Properties Of Thermal Insulation Materials Research Articles

Analysis of Thermal Properties of Materials Used to Insulate External Walls.

This article emphasizes the significance of understanding the actual thermal properties of thermal insulation materials, which are crucial for avoiding errors in building design and estimating heat losses within the energy balance. The aim of this study was to analyse the thermal parameters of selected thermal insulation materials, particularly in the context of their stability after a period of storage under specific conditions. The materials chosen for this study include commonly used construction insulations such as polystyrene and mineral wool, as well as modern options like rigid foam composites. Experimental studies were conducted, including the determination of the thermal conductivity coefficient λ, as well as numerical analyses and analytical calculations of heat flow through a double-layer external wall with a window. The numerical analyses were performed using the TRISCO software version 12.0w, based on the finite element method (FEM). A macrostructural analysis of the investigated materials was also performed. The findings indicated that improper storage conditions adversely affect the thermal properties of insulation materials. Specifically, storing materials outdoors led to a deterioration in insulating properties, with an average reduction of about 4% for the standard materials and as much as 19% for the tested composite material. Insufficient understanding of the true thermal properties of insulation materials can result in incorrect insulation layer thickness, degrading the fundamental thermal parameters of external walls. This, in turn, increases heat loss through major building surfaces, raises heating costs, and indirectly contributes to greenhouse gas emissions.

Estimation of heat source, specific heat, and thermal conductivity of insulation materials using modified conjugate gradient method

The use of insulation materials is crucial for minimizing thermal losses in various industries like automotive, building, solar, and aerospace. Plexiglass and Expanded Polystyrene (EPS) foam are popular choices due to their effective temperature regulation, lightweight nature, and cost-effectiveness. Accurate measurement of their thermal properties is vital for achieving conservation goals. While the parallel hot wire technique provides valuable insights, accurately determining heat source strength (HW) poses a challenge, impacting measurement accuracy. To address this, the modified Conjugate Gradient Method (CGM) is employed for simultaneous estimation of thermal conductivity (λ), specific heat (c) and HW of Plexiglass and EPS foam. The direct problem result has been validated with published experimental work that shows deviations less than 2 %. The study investigates the impact of sensor positioning relative to the hot-wire (rm) and introduces artificial Gaussian error with standard deviations (θ) of 0.01 °C, 0.02 °C and 0.1 °C. At θ = 0.1 °C the percentage relative errors in the estimation of λ, c and HW with rm = 5 mm for Plexiglass are 5 %, 1.442 %, and 4.651 % respectively. For EPS foam the corresponding errors are 2.44 %, 1.26 %, and 1.74 %. The modified CGM emerges as a reliable algorithm for the measurement of thermal properties of insulation materials.

A Parametric Physics-Informed Deep Learning Method for Probabilistic Design of Thermal Protection Systems

Precise and efficient calculations are necessary to accurately assess the effects of thermal protection system (TPS) uncertainties on aerospacecrafts. This paper presents a probabilistic design methodology for TPSs based on physics-informed neural networks (PINNs) with parametric uncertainty. A typical thermal coating system is used to investigate the impact of uncertainty on the thermal properties of insulation materials and to evaluate the resulting temperature distribution. A sensitivity analysis is conducted to identify the influence of the parameters on the thermal response. The results show that PINNs can produce quick and accurate predictions of the temperature of insulation materials. The accuracy of the PINN model is comparable to that of a response surface surrogate model. Still, the computational time required by the PINN model is only a fraction of the latter. Considering both computational efficiency and accuracy, the PINN model can be used as a high-precision surrogate model to guide the TPS design effectively.

