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  1. 15 Fibres & Textiles in Eastern Europe
  2. 14 Archives of Metallurgy and Materials
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  1. 12 Garbalińska H.
  2. 11 Koniorczyk P.
  3. 9 Zmywaczyk J.
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1
Wyznaczanie współczynnika przewodzenia ciepła w warunkach laboratoryjnych
100%
Łukasiewicz J. , Szymczak M.
Zeszyty Naukowe. Mechanika / Akademia Techniczno-Rolnicza w Bydgoszczy
|
2002
|
tom Z. 52(240)
65-74
PL
W artykule przedstawiono niektóre problemy wyznaczania wartości współczynnika przewodzenia ciepła [lambda] w warunkach laboratoryjnych. Zaprezentowano aparaturę i sposoby prowadzenia badań przewodności cieplnej cieczy, gazów i ciał stałych.
EN
The article covers some of the problems with defining the value of thermal conductivity [lambda] under laboratory conditions. There have been presented apparatuses and liquid, gas and solids thermal conductivity research methods.
2
Content available remote Experiment design for estimation of temperature dependent thermal conductivity
100%
Majchrzak E. , Freus K. , Freus S.
Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej
|
2010
|
tom Vol. 9, nr 1
83-88
EN
The nonlinear Poisson equation is considered, in which the thermal conductivity is a function of temperature λ (T ) = p1T+p2, where p1, p2 are the unknown parameters. To solve the inverse problem consisting in the identification of p1 and p2 the additional information connected with the knowledge of temperature T at the set of points (sensors) selected from the domain considered is necessary. The fundamental problem is the selection of sensors location and here the algorithm assuring the optimal sensors location is proposed. In the final part of the paper the results of computations are shown.
3
Content available remote One-axis molecular rotation and phonon scattering in solid C2H6 and C2F6
80%
Pursky O. , Konstantinov V.
Open Physics
|
2011
|
tom 9
|
nr 1
257-259
EN
Using solid C2H6 and C2F6 as an example, the one-axis molecular rotation effect on thermal conductivity has been considered in orientationally-ordered (OO) and orientationally-disordered (OD) phases of simple molecular crystals. The influence of molecular rotation on the heat transfer processes has been studied by a modified method of reduced coordinates, which permitted separating phonon-phonon and phonon-rotation contributions to the total thermal resistance.
4
Content available Thermal conductivity of wooden floors in the context of underfloor heating system applications
80%
Pajchrowski G. , Noskowiak A.
Drewno : prace naukowe, doniesienia, komunikaty
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2018
|
tom vol. 61, nr 202
145--152
EN
Wood, as a traditional flooring material, has fairly low thermal conductivity; hence achieving heat resistance at a level ensuring good heat transfer from the heating system to the room is very important. This can be achieved by selecting the right materials or by applying appropriate design solutions. Determining properties associated with heat transport for construction products usually involves determining the heat transfer coefficients of building envelopes in the context of thermal insulation. However, in the case of buildings with underfloor heating the expectations are reversed – flooring elements should have good thermal conductivity, i.e. low thermal resistance (below 0.15 m2K/W). This condition was satisfied by almost all tested types of floorings. On comparison of the test results with the calculations, it was found that the calculated values of thermal resistance were lower than the experimental values, which may suggest that in relation to use on underfloor heating the calculated values imply better properties than are achieved in practice.
5
Content available remote Reduction of an effective thermal conductivity in the aspect of two flux model for absorbing, emitting and scattering media
80%
Koniorczyk P. , Zmywaczyk J. , Kowalski M.
Archives of Thermodynamics
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2004
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tom Vol. 25, no. 4
19-29
EN
The present paper deals with numerical analysis of the steadystate problem of the 'thickness effect curve' in semitransparent media, where simultaneos radiation and conduction heat transfer takes place. The analysis is conducted with the aid of a Two Flux Method (TFM) for absorbing, emitting and scattering media. Results are compared with the exact solution obtained fom a 1-D coupled radiation and conduction heat transfer model (RTE) in an emitting, absorbing as well as scattering medium.
6
Eksperymentalne badania radiacyjno-kondukcyjnej wymiany ciepła w macie aerożelowej Porogel Medium Space-Loft
80%
Zieliński M. , Koniorczyk P. , Zmywaczyk J.
