Thermophysical and Radiative Properties of Conductive Biopolymer Composite

2012 ◽  
Vol 714 ◽  
pp. 115-122 ◽  
Author(s):  
Zied Antar ◽  
Hervé Noel ◽  
Jean François Feller ◽  
Patrick Glouannec ◽  
Khaled Elleuch
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Conductivity Coefficient ◽  
Environmental Concern ◽  
Polymeric Materials ◽  
Raw Material ◽  
Radiative Properties ◽  
Solar Collectors ◽  
Promising Alternative ◽  
Significant Cost Reduction

Usual plate solar collectors, based on a metal absorber (Cu, Al) selectively coated are technologically very sophisticated, expensive to produce and they are great consumer of fossil raw material. Polymeric materials are considered as a promising alternative for many interesting properties; easy moldability, corrosion resistance, they also offer a significant cost-reduction for solar thermal collectors, and a mass production may thus benefit to a broader utilization of solar energy. Most drawbacks of polymers are their low thermal properties; essentially thermal conductivity coefficient may strongly affect the solar absorber efficiency and deteriorate the collector performance. Polymers used in solar collectors are mainly petroleum-derivative product and mass use of them is not a response to environmental concern. That is why the laboratory chose to explore the potentialities of bio-polymers for the production of absorbers. This group of material presents the same properties as ordinary polymers. It is on the other hand possible to modify the thermal properties of the basic matrix by the addition of loads, such as carbon black, graphite or carbon nanotubes. The thermal performance of a solar collector is closely related to the thermal properties of the absorber. Within this framework, many measurements are necessary, more particularly the conductivity, but also emissivity and absorptivity to solar radiation. The aim of this paper is to study the thermal properties of the PLA bio-polymer charged of exfoliated graphite and/or CNT. Thereafter, the total hemispherical absorptivity, an estimation of the total hemispherical emissivity and the thermal conductivity coefficient were measured for different load rates, we will conclude on the interest and the potentialities of tested materials.

scholarly journals Improving Thermal Conductivity Coefficient in Oriented Strand Lumber (OSL) Using Sepiolite

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 599 ◽  
Author(s):  
Hamid R. Taghiyari ◽  
Abolfazl Soltani ◽  
Ayoub Esmailpour ◽  
Vahid Hassani ◽  
Hamed Gholipour ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Core Temperature ◽  
Thermal Conductivity Coefficient ◽  
Urea Formaldehyde ◽  
Wood Products ◽  
Raw Material ◽  
Formaldehyde Resin ◽  
The Core ◽  
Uf Resin ◽  
Hardness Values

An issue in engineered wood products, like oriented strand lumber (OSL), is the low thermal conductivity coefficient of raw material, preventing the fast transfer of heat into the core of composite mats. The aim of this paper is to investigate the effect of sepiolite at nanoscale with aspect ratio of 1:15, in mixture with urea-formaldehyde resin (UF), and its effect on thermal conductivity coefficient of the final panel. Sepiolite was mixed with UF resin for 20 min prior to being sprayed onto wood strips in a rotary drum. Ten percent of sepiolite was mixed with the resin, based on the dry weight of UF resin. OSL panels with two resin contents, namely 8% and 10%, were manufactured. Temperature was measured at the core section of the mat at 5-second intervals, using a digital thermometer. The thermal conductivity coefficient of OSL specimens was calculated based on Fourier’s Law for heat conduction. With regard to the fact that an improved thermal conductivity would ultimately be translated into a more effective polymerization of the resin, hardness of the panel was measured, at different depths of penetration of the Janka ball, to find out how the improved conductivity affected the hardness of the produced composite panels. The measurement of core temperature in OSL panels revealed that sepiolite-treated panels with 10% resin content had a higher core temperature in comparison to the ones containing 8% resin. Furthermore, it was revealed that the addition of sepiolite increased thermal conductivity in OSL panels made with 8% and 10% resin contents, by 36% and 40%, respectively. The addition of sepiolite significantly increased hardness values in all penetration depths. Hardness increased as sepiolite content increased. Considering the fact that the amount of sepiolite content was very low, and therefore it could not physically impact hardness increase, the significant increase in hardness values was attributed to the improvement in the thermal conductivity of panels and subsequent, more complete, curing of resin.

