scholarly journals Weathering of Roofing Insulation Materials under Multi-Field Coupling Conditions

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3348 ◽  
Author(s):  
Shuangxi Zhou ◽  
Yang Ding ◽  
Zhongping Wang ◽  
Jingliang Dong ◽  
Anming She ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Loss ◽  
Polyurethane Foam ◽  
Thermal Insulation ◽  
Rigid Polyurethane Foam ◽  
Foam Concrete ◽  
Insulation Materials ◽  
Field Coupling ◽  
Vacuum Insulation

Rigid polyurethane foam, foam concrete, and vacuum insulation board are common roofing insulation materials. Their weathering performance under long-term multi-field coupling determines the overall service life of the roof. The weathering properties of rigid polyurethane foam, foam concrete and vacuum insulation panels were studied under freeze thaw, humid-heat, dry-wet, high-low temperature, and multi-field coupling cycles, respectively. The heat transfer and construction process of roof panels was simulated base on upper loading and moisture transfer factors. The result indicates that the mass loss of the foam concrete and the rigid polyurethane foam in the weathering test was significant, which led to the gradual increase of thermal conductivity. Meanwhile, the thermal conductivity and mass loss of vacuum insulation panels did not change due to the lack of penetration under external pressure, therefore, it is necessary to construct composite thermal–insulation materials to alleviate the adverse effects of the service environment on a single material and realize the complementary advantages and disadvantages of the two materials. The results of the numerical simulations indicated that the roof structure must be waterproofed, and its weatherproof performance index should be the same as that of the thermal insulation material. Considering structural deformation, the overall heat transfer performance of the product was increased by around 5%.

PROCESSED STRAW AS EFFECTIVE THERMAL INSULATION FOR BUILDING ENVELOPE CONSTRUCTIONS

2012 ◽  
Vol 4 (3) ◽  
pp. 96-103 ◽  
Author(s):  
Jolanta Vėjelienė
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Building Envelope ◽  
Gas Content ◽  
Barley Straw ◽  
Conductivity Measurements ◽  
Insulation Materials ◽  
Thermal Transfer ◽  
The Impact

The efficiency of thermal insulation materials obtained from renewable resources depends on the possibilities of reducing thermal transfer via solid and gaseous conduction, thermal radiation and, in some cases, convection. The heat transfer mechanism for thermal insulation materials mostly depends on the structure and density of the material used. Efficient thermal insulation materials consist of a gaseous phase and a solid skeleton. Gas content in such materials can take more than 99% of material by volume. In this case, thermal transfer via solid conductivity is negligible. The current work analyses the possibilities of reducing heat transfer in the straw of a varying structure. For conducting experiments, barley straw was used. To evaluate the impact of straw stalk orientation in a specimen on thermal conductivity, strongly horizontally and vertically oriented specimens of straw stalks were prepared. To reduce heat transfer via gaseous conduction and convection in large cavities in straw stalks and between stalks, barley straw were chopped and defibered. In order to decrease heat transfer via radiation after thermal conductivity measurements, mechanically processed straw were coated with infrared absorbers. Due to thermal conductivity measurements of chopped and defibered straw, an optimal amount of infrared absorbers were determined.

Preparation of Rigid Polyurethane Foam and Research Progress of its Reinforced Technology by Inorganic Materials

2012 ◽  
Vol 562-564 ◽  
pp. 385-389
Author(s):  
Ming Ming Cheng ◽  
Fei Wang ◽  
Lin Jing Ma ◽  
Chao Fan
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Thermal Insulation ◽  
Light Quality ◽  
Inorganic Materials ◽  
Research Progress ◽  
Rigid Polyurethane Foam ◽  
Processing Technologies ◽  
Low Thermal Conductivity

Rigid polyurethane foam has many advantages such as low thermal conductivity, good thermal insulation, good antisepsis ability, non-toxic, and light quality. Based on the above reasons, this paper systematically summarized the processing technologies of rigid polyurethane foam, and research progress of its reinforced technology by inorganic materials was briefly discussed.

scholarly journals Structure, Mechanism, and Application of Vacuum Insulation Panels in Chinese Buildings

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Changhai Peng ◽  
Jianqiang Yang
Keyword(s):  
Thermal Conductivity ◽  
Construction Industry ◽  
Thermal Insulation ◽  
Fire Resistance ◽  
New Materials ◽  
Insulation Materials ◽  
Vacuum Insulation ◽  
Application Potential ◽  
Reduce Energy Consumption ◽  
Sealing Layer

Thermal insulation is one of the most used approaches to reduce energy consumption in buildings. Vacuum insulation panels (VIPs) are new thermal insulation materials that have been used in the domestic and overseas market in the last 20 years. Due to the vacuum thermal insulation technology of these new materials, their thermal conductivity can be as low as 0.004 W/(m·K) at the center of panels. In addition, VIPs that are composites with inorganic core and an envelope out of commonly three metallized PET layers and a PE sealing layer can provide B class fire resistance (their core materials are not flammable and are classified as A1). Compared with other conventional thermal insulation materials, the thermal insulation and fire resistance performances form the foundation of VIP’s applications in the construction industry. The structure and thermal insulation mechanism of VIP and their application potential and problems in Chinese buildings are described in detail.

scholarly journals Study of behaviour of thermal insulation materials under extremely low pressure

2019 ◽  
Vol 282 ◽  
pp. 02044
Author(s):  
Jiří Zach ◽  
Jitka Peterková ◽  
Jan Bubeník
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Heat Transport ◽  
Thermal Insulation ◽  
Pressure Change ◽  
Low Pressure ◽  
The Other ◽  
Atmosphere Pressure ◽  
Insulation Materials ◽  
Vacuum Insulation

In most thermal insulation materials, reduced internal pressure improves thermal insulation properties. It reduces heat transport by convection as well as heat conduction in gases in the material´s pore structure. The dependence of thermal conductivity on pressure is individual to every type of insulation with open porosity. In general, a material with fine porosity is not very sensitive to pressure change within the range of very low pressure to vacuum. On the other hand, materials with a larger number of bigger pores are more sensitive to changing pressure. Any pressure change between atmosphere pressure and vacuum causes a change in thermal conductivity. The paper presents the results of an investigation into the behaviour of alternative fibrous insulations usable in the production of vacuum insulation panels at low pressure.

