An inverse problem in estimating simultaneously the effective thermal conductivity and volumetric heat capacity of biological tissue

This paper investigates the numerical analysis to determine the thermo-physical characteristics of materials. This method is based on a heating probe kept at a constant temperature and maintained in contact with a cylindrical sample. The heat power dissipated in the sample is measured by the probe. The results address to identify simultaneously the thermal conductivity, the volumetric heat capacity and the heat transfer coefficient using the inverse problem.

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

Materials ◽

10.3390/ma14123241 ◽

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.

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Using CPTs to derive thermal properties of soil

E3S Web of Conferences ◽

10.1051/e3sconf/202020504005 ◽

2020 ◽

Vol 205 ◽

pp. 04005

Author(s):

Philip J. Vardon ◽

Joek Peuchen

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Laboratory Tests ◽

Field Investigation ◽

Volumetric Heat Capacity ◽

Cone Penetration ◽

Cone Penetration Tests ◽

Penetration Tests ◽

Properties Of Soil

A method of utilizing cone penetration tests (CPTs) is presented which gives continuous profiles of both the in situ thermal conductivity and volumetric heat capacity, along with the in situ temperature, for the upper tens of meters of the ground. Correlations from standard CPT results (cone resistance, sleeve friction and pore pressure) are utilized for both thermal conductivity and volumetric heat capacity for saturated soil. These, in conjunction with point-wise thermal conductivity and in situ temperature results using a Thermal CPT (T-CPT), allow accurate continuous profiles to be derived. The CPT-based method is shown via a field investigation supported by laboratory tests to give accurate and robust results.

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In-situ rapid determination of walls’ thermal conductivity, volumetric heat capacity, and thermal resistance, using response factors

Applied Energy ◽

10.1016/j.apenergy.2019.113539 ◽

2019 ◽

Vol 253 ◽

pp. 113539 ◽

Cited By ~ 6

Author(s):

Arash Rasooli ◽

Laure Itard

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Thermal Resistance ◽

Rapid Determination ◽

Volumetric Heat Capacity ◽

Response Factors

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Effect of timeliness on the thermal properties of paraffin-based Al2O3 nanofluids

Modern Physics Letters B ◽

10.1142/s0217984919500519 ◽

2019 ◽

Vol 33 (05) ◽

pp. 1950051

Author(s):

Yangyang Wu ◽

Baichao Wang ◽

Dong Li ◽

Changyu Liu

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Thermal Diffusivity ◽

Specific Heat ◽

Volume Concentration ◽

Volume Fraction ◽

Thermal Conversion ◽

Volumetric Heat Capacity ◽

Energy Storage Material ◽

Over Time

Paraffin is an excellent photo-thermal conversion phase change energy storage material, and extensively used in the thermal storage field at the medium-low temperature. However, the low thermal conductivity of paraffin restricts its application in practice. Adding nanoparticles into paraffin is one of the effective methods to improve its thermal conductivity. Nevertheless, the thermal diffusivity, specific heat and volumetric heat capacity of paraffin as well as timeliness were affected after the addition of nanoparticles. In this paper, the influences of volume fraction of Al2O3 nanoparticle and timeliness on these thermal parameters of paraffin were investigated. The results show that the thermal conductivity of paraffin-based Al2O3 nanofluids increases first and then decreases with time, and the maximum thermal conductivity is 0.34 W/[Formula: see text] for volume fraction 1% on third day. The higher volume concentration, the lower specific heat and volumetric heat capacity, all present downtrend over time, until stable in the range of 0.3 MJ/[Formula: see text] and 0.4 MJ/[Formula: see text]. The average enhancement rate of specific heat and volumetric heat capacity are concentrates on −6% to 9%, −10% to 0%, respectively. While increasing the volume concentration, the thermal diffusivity has no obvious regularity, and presents undulatory property over time.

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Mechanical, Hygric and Thermal Properties of Flue Gas Desulfurization Gypsum

Acta Polytechnica ◽

10.14311/626 ◽

2004 ◽

Vol 44 (5-6) ◽

Author(s):

P. Tesárek ◽

J. Drchalová ◽

J. Kolísko ◽

P. Rovnaníková ◽

R. Černý

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Thermal Expansion ◽

Flue Gas ◽

Linear Thermal Expansion Coefficient ◽

Linear Thermal Expansion ◽

Moisture Diffusivity ◽

Flue Gas Desulfurization ◽

Volumetric Heat Capacity ◽

Reference Measurements

The reference measurements of basic mechanical, thermal and hygric parameters of hardened flue gas desulfurization gypsum are carried out. Moisture diffusivity, water vapor diffusion coefficient, thermal conductivity, volumetric heat capacity and linear thermal expansion coefficient are determined with the primary aim of comparison with data obtained for various types of modified gypsum in the future.

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