http://hdl.handle.net/10174/995 2026-04-19T20:30:53Z http://hdl.handle.net/10174/41768 Title: Heat flow and deep temperature in South Portugal Authors: Duque, Maria Rosa; Mendes-Victor, Luís Abstract: Heat-flow density determinations were made in South Portugal. The region of study covers the Algarve Basin, the South Portuguese Zone, part of the Ossa Morena Zone and part of the Lusitanian Basin. Two sets of data were used to obtain heat-flow density values in this region: 13 determinations were made in boreholes under equilibrium conditions and 4 determinations in oil exploration boreholes. Gravity and aeromagnetic data were used to constrain the interpolation of the heat-flow density isolines in the South Portuguese Zone and part of the Ossa Morena Zone. Seismic data were used to model two-dimensional heat transfer through a vertical cross section located in the South Portuguese Zone. The radiogenic heat source distribution was estimated using a relationship between seismic velocity (Vp) and radiogenic heat production (A). A temperature profile was computed taking into account the effect of temperature on thermal conductivity and on the seismic velocity. 1993-08-31T22:00:00Z http://hdl.handle.net/10174/39957 Title: NONCONVENTIONAL METHODS USED TO STUDY EARTH'S THERMAL PROPERTIES INCLUDING GEOTHERMAL HEAT FLOW Authors: Duque, Maria Rosa Abstract: Nonconventional methods have been used to obtain geothermal density data in regions without adequate holes need to make measurements or where detailed distribution values of this parameter are required. The method used in the present work uses data obtained from seismic tomography, velocity distribution of P waves and VP/VS ratio values, to define “warm” and “cold” regions in the crust.The distribution and intensity of radioactive heat sources near the surface is obtained using radiometric data from rocks. The heat flow at the surface of the Earth is obtained by addition of the heat generated by the sources studied with the heat flowing from deeper regions. With the method presented it is possible to obtain detailed maps of geothermal heat flow density at the Earth’s surface. It is also possible to obtain the depth location of “warm” layers with fluids that can be used in several applications. Physical properties including radioactivity, thermal conductivity and heat expansion coefficient may be used to explain some earthquakes located near the contact zone of different geological materials. 2025-01-01T00:00:00Z http://hdl.handle.net/10174/39892 Title: Geothermal Heat Flow by Conduction in Mainland Portugal Authors: Duque, Maria Rosa Abstract: Heat flow density measurements in Portugal were made in boreholes used for mining prospecting. Heat flow density values in the sedimentary basins of the western and southern margins of the country were obtained using data from oil or gas prospecting works. Due to the scarcity of data in the central and northern regions of the country, numerical models based on some characteristics of the region were used to obtain more heat flow values. The total of heat flow values used in this work is 69, with 17 values obtained using numerical models, 36 obtained in boreholes and 16 obtained from oil/gas prospecting wells data. The analysis and location of these data allows to define different regions in the territory and characterize them using average values of heat flow density, temperature gradient and thermal conductivity. Statistical values with all the data in the territory are also presented. 2024-01-01T00:00:00Z http://hdl.handle.net/10174/38899 Title: Thermal performance of a hybrid steel-concrete tank section for thermal energy storage in concentrated solar power plants Authors: Guerreiro, Luis; Lucio, Tamara; Alonso, Maria; Villardón, Rafael; Lopez, Javier; Martin, Mariano Editors: F. Cabeza, Luisa Abstract: Several studies of thermocline molten salt tanks have proven to be suitable for thermal energy storage systems. However, there is a lack of experimental investigations performed. The building of a hybrid section and its assessment operating as a thermocline tank are the main objectives of this research work. The novelty is to prove the performance of the hybrid tank concept made of a thick concrete layer and a thin steel liner. The tank section studied comprises the following layers of materials: a steel liner, an air gap interface, a high thermal concrete layer and insulating materials. The thermal response was monitored using thermocouples located between the layers, at different heights and widths of the whole tank section length. The performance during the commissioning (first heat) and the operation (3 heat/cool cycles between 200/500 °C) of the tank section is analysed. The thermal appropriateness of using concrete as part of the thermocline tank has demonstrated the suitability and good thermal response up to 425 °C showing isolating and thermal inertia. The presence of the air gap interface between the steel liner and the concrete generates a heat convection current with local energy gradients along the section height. 2023-03-31T23:00:00Z