Thermophysical Properties of Metakaolin Geopolymers Based on Na2SiO3/NaOH Ratio

2018 ◽  
Vol 280 ◽  
pp. 487-493 ◽  
Author(s):  
Ain Jaya Nur ◽  
Yun Ming Liew ◽  
Mohd Mustafa Abdullah Al Bakri ◽  
Cheng Yong Heah
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Sodium Silicate ◽  
Thermophysical Properties ◽  
Insulating Material ◽  
Thermal Insulating ◽  
High Specific Heat ◽  
Alkaline Activator

In the present work, the effect of different sodium silicate-to-sodium hydroxide ratio on the physical, mechanical and thermophysical properties of metakaolin geopolymers (MkGPs) was investigated. Geopolymers were prepared by activating the metakaolin with a mixture of NaOH and sodium silicate (Na2SiO3). The products obtained were characterized after 28 days of ageing. The density, porosity, compressive strength, thermal conductivity (TC), thermal diffusivity and specific heat capacity were determined. In general, the Na2SiO3/NaOH ratio has a significant effect on the compressive strength of the MkGPs. The thermal conductivity, thermal diffusivity and specific heat of MkGps measured in this work were in the range between 0.44 to 0.92 W/mK, 0.22 to 0.44 mm2/s and 1 to 3.7 MJ/m3K respectively. The highest compressive strength was 32 MPa achieved with Na2SiO3/NaOH ratio of 1.0. This mix has the best thermophysical performance due to low thermal conductivity, low thermal diffusivity and high specific heat compared to the other alkaline activator ratios. The results showed that the geopolymer is able to be used as the thermal insulating material.

Thermophysical Properties of Germanium for Thermal Analysis of Growth from the Melt

1981 ◽  
Vol 9 ◽  
Author(s):  
Roger K. Crouch ◽  
A. L. Fripp ◽  
W. J. Debnam ◽  
R. E. Taylor ◽  
H. Groot
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Room Temperature ◽  
Bridgman Method ◽  
The Other ◽  
Temperature Range ◽  
Diffusivity Measurements

ABSTRACTThe thermal diffusivity of Ge has been measured over a temperature range from 300° C to 1010° C which includes values for the melt. Specific heat has been measured from room temperature to 727° C. Thermal conductivity has been calculated over the same temperature range as the diffusivity measurements. These data are reported along with the best values from the literature for the other parameters which are required to calculate the temperature and convective fields for the growth of germanium by the Bridgman method. These parameters include the specific heat, the viscosity, the emissivity, and the density as a function of temperature.

scholarly journals Determination of thermophysical properties of cupuassu (Theobroma grandiflorum) dry almonds

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Elisa Santana Cunha ◽  
Geovana Pires Araújo Lima ◽  
Jorge Henrique Oliveira Sales ◽  
Elizama Aguiar de Oliveira
Keyword(s):  
Thermal Conductivity ◽  
Activation Energy ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Effective Diffusivity ◽  
Theobroma Grandiflorum

In comparison to cocoa, little has been reported on the drying of cupuassu almonds that can be used to produce cupulate, a chocolate type product. Thus, in this study thermophysical properties of cupuassu dry almonds (moisture = 9.68 % d.b.) were determined as: thermal conductivity (k) of 0.14 kW/(m.K), specific heat (cp) of 2.86 kJ/(kg.K), thermal diffusivity (?) of 4.8·10-5 m²/s, effective diffusivity (Deff) of 9.94·10-10 - 6.29·10-10 m²/s and activation energy (Ea) of 14.90 kJ/mol. These results showed a similarity of values between cupuassu and cocoa and allows to perform more specific studies for the development of dryers for the cupuassu almonds.

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%.

Thermophysical Characterization of Genipap Pulp

2010 ◽  
Vol 6 (3) ◽  
Author(s):  
Normane Mirele Chaves da Silva ◽  
Renata Cristina Ferreira Bonomo ◽  
Luciano Brito Rodrigues ◽  
Modesto Antonio Chaves ◽  
Rafael da Costa Ihéu Fontan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Water Content ◽  
Thermophysical Properties ◽  
Empirical Models ◽  
Influence Of Temperature ◽  
Thermophysical Characterization

The influence of temperature and water content on thermophysical properties (density, thermal diffusivity, thermal conductivity and specific heat) of genipap (Genipa americana, L) pulp at medium maturity were studied. The thermophysical properties were determined at concentrations between 6.0% m/m and 24.0% m/m of water content and temperatures range of 5 to 80°C. The density decreased with increase in temperature and water content, while the thermal diffusivity and conductivity increased as temperature and water content increased. The specific heat decreased with the moisture content. Empirical models were fitted to the experimental data for each property and the accuracy of those models was checked.

