scholarly journals Integrated Approach for Detecting Convection Effects in Geothermal Environments Based on TIR Camera Measurements

2021 ◽  
Vol 11 (7) ◽  
pp. 3185
Author(s):  
Susana Del Pozo ◽  
Cristina Sáez-Blázquez ◽  
Ignacio Martín Nieto ◽  
Susana Lagüela
Keyword(s):  
Thermal Conductivity ◽  
Infrared Camera ◽  
Heat Rate ◽  
Thermal Characterization ◽  
Thermal Infrared ◽  
Integrated Approach ◽  
Geothermal System ◽  
Radiometric Calibration ◽  
Geothermal Systems

Thermal characterization of soils is essential for many applications, including design of geothermal systems. Traditional devices focus on the computation of thermal conductivity, omitting the analysis of the convection effect, which is important for horizontal geothermal systems. In this paper, a procedure based on the monitoring of the surface of the soil with a thermal infrared (TIR) camera is developed for the evaluation of the global thermal imbalance on the surface and in-depth. This procedure allows for the computation of thermal conductivity and global convection heat rate, consequently constituting a complete thermal characterization of the geothermal system. The validation of the results is performed through the evaluation of the radiometric calibration of the thermal infrared camera used for the monitoring and the comparison of the thermal conductivity values obtained in-depth, with traditional methods, and for the surface of the system.

scholarly journals Analysis of the Influence of Reducing the Duration of a Thermal Response Test in a Water-Filled Geothermal Borehole Located in Spain

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6693
Author(s):  
Ignacio Martín Nieto ◽  
Cristina Sáez Blázquez ◽  
Arturo Farfán Martín ◽  
Diego González-Aguilera
Keyword(s):  
Thermal Response ◽  
Thermal Characterization ◽  
Geothermal System ◽  
Thermal Response Test ◽  
Geothermal Systems ◽  
Time Intervals ◽  
Response Test ◽  
High Investment ◽  
Time Reduction

Usually thermal response tests are restricted to big geothermal projects; the high investment makes them less suitable for designing domestic low-enthalpy geothermal energy systems. The work here presented aims to study the influence of time reduction in thermal response tests on their precision. Due to the importance of the correct assessment of the thermal characterization of the ground for any kind of geothermal system, time reduction in this essay could make it more affordable to be implemented in some domestic systems. A thermal response test has been implemented, and several time intervals of the test have been considered in order to obtain different results for the thermal conductivity of the ground. The mentioned results have been then compared and also the domestic geothermal systems designed from them by the use of the geothermal software GES-CAL. Results have shown that, in some cases (our testing borehole has some singular characteristics), a significant time reduction in the data acquisition process of the thermal response test does not compromise seriously the precision of the results.

Evaluation of Thermal Characterization Techniques and Tools for Thermal Conductivity Measurement of Sub 100 Angstrom Thick Silicon Layers

2007 ◽  
Author(s):  
Keivan Etessam-Yazdani ◽  
Mehdi Asheghi
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurement ◽  
Thermal Characterization ◽  
Phonon Transport ◽  
Thermal Conductivity Measurement ◽  
Great Success ◽  
Silicon Structures ◽  
Thin Silicon ◽  
20 Nm

Experimental measurement of thermal conductivity is considered the most reliable tool for the study of phonon transport in ultra-thin silicon structures. While there has been a great success in thermal conductivity measurement of ultra-thin silicon layers down to 20 nm over the past decade, it is not clear if the existing techniques and tools can be extended to the measurements of sun 100 Angstrom layers. In this paper, an analytical study of the feasibility of electrical Joule heating and thermometry in patterned metal bridges is presented. It is concluded that thermal conductivity of silicon layers as thin as 5 nm can be obtained (uncertainty 20%) by performing steady-state measurements using an on-substrate nanoheater structure. The thermal characterization of silicon layers as thin as 1 nm may be possible using frequency domain measurements.

scholarly journals Thermal characterization of different graphite polystyrene

2018 ◽  
Vol 9 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Á. Lakatos ◽  
I. Deák ◽  
U. Berardi
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Thermal Characterization ◽  
Expanded Polystyrene ◽  
High Moisture ◽  
Insulating Materials ◽  
Insulation Materials ◽  
Vacuum Insulation ◽  
Study Laboratory

The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.

scholarly journals Review on Techniques for Thermal Characterization of Graphene and Related 2D Materials

