Fibrous Insulation Research Articles

Moisture Dynamics of Wood-Based Panels and Wood Fibre Insulation Materials.

Moisture performance is an important factor determining the resistance of wood-based building materials against fungal decay. Understanding how material porosity and chemistry affect moisture performance is necessary for their efficient use, as well as for product optimisation. In this study, three complementary techniques (X-ray computed tomography, infrared and low-field NMR spectroscopy) are applied to elucidate the influence of additives, manufacturing process and material structure on the liquid water absorption and desorption behaviour of a selection of wood-based panels, thermally modified wood and wood fibre insulation materials. Hydrophobic properties achieved by thermal treatment or hydrophobic additives such as paraffin and bitumen, had a major influence on water absorption and desorption rates. When hydrophobic additives did not play a role, pore distributions and manufacturing process had a decisive influence on the amount and rate of absorption and desorption. In that case, a higher porosity resulted in a higher water absorption rate. Our results show that there is a clear potential for tailoring materials towards specific moisture performance by better understanding the influence of different material characteristics. This is useful both for achieving desired moisture buffering as well as to increase service life of wood-based materials. From a sustainability perspective, fit-for-purpose moisture performance is often easier to achieve and preferred than wood protection by biocide preservative treatments.

Performance of high-temperature lightweight multilayer insulations

Multilayer insulation (MLI) is a kind of high-temperature insulation which employs multiple high-reflective screens to retard the radiation heat, but analyzing and optimizing its heat transfer characteristics by experimental and theoretical models remains low-efficiency and non-visualization. In this work, finite element analysis (FEA) models verified by comparing the simulation and experiment results are established to systematically reveal the numerous and complex effect factors, including the number of layers, thermal boundary, fibrous insulation density and emissivity of reflective screens. The results show that the top temperature of MLIs can be reduced by increasing the number and the emissivity of reflective screens, and the density of fibrous insulation, but there is a reasonable number of layers to achieve the best comprehensive performance of MLI. In addition, the proportion of radiative heat transfer in the total heat transfer increases with increasing heating temperature. The feasibility of optimizing thermal insulation performance based on the FEA models is confirmed by designing the MLIs with stainless steel and aluminum as reflective screens. And the results indicate that the FEA methods can significantly reduce the number of trials and realize the optimal design of MLI.

Effect of vacuum insulation panel integration in phase change material-based passive thermal management system for electronics package exposed to hot air environment

Harsh environment conditions are challenging for thermal management of electronics devices due to the thermal load from the surroundings. Phase Change Material (PCM) based Passive Thermal Management Systems (PTMSs) are gaining more attention for electronics cooling, and thermal insulation protection is crucial in hot air environments. In this work, an experimental setup was developed to study the thermal response of a PCM based PTMS under the thermal protection of different insulation when exposed to a hot air environment. Stearyl Alcohol was used as the PCM for PTMS. The effect of Vacuum Insulation Panel (VIP) integration in PTMS under a heat flux range of 0.3 to 1.4 kW/m2 was analysed and compared with the performance of a commercial Cellulose Fibre Insulation (CFI). Effect of thermal insulation thermal protection and thermal energy storage capability of PCM on the thermal response of the PTMS was investigated separately in different configurational settings. PTMS integrated with VIP having thermal conductivity of 6.2 mW/m-K showed better performance in Set-Point Temperature analysis. The results confirmed the synergic effect of VIP integration and PCM on extending the Safe Operational Time (SOT) of the PTMS. PCM based PTMS with VIP showed a 41.63 % average improvement in SOT. Duration for complete phase transition of PCM was improved to 46.34 % through VIP integration over different heat generation rates. VIP outperformed CFI on improving SOT by offering better thermal resistance against thermal load from hot air environment, thereby proving its potential application in PTMS under a hot air environment.

Life Cycle Environmental and Cost Analysis of Building Insulated with Hemp Fibre Compared to Alternative Conventional Insulations – a Swedish Case Study

This study presents a comparative life cycle analysis (LCA) and life cycle costing (LCC) assessments of hemp fibre and conventional alternative insulations for the climate shell of a building. The conventional alternative insulations compared to the hemp fibre are cellulose and glass wool. The object of the analysis is a one-story single-family house, in Växjö, Sweden, and the lifetime of the house is set to 50 years. The LCA focuses on the Global Warming Potential (GWP) impact and the LCC during the lifetime of the different insulations for the building are calculated using the net present value method. The results show that the net GWP-impact for hemp fibre insulation is about 10 % lower and the cost is about 20 % higher than the conventional glass wool alternative. Furthermore, the analysis shows that cellulose insulation has slightly lower GWP-impact and nearly the same cost as the glass wool alternative. Sensitivity analyses regarding five different issues were performed and these show that: for cellulose coming from recycled paper, it contributed to less fossil emissions than non-recycled paper. If the data source for glass wool insulation is changed from environmental product declarations (EPD) to generic data, the greenhouse gas emissions increased. By replacing district heating system with geothermal heating system, fossil GWP-impacts also increased while the LCC analysis shows that operating costs is reduced. If the fuel is changed from diesel to electricity, fossil emissions are reduced over the life cycle of the building. If only part A1 – A5 is reported, as required for the Swedish climate declaration, the results point to the outcomes that glass wool insulation gives the least fossil GWP-impact while the hemp fibre gives the least net GWP-impact.

