Thermal Conductivity, Thermal Diffusivity and Specific Heat of TPNR Hybrid Nanocomposites at Different Temperatures

2012 ◽  
Vol 576 ◽  
pp. 296-299 ◽  
Author(s):  
Mou'ad A. Tarawneh ◽  
Sahrim H. Ahmad ◽  
Ku Zarina Ku Ahmad ◽  
Hassan Norita
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Hybrid Composites ◽  
Laser Flash ◽  
Hybrid Nanocomposites ◽  
Measured Temperature ◽  
Different Temperatures ◽  
Multi Walled Carbon Nanotubes

This paper discusses the inclusion of hybrid nanofillers nanoclay and multi-walled carbon nanotubes (MWNTs) as reinforcing agents to improve the thermal properties of TPNR. The laser flash technique was also employed to determine the thermal conductivity, thermal diffusivity and specific heat capacity of the nanocomposite. Two types of hybrid nanofillers were introduced into TPNR, which are untreated hybrid composites (UTH) prepared from MWNTs (without acid treatment)-nanoclay and treated hybrid composites (TH), consisting of acid treated MWNTs and nanoclay. The thermal properties of treated hybrid composites are better than untreated hybrid composites. The thermal conductivity of untreated hybrid composites that were sintered at 30 to 150 oC did not show a monotonous change with MWNTs as the filler has a high thermal conductivity compared to nanoclay. The results showed that the thermal diffusivity decreased with the increasing of temperature. The specific heat of all the measured samples increases linearly with the measured temperature from 30°C to 150°C.

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.

Experimental Study on Thermal Properties of Hollow Sphere Structures

2021 ◽  
Vol 407 ◽  
pp. 185-191
Author(s):  
Josef Tomas ◽  
Andreas Öchsner ◽  
Markus Merkel
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Hollow Sphere ◽  
Plane Source ◽  
Source Method ◽  
Transient Plane Source ◽  
Transient Plane Source Method

Experimental analyses are performed to determine thermal conductivity, thermal diffusivity and volumetric specific heat with transient plane source method on hollow sphere structures. Single-sided testing is used on different samples and different surfaces. Results dependency on the surface is observed.

Influence of Mesocarp Fibre Inclusion on Thermal Properties of Foamed Concrete

2021 ◽  
Vol 87 (1) ◽  
pp. 1-11
Author(s):  
Siti Shahirah Suhaili ◽  
Md Azree Othuman Mydin ◽  
Hanizam Awang
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Volume Fraction ◽  
Thermal Constant ◽  
Volume Fractions ◽  
Foamed Concrete

The addition of mesocarp fibre as a bio-composite material in foamed concrete can be well used in building components to provide energy efficiency in the buildings if the fibre could also offer excellent thermal properties to the foamed concrete. It has practical significance as making it a suitable material for building that can reduce heat gain through the envelope into the building thus improved the internal thermal comfort. Hence, the aim of the present study is to investigate the influence of different volume fractions of mesocarp fibre on thermal properties of foamed concrete. The mesocarp fibre was prepared with 10, 20, 30, 40, 50 and 60% by volume fraction and then incorporated into the 600, 1200 and 1800 kg/m3 density of foamed concrete with constant cement-sand ratio of 1:1.5 and water-cement ratio of 0.45. Hot disk thermal constant analyser was used to attain the thermal conductivity, thermal diffusivity and specific heat capacity of foamed concrete of various volume fractions and densities. From the experimental results, it had shown that addition of mesocarp fibre of 10-40% by volume fraction resulting in low thermal conductivity and specific heat capacity and high the thermal diffusivity of foamed concrete with 600 and 1800 kg/m3 density compared to the control mix while the optimum amount of mesocarp fibre only limit up to 30% by volume fraction for 1200 kg/m3 density compared to control mix. The results demonstrated a very high correlation between thermal conductivity, thermal diffusivity and specific heat capacity which R2 value more than 90%.