Ciepłownictwo, Ogrzewnictwo, Wentylacja
|
2019
|
tom T. 50, nr 7
257--260
PL
Przedstawiono wyniki pomiarów przewodności cieplnej k maty aerożelowej o nazwie handlowej Porogel Medium Space-Loft firmy Aspen Aerogels (USA). Obiektem badań były cztery próbki: a) warstwa maty aerożelowej o grubości 10 mm, b) dwie warstwy maty o łącznej grubości 20 mm, c) trzy warstwy o łącznej grubości 30 mm, d) czterech warstw o łącznej grubości 40 mm. Pomiary wykonano w zakresie temp. od około 0oC do około 50oC Wyniki badań k w funkcji grubości próbki l oraz w funkcji temp. T porównano z takimi samymi badaniami wykonanymi w ostatnich latach przez autorów dla styropianu białego w kropki firmy Termoorganika (Polska) oraz styropianu grafitowego firmy Arbet (Austria) [3-6].
EN
The results of thermal conductivity measurements of the aerogel blanket Porogel Medium Space-Loft manufactured by Aspen Aerogels (USA) were presented. Measurements were made for four samples: a) layer of aerogel blanket with a thickness of 10 mm, b) two layers of blanket with a total thickness of 20 mm, c) three layers with a total thickness of 30 mm, d) four layers with a total thickness of 40 mm. The measurements were carried out in the temperature range from about 0oC to about 50oC. Thermal conductivity test results as a function of sample thickness k(l) and in function of temperature k(T) were compared with the same tests made in recent years by the authors for Polystyrene in Dots manufactured by Termoorganika (Poland) and Styrofoam Graphite manufactured by Arbet (Austria) [2-6].
7
Content available Effect of Metallic Additives to Polymer Matrix on Properties of Composite Adhesives Dedicated for Light Metal Joining
80%
Mamala A. , Kwaśniewski P. , Nowak A. , Grzebinoga J. , Ściężor W. , Kowal R.
Archives of Metallurgy and Materials
|
2017
|
tom Vol. 62, iss. 4
2287--2294
EN
The most recent and promising trends in development of renewable sources of energy are Combined Heat and Power (CHP) systems. The newest solutions from this field are hybrid compact solar panels. The correct operation of both systems, i.e. the photovoltaic panel and the heat exchanger requires an effective connection between the two. The adhesives utilized to interconnect above elements should provide a stable and hermetic joint able to withstand mechanical and thermal impacts of the surrounding environment factors. The paper presents the research results over the impact of the type and the amount of reinforcing phase on the physical and mechanical properties of epoxy resin matrix composites reinforced with particles of non-ferrous metals (Ag, Cu, W, Al), dedicated as adhesives for connections between photovoltaic panels and heat exchangers. Based on the experimental findings the usefulness of classical analytic models for valuation of polymer-metal composites properties was validated.
8
Content available Working temperature calculation of single-core cable by nonlinear finite element method
80%
Meng X. , Han P. , Liu Y. , Lu Z. , Jin T.
Archives of Electrical Engineering
|
2019
|
tom Vol. 68, nr 3
643--656
EN
By simulating the actual working conditions of a cable, the temperature variation rule of different measuring points under different load currents was analyzed. On this basis, a three-dimensional finite element model (FEM) was established, and the difference and influence factors between the simulation temperature and the experimental measured value were discussed, then the influence of thermal conductivity on the operating temperature of the conductor layer was studied. Finally, combined with the steady-state thermal conductivity model and the experimental measured data, the relation between thermal conductivity and load current was obtained.
9
Content available An Idea of a Measurement System for Determining Thermal Parameters of Heat Insulation Materials
80%
Chudzik S. , Minkina W.
|
|
nr 2
10
Content available remote Dimensions of the nucleus agent pore former closed spherical pores
80%
Pavlenko A. , Cheylitko A. , Koshlak H. , Piotrowski J. Z.