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ ТЕПЛОПРОВІДНОСТІ ТЕПЛОІЗОЛЯЦІЙНИХ МАТЕРІАЛІВ ІЗ МІНЕРАЛЬНОЇ ВАТИ

According to the analysis of domestic and foreign literature sources, it is noted that reducing energy consumption to create an optimal microclimate of buildings involves reducing heat loss through external enclosing structures. Construction of new buildings and thermal modernization of existing ones is carried out with the use of different properties of thermal insulation materials, passport data of manufacturers on their characteristics need to be clarified in determining the energy efficiency of buildings. Mineral wool was selected for experimental studies of thermal insulation material used to improve the thermal insulation shell. The energy efficiency of mineral wool was studied using an installation with a climate chamber with a homogeneous heat flux over the cross-sectional area of ​​the sample. To register the change in the amount of heat flux, thermocouples were used, which are located at different points of the climate chamber with a sample of mineral wool. Data on the change in temperature during the observation period before the stabilization of the heat flux was determined by the automatic registration unit. The change in time of the temperature regime at different points of the mineral wool sample is obtained. The thermal conductivity, which characterizes the efficiency of the thermal insulation material made of mineral wool, was calculated according to the known Fourier formula for stationary thermal regime from the values ​​of the temperature difference in the characteristic cross sections of the sample. The discrepancy between the values ​​of thermal conductivity of the investigated sample and the passport data of thermal conductivity of mineral wool provided by its manufacturer is revealed.

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

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.

Mathematical modeling of the properties of thermal insulation materials based on hollow ceramic microspheres and phenylon

In this work, the creation of heat-insulating materials that are still operable at temperatures up to + 400 °C and have increased physical and mechanical characteristics was studied. This aim was achieved by using a heat-resistant polymer binder phenylon (an aromatic polyamide) and hollow ceramic microspheres, that were used as a filler. Phenylon was produced by OJSC «Polimersintez» in Vladimir. Hollow ceramic microspheres are the floating fractions of flue emissions from solid-fuel thermal power plants. Thermal insulation materials were made by mixing hollow ceramic microspheres with a phenylon solution in dimethylacetamide to the state of «wet sand». Then, the obtained substance was molded the solvent residues were removed. Furthermore, the main properties of the obtained materials were also studied. It was established that the thermal insulation material is characterized by high strength characteristics, has significant resistance to impact loads and is operable at temperatures up to 400 °C The developed thermal insulation materials are intended to be used in the construction of objects operating under the conditions of cyclic exposure to high temperatures (for example, power plants) and in the construction of objects operating under the conditions of cyclic exposure to high temperatures (for example, power facilities).

Thermal Insulation Materials Based on Expanded Vermiculite and Foamed Liquid Glass

The authors have studied the properties of thermal insulation materials obtained based on expanded vermiculite and liquid-glass binder produced by foaming with a gas-generating (foaming) agent and volumetrically solidified by reacting it with sodium fluorosilicate. The quantitative binder-to-filler ratio was determined, which allows forming the products by casting and obtain materials with various strength, thermal conductivity and density.

Thermal insulation materials based on expanded vermiculite and foamed liquid glass

This article examines the properties of thermal insulation materials made on the basis of expanded vermiculite and a liquid-glass binder obtained by foaming with a gas-forming agent (foaming agent) and volume-cured by chemical reaction with sodium fluorosilicate. The relations between the amount of binder and filler are determined, which make it possible to form products by injection molding and obtain materials with different strength, thermal conductivity and density.

A rapid screening method for thermal conductivity properties of thermal insulation materials by a thermochemiluminescence probe

Acridine-based 1,2-dioxetane as a thermochemiluminescence (TCL) probe for temperature sensing exhibited an excellent response for temperature in the range of 85-130 °C with favorable sensitivity and good resolution. The proposed TCL probe could be applied to screen thermal conductivity properties of different thermal insulation materials.

Effect of Slurry Dispersion on Properties of Silica Fiber Based Thermal Insulation Materials

Short silica fibers are prone to conglomerate in aqueous medium, which means that dispersity and suspension stability show key effect on the uniformity of ceramics with silica fibers as raw materials. In this work, various parameters including pH values, dispersants and dispersing approaches, were systematically studied to investigate the effect of slurry dispersion on properties of thermal insulation materials with silica fibers as matrix. Moreover, the novel composite dispersants were creatively introduced in this work and the corresponding synergetic dispersion mechanism was investigated as well. Fiber slurries with optimized dispersing and suspension properties was obtained when pH values were set as 4, the content of R type dispersant was adjusted to 0.12% and the addition of PEO was fixed at 0.04%. After settling for 360s, no obvious agglomeration could be found. Rigid thermal insulation materials with homogeneous structure and high performance were obtained with conditions mentioned above, which can be expected to further expand the application of short silica fibers.

