Germany.
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