Modeling of the effective thermal conductivity of sintered porous pastes (original) (raw)
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Modeling of Effective Thermal Conductivity of Dunite Rocks as a Function of Temperature
The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.
International Journal of Thermophysics, 2007
The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.
Natural Science, 2010
The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.
A theoretical model for determining thermal conductivity of porous solid materials
2012
In present study a new-developed simple algebraic equation is used to find out the effective thermal conductivity of new–produced composite materials that have nonhomogenous microscopic porosity. Thermal power plant ashes, tragacanth and portland cement are used as binding components of these porous composite materials. By varying the mixing ratio of three components, 24 samples have been produced. Effective thermal conductivity coefficients obtained by the algebraic method is then compared to the ones obtained by experimental measurement techniques. The theoretical results are found to be agreeable with the experimental results.
Effective thermal conductivity of sintered porous media: Model and experimental validation
International Journal of Heat and Mass Transfer, 2013
Sintered porous media has been employed on mini heat pipes (MHP) in the capillary transport of working fluid from the condenser to the evaporator section. High porosity media has high permeability representing low liquid pressure drop, while low porosity media increases the capillary pumping capacity of the heat pipe. LABTUCAL (Heat Pipe Laboratory-UFSC, Brazil) developed porous media made of layers of different porosities, which can provide high capillary pumping performance and keep low liquid pressure drops. The combination of these two properties should enhance the heat transfer capacity of the mini heat pipe. The effective thermal conductivity of such porous media is an important parameter employed in the design of mini heat pipes. In this work, a set up developed for measuring the effective thermal conductivity of porous media is described. Samples with porous media layers were constructed and tested in vacuum and filled with saturated distilled water. The tests were conducted in the temperature range of 20 °C to 80 °C. The experimental data were compared with literature model results. The samples were tested on a vacuum chamber with a guard heater as radiation insulator. The samples used had nominal dimensions of 200mm x 30mm x 10mm. The two porous media layers were fabricated from 95% of pure atomized copper powder, with different particle size (average size of 20 and 50µm) and deposited as overlapping layers resulting in porosities of 42 and 52%, respectively. The interfacial characteristic length was determined applying statistical image analyses using software IMAGO ®. Porosity and frequency correlations were used as evaluation parameters. The effect of porosity and of the presence of the working fluid in the effective thermal conductivity was analyzed and evaluated.
Indian Journal of Physics, 2014
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A Model for Determining the Effective Thermal Conductivity of Porous Heterogeneous Materials
International Journal of Thermophysics, 2018
In this study, an algebraic equation is shown for determining thermal conductivity coefficient of a porous heterogeneous solid material with two components. This equation was developed based on the porosity of the material, ratio, density and thermal conductivities of its components. This equation was applied to the waste EPS aggregate and samples with cement or gypsum mixed binders. Packaging waste EPSs were collected, decomposed to particles of 0-3 mm diameter and mixed with each binder volumetrically in the ratios of 20 %, 40 %, 60 % and 80 % separately. Thermal conductivity coefficient of the samples was determined by using the hot wire method. The calculated values were 4.41 % to 26.04 % higher than the measured values in the samples with cement, and they were 5.79 % to 15.62 % higher than the measured values in the samples with gypsum. The equation was applied similarly to the samples with expanded clay and cement with pumice aggregates.
This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
Thermal conductivity of porous sintered metal powder and the Langmuir shape factor
Heat and Mass Transfer, 2021
The objective of this study is to reexamine the classical parallel and classical series models of the effective thermal conductivity of porous media and review the underlying assumptions used to develop these asymptotic models. The Langmuir shape factor concept is introduced to gain insight into these classical models and add extra degrees of freedom to formulate semi-empirical correlations for the effective thermal conductivity based on the parallel, series, and combination of parallel and series heat flow configurations. The analytical models reveal the average areas of the heat flow as potential targets for curve fitting equations with fitting parameters. Experimental data for sintered porous copper were used to calibrate the theoretical models. Correlations for the effective thermal conductivity, Langmuir shape factors, average heat conduction areas, and the average lengths of the heat transfer pathway of the two phases as functions of porosity were obtained and compared graphically.
Effective thermal conductivity of partially saturated porous rocks
International Journal of Solids and Structures, 2007
The purpose of the present work is to develop a reasonable-cost, simple, and robust laboratory apparatus for determining the thermal properties of soils that can be replicated by others in geotechnical engineering field. The apparatus is then used to investigate the behaviour of thermal properties of partially saturated soils. The results of a series of laboratory tests have shown that below a certain degree of saturation (5% for the tested sand), the moisture in the porous started to migrate from the hotter region to the cooler region in shorter durations compared to higher degrees of saturations which affected the thermal steady state condition.