scholarly journals A new method for thermal conductivity measurement: application to complex heterogeneous materials used in thermal batteries

2021 ◽  
Vol 2116 (1) ◽  
pp. 012041
Author(s):  
T Ledevin ◽  
M William-Louis ◽  
L Courty ◽  
D Fabre ◽  
L Faget
Keyword(s):  
Thermal Conductivity ◽  
Heterogeneous Materials ◽  
Conductivity Measurement ◽  
Phase Shifts ◽  
Experimental Measurements ◽  
Thermal Signal ◽  
Thermal Batteries ◽  
Different Temperatures ◽  
Materials Used ◽  
Thermal Conductivity Λ

Abstract The thermal conductivity of heterogeneous materials used in thermal batteries is difficult to measure. These materials must be handled under controlled atmosphere with methods adapted to their porous nature. The method presented in this work uses heating plates to send a sinusoidal thermal signal to the tested sample. The whole setup is confined in a glovebox to ensure the composition and hygrometry of the atmosphere. Parametric computer simulations with varying thermal conductivity (λ) of the sample and thermal resistance (h) of the contacts as inputs were performed to calculate the phase shifts associated with two thicknesses of the sample. Experimental measurements of phase shifts on these two configurations allowed the identification of the only couple (λ,h) which matches the phase shifts on the respective thicknesses. This method is validated using the reference material BK7 at different temperatures. Thermal conductivities of a heterogeneous cathode used in thermal batteries is also given using this method.

scholarly journals Finite Element Method and Cut Bar Method-Based Comparison Under 150°, 175° and 310 °C for an Aluminium Bar

2019 ◽  
Vol 10 (1) ◽  
pp. 296
Author(s):  
José Eli Eduardo Gonzalez Duran ◽  
Oscar J. González-Rodríguez ◽  
Marco Antonio Zamora-Antuñano ◽  
Juvenal Rodríguez-Reséndiz ◽  
Néstor Méndez-Lozano ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Method ◽  
Finite Element ◽  
Measurement System ◽  
Conductivity Measurement ◽  
Maximum Temperature ◽  
Metallic Materials ◽  
Solid Materials ◽  
Materials Used ◽  
Element Method

Analyses were developed using a finite element method of the experimental measurement system for thermal conductivity of solid materials, used by the Centro Nacional de Metrología (CENAM), which operates under a condition of permanent heat flow. The CENAM implemented a thermal conductivity measurement system for solid materials limited in its operating intervals to measurements of maximum 300 ° C for solid conductive materials. However, the development of new materials should be characterised and studied to know their thermophysical properties and ensure their applications to any temperature conditions. These task demand improvements in the measurement system, which are proposed in the present work. Improvements are sought to achieve high-temperature measurements in metallic materials and conductive solids, and this system may also cover not only metallic materials. Simulations were performed to compare the distribution of temperatures developed in the measurement system as well as the radial heat leaks, which affect the measurement parameters for an aluminium bar, and uses copper bars as reference material. The simulations were made for measurements of an aluminium bar at a temperature of 150 ° C, in the plane and 3D, another at 175 ° C and one more known maximum temperature reached by a sample of the aluminium bar with a new heater acquired at 310 ° C.

scholarly journals Impact analysis of humidity and temperature on the value of thermal conductivity λ coefficient of insulating materials used inside buildings

2013 ◽  
Vol 12 (4) ◽  
pp. 165-176
Author(s):  
Maciej Trochonowicz ◽  
Beata Witek ◽  
Marcin Chwiej
Keyword(s):  
Thermal Conductivity ◽  
Laboratory Tests ◽  
Impact Analysis ◽  
Insulating Materials ◽  
Coefficient Of Thermal Conductivity ◽  
Temperature And Humidity ◽  
Specific Temperature ◽  
Materials Used ◽  
Thermal Conductivity Λ ◽  
Cellular Concrete

The aim of the article is to present the issues related to the use of climate panels as insulating materials used inside buildings. The study involved four materials, the two of them is a lightweight cellular concrete, the other two were produced on the basis of lime silicate. The main aim of the laboratory tests was to determine the coefficient of thermal conductivity λ depending on the changing temperature and humidity. Based on research the sorption materials curves were determined. The study allows you to specify the amount of moisture that can be accepted by the material in specific temperature and humidity conditions. In addition, the examined coefficients of thermal conductivity compared with the values declared by suppliers to assess compliance with the data contained in the data sheet.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

Rolling Resistance Calculation Procedure Using the Finite Element Method

2019 ◽  
Vol 48 (3) ◽  
pp. 224-248
Author(s):  
Pablo N. Zitelli ◽  
Gabriel N. Curtosi ◽  
Jorge Kuster
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Rolling Resistance ◽  
Element Model ◽  
The Finite Element Method ◽  
Temperature Changes ◽  
Rubber Compounds ◽  
Different Temperatures ◽  
Materials Used ◽  
Account Temperature

ABSTRACT Tire engineers are interested in predicting rolling resistance using tools such as numerical simulation and tests. When a car is driven along, its tires are subjected to repeated deformation, leading to energy dissipation as heat. Each point of a loaded tire is deformed as the tire completes a revolution. Most energy dissipation comes from the cyclic loading of the tire, which causes the rolling resistance in addition to the friction force in the contact patch between the tire and road. Rolling resistance mainly depends on the dissipation of viscoelastic energy of the rubber materials used to manufacture the tires. To obtain a good rolling resistance, the calculation method of the tire finite element model must take into account temperature changes. It is mandatory to calibrate all of the rubber compounds of the tire at different temperatures and strain frequencies. Linear viscoelasticity is used to model the materials properties and is found to be a suitable approach to tackle energy dissipation due to hysteresis for rolling resistance calculation.

Construction of a thermal conductivity measurement system for small single crystals of organic conductors

2018 ◽  
Vol 135 (5) ◽  
pp. 2831-2836 ◽  
Author(s):  
Tetsuya Nomoto ◽  
Shusaku Imajo ◽  
Satoshi Yamashita ◽  
Hiroki Akutsu ◽  
Yasuhiro Nakazawa ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Crystals ◽  
Measurement System ◽  
Conductivity Measurement ◽  
Organic Conductors ◽  
Thermal Conductivity Measurement

scholarly journals Improved Copper–Epoxy Adhesion by Laser Micro- and Nano-Structuring of Copper Surface for Thermal Applications

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1721
Author(s):  
Mario Mora ◽  
Hippolyte Amaveda ◽  
Luis Porta-Velilla ◽  
Germán F. de la Fuente ◽  
Elena Martínez ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Bonding Strength ◽  
Copper Surface ◽  
Heat Sinks ◽  
Electrical Insulation ◽  
Cryogenic Temperatures ◽  
Shear Tests ◽  
Patterned Structures ◽  
Different Temperatures ◽  
Mechanical Tensile

The objective of this work is the enhancement of metal-to-metal bonding to provide high thermal conductivity together with electrical insulation, to be used as heat sinks at room and cryogenic temperatures. High thermal conductive metal (copper) and epoxy resin (Stycast 2850FT) were used in this study, with the latter also providing the required electrical insulation. The copper surface was irradiated with laser to induce micro- and nano-patterned structures that result in an improvement of the adhesion between the epoxy and the copper. Thus, copper-to-copper bonding strength was characterized by means of mechanical tensile shear tests. The effect of the laser processing on the thermal conductivity properties of the Cu/epoxy/Cu joint at different temperatures, from 10 to 300 K, is also reported. Using adequate laser parameters, it is possible to obtain high bonding strength values limited by cohesive epoxy fracture, together with good thermal conductivity at ambient and cryogenic temperatures.

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