Analysis of water sorption and thermal conductivity of expanded polystyrene insulation materials

The energy efficiency of buildings is well documented. However, to improve standards of energy efficiency, the embodied energy of materials included in the envelope is also increasing. Natural fibers like wood and hemp are used to make low environmental impact insulation products. Technical characterizations of five bio-based materials are described and compared to a common, traditional, synthetic-based insulation material, i.e., expanded polystyrene. The study tests the thermal conductivity and the vapor transmission performance, as well as the combustibility of the material. Achieving densities below 60 kg/m3, wood and hemp batt insulation products show thermal conductivity in the same range as expanded polystyrene (0.036 kW/mK). The vapor permeability depends on the geometry of the internal structure of the material. With long fibers are intertwined with interstices, vapor can diffuse and flow through the natural insulation up to three times more than with cellular synthetic (polymer) -based insulation. Having a short ignition times, natural insulation materials are highly combustible. On the other hand, they release a significantly lower amount of smoke and heat during combustion, making them safer than the expanded polystyrene. The behavior of a bio-based building envelopes needs to be assessed to understand the hygrothermal characteristics of these nontraditional materials which are currently being used in building systems.

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Thermal characterization of different graphite polystyrene

International Review of Applied Sciences and Engineering ◽

10.1556/1848.2018.9.2.12 ◽

2018 ◽

Vol 9 (2) ◽

pp. 163-168 ◽

Cited By ~ 8

Author(s):

Á. Lakatos ◽

I. Deák ◽

U. Berardi

Keyword(s):

Thermal Conductivity ◽

High Performance ◽

Thermal Characterization ◽

Expanded Polystyrene ◽

High Moisture ◽

Insulating Materials ◽

Insulation Materials ◽

Vacuum Insulation ◽

Study Laboratory

The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.

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Prospects for the Application of Wavelet Analysis to the Results of Thermal Conductivity Express Control of Thermal Insulation Materials

Energies ◽

10.3390/en14175223 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5223

Author(s):

Oleksandra Hotra ◽

Svitlana Kovtun ◽

Oleg Dekusha ◽

Żaklin Grądz

Keyword(s):

Thermal Conductivity ◽

Wavelet Transform ◽

Data Processing ◽

Thermal Insulation ◽

Control Method ◽

Measurement Data ◽

Conductivity Measurement ◽

Differential Method ◽

Expanded Polystyrene ◽

Insulation Materials

This article discusses an express control method that allows in situ measurements of the thermal conductivity of insulation materials. Three samples of the most common thermal insulation materials, such as polyurethane, extruded polystyrene, and expanded polystyrene, were studied. Additionally, optical and organic glasses were investigated as materials with a stable value of thermal conductivity. For the measurement of thermal conductivity, the express control device, which implements the differential method of local heat influence, was used. The case studies were focused on the reduction of fluctuations of the measured signals caused by different influencing factors using wavelet transform. The application of wavelet transform for data processing decreased the thermal conductivity measurement’s relative error for organic glass SOL and optical glasses TF-1 and LK-5. The application of wavelet transform thermal conductivity measurement data for polyurethane, extruded polystyrene, and expanded polystyrene allowed to reduce twice the duration of express control while maintaining the same level of measurement error. The results of the investigation could be used to increase the accuracy in express control of the thermal conductivity of insulation materials by improving the data processing. This approach could be implemented in software and does not require a change in the design of the measuring equipment or the use of additional tools.

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Investigation of thickness and density dependence of thermal conductivity of expanded polystyrene insulation materials

Materials and Structures ◽

10.1617/s11527-012-9956-5 ◽

2012 ◽

Vol 46 (7) ◽

pp. 1101-1105 ◽

Cited By ~ 32

Author(s):

Ákos Lakatos ◽

Ferenc Kalmár

Keyword(s):

Thermal Conductivity ◽

Density Dependence ◽

Expanded Polystyrene ◽

Insulation Materials

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Experimental Study on the Thermal Conductivity of Thermal Insulation Materials Used in Residential Buildings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1025-1026.535 ◽

2014 ◽

Vol 1025-1026 ◽

pp. 535-538

Author(s):

Young Sun Jeong

Keyword(s):

