Thermal Conductivity Research of Gaseous and Liquid Naphthenic Hydrocarbons Over a Wide Range of State Parameters

1983 ◽  
pp. 275-284
Author(s):  
Ya. M. Naziev ◽  
A. H. Shakhverdiyev
Keyword(s):  
Thermal Conductivity ◽  
Wide Range ◽  
Naphthenic Hydrocarbons

Study of Method for Determination of Thermal Conductivity of Automotive Interior Materials

2014 ◽  
Vol 526 ◽  
pp. 46-51
Author(s):  
Li Xiong Zhang ◽  
Rong Gang Gao
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurement ◽  
Transient Heat Conduction ◽  
Traditional Theory ◽  
Infinite Plane ◽  
Plane Source ◽  
Transient Plane Source ◽  
Wide Range ◽  
Automotive Interior

Based on the traditional theory of transient plane source for thermal conductivity measurement, this paper designed and developed a new pattern of heating and temperature sensing probe, presented the study of transient heat conduction of half-infinite plane while being heated, established a modified mathematical model of transient plane source method, and achieved the measurement of thermal conductivity of automotive interior material sample by the data processing method of mathematical iteration and liner regression using the modified transient plane source probe. According to the data of experiments, the instrument which this paper designed has a high precision of 5% and a wide range of 0.003-1W/(mK).This paper provides a practicable way for heat capacity determination of automotive interior materials.

Evaporite Palynology: a case study on the Permian (Lopgingian) Zechstein Sea

2021 ◽  
pp. jgs2020-174
Author(s):  
Martha E. Gibson ◽  
David J. Bodman
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Rapid Growth ◽  
Western Europe ◽  
Thermal Maturity ◽  
Near Surface ◽  
Wide Range ◽  
Terrestrial Environments ◽  
Insight Into

Evaporites characterize the Lopingian of Europe but present obstacles for biostratigraphic analysis. Here we present a case study for processing the Lopingian Zechstein Group evaporites of central-western Europe for the recovery of palynomorph assemblages. We demonstrate that full recovery is easily achieved with two main modes of palynomorph preservation observed; palynomorphs are either exceptionally well-preserved and orange-brown in colour, or poorly-preserved, brown-black, opaque and fragmented. The latter are reminiscent of palynomorphs of high thermal maturity. However, we propose that the intact nature of preservation is a result of the rapid growth of near-surface halite crystals, with their darkening a consequence of locally-enhanced heat flux due to the relatively high thermal conductivity of salt. This case study has enabled novel insight into an otherwise undescribed environment, and demonstrates the utility and possibility of extracting palynomorphs from a variety of rock salt types. This method should be applicable to a wide range of ancient evaporite and could also be applied to other Permian evaporite systems, which are used as analogues for extra-terrestrial environments.

An Investigation of Hydrological Effects on the Thermal Performance of Standing Column Well Using the in-situ Thermal Response Test

2019 ◽  
Vol 27 (02) ◽  
pp. 1950015 ◽  
Author(s):  
Keun Sun Chang ◽  
Young Jae Kim ◽  
Min Jun Kim
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Flow Rate ◽  
Large Scale ◽  
Thermal Response ◽  
Thermal Response Test ◽  
Response Test ◽  
Geological Conditions ◽  
Wide Range ◽  
Borehole Thermal Resistance

The standing column well (SCW) for ground source heat pump (GSHP) systems is a highly promising technology with its high heat capacity and efficiency. In this study, a large-scale thermal response tester has been built, which is capable of imposing a wide range of heat on the SCW ground heat exchangers and measuring time responses of their thermal parameters. Two standing column wells in one site but with different well hydrological and geological conditions are tested to study their effects on the thermal performances. Borehole thermal resistance ([Formula: see text]) and the effective thermal conductivity ([Formula: see text]) are derived from data obtained from the thermal response test (TRT) by using a line source method. Results show that the influence of groundwater movement on the thermal conductivity of the SCW is not very significant (3.6% difference between two different geological conditions). This indicates that results of one TRT measurement can be applied to other SCWs in the same site, with which considerable time and cost are saved. The increase of circulation flow rate enhances the ground thermal conductivity moderately (4.5% increase with flow rate increase of 45%), but the borehole thermal resistance is substantially lowered (about 25.9%).

