scholarly journals Microwave Absorption in Layered Media: Application to Landmine Detection

2000 ◽  
Vol 53 (5) ◽  
pp. 723 ◽  
Author(s):  
J. A. Hermann
Keyword(s):  
Thermal Properties ◽  
Microwave Absorption ◽  
Time Evolution ◽  
Microwave Radiation ◽  
Thermal Energy ◽  
Thermal Conduction ◽  
Landmine Detection ◽  
Composite Media ◽  
Conduction Model ◽  
One Dimensional

The absorption of microwave radiation and subsequent thermal conduction by simple composite media, consisting of parallel layers with disparate thermal properties,is analysed.The solutions for a one-dimensional conduction model are used to investigate the time evolution and distribution of thermal energy within moisture-laden soils containing non-absorbing objects.The application of these results to the detection of landmines is discussed and evaluated.

scholarly journals Thermal impact of Heinrich stadials in cave temperature and speleothem oxygen isotope records

2020 ◽  
pp. 1-14
Author(s):  
David Domínguez-Villar ◽  
Kristina Krklec ◽  
José Antonio López-Sáez ◽  
Francisco J. Sierro
Keyword(s):  
Thermal Conduction ◽  
Temperature Anomaly ◽  
Thermal Anomaly ◽  
Thermal Impact ◽  
Conduction Model ◽  
Temperature Changes ◽  
One Dimensional ◽  
Average Temperature ◽  
The Tropics ◽  
Thermal Variability

Abstract During each Heinrich stadial (HS), temperatures in southern Europe typically dropped several degrees during several hundred to few thousand years. We have developed a one-dimensional thermal conduction model that transfers the typical surface temperature anomaly of a HS to a series of hypothetical underlying caves. The results show that with increasing depth, the thermal anomaly is attenuated, the lag time increases, and the signal structure experiences larger modifications. The model suggests that in most cases, it is not acceptable to assume a synchronous thermal variability and similar average temperature values between the surface atmosphere and the cave interior at millennial timescales. We also simulated the thermal impact of the modeled HS on speleothem δ18O records. The outputs of most model scenarios suggest that temperature changes associated with the HS produce δ18O anomalies capable of contributing significantly or even decisively to the speleothem isotope variability. Therefore, despite controls other than temperature often being considered more important when interpreting Pleistocene speleothem δ18O records in temperate climates, this research suggests that temperature is expected to be one of the major controls of δ18O values in most cave sites outside the tropics and should be included as a significant parameter affecting Pleistocene speleothem δ18O records.

Conduction of Heat across Rectangular Cellular Enclosures

1981 ◽  
Vol 103 (3) ◽  
pp. 591-595 ◽  
Author(s):  
J. Eftekhar ◽  
G. Darkazalli ◽  
A. Haji-Sheikh
Keyword(s):  
Heat Flux ◽  
Analytical Model ◽  
Thermal Conduction ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Numerical Data ◽  
Form Solution ◽  
Geometrical Configuration ◽  
Conduction Model ◽  
One Dimensional

A simplified analytical model for the computation of thermal conduction across rectangular-celled enclosures based on the assumption of quasi-one-dimensional conduction in the cell partitions is presented. The rectangular enclosures may contain solid or liquid for which the conduction is two or three-dimensional depending on the geometrical configuration. Additional assumptions concerning radiation interchange between participating surfaces are necessary when the enclosure contains a stagnant gas. This analytical model leads to a closed form solution for temperature distribution in the partitions and the multidimensional conductive region. A parametric study of heat flux is presented. The numerical data define a range of parameters for which a one-dimensional conduction model is satisfactory.

scholarly journals Demonstration of Phase Change Thermal Energy Storage in Zinc Oxide Microencapsulated Sodium Nitrate

2021 ◽  
Vol 11 (13) ◽  
pp. 6234
Author(s):  
Ciprian Neagoe ◽  
Ioan Albert Tudor ◽  
Cristina Florentina Ciobota ◽  
Cristian Bogdanescu ◽  
Paul Stanciu ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Sodium Nitrate ◽  
Thermal Energy Storage ◽  
Metal Corrosion ◽  
Scanning Calorimetry

