scholarly journals Graphene nanoplatelets: Thermal diffusivity and thermal conductivity by the flash method

AIP Advances ◽  
2017 ◽  
Vol 7 (7) ◽  
pp. 075214 ◽  
Author(s):  
M. Potenza ◽  
A. Cataldo ◽  
G. Bovesecchi ◽  
S. Corasaniti ◽  
P. Coppa ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Graphene Nanoplatelets ◽  
Flash Method

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

A Study of Porosity Influence on Thermal Diffusivity of Aluminium Foam by Experimental Analysis and Numerical Simulation

2010 ◽  
Vol 297-301 ◽  
pp. 814-819 ◽  
Author(s):  
A. Adamčíková ◽  
B. Taraba ◽  
J. Kováčik
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Thermal Diffusivity ◽  
Transfer Task ◽  
Aluminium Foam ◽  
Flash Method ◽  
Inverse Heat Transfer ◽  
High Thermal Diffusivity ◽  
Specific Heat Capacities ◽  
Measured Specific Heat

Aluminium foam is a unique material possessing very high thermal diffusivity due to high thermal conductivity of the cell walls accompanied with rather low overall thermal conductivity, controlled via porosity [1]. There is a presumption of increasing influence at thermal diffusivity of aluminium foam by decreasing porosity, following the presented results (e.g. by using the transient plane source method [2]) and relation between thermal diffusivity and density. Thermal diffusivity of aluminium foam considering various porosity and various compositions of precursors were observed. The Aluminium foam was prepared by the powder metallurgy route, also well known as the ALULIGHT process, and various densities were achieved by changing of parameters (temperature, time) of foaming. The following types of foamable precursors were used: AlMg1Si0.6, AlSi10, as blowing agent was used 0.8 wt. % of TiH2.The thermal diffusivity of particular precursors by the flash method was measured. Specific heat capacities of samples with different density were measured by a calorimeter for various temperatures. The coefficient of thermal conductivity as a function of temperature was calculated by heat transient experiment data and numerical simulation consequently as an inverse heat transfer task. The problem was solved by the finite element method using the engineering-scientific program code ANSYS. The results depend on the thermal diffusivity, on the porosity and the type of precursor. Despite that aluminium foam is considered as a type of composite, thermophysical properties could be calculated upon known volume of aluminium alloy and air in the pores However there is a presumption that this rule cannot be used in case of porous materials. Values obtained by the mentioned methodology shown a significant influence on the porosity and the thermal diffusivity of the aluminium foam.

Thermal Properties of Carbon and Graphite Foams

2012 ◽  
Author(s):  
Melanie Patrick ◽  
Amber Vital ◽  
Darian Bridges ◽  
Messiha Saad
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Flash Method ◽  
Petroleum Pitch ◽  
Energy Storage Devices ◽  
Carbon And Graphite ◽  
Temperature Levels

Thermal properties such as specific heat, thermal diffusivity, and thermal conductivity of carbon and graphite foams are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of the material; it plays a critical role in the performance of materials in high temperature applications and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this paper is to develop a thermal properties data base for carbon and graphite foams. Carbon foams are commercially produced from urethane, petroleum pitch-based and coal-based processes, and they typically have large pores (> 350 μm) and low density (< 1.0 g/cm3). Petroleum pitch-base and coal-base carbon/graphite foams can be tailored to be thermally conductive or thermally insulating. The thermophysical properties of carbon and graphite foams have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the foams; this method is based on America Society for Testing and Materials standard (ASTM E1461). In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density data were used to compute the thermal conductivity of the foams.

Laser Flash Measurement of Samples With a Transparent Reference Layer

2009 ◽  
Author(s):  
Heng Ban ◽  
Zilong Hua
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Temperature Response ◽  
Front Surface ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Thermal Diffusivity Measurement ◽  
Reference Layer

The laser flash method is a standard method for thermal diffusivity measurement. This paper reports the development of a method and theory that extends the standard laser flash method to measure thermal conductivity and thermal diffusivity simultaneously. By attaching a transparent reference layer with known thermal properties on the back of a sample, the thermal conductivity and thermal diffusivity of the sample can be extracted from the temperature response of the interface between the sample and the reference layer to a heating pulse on the front surface. The theory can be applied for sample and reference layer with different thermal properties and thickness, and the original analysis of the laser flash method becomes a limiting case of the current theory with an infinitely small thickness of the reference layer. The uncertainty analysis was performed and results indicated that the laser flash method can be used to extract the thermal conductivity and diffusivity of the sample. The results can be applied to, for instance, opaque liquid in a quartz dish with silicon infrared detector measuring the temperature of liquid-quartz interface through the quartz.

scholarly journals Thermal Conductivity of an AZ31 Sheet After Accumulative Roll Bonding

2018 ◽  
Author(s):  
Zuzanka Trojanová ◽  
Kristýna Halmešová ◽  
Zdeněk Drozd ◽  
Vladimír Šíma ◽  
Pavel Lukáč ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Magnesium Alloys ◽  
Accumulative Roll Bonding ◽  
Laser Flash ◽  
Flash Method ◽  
Roll Bonding ◽  
Az31 Sheet ◽  
Temperature Load ◽  
Significant Factors

Accumulative roll bonding (ARB) is one of methods of severe plastic deformation which is relevant for industrial production of sheets. While mechanical properties of several magnesium alloys subjected to ARB process have been studied, the physical properties have been reported only for some magnesium alloys. These properties are influenced by the texture developed during the ARB process and the temperature load. In the presented contribution, we studied thermal diffusivity and thermal conductivity of an AZ31 magnesium alloy after 1 and 2 passes through the rolling mill. Thermal diffusivity was measured with the laser-flash method in the temperature range between 20 and 350 &deg;C. Thermal conductivity depends on the number of rolling passes. The microstructure and texture of sheets are significant factors influencing the thermal properties.