Development and Research of Thermal Insulation Materials from Natural Fibres

2014 ◽  
Vol 604 ◽  
pp. 285-288 ◽  
Author(s):  
Saulius Vaitkus ◽  
Rūta Karpavičiūtė ◽  
Sigitas Vėjelis ◽  
Lina Lekūnaitė
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Preparation Method ◽  
Raw Materials ◽  
Natural Fibres ◽  
Current Work ◽  
Insulation Materials ◽  
Flax Fibres ◽  
Hemp Fibres

Natural fibres from flax and hemp are used as raw materials for efficient thermal insulation. In current work, tests were carried out using chopped and combed long flax fibres as well as chopped and combed long hemp fibres. Investigations have shown that thermal conductivity of natural fibres depends on their preparation method (combing, chopping) and materials density.

scholarly journals Thermal insulation properties of green vacuum insulation panel using wood fiber as core material

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 3339-3351 ◽  
Author(s):  
Baowen Wang ◽  
Zhihui Li ◽  
Xinglai Qi ◽  
Nairong Chen ◽  
Qinzhi Zeng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Bulk Density ◽  
Thermal Insulation ◽  
Wood Fiber ◽  
Core Material ◽  
High Porosity ◽  
Total Thermal Conductivity ◽  
Wood Fibers ◽  
Vacuum Insulation ◽  
Vacuum Insulation Panel

Wood fibers were prepared as core materials for a vacuum insulation panel (VIP) via a dry molding process. The morphology of the wood fibers and the microstructure, pore structure, transmittance, and thermal conductivity of the wood fiber VIP were tested. The results showed that the wood fibers had excellent thermal insulation properties and formed a porous structure by interweaving with one another. The optimum bulk density that led to a low-cost and highly thermally efficient wood fiber VIP was 180 kg/m3 to 200 kg/m3. The bulk density of the wood fiber VIP was 200 kg/m3, with a high porosity of 78%, a fine pore size of 112.8 μm, and a total pore volume of 7.0 cm3·g-1. The initial total thermal conductivity of the wood fiber VIP was 9.4 mW/(m·K) at 25 °C. The thermal conductivity of the VIP increased with increasing ambient temperature. These results were relatively good compared to the thermal insulation performance of current biomass VIPs, so the use of wood fiber as a VIP core material has broad application prospects.

scholarly journals Bio-based rigid polyurethane foam prepared from apricot stone shell-based polyol for thermal insulation application – Part 2: Morphological, mechanical, and thermal properties

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6080-6094
Author(s):  
Muhammed Said Fidan ◽  
Murat Ertaş
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Properties ◽  
Thermogravimetric Analysis ◽  
Polyurethane Foam ◽  
Flame Retardants ◽  
Compressive Modulus ◽  
Cell Diameter ◽  
Mechanical And Thermal Properties ◽  
Rigid Polyurethane Foam

The procedure for the liquefaction of apricot stone shells was reported in Part 1. Part 2 of this work determines the morphological, mechanical, and thermal properties of the bio-based rigid polyurethane foam composites (RPUFc). In this study, the thermal conductivity, compressive strength, compressive modulus, thermogravimetric analysis, flammability tests (horizontal burning and limited oxygen index (LOI)) in the flame retardants), and scanning electron microscope (SEM) (cell diameter in the SEM) tests of the RPUFc were performed and compared with control samples. The results showed the thermal conductivity (0.0342 to 0.0362 mW/mK), compressive strength (10.5 to 14.9 kPa), compressive modulus (179.9 to 180.3 kPa), decomposition and residue in the thermogravimetric analysis (230 to 491 °C, 15.31 to 21.61%), UL-94 and LOI in the flame retardants (539.5 to 591.1 mm/min, 17.8 to 18.5%), and cell diameter in the SEM (50.6 to 347.5 μm) of RPUFc attained from liquefied biomass. The results were similar to those of foams obtained from industrial RPUFs, and demonstrated that bio-based RPUFc obtained from liquefied apricot stone shells could be used as a reinforcement filler in the preparation of RPUFs, specifically in construction and insulation materials. Moreover, liquefied apricot stone shell products have potential to be fabricated into rigid polyurethane foam composites.

scholarly journals Rigid Polyurethane Foams Modified with Biochar

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5616
Author(s):  
Katarzyna Uram ◽  
Maria Kurańska ◽  
Jacek Andrzejewski ◽  
Aleksander Prociak
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Thermal Insulation ◽  
Foam Cells ◽  
Polyurethane Foams ◽  
Cross Sectional ◽  
Rigid Polyurethane Foams ◽  
Insulation Materials

This paper presents results of research on the preparation of biochar-modified rigid polyurethane foams that could be successfully used as thermal insulation materials. The biochar was introduced into polyurethane systems in an amount of up to 20 wt.%. As a result, foam cells became elongated in the direction of foam growth and their cross-sectional areas decreased. The filler-containing systems exhibited a reduction in their apparent densities of up to 20% compared to the unfilled system while maintaining a thermal conductivity of 25 mW/m·K. Biochar in rigid polyurethane foams improved their dimensional and thermal stability.

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