The Estimation of the Thermal Properties of Refractory Materials According to the Temperatures Acceleration Curve at the Blast Furnace Blowing-In

2015 ◽  
Vol 1095 ◽  
pp. 476-482 ◽  
Author(s):  
A.N. Dmitriev ◽  
Maxim O. Zolotykh ◽  
Yury A. Chesnokov ◽  
Oleg Yu. Ivanov ◽  
Galina Yu. Vitkina
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Blast Furnace ◽  
Thermal Properties ◽  
Thermal Conductivity Coefficient ◽  
Refractory Materials ◽  
Different Types ◽  
Definition Of ◽  
The Mathematical Model

In a laying of a hearth it is usually used to ten different types of the flameproof materials. The characteristics of materials declared by the manufacturer can differ from the actual. For creation of the mathematical model [1, 2] temperatures distributions in a laying of the concrete furnace it is necessary to know thermal conductivity of materials of the specific parties used at construction of the furnace. Definition of the thermal conductivity coefficient allows adapt mathematical model for specific conditions of use. The technique of determination of thermal properties of refractory materials on the temperatures acceleration curve at blowing-in of the blast furnace is described.

scholarly journals Experimental Analysis PVP Coated Silver Nanofluid Properties for Application in Photovoltaic/Thermal (PVT) Collectors

2020 ◽  
Vol 1 (3) ◽  
pp. 28-40
Author(s):  
A. Naderi ◽  
Gazori H. ◽  
M. Bozegi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Base Fluid ◽  
Fossil Fuels ◽  
Working Fluid ◽  
Solar Collectors ◽  
Step Method ◽  
Energy Technologies ◽  
Pv Module ◽  
Utility Systems

Nowadays, supplying energy for the global population has turned into a prominent issue for countries engendering the consumption of huge amounts of fossil fuels which leads to some serious environmental problems. Among the renewable energy technologies, solar collectors can play major role to improve the efficiency, in air conditioning utility systems by minimum pollution. In photovoltaic/thermal (PVT) solar collectors, which are currently considered as the most advanced type to produce electricity and heat simultaneously, working fluid absorbs Energy from photovoltaic (PV) module engendering to decrease temperature of PV module and increase the electricity efficiency and also provide permissible amount of heat for other residential applications. Meanwhile, utilizing nanofluid as the working fluid in collector, regarding that the nanofluid has enhanced thermal properties relative to the base fluid, leads to a higher collector efficiency. In this research, PVP coated silver nanofluid was prepared in three volume concentration being 250, 500 and 1000 ppm by two-step method. To assess the stability of nanofluid the zeta potential is calculated which is obtained -41.6 V. Also, the prominent thermal properties of the nanofluid were analyzed regarding PVT solar collector applications. According to the results, thermal conductivity of the PVP coated silver nanofluid, improves the properties of base fluid, to the extent that thermal conductivity coefficient grows up 50% in some temperatures and increased from 0.594 for base fluid to 1.098 W/mK by escalation of concentration to 1000 ppm. Thus, PVP coated silver nanofluid can be deemed as the vital working fluid to improve the performance of PVT solar collectors.

scholarly journals Transient method measured thermal properties of concrete with microspheres and latex based addition

2018 ◽  
Vol 196 ◽  
pp. 04037
Author(s):  
Roman Jaskulski ◽  
Wojciech Kubissa
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Fly Ash ◽  
Thermal Diffusivity ◽  
Thermal Conductivity Coefficient ◽  
Transient Method ◽  
Volumetric Heat Capacity

The goal of the performed research was to determine the influence of microspheres from fly ash and the latex based addition on the thermal properties of concrete. The tested additions were used in two different proportions each and they were combined with each other. As a reference two series of concrete were used: one without any addition and another with 0.2% of air entraining agent. The thermal properties were measured using transient method with ISOMET 2114 apparatus. No clear trends were observed in case of the results of the measurements of the thermal diffusivity and the volumetric heat capacity. While the results of the thermal conductivity coefficient show that both additions has a potential of lowering the thermal conductivity but they are not so efficient as air entraining agent.

The Use of Industrial Waste as a Secondary Raw Material in Restoration Plaster with Thermal Insulating Effect

2014 ◽  
Vol 897 ◽  
pp. 204-214 ◽  
Author(s):  
Vojtěch Václavík ◽  
Jaromír Daxner ◽  
Jan Valíček ◽  
Tomáš Dvorský ◽  
Milena Kušnerová ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Life Cycle ◽  
Industrial Waste ◽  
Thermal Conductivity Coefficient ◽  
Raw Material ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Thermal Insulating ◽  
Volume Weight ◽  
Secondary Raw Material

The article describes the results of an experimental research dealing with the use of industrial waste in the form of secondary raw material - polyurethane foam after the end of its life cycle, as a 100% substitute of filler in restoration plaster with thermal insulating effect. The article presents the formulas of restoration plaster and its properties. They are: mortar consistency, volume weight, strength characteristics, thermal conductivity coefficient, coefficient of capillary water absorption, porosity and resistance against salts.

scholarly journals Thermal properties of commercial hydrobionts’ tissues in the freezing process

2019 ◽  
pp. 247-254
Author(s):  
Valery Bogdanov ◽  
Andrei Simdyankin
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Conductivity Coefficient ◽  
Raw Materials ◽  
Freezing Process ◽  
Pacific Herring ◽  
Tissue Density