Laser Flash Raman Spectroscopy Method for Characterizing Thermal Diffusivity of Suspended and Supported 2D Nanomaterials

2016 ◽  
Author(s):  
Qin-Yi Li ◽  
Xing Zhang
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Thermal Diffusivity ◽  
Laser Power ◽  
2D Materials ◽  
Laser Flash ◽  
Spectroscopy Method ◽  
Measured Temperature ◽  
Laser Absorption ◽  
2D Nanomaterials

2D nanomaterials have been attracting extensive research interests due to their superior properties and the accurate thermophysical characterization of 2D materials is very important for nanoscience and nanotechnology. Recently, a noncontact technique based on the temperature dependent Raman band shifts has been used to measure the thermal conductivity of 2D materials. However, the heat flux, i.e. the absorbed laser power, was either theoretically estimated or measured by a laser power meter with uncertainty, resulting in large errors in thermal conductivity determination. This paper presents a transient “laser flash Raman spectroscopy” method for measuring the thermal diffusivity of 2D nanomaterials in both the suspended and supported forms without knowing laser absorption. Square pulsed laser instead of continuous laser is used to heat the sample and the laser absorption can be eliminated by comparing the measured temperature rises for different laser heating time and laser spot radii. This method is sensitive for characterizing typical 2D materials and useful for nanoscale heat transfer research.

scholarly journals Effect of moisture content on the thermal properties of Horse-Eye Bean seeds relevant to its processing

2020 ◽  
Vol 45 (4) ◽  
pp. 71-80
Author(s):  
Ide Ejike ◽  
Ike Oluka ◽  
Eze Chukwuka
Keyword(s):  
Thermal Conductivity ◽  
Regression Analysis ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Moisture Content ◽  
Specific Heat ◽  
Bulk Density ◽  
Food Processing ◽  
Positive Relationship ◽  
Measured Specific Heat

The specific heat, thermal conductivity and thermal diffusivity of the Horse-Eye bean (Mucuna sloanei) were determined as a function of moisture content using the method reported by A.O.A.C (2000). The sample varieties used were the Big Sized and the Small Sized Horse-Eye bean. The specific heat and the thermal conductivity were measured using a Bomb Calorimeter. The thermal diffusivity was calculated from the measured specific heat, thermal conductivity and bulk density of the samples. Within the moisture range of 10.5% to 16.87% (b.b), the specific heat, thermal conductivity and thermal diffusivity varied with the moisture content. Results showed that the specific heat, thermal conductivity and thermal diffusivity of the Horse-Eye bean seeds ranged from 116.76 to 203.29 kJ/kgK; 21.07 to 32.23 W/moC; and 3.12 x 10-7 to 9.19 x 10-7 m 2 /s, for the Big Sized varieties, and 112.06 to 194.61 kJ/kgK; 19.85 to 24.08 W/moC; and 3.05 x 10-7 to 6.71 x 10-7 m 2 /s, for the Small Sized varieties as the moisture content increases from 10.5% to 16.87%. Regression analysis were also carried out on the thermal properties of the Horse-Eye bean varieties and moisture content, and there was positive relationship between the parameters. There were significant effects of moisture content (p < 0.05) on all the parameters conducted. The findings and the data generated will create an impact in the food processing industries for Horse-Eye bean.

A Combined Experimental-Numerical Method to Evaluate Powder Thermal Properties in Laser Powder Bed Fusion

2018 ◽  
Author(s):  
Bo Cheng ◽  
Brandon Lane ◽  
Justin Whiting ◽  
Kevin Chou
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Laser Flash ◽  
Powder Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Powder Particles