Thermophysical Properties of AS4/3501-6 Carbon-Epoxy Composite

2013 ◽  
Author(s):  
Amber Vital ◽  
Bradley Doleman ◽  
Messiha Saad
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Critical Role ◽  
Flash Method ◽  
Energy Storage Devices ◽  
Temperature Levels ◽  
American Society

As today’s technology continues to develop at a rate that was once unimaginable, the demand for new materials that will outperform traditional materials also increases dramatically. To meet these challenges, monolithic materials are being combined to develop new unique materials called composites. Thermophysical properties of composite materials such as thermal conductivity, diffusivity, specific heat, and thermal expansion are very important in 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 a material and plays a critical role in the performance of materials in high temperature applications. This parameter is important in problems involving heat transfer and thermal structures. The objective of this paper is to develop a thermal properties database for the carbon-epoxy AS4/3501-6 composite. The AS4 carbon fiber used is a unidirectional continuous PAN based fiber, and the 3501-6 epoxy resin is amine cured and provides low shrinkage during the curing process while maintain resistance to chemicals and solvents. The thermophysical properties of the AS4 composite have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the composite based on the American 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 were used to compute the thermal conductivity, thus adding to the currently insufficient database for composite materials and foams.

scholarly journals Effect of Rubber Aggregates on the Thermophysical Properties of Self-Consolidating Concrete

2014 ◽  
Vol 08 (1) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermal Performance ◽  
Thermophysical Properties ◽  
Self Consolidating Concrete ◽  
Rubber Aggregates

n this work, our choice fell on the exploitation of rubber aggregates from used tires. In this context, an experimental study was conducted to provide more data on the effect of rubber aggregates on the thermophysical properties of self- consolidating concrete (SCC). To this end , four sets of rectangular specimens were prepared by varying the proportion of the rubber aggregates with percentages of 0 %, 10 %, 20 % and 30 % of the volume of gravel .Tests on hardened self-consolidating concrete rubber SCCR included measuring the thermal conductivity and the thermal diffusivity by the method of the boxes at steady and determining the specific heat . The results showed that the thermal conductivity and thermal diffusivity were decreased according to the increase of the percentage of rubber aggregates. This decrease was significantly improved thermal performance of the SCCR.

Thermophysical Properties of Baled Switchgrass

2021 ◽  
Vol 37 (6) ◽  
pp. 1107-1114
Author(s):  
Drew F Schiavone ◽  
Michael D Montross
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Multiple Regression ◽  
Thermophysical Properties ◽  
Material Properties ◽  
Thermal Probe ◽  
Transfer Rates ◽  
Thermophysical Parameters

HighlightsThermal conductivity and thermal diffusivity of baled switchgrass were measured with a dual thermal probe.Specific heat of baled switchgrass was estimated based on other thermophysical parameters.Thermophysical parameters were modeled as functions of the material properties using multiple regression.Anisotropism was observed with different heat transfer rates occurring in each directional orientation.Abstract.Although the thermophysical properties of baled biomass play a critical role in developing postharvest quality models, these parameters have not been investigated for many bulk agricultural feedstocks including switchgrass. In this study, a dual thermal probe, consisting of a thermal conductivity probe and separate thermal diffusivity probe, was used to determine the thermal conductivity, thermal diffusivity, and specific heat of lab-scale rectangular bales of switchgrass (~10.16 × 10.16 × 30.48 cm). Thermal conductivity, thermal diffusivity, and specific heat ranged from 1.04E-2 to 6.10E-2 W m-1 °C-1, 0.863E-7 to 2.284E-7 m2 s-1, and 0.40 to 2.51 kJ kg-1 °C-1, respectively, depending on temperature (20.3°C, 30.2°C, and 40.1°C), moisture content (11.4%, 20.8%, 29.0%, and 42.3% on a wet basis), bulk density (157.2, 172.4, 197.2, and 230.1 kg m-3) and directional orientation (lateral or transverse). The results of this study promote a practical understanding of heat transfer within baled switchgrass while defining the dynamic relationship to material properties through multiple regression analysis. Anisotropism between the lateral and transverse bale orientations was observed with different heat transfer rates observed in both directional orientations. This anisotropism was attributed to the unique physical composition of the bulk material in the axial direction of bale compression (i.e., variation in porosity, discontinuous porous cavities, and material heterogeneity) compared to the composition of continuous stem material forming a layered flake of the rectangular bale. Keywords: Biomass, Bioprocessing, High solids, Thermal conductivity, Thermal diffusivity.