Thermal Conductivity ◽

Thermal Insulation ◽

Building Materials ◽

Residential Buildings ◽

Building Envelope ◽

Expanded Polystyrene ◽

Exterior Wall ◽

Insulation Materials ◽

Design Documents ◽

Materials Used

The most basic way to keep comfortable indoor environments for a building’s occupants and save energy for space heating and cooling in residential buildings is to insulate the building envelope. Among the building materials to be used, thermal insulation materials primarily influence thermal performance. In particular, the type, thermal conductivity, density, and thickness of heat insulator, are important factors influencing thermal insulation performance. We investigate the design status of residential buildings which were designed in accordance with the building code of Korea and selected the type of thermal insulation materials applied to the walls of buildings. The present study aims at measuring the thermal conductivity of thermal insulation materials used for building walls of residential buildings. In this study, after collecting the design documents of 129 residential buildings, we investigated the type and thickness of insulation materials on the exterior wall specified in the design documents. As the thermal insulation materials, extruded polystyrene (XPS) board and expanded polystyrene(EPS) board are used the most widely in Korea when designing residential buildings. The thickness of thermal insulation materials applied to the exterior wall was 70mm, most frequently applied to the design. We measured the thermal conductivity and the density of XPS board and EPS board. When the density of XPS and EPS was 30~35 kg/㎥, the thermal conductivity of XPS was 0.0292 W/mK and it of EPS was 0.0316 W/mK.

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Thermal Conductivity and Specific Heat Capacity of Insulation materials at Different Mean Temperatures

Journal of Physics Conference Series ◽

10.1088/1742-6596/2069/1/012090 ◽

2021 ◽

Vol 2069 (1) ◽

pp. 012090

Author(s):

Y Yousefi ◽

F Tariku

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Regression Model ◽

Specific Heat ◽

Specific Heat Capacity ◽

Correlation Coefficients ◽

Cellulose Fiber ◽

Mineral Wool ◽

Expanded Polystyrene ◽

Insulation Materials

Abstract Thermal conductivity and heat capacity are among the most essential properties of a building insulation in calculating thermal performance which are subjected to change when exposed to temperatures variation in service. Ignoring the temperature dependency of these material properties can result in under and over estimations of buildings energy uses and the corresponding equipment sizing. To obtain more realistic conductivity values of insulation materials, in this paper, thermal conductivity tests are conducted at various mean temperatures. For the study six commonly used insulations including Cellulose fiber, Expanded Polystyrene, Extruded Polystyrene, Open Cell Spray Polyurethane, Polyisocyanurate, and Mineral Wool are considered, and their thermal conductivity are measured at seven mean temperatures ranging from 5°C to 60°C. Furthermore, their specific heat capacity are measured at nine mean temperatures ranging between 16°C and 36°C. The results showed that except Polyisocyanurate board, the thermal conductivities and specific heat capacities of all insulation materials increased linearly with rising temperature, presenting a linear regression model with correlation coefficients (R2) values between 0.96 and 0.98. The curve fitting of the Polyisocyanurate thermal conductivity measurements resulted a nonlinear regression model with R2 of 0.97. The thermal conductivity of six insulations as a function of temperature have been established.

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The Numerical and Experimental Investigation of the Change of the Thermal Conductivity of Expanded Polystyrene at Different Temperatures and Densities

International Journal of Polymer Science ◽

10.1155/2019/6350326 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Battal Doğan ◽

Hüsamettin Tan

Keyword(s):

Thermal Conductivity ◽

Numerical Study ◽

Expanded Polystyrene ◽

Insulation Materials ◽

Numerical Studies ◽

Different Temperatures ◽

Three Stages ◽

Structure Geometry ◽

C 30

The determination of the thermal conductivity of insulation materials depending on which parameters in the application as well as the production is very important. In this direction, the parameters affecting thermal conductivity should be determined to improve the efficiency of the insulation materials. It is also a fact that expanded polystyrene blocks have different thermal conductivities at the same density value depending on the production process. In this study, it was determined, experimentally and numerically, that the thermal conductivity of expanded polystyrene material at different densities is dependent on which parameters and changes in temperature. Expanded polystyrene materials consist of blocks of 30×30 cm with density of 16, 21, and 25 kg/m3 and a thickness of 20 mm. Thermal conductivity measurements were performed in FOX 314 (Laser Comp., USA) operating in accordance with ISO 8301 and EN 12667 standards. The measurements were made for expanded polystyrene blocks at the average temperatures of 10°C, 20°C, 30°C, and 40°C. The numerical study has three stages as the acquisition of electron microscope images (SEM) of expanded polystyrene blocks, modeling of internal structure geometry with CAD program, and realization of solutions with a finite element-based ANSYS program. Findings from experimental and numerical studies and the parameters affecting thermal conductivity were determined. Finally, it is thought that numerical methods can be used to obtain a preliminary idea for EPS material in determining thermal conductivity by comparing the findings of experimental and numerical studies.

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