Franck Brachelet

In situ characterization of thermophysical soil properties—Measurements and monitoring of soil water content with a thermal probe

In a period of surging energy prices, resource depletion, and concerns over the use of nuclear power, energy savings are paramount and a major component of ongoing sustainable development. Geothermal energy is the energy stored in the form of heat beneath the surface of the Earth. Related to this, the thermal properties of soils are of great importance, particularly with regard to the modern trends of utilizing the subsurface for transmission of either heated fluids or high power currents. For example, in geothermal hydrology or geotechnical engineering applications, the thermal conductivity must be determined to assess the energy potential of the soil. The presence of water (groundwater, rainfall, natural moisture) improves both the thermal conductivity and thermal capacity fields. We present an original method—based on a thermal study and the use of non-integer order models—to determine the thermophysical parameters of different soils in near-surface layers, and link them to the water content variations...

Active thermography based on the heat transfer process in determining the influence of micro defects in bio-ceramic materials surface

This paper presents a non-destructive technique (NDT) using active infrared thermography and the thermal excitation consisting in an electric plane, applicable for bio-ceramic surface micro-defects detection. For this work we chose to study samples made of bio-ceramic (hydroxyl-apatite), having a cylindrical form with a diameter of φ = 15.20 mm and a thickness of 2.00 mm. The aim of this paper was to study the influence of surface defects in the heat transfer process for the bio-ceramic materials. The advantages of this method are the rapidity of determining and the safety of the material structure after the thermal excitation. For the concluding results there are necessary only a few seconds and a temperature difference of few Celsius degrees to discover the defect and the heat loss on the sample surface.