Transient Plane Source Method for Thermal Property Measurements of Metal Hydrides

2008 ◽  
Author(s):  
Scott Flueckiger ◽  
Yuan Zheng ◽  
Timothe´e Pourpoint
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Diffusivity ◽  
Hydrogen Storage ◽  
Thermal Property ◽  
Metal Hydride ◽  
Metal Hydrides ◽  
Flash Method ◽  
Plane Source ◽  
Transient Plane Source

Metal hydrides are promising hydrogen storage materials with potential for practical use in a passenger car. To be a viable hydrogen storage option, metal hydride heat transfer behavior must be well understood and accounted for. As such, the thermal properties of the metal hydride are measured and compiled to assess this behavior. These properties include thermal conductivity, specific heat, and thermal diffusivity. The transient plane source (TPS) method was selected primarily due to a high level of versatility, including customization for high pressure hydrogen environments. To perform this measurement, a TPS 2500 S thermal property analyzer by the Hot Disk Company was employed. To understand the measurement and analysis process of the TPS method, two different sample materials were evaluated at ambient conditions. These samples included a stainless steel pellet and an inactivated (non-pyrophoric) metal hydride pellet. Thermal conductivity and thermal diffusivity of these samples were measured using the TPS method. The thermal property measurements are compared to the data available in the literature (stainless steel) and the data obtained using laser flash method (metal hydride). The improvements needed to successfully implement the TPS method are discussed in detail.

Thermal Properties of Microcrystalline Cellulose Derived Carbons

2007 ◽  
Author(s):  
Yo-Rhin Rhim ◽  
Dajie Zhang ◽  
Dennis C. Nagle ◽  
Michael Rooney ◽  
Cila Herman
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Microcrystalline Cellulose ◽  
Heat Treatment Temperature ◽  
Structural Characteristics ◽  
Treatment Temperature ◽  
Carbon Clusters ◽  
Flash Method

The thermal transport properties were studied for carbons produced by the carbonization of microcrystalline cellulose. Thermal diffusivity, specific heat, and thermal conductivity were measured via flash method for cellulose derived carbons prepared at various heat treatment temperatures ranging from 250°C to 1000°C. The thermal diffusivity as a function of increasing heat treatment temperature was observed to have four distinct linear regions, which could be related directly to the microstructures of the materials generated by the specific heat treatment temperature. Specific heat values indicated the coexistence of polar and non-polar phases in both partially carbonized materials obtained at lower heat treatment temperatures and fully carbonized materials formed at higher heat treatment temperatures. For partially carbonized materials, the polar groups consisting of residual hydroxyl and carboxyl were still present. For fully carbonized materials, the polar phases have largely been volatilized and conductive nano-carbon clusters were nucleated and observed to grow in an amorphous carbon bed until percolation effects were observed. Such structural characteristics are well supported by FT-IR characterizations. Lastly, a linear relationship between testing temperature and thermal conductivity indicates boundary scattering between highly conductive carbon clusters as the main mechanism for heat conduction.

Thermal Properties Measurement of Particulate Fouling Samples of Air-Cooled Heat Exchangers Using Laser Flash Method

2020 ◽  
Author(s):  
Arjun Sharma ◽  
M. D. Islam ◽  
Ebrahim Al Hajri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Middle East ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Heat Exchangers ◽  
Laser Flash ◽  
Flash Method ◽  
Particulate Fouling ◽  
Major Factors

Abstract Fouling is one of the major factors that drastically affects heat exchanger performance. Especially in Middle East where most of the heat exchangers are air cooled due to scarcity of water. As these heat exchangers are placed in a harsh climate, they are at high risk of low performance due to dusty/sticky particulate fouling. In order to identify possible active/passive methods to control or ideally eliminate particulate fouling, it is desirable to know exact thermophysical properties of such particulate fouling. This study presents thermophysical property characterization of selected fouling samples from eight different fin fan heat exchangers installed in an oil & gas facility in the Middle East. Laser flash Analysis (LFA) method is a well-known technique for measurement of the thermophysical properties: thermal diffusivity, specific heat and thermal conductivity of materials. A new technique was developed to prepare powder particulate fouling samples to make them as disc shaped samples while maintaining the range of ± 12 mm diameter and ± 2 mm thickness. The LFA measurements was conducted using LFA 447 Nano Flash Netzsch over the temperature range from 25 °C to 125°C. The thermal diffusivity was measured with an accuracy of ± 3% and the specific heat capacity with an accuracy of ± 5%. As the thermal conductivity is a product of these two measured values, is calculated with an accuracy of ± 5.8% and the measurement repeatability was within 2%.

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