Journal of New Technologies in Environmental Science
|
2017
|
tom Vol. 1, nr 3
101--107
EN
Many experimental data indicate a relationship between the porosity of the material and its thermophysical properties [1-3]. Influence of porosity on the thermal conductivity of the material can be considered following the example of experimental data [2]. The values of thermal conductivity coefficient of iron (58.19 W/(m∙K)) and a rock formation (3.26 W/(m∙K)) differ by almost 18 times, but the filling of iron balls and balls rock formation of the same a porosity of 62.5% has nearly the same coefficient of thermal conductivity (0.0403 W/(m∙K) and 0.0402 W/(m∙K) respectively). However, the way of forming the porous structure has not yet been investigated, and a clear relationship between the porosity and the physical properties of the material not found.
11
Content available The Heat Transfer Process Between Two Bodies with a Large Temperature Difference
80%
Przyłucka-Bednarska A. , Rywotycki M. , Sołek K. , Malinowski Z.
Archives of Metallurgy and Materials
|
2022
|
tom Vol. 67, iss. 3
1161--1165
EN
Heat transport when two surfaces of solids come into contact is an important phenomenon in many metallurgical processes. Determining the boundary conditions of heat transfer allows to obtain the correct solutions of the heat conduction equation. The paper presents models for determining the heat transfer coefficient between steel materials in contact. Experimental tests were carried out to measure the temperature changes of the contacting samples made of steel S235 (1.0038) and steel 15HM (1.7335) under the pressure of 10, 15 and 20 MPa. There was a large temperature difference between the samples. The results of the experiment were compared with numerically calculated temperatures and the value of the heat transfer coefficient was determined at different pressure values depending on the time.
12
Content available remote Heat transfer in the plastic phases I and II of cyclopentane
80%
Konstantinov V. , Sagan V. , Revyakin V. , Karachevtseva A. , Pursky O.
Open Physics
|
2014
|
tom 12
|
nr 9
654-659
EN
Thermal conductivity of solid cyclopentane C5H10 has been measured at isochoric conditions in the plastic phases I and II for samples of different densities. Isochoric thermal conductivity is nearly constant in phase II and increases with temperature in phase I. Such behaviour is attributed to weakening of the translational orientational coupling which, in turn, leads to a decrease of phonon scattering on rotational excitations. The experimental data are described in terms of a modified Debye model of thermal conductivity with allowance for heat transfer by both low-frequency phonons and diffusive modes.
13
Content available remote Obliczeniowa przewodność cieplna na potrzeby symulacji komputerowej stanów termicznych budynków
80%
Bobociński A.
Czasopismo Techniczne. Budownictwo
|
2006
|
tom R. 103, z. 5-B/1
57-64
PL
Referat dotyczy obliczeniowej przewodności cieplnej na potrzeby symulacji komputerowej stanów termicznych budynków. Przedstawiono wyniki badań przewodności cieplnej materiałów o sorpcyjnej i ponadsorpcyjnej zawartości wilgoci. Badania objęły betony komórkowe oraz materiały do izolacji cieplnej. Stwierdzono, że czynniki konwersji współczynnika przewodzenia ciepła ze względu na zawartość wilgoci, określone zgodnie z PN ISO 10456 dla potrzeb projektowania są generalnie zawyżone w porównaniu z określonymi na podstawie wyników badań własnych - w zależności od typu, odmiany i gęstości materiału. Do symulacji zalecono przyjmowanie czynników konwersji określonych na podstawie badań wykonanych dla potrzeb takich obliczeń.
EN
This work refers to computational thermal conductivity for computer simulation of thermal processes in buildings. One presents results of own tests of thermal conductivity of materials with sorption and over sorption moisture content. This tests including cellular concretes and thermal insulations. It has been found that conversion factors of thermal conductivity in view of moisture content, determines in compliance with PN ISO 10456 are generally over estimated in relation to ones based on test results - according to type, variety and density of material. For PC computer simulation one recommends the conversion factors based on tests performed for needs of such calculations.