Microencapsulation of sodium nitrate (NaNO3) as phase change material for high temperature thermal energy storage aims to reduce costs related to metal corrosion in storage tanks. The goal of this work was to test in a prototype thermal energy storage tank (16.7 L internal volume) the thermal properties of NaNO3 microencapsulated in zinc oxide shells, and estimate the potential of NaNO3–ZnO microcapsules for thermal storage applications. A fast and scalable microencapsulation procedure was developed, a flow calorimetry method was adapted, and a template document created to perform tank thermal transfer simulation by the finite element method (FEM) was set in Microsoft Excel. Differential scanning calorimetry (DSC) and transient plane source (TPS) methods were used to measure, in small samples, the temperature dependency of melting/solidification heat, specific heat, and thermal conductivity of the NaNO3–ZnO microcapsules. Scanning electron microscopy (SEM) and chemical analysis demonstrated the stability of microcapsules over multiple tank charge–discharge cycles. The energy stored as latent heat is available for a temperature interval from 303 to 285 °C, corresponding to onset–offset for NaNO3 solidification. Charge–self-discharge experiments on the pilot tank showed that the amount of thermal energy stored in this interval largely corresponds to the NaNO3 content of the microcapsules; the high temperature energy density of microcapsules is estimated in the range from 145 to 179 MJ/m3. Comparison between real tank experiments and FEM simulations demonstrated that DSC and TPS laboratory measurements on microcapsule thermal properties may reliably be used to design applications for thermal energy storage.

scholarly journals Multidisciplinary Approaches for Assessing a High Temperature Borehole Thermal Energy Storage Facility at Linköping, Sweden

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4379
Author(s):  
Max Hesselbrandt ◽  
Mikael Erlström ◽  
Daniel Sopher ◽  
Jose Acuna
Keyword(s):  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermal Response ◽  
Site Investigation ◽  
Thermal Response Test ◽  
Response Test ◽  
Crystalline Bedrock

Assessing the optimal placement and design of a large-scale high temperature energy storage system in crystalline bedrock is a challenging task. This study applies and evaluates various methods and strategies for pre-site investigation for a potential high temperature borehole thermal energy storage (HT-BTES) system at Linköping in Sweden. The storage is required to shift approximately 70 GWh of excess heat generated from a waste incineration plant during the summer to the winter season. Ideally, the site for the HT-BTES system should be able to accommodate up to 1400 wells to 300 m depth. The presence of major fracture zones, high groundwater flow, anisotropic thermal properties, and thick Quaternary overburden are all factors that play an important role in the performance of an HT-BTES system. Inadequate input data to the modeling and design increases the risk of unsatisfactory performance, unwanted thermal impact on the surroundings, and suboptimal placement of the HT-BTES system, especially in a complex crystalline bedrock setting. Hence, it is crucial that the subsurface geological conditions and associated thermal properties are suitably characterized as part of pre-investigation work. In this study, we utilize a range of methods for pre-site investigation in the greater Distorp area, in the vicinity of Linköping. Ground geophysical methods, including magnetic and Very Low-Frequency (VLF) measurements, are collected across the study area together with outcrop observations and lab analysis on rock samples. Borehole investigations are conducted, including Thermal Response Test (TRT) and Distributed Thermal Response Test (DTRT) measurements, as well as geophysical wireline logging. Drone-based photogrammetry is also applied to characterize the fracture distribution and orientation in outcrops. In the case of the Distorp site, these methods have proven to give useful information to optimize the placement of the HT-BTES system and to inform design and modeling work. Furthermore, many of the methods applied in the study have proven to require only a fraction of the resources required to drill a single well, and hence, can be considered relatively efficient.

scholarly journals Investigating the effects of adding hybrid nanoparticles, graphene and boron nitride nanosheets, to octadecane on its thermal properties

RSC Advances ◽  
2020 ◽  
Vol 10 (25) ◽  
pp. 14785-14793
Author(s):  
Hossein Tafrishi ◽  
Sadegh Sadeghzadeh ◽  
Fatemeh Molaei ◽  
Hossein Siavoshi
Keyword(s):  
Thermal Properties ◽  
Boron Nitride ◽  
Ambient Temperature ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Hybrid Nanoparticles ◽  
Boron Nitride Nanosheets ◽  
Change Material

Octadecane is an alkane that is used to store thermal energy at ambient temperature as a phase change material.

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