scholarly journals Experimental investigation of rockwool insulation hygrothermal properties related to material structure

2015 ◽  
Vol 19 (3) ◽  
pp. 923-928 ◽  
Author(s):  
Maja Djurovic-Petrovic
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Sorption Properties ◽  
Material Structure ◽  
Insulation Material ◽  
Wide Range ◽  
Two Samples

The hygrothermal properties related to rockwool insulation material structure with different additives are presented using rockwool insulation products obtained from row material of southern Serbia (Vranje region) in the wide range of reference temperatures (10?C to 70?C). The hygrothermal properties of basic sample (without additives) are compared to two samples with different additives for two sets of rockwool insulation samples namely: light-soft-panels (LSP) with density of 50 kg/m3, and middle-weight-panels (MWP) with density of 80 kg/m3. It is shown that there is significant (approximately 10%) improvement of thermal conductivity for additives based on zeolite. Also, correlation of thermal conductivity and sorption properties of selected samples are presented.

scholarly journals A Computational Survey of Semiconductors for Power Electronics

2019 ◽  
Author(s):  
Prashun Gorai ◽  
Robert McKinney ◽  
Nancy Haegel ◽  
Andriy Zakutayev ◽  
Vladan Stevanovic
Keyword(s):  
Thermal Conductivity ◽  
Power Electronics ◽  
Figure Of Merit ◽  
Large Scale ◽  
Lattice Thermal Conductivity ◽  
Consumer Products ◽  
Breakdown Field ◽  
Experimental Investigations ◽  
Wide Range ◽  
Screening Parameter

Power electronics (PE) are used to control and convert electrical energy in a wide range of applications from consumer products to large-scale industrial equipment. While Si-based power devices account for the vast majority of the market, wide band gap semiconductors such as SiC, GaN, and Ga2O3 are starting to gain ground. However, these emerging materials face challenges due to either non-negligible defect densities, or high synthesis and processing costs, or poor thermal properties. Here, we report on a broad computational survey aimed to identify promising materials for future power electronic devices beyond SiC, GaN, and Ga2O3. We consider 863 oxides, sulfides, nitrides, carbides, silicides, and borides that are reported in the crystallographic database and exhibit finite calculated band gaps. We utilize ab initio methods in conjunction with models for intrinsic carrier mobility, and critical breakdown field to compute the widely used Baliga figure of merit. We also compute the lattice thermal conductivity as a screening parameter. In addition to correctly identifying known PE materials, our survey has revealed a number of promising candidates exhibiting the desirable combination of high figure of merit and high lattice thermal conductivity, which we propose for further experimental investigations.

Development of high-insulating materials with aerogel for protective clothing applications – an overview

2021 ◽  
Vol 112 (2) ◽  
pp. 164-172
Author(s):  
Agnieszka Greszta ◽  
Sylwia Krzemińska ◽  
Grażyna Bartkowiak ◽  
Anna Dąbrowska
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Protective Clothing ◽  
State Of The Art ◽  
Knitted Fabrics ◽  
Insulating Materials ◽  
Textile Materials ◽  
Wide Range ◽  
Properties Of Materials ◽  
Hot Environments

Abstract Aerogels are ultra-light solids with extremely low thermal conductivity (even lower than air), thanks to which they have a huge potential in a wide range of applications. The purpose of this publication is to present the state-of-the art knowledge of the possibility of using aerogels to increase the thermal insulation properties of clothing materials intended for use in both cold and hot environments. Various methods of aerogels application to textile materials (non-woven, woven and knitted fabrics) are discussed, indicating their advantages and limitations. Numerous research studies confirm that aerogels significantly improve the thermal insulation properties of materials, but due to their delicate and brittle structure and their tendency to dusting, their application still poses considerable problems.