Исследование свойств жидких керамических теплоизоляционных материалов

Исследование свойств жидких керамических теплоизоляционных материалов

ANALYTICAL APPROACH TO THE INSULATION PROPERTIES OF SPECIAL CLOTHING

The emergence of a variety of textile materials with new properties, the development of computer technology has changed the traditional approach to the processes of selecting materials, design and producing special clothing. The article discusses the analytical approach of Russian and foreign scientists in the investigation of insulating properties of special clothing. Regression modeling techniques, optimization theory with the use of computer technology are widely used under these conditions. The study examines the different regression models, the results of the correlation, factor analysis in the calculation of the correlation of various parameters: the total thermal resistance, surface density, water vapor permeability, air permeability, hygroscopicity, surface filling, total porosity, thickness, water yielding. On the basis of calculations of required insulation protective clothing, the time of continuous stay in the cold for southern region of Russia workers engaged in Oil production we have developed a computer program. Based on the proposed regression model the problem of maximizing the quality criterion has been solved. With the help of quadratic programming methods we defined: the optimum value of the thickness of the package material, the thickness of the coating materials, the minimum possible value of air permeability in the end - a target set insulation materials. Due to this approach it has been possible to establish the maximum acceptable construction of special clothing for such conditions, as well as to adapt the process of picking a package of materials for these clothes. The issue complete materials package and the need to study the properties of thermal insulation materials selected as close as possible for creating a comfortable working environment are related in this article. Designing heatproof special clothing includes the processes of its testing under different conditions. One of the problems to be solved in the course of our tests is an analysis of changes in the thermal fields of workers with different body masses in the process of employment.

Computer Modeling of the Process of Synthesis of Porous Glass-Composite Materials

The operational properties of thermal insulation materials directly depend on their structure. The processes of pore formation occur inside the material after high-temperature treatment, which makes their studying more expensive and complicated. On the basis of experimental data, a computer simulation program for the process of pore formation has been developed, which makes it possible to simulate the processes of changing the structure of foam glass during heat treatment without repeated laboratory experiments.

Evaluation of thermal properties of insulation systems in pitched roofs

The article outlines the basic requirements for pitched roof insulation systems. The analysis of the properties of thermal insulation materials used in insulation systems was conducted. It is substantiated that the thermal resistance of such structures on the surface of the roof is formed taking into account the thermal conductivity of thermal insulation, thermal conductivity of wooden rafters and heat loss through the leakiness of joints and mounting devices. An assessment was made of the effect of loads of various types on the heat-insulating layer, namely: the effect of the air flow in the ventilated gap; the movement of the vapor-air mixture in the material; condensation of water vapor and penetration of drip liquid; exfiltration of air at the joints of the plates and on the surfaces of contact with the supporting structures. The expediency of using products on the basis of unstitched polyethylene foam in the construction of pitched roofs with a wooden roof system, taking into account the advantages and features of this material, as well as taking into account the possibility of creating a seamless insulating shell, is substantiated.

Radiation Effects in Heat Transfer Mechanisms by Dispersive Materials: Numerical Analysis in Diffusive Enclosure Model of Thermal Insulation

The current development of global warming and CO2 emission problems cannot be overlooked. Thus, global scale measures of efforts are becoming crucial. Thermal properties of insulation materials need to be considered as high performance thermal insulation systems are crucial for efficient energy saving. The most important parameter as indicator of a thermal insulation material is the effective thermal conductivity, but elements that affect the thermal insulation performance are rather complicated. Generally, conduction and radiation heat transfer are needed to be separately considered in precisely evaluating the thermal insulation performance as they coexist in the heat transfer process inside a multilayer insulation system. In this paper, numerical analysis of a complete diffusive enclosure model as a thermal insulation is observed to investigate the radiation effects by its dispersive heat transfer mechanisms. View factor of each relatively large dispersed material is derived in the enclosure model, where it is applicable to various shapes and any particular arrangements of dispersed materials. As this paper is the first part of a three-part working research paper, numerical analysis in this paper is carried out by assuming that the medium within the space inside the insulation system is taken to be nonparticipating, therefore conduction and convection effects during the heat exchange are negligible. This paper will be continued with application of the numerical analysis in observing radiation heating effects by wall-ceiling integration towards indoor environment and radiation–conduction heat transfer mechanisms in one-dimensional multilayer insulation system.