Research on Thermal-Insulating Material and Roadway Cooling with High Geotherm

2012 ◽  
Vol 512-515 ◽  
pp. 915-921
Author(s):  
Yan Wei Liu ◽  
Guo Fu Li ◽  
Xiao Yong Liu
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
High Performance ◽  
Experimental Models ◽  
Industrial Test ◽  
Mine Pressure ◽  
Test Model ◽  
Insulating Materials ◽  
Insulating Material ◽  
Thermal Insulating

The research aims to develop inorganic thermal-insulating materials of high performance, decrease high geothermal emissions from hot rock to the roadway, reduce the roadway airflow temperature, and achieve mine cooling and energy saving eventually. Firstly, the best proportion of inorganic thermal-insulating materials of high performance was designed, and a test model for thermal conductivity and mechanical analysis has been built. And through the test of thermal-insulating of the material and mechanical properties, the relation equations between vitreous micro-bead content (the main agent of thermal-insulating material) and thermal conductivity, uniaxial compressive strength, confined compressive strength have been obtained respectively. Secondly, the feature, the fitting and coupling features between the experimental models and engineering conditions in practice were analyzed comparatively, which could provide theoretical basis for the design and application of thermal-insulating materials of high performance. The industrial test shows that with thermal-insulating materials of high performance in application, the roadway airflow temperature was reduced significantly and could meet the requirements of mine pressure. Therefore, the research could offer an effective way for the mine thermal-insulating and cooling under high geothermal conditions.

scholarly journals Effect of Frying Temperature and Time on Thermophysical Properties and Quality Attributes of Deep-Fat Fried Plantain (Dodo)

2021 ◽  
pp. 1-6
Author(s):  
J. A. Adeyanju ◽  
B. E. Alabi ◽  
A. O. Abioye ◽  
A. A. Adekunle ◽  
A. A. Oloyede
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Moisture Content ◽  
Specific Heat ◽  
Product Quality ◽  
Thermophysical Properties ◽  
Quality Attributes ◽  
Processing Conditions ◽  
Frying Temperature ◽  
Acceptable Quality

This study investigated the effect of the processing conditions (frying temperature and time) on the thermophysical properties and product quality attributes of deep-fat fried plantain (dodo). The plantain were deep-fried at various frying temperatures (150-190 °C) and time intervals (120-240 sec). The thermophysical properties determined include specific heat, thermal conductivity, thermal diffusivity and density. The product quality attributes were moisture content, oil content and colour. The specific heat, thermal conductivity, thermal diffusivity and density of the deep-fat fried plantain ranged from 2.68 to 2.33 kJ/kgK, 0.37 to 0.33 W/mK, 1.12 to 1.36 x10-7 m2/s and 1049.50 to 1257.00 kg/m3, respectively. The quality attributes of dodo varied from 0.24 to 0.65 abs, 30.37 to 43.40% and 9.96 to 14.25% for colour, It was observed that the specific heat, thermal conductivity, thermal diffusivity and moisture content of the deep-fat fried plantain were significantly reduced as frying temperature and time increased. The colour and fat content of dodo were found to increase with increased temperature and time of frying. Outcome of the study resulted in the development of dodo with high acceptable quality characteristics. Therefore, generated data will be useful in choice of processing conditions for plantain and development of fryer.

A Novel Poly(Ionic Liquid) as the Thermal Insulating Material

2020 ◽  
Vol 13 (3) ◽  
pp. 241-247
Author(s):  
Wenxin Wei ◽  
Guifeng Ma ◽  
Hongtao Wang ◽  
Jun Li
Keyword(s):  
Thermal Conductivity ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Resistance ◽  
Insulating Material ◽  
Low Thermal Conductivity ◽  
Thermal Insulating ◽  
Poly Ionic Liquid

Objective: A new poly(ionic liquid)(PIL), poly(p-vinylbenzyltriphenylphosphine hexafluorophosphate) (P[VBTPP][PF6]), was synthesized by quaternization, anion exchange reaction, and free radical polymerization. Then a series of the PIL were synthesized at different conditions. Methods: The specific heat capacity, glass-transition temperature and melting temperature of the synthesized PILs were measured by differential scanning calorimeter. The thermal conductivities of the PILs were measured by the laser flash analysis method. Results: Results showed that, under optimized synthesis conditions, P[VBTPP][PF6] as the thermal insulator had a high glass-transition temperature of 210.1°C, high melting point of 421.6°C, and a low thermal conductivity of 0.0920 W m-1 K-1 at 40.0°C (it was 0.105 W m-1 K-1 even at 180.0°C). The foamed sample exhibited much low thermal conductivity λ=0.0340 W m-1 K-1 at room temperature, which was comparable to a commercial polyurethane thermal insulating material although the latter had a much lower density. Conclusion: In addition, mixing the P[VBTPP][PF6] sample into polypropylene could obviously increase the Oxygen Index, revealing its efficient flame resistance. Therefore, P[VBTPP][PF6] is a potential thermal insulating material.

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