scholarly journals STUDY OF ENERGY-SAVING LIQUID THERMAL INSULATING COATINGS BASED ON LOCAL FINELY DISPERSED SYSTEMS

2021 ◽  
Vol 17 (37) ◽  
pp. 189-203
Author(s):  
Zhanar O. ZHUMADILOVA ◽  
Vladimir P. SELYAEV ◽  
Ruslan E. NURLYBAEV ◽  
Yelzhan S. ORYNBEKOV ◽  
Indira B. SANGULOVA
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Building Materials ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Hollow Microspheres ◽  
Stationary Heat ◽  
Thermal Insulating ◽  
Polymer Binders ◽  
Topological Features

Introduction: In recent years, in building materials science, there has been a tendency for the active introduction of hollow microspheres of various types for modifying the properties of building materials. Hollow microspheres are most widely used in the production of liquid thermal insulating coatings, which reduce heat loss, protect structures from corrosion and overheating, prevent condensation formation, reduce operating costs and increase the time between repairs. Aim: Assessment of the influence of the structural characteristics of granular systems on the properties of thermal insulating materials. Methods: It is proposed to determine and evaluate the structural characteristics of filler powders by the method of small-angle X-ray scattering. The most important feature of this method is analyzing the internal structure of disordered systems - particles, pore space, interfaces between heterogeneities of heterogeneous substances. When assessing thermal conductivity and thermal resistance, the stationary heat flux method was used following GOST 30290–94. The essence of the method is to create a stationary heat flux passing through a flat sample of a certain thickness and directed perpendicular to the front (largest) faces of the sample, measuring the density of this heat flux, the temperature of the opposite front faces and the thickness of the sample. Results and Discussion: The paper discusses the results of experimental studies that make it possible to create liquid thermal insulation coatings (LTIC) based on polymer binders, fine mineral powders, and a complex of modifying additives. Experimental studies of the structure and properties of heat-insulating coatings based on filled polymer binders confirm their superiority over foreign analogs. Conclusions: It has been established that during the production of LTIC, their heat-shielding properties can be regulated by changing: pressure, the viscosity of the molecular weight of the gas; porosity of macrostructure and clusters; the thermal conductivity of the solid and gas phase of the system; the coefficient of accommodation; coordination number; primary particle size; fractal dimension characterizing the topological features of the structure of particles, aggregates, globules, clusters and their tendency to dissipate the energy of gas molecules.

scholarly journals Thermal Conductivity of Silica-aerogel (SA) and Autoclave Aerated Concrete (AAC) Composites

2020 ◽  
Vol 172 ◽  
pp. 21007
Author(s):  
Qu Mingliang ◽  
Tian Shuaiqi ◽  
Fan Liwu ◽  
Yu Zitao ◽  
Ge Jian
Keyword(s):  
Thermal Conductivity ◽  
Building Materials ◽  
Experimental Tests ◽  
Practical Significance ◽  
Mechanical And Thermal Properties ◽  
Impregnation Method ◽  
Relative Improvement ◽  
Thermal Insulating ◽  
Building Energy Conservation ◽  
Aerated Concrete

Improving the thermal insulating performance of porous building materials is of great practical significance for building energy conservation. In this work, silica aerogels (SA) with ultralow thermal conductivity were proposed as an appropriate candidate to be integrated with autoclaved aerated concrete (AAC) to produce novel SA-AAC composites with higher thermal insulating performance by physical solution impregnation method. The pore-structures, mechanical and thermal properties of the SA-AAC composites were probed by various experimental tests. According to the microscopy and porosimetry results, SA were observed to adhere to the surface walls of the AAC holes, thus reducing the amount of macro-sized pores. In addition, the improved thermal insulating performance of AAC was successfully achieved with the relative improvement depending on the porosity of the pristine AAC. At the mass fraction of SA of ~7%, the highest relative improvement was found to be ~30% The results of this work exhibited a great potential of this novel SA-AAC composite in engineering applications.

Research of Relations between Thermodynamic Quantities of Building Materials in Connection with Heat Dissipation

2015 ◽  
Vol 244 ◽  
pp. 48-53
Author(s):  
Milena Kušnerová ◽  
Jan Valíček ◽  
Vojtěch Václavík ◽  
Marta Harničárová ◽  
Lukáš Gola
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Capacity ◽  
Dissipation Rate ◽  
Building Materials ◽  
Material Parameter ◽  
Heat Dissipation ◽  
Temporal Change ◽  
Point Of View ◽  
Physical Point

This paper proposes the evaluation of material coefficient of heat dissipation rate for building materials, in particular using partial entropies, a temporal change in entropy upon heating a sample of a studied material and a temporal change in entropy upon overheating a sample of a studied material, in order to evaluate the rate of heat dissipation on samples of building materials with thermal insulating properties. From a physical point of view, the material parameter “specific heat capacity” generally refers to the ability of material to “conceive heat” so it can be said that the illustrated material Ytong has a slightly higher specific heat capacity than that of polyurethane. From a physical point of view, the material parameter “thermal conductivity” generally refers to the ability of a given material to “conduct heat through the material in connection with stationary heat flux”, so it can be assumed as well as verified by measuring that Ytong also has a higher thermal conductivity than that of polyurethane. From a physical point of view, the newly proposed material parameter “heat dissipation rate” generally indicates the “rate of heat loss to the external environment in connection with non-stationary heat flux”, so it may also be assumed and verified by measuring that the heat dissipation rate of Ytong will be higher than that of polyurethane.