Diffusion

2005 ◽  
Author(s):  
Boris S. Bokstein ◽  
Mikhail I. Mendelev ◽  
David J. Srolovitz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Nearest Neighbor ◽  
Thermal Motion ◽  
Concentration Gradients ◽  
Entropy Of Mixing ◽  
Wide Range ◽  
P Diffusion ◽  
Phase Systems ◽  
Increasing Temperature

Diffusion is associated with the random, thermal motion of atoms that produces a change in the macroscopic concentration profile. This process occurs in gases, liquids, amorphous and crystalline solids of metals, ceramics, polymers, semiconductors, etc. The investigation of diffusion provides valuable information about the atomic structure of materials and the defects within them. Perhaps, most importantly, diffusion controls the rates of a wide range of kinetic processes associated with the synthesis of materials, processes by which we modify materials, and processes by which materials fail. The most common driving force for diffusion in a single-phase systems is associated with the entropy of mixing of its constituents (recall that we showed that the entropy of mixing of gases and the components of an ideal solution are always positive—see Sections 1.2.6 and 3.3). Since diffusional processes occur through the thermal motion of atoms (see below), it will not be surprising to learn that the rate of diffusion increases with increasing temperature. However, note that while the mechanisms of thermal motion in gases (random collision of atoms with each other) and liquids (e.g. Brownian motion) necessarily lead to mixing, the mechanisms of mixing within a solid are not as obvious. In solids, thermal motion corresponds to the vibrations of atoms near their equilibrium positions. Since the amplitude of such vibrations is much smaller than the nearest-neighbor separation, it would seem that such thermal motions cannot lead to mixing. Thus, the question ‘‘how do atoms migrate in solids’’ is not so simple. The equations describing diffusion were suggested by the physiologist Fick in 1855 as a generalization of the equations for heat transfer suggested by Fourier in 1824. Fick’s equations for diffusion can be obtained by analogy with Fourier’s equations for heat transfer by replacing heat with the number of atoms, temperature with concentration, and thermal conductivity with diffusivity. Fick’s first law provides a relationship between atomic currents and concentration gradients. As discussed above, this relationship can be understood by analogy with thermal conductivity or electrical conductivity.

Thermographic Studies of Aerogel Composites

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
K. Keerthi Sanghamitra ◽  
A. Yamini ◽  
A. Venu Vinod ◽  
Neha Hebalkar
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Cold Water ◽  
High Porosity ◽  
Fiber Mats ◽  
Aerospace Applications ◽  
Thermal Insulating ◽  
Wide Range ◽  
Composite Form ◽  
Insulation Performance

AbstractAerogels are regarded as the superior thermal insulating materials for wide range of temperatures, from cryogenic insulation, cold water diving garments to high temperature applications and even to defense and aerospace applications. For most of such applications, the aerogels are used in composite form rather than monolithic form as aerogels are fragile in nature due to its high porosity of up to 98%. These composites constitute aerogel infiltrated fiber mats to give flexibility, on the other hand, compromises on the insulation performance due to reinforcing aerogel with fibers that have comparatively higher thermal conductivity than silica aerogel. To increase the efficiency, density of the fiber mat needs to be reduced to incorporate higher loading of silica aerogel. Many techniques are being used to study the insulation performance of these composites. This paper presents about the study of insulation performance of fibre mats with different aerogel content and composition using a well-known thermography technique. The morphological, compositional, thermal and physical studies of the fiber mats and its composites using FESEM, EDAX, BET, thermal conductivity etc., are discussed.

Synergistic modulation of mobility and thermal conductivity in (Bi,Sb)2Te3 towards high thermoelectric performance

2019 ◽  
Vol 12 (2) ◽  
pp. 624-630 ◽  
Author(s):  
Yu Pan ◽  
Yang Qiu ◽  
Ian Witting ◽  
Liguo Zhang ◽  
Chenguang Fu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Performance ◽  
Second Phase ◽  
Wide Range ◽  
Synergistic Modulation

Two-step sintering efficiently enhances zT by tuning the microstructure in a wide range from atomic defects to micrometer second phase.

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