The paper describes changes in thermal properties in the process of freezing of marine raw materials. The study objects were the skin of giant octopus (Octopus dofleini L.), pallium of Pacific squid (Todarodes pacificus L.), milt of Pacific herring (Clupea pallasii L .), a nd muscle t issue of Japanese c ucumaria (Cucumaria japonica L.). The mathematical relations of the studied thermal parameters allowing the calculation of specific heat capacity, thermal conductivity coefficient and tissue density of the studied objects in the process of freezing were obtained. It was found that the change in the total specific heat capacity during the freezing of all the objects under study was of the same type: first, this figure increases due to the intensive ice formation in the tissues of hydrobionts, and then decreases due to a significant decrease in the content of the liquid aqueous phase. The values of the total specific heat capacity before the freezing of seafood were determined (kJ/kg·K): 4.26 for squid, 3.58 for milt of Pacific herring, 3.66 for octopus skin, and 3.95 for the shell of cucumaria. It was revealed that an increase in the amount of frozen out water decreased the density of samples of frozen raw materials. This was due to the high (77.4–88.9%) content of water, turning into ice, which has a lower density index. The values of hydrobionts’ tissue density before freezing were obtained ( 0 ρ , kg/m3): 1226.74 for squid, 1209.6 for milt of Pacific herring, 1128.55 for octopus skin, and 031.26 for shell of cucumaria. It was established that the thermal conductivity of the hydrobiont tissue samples in the process of freezing increased with the growth of the proportion of frozen out water contained, approaching the thermal conductivity of ice. The calculated values of thermal conductivity coefficient of seafood tissue prior to freezing equal (W/m·K): 0.52 for squid, 0.47 for milt of Pacific herring, 0.63 for octopus skin, and 0.53 for cucumaria. The obtained thermal characteristics values of the objects studied are recommended for use in technical and technological calculations of aquatic biological resources cooling treatment processes.

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.

scholarly journals Testing a Gypsum Composite Based on Raw Gypsum with a Direct Admixture of Paraffin and Polymer to Improve Thermal Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3241
Author(s):  
Krzysztof Powała ◽  
Andrzej Obraniak ◽  
Dariusz Heim
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Phase Change ◽  
Large Scale ◽  
Building Materials ◽  
Residential Buildings ◽  
Energy Performance ◽  
Polymer Content ◽  
Volumetric Heat Capacity

The implemented new legal regulations regarding thermal comfort, the energy performance of residential buildings, and proecological requirements require the design of new building materials, the use of which will improve the thermal efficiency of newly built and renovated buildings. Therefore, many companies producing building materials strive to improve the properties of their products by reducing the weight of the materials, increasing their mechanical properties, and improving their insulating properties. Currently, there are solutions in phase-change materials (PCM) production technology, such as microencapsulation, but its application on a large scale is extremely costly. This paper presents a solution to the abovementioned problem through the creation and testing of a composite, i.e., a new mixture of gypsum, paraffin, and polymer, which can be used in the production of plasterboard. The presented solution uses a material (PCM) which improves the thermal properties of the composite by taking advantage of the phase-change phenomenon. The study analyzes the influence of polymer content in the total mass of a composite in relation to its thermal conductivity, volumetric heat capacity, and diffusivity. Based on the results contained in this article, the best solution appears to be a mixture with 0.1% polymer content. It is definitely visible in the tests which use drying, hardening time, and paraffin absorption. It differs slightly from the best result in the thermal conductivity test, while it is comparable in terms of volumetric heat capacity and differs slightly from the best result in the thermal diffusivity test.

scholarly journals High Thermal Conductivity in Anisotropic Aligned Polymeric Materials

2021 ◽  
Vol 3 (2) ◽  
pp. 578-587
Author(s):  
Xinglong Pan ◽  
Michael G. Debije ◽  
Albert P. H. J. Schenning
Keyword(s):  
Thermal Conductivity ◽  
Polymeric Materials ◽  
High Thermal Conductivity

The effect of variable properties and rotation in a visco-thermoelastic orthotropic annular cylinder under the Moore–Gibson–Thompson heat conduction model

2021 ◽  
pp. 146442072098589
Author(s):  
Ahmed E Aboueregal ◽  
Hamid M Sedighi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stresses ◽  
Thermal Conductivity Coefficient ◽  
Variable Properties ◽  
Transformation Technique ◽  
Present Contribution ◽  
Conduction Model ◽  
Thermoelastic Model ◽  
Shock Heating ◽  
Physical Fields

The present contribution aims to address a problem of thermoviscoelasticity for the analysis of the transition temperature and thermal stresses in an infinitely circular annular cylinder. The inner surface is traction-free and subjected to thermal shock heating, while the outer surface is thermally insulated and free of traction. In this work, in contrast to the various problems in which the thermal conductivity coefficient is considered to be fixed, this parameter is assumed to be variable depending on the temperature change. The problem is studied by presenting a new generalized thermoelastic model of thermal conductivity described by the Moore–Gibson–Thompson equation. The new model can be constructed by incorporating the relaxation time thermal model with the Green–Naghdi type III model. The Laplace transformation technique is used to obtain the exact expressions for the radial displacement, temperature and the distributions of thermal stresses. The effects of angular velocity, viscous parameter, and variance in thermal properties are also displayed to explain the comparisons of the physical fields.

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