14
Content available remote Problems for determining the thermal conductivity of TBCs by laser-flash method
80%
Altun O. , Erhan Boke Y. , Kalemtas A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2008
|
tom Vol. 30, nr 2
115-120
EN
Purpose: The purpose of this paper was to investigate the parameters which effect the results of determining the thermal conductivity of thermal barrier coatings (TBCs) by laser-flash method. Design/methodology/approach: The air plasma-spray (APS) technique was used to deposition of two- and three-layered samples. Two-layered samples were composed of metal substrate (321 stainless steel), and ceramic top coat (8YSZ). Three-layered samples were composed of metal substrate (321 stainless steel), bond coat (NiCrAlY) and top coat (8YSZ). Thermal diffusivity of each layer have been measured in the temperature range from room temperature (RT) to 900° C by laser-flash method. The thermal conductivity was calculated with respect to density, specific heat and diffusivity of the materials. Findings: Obtained results show that the specific heat, density and thicknesses of metal substrate, bond coat and top coat play important role in the thermal conductivity measurement. Research limitations/implications: To obtain the correct results in laser-flash technique thickness, density, and cp of the materials are needed to be measured accurately and surface smoothness of samples should be provided sensitively. Errors in these parameters cause high deviations in measurements. Practical implications: It has been aimed offer an insight into the experimental determination of thermal conductivity of layered TBC system which are used in high technologic applications. Originality/value: Laser-flash method is the most widely used experimental technique to determine the thermal conductivity of APS TBCs at high temperatures. The research contributes to better understanding and recognition the importance of sample preparation in laser-flash method.
15
Content available Full-scale dynamometer test of composite railway brake shoes – study on the effect of the reinforcing fibre type
80%
Wasilewski P.
Acta Mechanica et Automatica
|
2018
|
tom Vol. 12, no. 3
204--208
EN
When designing or developing friction materials, it is crucial to predict how the modification of the formulation will affect their properties. Fibres are introduced in the composition of the phenolic-based brake friction materials to improve their mechanical strength. Apart from reinforcing the composite, fibres can also affect its tribological and thermophysical properties. In this study two composite friction materials are compared. The difference between the materials was the type of reinforcing fibre used in the formulation – in one case it was glass fibre, in the other steel fibre. Thermal diffusivity of both materials was measured and thermal conductivity was calculated. Frictional characteristics determined by means of full-scale dynamometer tests are analysed and discussed. Substitution of glass fibre with steel fibre led to increase in the friction coefficient. Maximum average temperature below wheel surface, observed during the test of the material containing steel fibre, was lower as compared to the test results of the material with glass fibre in its formulation, despite higher heat flux in the course of brake applications. Thermal conductivity of the friction material was enhanced by including steel fibre in the formulation.
16
Estimation of temperature dependent thermal conductivity - steady state problem
80%
Majchrzak E.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2006
|
tom z. 88
235-240
EN
In the paper the application of the BEM for numerical solution of the inverse parametric problem is presented. On the basis of the knowledge of temperature field in the domain considered the temperature dependent thermal conductivity is identified. The steady state is considered and 2D problem is solved using the least squares criterion in which the sensitivity coefficients appear.
17
Content available remote Experimental determination thermal conductivity of dolomitic limestone
80%
Nemec P. , Malcho M.
Journal of New Technologies in Environmental Science
|
2018
|
tom Vol. 2, nr 1
3--7
EN
The origin of geothermal energy is in the hot core of the Earth. Due its inexhaustible potential, it is also included among renewable sources. Renewable sources are, from the point of view of national economies, domestic resources that have the potential to replace and in the future, in certain applications, completely dispose of fossil fuels. These sources already offer the opportunity to significantly diversify energy sources in each country. Their development is also seen as an important tool to protect the national economy from future shocks from the rise in imported fuel prices and the cost of environmental damage [1]. Heat from the Earth's rock is obtained from deep boreholes of 100 m to 300 m. Systems for acquiring natural thermal energy from the ground are referred to as ground (wells) - water, i.e. that the rocks are the source of thermal energy that is pumped from the rocks through a circulating antifreeze mixture into a hermetically sealed collector. The heat pump produces a heat output of up to 65°C through the compressor, which is sufficient for the hot water heating system or for hot water heating [2]. Limestone and dolomite make up four fifths of all sediments on the Earth's surface. The transition between dolomite and limestone is not sharp, and thus is form a dolomitic limestone - a rock made of dolomite and a predominant limestone. Dolomite is a rock of sedimentary origin. It consists predominantly of a mineral of the same name. It is formed by settling of CaMg(CO3) in hypersalinic aqueous medium, but more often it results from dolomitization of settled limestones [3]. In Slovakia and especially in the Žilina region there is a large number of sites on dolomitic limestone, so it is necessary to know the properties of these rocks in what composition they occur in nature. The course of the temperature field in the rock mass can be determined by direct field measurements and analytical calculations. Mostly on-site measurement results provide input data for analytical calculation. On the other hand, the analytical calculation applies to the ideal body, and the information thus obtained provides a sort of temperature field course. By comparison, we can determine whether the temperature field in a rock mass based on the calculations is real or is loaded by errors (in measurements, in ignorance of structural - texture parameters, moisture and other aspects of material and mass) [4].