Powder bed metal additive manufacturing (AM) utilizes a high-energy heat source scanning at the surface of a powder layer in a pre-defined area to be melted and solidified to fabricate parts layer by layer. It is known that powder bed metal AM is primarily a thermal process and further, heat conduction is the dominant heat transfer mode in the process. Hence, understanding the powder bed thermal conductivity is crucial to process temperature predictions, because powder thermal conductivity could be substantially different from its solid counterpart. On the other hand, measuring the powder thermal conductivity is a challenging task. The objective of this study is to investigate the powder thermal conductivity using a method that combines a thermal diffusivity measurement technique and a numerical heat transfer model. In the experimental aspect, disk-shaped samples, with powder inside, made by a laser powder bed fusion (LPBF) system, are measured using a laser flash system to obtain the thermal diffusivity and the normalized temperature history during testing. In parallel, a finite element model is developed to simulate the transient heat transfer of the laser flash process. The numerical model was first validated using reference material testing. Then, the model is extended to incorporate powder enclosed in an LPBF sample with thermal properties to be determined using an inverse method to approximate the simulation results to the thermal data from the experiments. In order to include the powder particles’ contribution in the measurement, an improved model geometry, which improves the contact condition between powder particles and the sample solid shell, has been tested. A multi-point optimization inverse heat transfer method is used to calculate the powder thermal conductivity. From this study, the thermal conductivity of a nickel alloy 625 powder in powder bed conditions is estimated to be 1.01 W/m·K at 500 °C.

The Effect of Ultrasonic Treatment and Gamma Radiation on the Thermal Conductivity of TPNR Hybrid Nanocomposites

2012 ◽  
Vol 626 ◽  
pp. 29-33
Author(s):  
Mou’ad A. Tarawneh ◽  
Sahrim Haji Ahmad
Keyword(s):  
Thermal Conductivity ◽  
Gamma Radiation ◽  
Ultrasonic Treatment ◽  
Treatment Time ◽  
Laser Flash ◽  
Hybrid Nanocomposites ◽  
Hybrid Nanoparticles ◽  
Hybrid Nanocomposite ◽  
Preparation Conditions ◽  
Multi Walled Carbon Nanotubes

This paper discusses the effect of Gamma radiation and ultrasonic treatment time on hybrid nanofillers nanoclay and multi-walled carbon nanotubes (MWCNTs) as reinforcing agents to improve the thermal conductivity of TPNR. The laser flash technique was also employed to determine the thermal conductivity of the hybrid nanocomposite. The thermal conductivity of hybrid nanocomposites that were sintered at 30 to 150 °C did not show a monotonous change with MWCNTs as the filler has a high thermal conductivity compared to nanoclay by using different dose of gamma radiation or with different time of ultrasonic treatment. TEM results showed a combination of intercalated-exfoliated structure of OMMT and the dispersion of MWCNTs in the TPNR composite. The probability that hybrid nanoparticles form a network depends on the interaction between the particles, on their shape (aspect ration), preparation conditions and on their inter-particle distance will control the thermal conductivity of the hybrid nanocomposite.

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 Properties of Plaster Reinforced with Date Palm Fibers

2020 ◽  
Vol 16 (2) ◽  
pp. 259-266
Author(s):  
Mokhtar Rachedi ◽  
Abdelouahed Kriker
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Date Palm ◽  
Thermal Effusivity ◽  
Date Palm Fibers ◽  
Different Types ◽  
Local Materials ◽  
Significant Point

AbstractThis study aims both to investigate the thermal properties of plaster reinforced with date palm fibers and local natural resources valorization to batter using materials construction. For that, studying the effect of addition date palm fibers on the plaster's thermal properties is a significant point. In this work, we measured effective thermal conductivity, thermal diffusivity, specific heat, and thermal effusivity of date palm fibers reinforced plaster has been studied by CT meter. Samples configurations with four lengths (10 mm - 40 mm) and four-weight ratios (0.5 % - 2 %) of palm fibers in plaster. The results obtained demonstrate that an increase in the fraction of date palm fiber engenders to a significant decrease in the thermal conductivity, thermal diffusivity, and effusivity, even an increase for the specific heat of different types of samples. Finally, this study is a contribution to the valorization of local materials in southern Algeria, and results encourage the use of plaster and date palm fibers in the field of construction and go to eco-friendly buildings.

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