Moisture and wetting properties of thermal insulation materials based on hemp fiber, cellulose and mineral wool in a loose state

ABSTRACTThe paper presents the results of research concerning three fiber materials – hemp fiber, cellulose fiber and mineral wool as a loose-fill thermal insulation materials. It focused on the study of moisture properties and wettability of these materials. The analysis involved evaluation of moisture sorption in different relative humidity conditions and evaluation of wettability of fibers by contact angle measurement. The study showed that the sorption equilibrium has been achieved at different times, which proves the various nature and properties of the materials. Hemp fibers were less wet than cellulose fiber, but the time needed to stabilize was shorter. The largest contact angles, indicating the strongly hydrophobic properties, were shown by mineral wool. Some samples of hemp and cellulose fibers were characterized by similar contact angles providing high wetting properties.

Coupling controlled environmental forcing and transient plane source method: An innovative thermal characterization procedure for building insulation materials

Thermal insulation materials can be considered as an effective strategy to decrease thermal losses through the building envelope. According to international standards, the thermal characterization of such materials is carried out at the mean temperature of 10 °C in terms of thermal conductivity. However, realistic thermal profiles can significantly detach from such reference value, and consequently, the overall thermal behavior of the building envelope can seriously differ from the designed condition. In other to bridge this gap, any design condition in the range 0–30 °C is generally evaluated according to acknowledged standards. In this work, environmental forcing and transient plane source method are simultaneously applied to define reliable temperature-dependent profiles in a relatively short timescale for three basic properties of thermal insulation materials, i.e. thermal conductivity, thermal diffusivity and volumetric specific heat. Results show that the proposed methodology can be considered as an effective tool for the realistic thermal characterization of building insulation materials.

Thermo-Physical Characteristics of Building Glass Wool Insulant: A Review of Experimental Results and Well-Adapted Techniques

There is need of experimental determination of thermo-physical properties of building materials to bridge the gap between theoretically prediction and real performance of buildings. Few references present structural, hydric and thermal properties of insulation materials in the same publication. This study aims to determine main thermo-physical characteritics of two glass wools. This publication wants also to review well-adapted experimental techniques because of their structural morphology. Inter-fiber space (pores) and fibers were studied by scanning electron microscope imaging (SEM) at the microscopic scale. The chemical composition of the fibers and binder will then be shown by coupling SEM to EDX detector. On macroscopic scale, the structural characteristics such as fiber diameter, the pore radius, total porosity, the surface area and the air permeability will be introduced. The hydraulic properties (such as sorption isotherm and vapor permeability) and thermal properties (conductivity and diffusivity) are then studied. Some influences between these thermo-physical parameters are presented. Relations between air permeability and humidity content against thermal will be analyzed.

Laboratory measurement of thermal distribution throughout the insulation materials using the Peltier module while managing elimination of external influences

Testing of the actual properties of insulation materials is usually connected with the actual situation when measurement realization requires suitable weather conditions, for instance the winter time. The previous research [6], in which measurements of polystyrene were conducted, was testing its thermal properties under actual conditions every 30min, being directly dependent on the building environment where the insulation material was tested. Laboratory simulation of the actual application on the outside of the building to test the thermal properties of insulation materials can circumvent the dependency on the actual environmental conditions during the experiment. Here the actual thermal conductivity through the material of a specific thickness was tested using a new experimental measuring method. The method is based on generating an outside temperature of −18°C using the Peltier module on one side of the block-shaped piece of insulation material. The methodology also enables testing of the internal thermal behavior of the material with the proper thickness as well as the shape of the material. The research results are especially useful when deciding on the effective thickness of the building’s insulating material; using statistical methods. The analytical expression of the insulation properties inside the material would also serve for that purpose.

Engineering Test Research of XPS Insulation Structure Applied in High Speed Railway of Seasonal Frozen Soil Roadbed

Dynamic performance and thermal properties of insulation materials are the key parameters during the insulation application for high-speed railway subgrade. This paper conducted field tests and field monitoring for the materials, especially for thermal performance, elastic deformation, and accumulated deformation of insulation materials. Experiment results show that mechanical properties of full section insulation layer structure is stable, which satisfies the requirements of the high speed railway.