18
Content available The Effect of Using Naphthalene and Local Soil with Concrete Mixture on Thermal Conductivity, Case of Mafraq City – Jordan
80%
Alzoubi H. H. , Al-Olaimat D. J.
Journal of Ecological Engineering
|
2019
|
tom Vol. 20, nr 4
42--53
EN
This study explores the effect of direct incorporation of different ratios of naphthalene with soil into the concrete used in Mafraq-Jordan on the thermal conductivity of concrete mixtures. The methodology involved testing 72 concrete cube samples. The basic samples were prepared only from a mixture of water, silica sand, and cement without additives. The additives of local soil and naphthalene of different ratios: 2.5%, 5%, 7%, 10% and 15%, were added to the tested samples. The samples were classified into two groups in terms of size and dimensions; 36 cubes with 5×5×5 cm were tested only for thermal conductivity, and 36 cubes with 3×3×3 cm were tested for compressive strength and thermal conductivity. All samples were tested after 28 days of casting, according to the concrete standards. The results show that adding naphthalene and soil to the cementitious mixtures substantially decreases the thermal conductivity of concrete elements. A reasonable reduction in thermal conductivity was achieved compared with the basic case samples. However, the compressive strength of samples remained within the acceptable values from the stand point of structural engineering. This enhancement in the thermal properties of concrete can be applied in building systems as concrete blocks used in internal and external walls.
19
Content available The impact of graphite impact on the thermal conductivity of the solidified grout
80%
Śliwa T. , Kowalski T. , Stryczek S. , Wiśniowski D. , Bieda A. , Piwowarczyk S. , Beszłej J. , Naklicki M. , Sapińska-Śliwa A.
AGH Drilling, Oil, Gas
|
2017
|
tom Vol. 34, no. 4
811--820
EN
The fast development of low-temperature geothermal energy affects the search for newer and newer solutions and materials used in the construction of borehole heat exchangers. One of the most important factors affecting the correct operation of heat pump systems with borehole heat exchangers is appropriately selected solidified grout. Solidifies grout has to be characterized by the highest thermal conductivity and good sealing borehole heat exchangers. The paper will present the impact of graphite on the thermal conductivity of solidified grout.
20
Content available remote Thermal properties of Fe-based bulk metallic glasses
80%
Nowosielski R. , Januszka A. , Babilas R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2012
|
tom Vol. 55, nr 2
349--354
EN
Purpose: The aim of paper is presentation of results bulk metallic glasses thermal properties such as temperatures typical for glassy transition and thermal conductivity. Design/methodology/approach: Investigations were realized for Fe36Co36B19.2>/sub>Si4.8Nb samples with dimension 3 mm in diameter. Bulk test pieces were fabricated by copper mold casting method. Thermal analysis of master alloy (DTA) and samples in as-cast state (DSC) was realized. For amorphous structure confirmation the X-ray diffraction phase analysis (XRD) was realized. Additionally scanning electron microscopy (SEM) micrographs were performed in order to structure analysis. Thermal conductivity was determined by prototype measuring station. Findings: The XRD and SEM analysis confirmed amorphous structure of samples. Broad diffraction “halo” was observed for every testing piece. Fracture morphology is smooth with many “veins” on the surface, which are characteristic for glassy state. DTA analysis confirmed eutectic chemical composition of master alloy. Thermal conductivity measurements proved that both samples have comparable thermal conductivity. Practical implications: The FeCo-based bulk metallic glasses have attracted great interest for a variety application fields for example precision machinery materials, electric applications, structural materials, sporting goods, medical devices. Thermal conductivity is useful and important property for example computer simulation of temperature distribution and glass forming ability calculation. Originality/value: The obtained results confirm the utility of applied investigation methods in the thermal and structure analysis of examined amorphous alloys. Thermal conductivity was determined using the prototype measuring station, which is original issue of the paper. In future, the measuring station will be expanded for samples with different dimensions.
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