Experimental Studies of the Physical and Mechanical Properties of Glued Building Materials Based on Modified Veneer

2021 ◽  
Vol 410 ◽  
pp. 817-822
Author(s):  
Ruslan R. Khasanshin ◽  
Ruslan R. Safin ◽  
Shamil R. Mukhametzyanov
Keyword(s):  
Building Materials ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Adhesive Interaction ◽  
Entire Volume ◽  
Timber Products ◽  
Ultraviolet Treatment ◽  
Birch Veneer

Today, glued timber products occupy a significant place in the volume of finished products of modern construction and woodworking enterprises. Plywood is one such product. The durability and structural characteristics of plywood depend on the quality of binder, the type of wood and the quality of veneer. The paper explores the technology of ultraviolet treatment of thermally modified birch veneer with subsequent production of waterproof plywood. The results of a study on the influence of the operating parameters of veneer modification on the complex of sorption and strength characteristics of plywood materials are presented. It is established that the combination of thermal modification of wood throughout the entire volume with surface treatment with ultraviolet radiation allows creating glued wood material with increased water resistance and high-quality adhesive interaction.

scholarly journals Assessment of the influence of the structural characteristics of granular systems of microsilicon on the properties of thermal insulation materials

2022 ◽  
Vol 320 (1) ◽  
pp. 5-14
Author(s):  
I.B. Sangulova ◽  
◽  
V.P. Selyaev ◽  
E.I. Kuldeev ◽  
R.E. Nurlybaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Granular Materials ◽  
Thermal Insulation ◽  
Structural Characteristics ◽  
Particle Surface ◽  
Experimental Studies ◽  
Granular Systems ◽  
Scattering Method ◽  
Gas Molecules

The article discusses experimental studies of the size and shape of structured particles of microsilica small angle x-ray scattering method and a photophonon theoretical description of the heat transfer process in complex heterogeneous structures to assessment of the structural characteristics of granular systems for the properties of thermal insulating materials. The mechanism of heat transfer in granular, porous systems is quite complex, since heat exchange occurs in a material consisting of two phases (solid and gas) and at the phase boundary. Heat transfer in liquid thermal insulation coatings can be carried out from one solid particle to another. In this case, the thermal conductivity will depend on: the chemical and elemental composition of the material; particle granulometry; surface topology - the presence of inhomogeneities, defects on the surface; the number of touches and the contact area between the particles. The heat transfer of gas in the pores is carried out when gas molecules collide. Thermal conductivity will be determined by the ratio of the free path of molecules and linear pore sizes, temperature and dynamic viscosity of the gas phase, the nature of the interaction of gas molecules with the solid phase. Heat transfer by radiation depends on the nature of the particles, the dielectric, magnetic permeability and the degree of blackness of the particle surface. Based on the analysis of possible mechanisms of heat transfer in granular systems, it can be argued that the effective thermal conductivity of the system depends, all other things being equal, on the structure of the pore space of granular materials, topology and the number of particle touches. Considering idealized models of the structure of granular materials in the form of ordered folds of perfectly smooth balls, we can obtain several variants of structures: with tetrahedral; hexagonal; cubic packing of balls.

scholarly journals Use of waste in production of thermal insulating slabs

2018 ◽  
Vol 251 ◽  
pp. 01035
Author(s):  
Ilya Morozov ◽  
Anna Loktionova ◽  
Nadezhda Galtseva ◽  
Vasily Korovyakov
Keyword(s):  
Thermal Conductivity ◽  
Building Materials ◽  
Heat Insulation ◽  
Optimum Composition ◽  
Gypsum Board ◽  
Rational Use ◽  
Thermal Insulating ◽  
The Individual

The purpose of the article is to find the rational use of waste formed in the course of production of heat-insulating plates on the basis of foamed polyisocyanurate, together with gypsum binder. Some tests were carried out to determine the thermal conductivity and strength of the obtained material, the estimation of their characteristics, the analysis of efficiency and needs of the final product in the market of building materials is given. It was established that when gypsum binder and additives are used together the result is a material with the best initial indicators of heat insulation and strength. The results of research showed that at the optimum composition of the gypsum and additives the material is not inferior to the individual indicators of drywall and gypsum. Board which proves both its efficiency and its need for construction.

scholarly journals Thermal Insulating Properties of Straw-Filled Environmentally Friendly Building Materials

2017 ◽  
Vol 13 (1) ◽  
pp. 52-57 ◽  
Author(s):  
Rositsa Petkova-Slipets ◽  
Penka Zlateva
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Energy Efficient ◽  
Building Materials ◽  
Thermal Conductivity Coefficient ◽  
Environmentally Friendly ◽  
Thermal Insulating ◽  
Insulating Properties ◽  
Thermal Physical Properties

AbstractThe paper presents results of a research for determination of a few general thermal-physical properties of environmentally friendly building materials made by clay, sand and straw. The aim of this study is to establish their heat insulating and energy-efficient capacity. All specific measurements were carried out by using the newest generation thermal conductivity analyser Mathis TCi.The results showed that the studied composite materials are good thermal insulators with thermal conductivity less than 0.5 W/m.K, which depends on the straw amount. Even less than 0.5 wt.% straw reflects on the insulating properties by decreasing the thermal conductivity coefficient with nearly 50 %.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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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