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2787
Author(s):  
Jing Liu ◽  
Pei Li ◽  
Hongsheng Zheng
Keyword(s):  
Thermal Conductivity ◽  
Energy Transport ◽  
Large Deviation ◽  
2D Materials ◽  
Single Layer ◽  
Thermal Characterization ◽  
Great Depth ◽  
Characterization Methods ◽  
Critical Issues

The discovery of graphene and its analog, such as MoS2, has boosted research. The thermal transport in 2D materials gains much of the interest, especially when graphene has high thermal conductivity. However, the thermal properties of 2D materials obtained from experiments have large discrepancies. For example, the thermal conductivity of single layer suspended graphene obtained by experiments spans over a large range: 1100–5000 W/m·K. Apart from the different graphene quality in experiments, the thermal characterization methods play an important role in the observed large deviation of experimental data. Here we provide a critical review of the widely used thermal characterization techniques: the optothermal Raman technique and the micro-bridge method. The critical issues in the two methods are carefully revised and discussed in great depth. Furthermore, improvements in Raman-based techniques to investigate the energy transport in 2D materials are discussed.

scholarly journals Thermal Characterization of a New Bio-Based Insulation Material Containing Puffed Rice

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5700
Author(s):  
Maatouk Khoukhi ◽  
Abeer Dar Saleh ◽  
Ahmed Hassan ◽  
Shaimaa Abdelbaqi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Characterization ◽  
Insulation Material ◽  
Optimal Range ◽  
Insulation Materials ◽  
Material Optimization ◽  
Sample Amount ◽  
Puffed Rice ◽  
Influential Parameters

Although many advanced insulation materials have been recently developed, very few are eco-friendly and their production requires a substantial amount of energy and complex manufacturing processes. To address this issue, a bio-based thermal insulation material was developed using short- and long-grained puffed rice. A set of experiments was subsequently carried out to identify the best rice type and the optimal range for the most influential parameters (sample amount, temperature, and moisture level). Our findings revealed that short-grained rice exhibited greater puffing ability and was thus adopted in further material optimization experiments. These assessments indicated that the most optimal thermal conductivity of the insulation material and the highest puffing ratio was attained at 12–15% moisture, 260–270 °C temperature, and 15–18 g sample weight. The thermal properties, including thermal conductivity and fire reaction, and thermal performance of samples obtained using these parameters were similar to those of common insulation materials.

A Phase-Sensitive Technique for the Thermal Characterization of Dielectric Thin Films

1999 ◽  
Vol 121 (3) ◽  
pp. 528-536 ◽  
Author(s):  
S. W. Indermuehle ◽  
R. B. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Temperature Response ◽  
Front Surface ◽  
Thermal Characterization ◽  
Fused Silica ◽  
Dielectric Thin Films ◽  
Phase Sensitive

A phase-sensitive measurement technique for determining two independent thermal properties of a thin dielectric film is presented. The technique involves measuring a specimen’s front surface temperature response to a periodic heating signal over a range of frequencies. The phase shift of the temperature response is fit to an analytical model using thermal diffusivity and effusivity as fitting parameters, from which the thermal conductivity and specific heat can be calculated. The method has been applied to 1.72-μm thick films of SiO2 thermally grown on a silicon substrate. Thermal properties were obtained through a temperature range from 25°C to 300°C. One interesting outcome stemming from analysis of the experimental data is the ability to extract both thermal conductivity and specific heat of a thin film from phase information alone. The properties obtained with this method are slightly below the bulk values for fused silica with a measured room temperature (25°C) thermal conductivity of 1.28 ± 0.12 W/m-K.

Growth and Thermal Characterization of Yb:Y0.923Lu0.071VO4

2013 ◽  
Vol 709 ◽  
pp. 192-196
Author(s):  
Shi Ming Zhang ◽  
Bing Teng ◽  
De Gao Zhong ◽  
Bing Tao Zhang ◽  
Shu Jie Zhuang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Diffusion Coefficients ◽  
Laser Crystal ◽  
Thermal Characterization ◽  
Czochralski Method ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Structure Density

A new mixed laser crystal, Yb0.006Y0.923Lu0.071VO4, has been successfully grown using the Czochralski method. X-ray powder diffraction analysis shows that the crystal has ZrSiO4 structure. Density, thermal expansion coefficients, specific heat and thermal diffusion coefficients were measured, and the thermal conductivity coefficients were determined.

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