Energy saving potential of passive dehumidification system combined with energy recovery ventilation using renewable energy

Passive dehumidification and solar collection (PDSC) employs fibrous insulation materials with excellent moisture adsorption and desorption characteristics to conduct dehumidification using renewable energy. This study proposes an improved PDSC-integrated energy recovery ventilation (ERV) system (PSE) to dehumidify indoor environments. Energy recovery ventilation (ERV) promotes the exchange of moisture and heat between returned and supplied air to reduce energy loss caused by ventilation. We explained the fundamental moisture movement principle based on thermodynamic energy and designed the air circulation paths of the proposed system for dehumidification and energy recovery. Five house models were simulated and compared: conventional house with no moisture effect, conventional house, conventional house with integrated ERV, the PDSC model, and the PSE model. Simulation results show that the PSE model has the best dehumidification performance, with an approximately 2.9 times latent heat load reduction effect compared with the PDSC model, in hot and humid summer. This study confirms that the proposed system has significant potential for dehumidifying the indoor environment and provides guidance for the future application of the PSE system to dwellings.

Experimental Assessment of the Thermal Conductivity of Basalt Fibres at High Temperatures

This paper investigates fibrous thermal insulation materials of various densities to assess the change in their thermophysical properties at high temperatures. The thermal conductivity of fibrous thermal insulation materials is discussed as a function of the temperature in the range from 50 °C to 500 °C. It is shown that the thermal insulating properties depend not only on the physical properties of the material (e.g., density or diameter of fibres), but also on the geometric parameters of the structure and on the orientation of the fibres. The influence of high temperatures on the mass change of fibrous materials associated with the burnout of synthetic binders is shown. These features should be taken into account during the design of thermal insulation operating at high temperatures to provide the optimal selection of the material and to guarantee the stability of their thermal properties.

Increase of uniformity of heat treatment of layer of fibrous heat insulation on horizontal conveyor at side supply of heat carrier

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Scalable fabrication of cross-linked porous centrifugally spun polyimide fibers for thermal insulation application

Flexible fibrous thermal insulators with low thermal conductivity are highly demanded to improve energy efficiency in many application fields, especially in the aerospace industry. In the present study, the cross-linked porous polyimide (PI) fibrous insulator was prepared using centrifugal spinning, a scalable and facile technique for fibers production. The influence of PI concentration and solvent composition was evaluated to find the optimum parameters for defect-free fiber fabrication. In the following step, the PI fibers were cross-linked to gain better solvent stability. The morphology, chemical properties, surface wettability, thermal resistance, and thermal conductivity of the obtained fibers were evaluated. The cross-linked fibers exhibit a low thermal conductivity of 0.029 W/mK with thermal stability up to 515 °C, hydrophobicity with a contact angle of 137.7°, and are flexible at high temperature. The successful fabrication of the PI fibers opens a new approach for the scalable fabrication of flexible fibrous insulators for aerospace applications.

Experimental Verification of Thermal Insulation in Timber Framed Walls.

Current environmental crisis calls for sustainable solutions in the building industry. One of the possible solutions is to incorporate timber-framed constructions into designs. Among other benefits, these structures are well established in many countries, originating in traditional building systems. This paper focuses on experimental timber-frame walls. Different wall assemblies vary in thermal insulation materials and their combinations. We investigated ten experimental wall structures that have been exposed to natural external boundary conditions since 2015. The emphasis was on their state in terms of visual deterioration, mass moisture content, and thermal conductivity coefficient. We detected several issues, including defects caused by inappropriate realization, causing local moisture increase. Material settlement in loose-fill thermal insulation was another issue. Concerning was a significant change in the thermal conductivity of wood fiber insulation, where the current value almost doubled in one case compared to the design value determined by the producer.

Three-dimensional sintering morphology simulation of silica fibrous insulator and its quantitative description

Silica fibrous insulator possessing excellent thermal properties is widely used in the aerospace engineering field. A finite element model is developed for simulating the solid-state sintering process in the preparation process of the fibrous insulator. The model is capable of simulating initial surfaces with complex geometric features. The model is validated by using the classic double-sphere diffusion model and comparing the simulation results with the experimental results in the reference. Results suggest sintered morphology is strongly controlled by the highest holding temperature and has little relationship with the heating rate. The detailed simulation parameters for sintering fibrous silica are determined by the experiment of sintering parallel fibers. Comparison between the simulation results of planar simplification model, double-sphere model, and double-cylinder model reveals the significance of neighborhood diffusion on the sintering of parallel fibers. We found the morphological geometric feature of the sintered fibrous body is consistent and accordingly the Feature Neck Ratio (FNR) is defined to quantitatively describe the degree of sintering and the morphology feature of the sintered fibers. From the perspective of the sintering morphology, when FNR reaches about 0.7–1 no matter how the sintering route is, the fibers are considered to be fully sintered together.

Cost Optimized Building Energy Retrofit Measures and Primary Energy Savings under Different Retrofitting Materials, Economic Scenarios, and Energy Supply

We analyze conventional retrofit building materials, aluminum, rock, and glass wool materials and compared such materials with wood-based materials to understand the lifecycle primary energy implications of moving from non-renewable to wood-based materials. We calculate cost optimum retrofit measures for a multi-apartment building in a lifecycle perspective, and lifecycle primary energy savings of each optimized measure. The retrofit measures consist of the thermal improvement of windows with varied frame materials, as well as extra insulation of attic floor, basement walls, and external walls with varied insulation materials. The most renewable-based heat supply is from a bioenergy-based district heating (DH) system. We use the marginal cost difference method to calculate cost-optimized retrofit measures. The net present value of energy cost savings of each measure with a varied energy performance is calculated and then compared with the calculated retrofit cost to identify the cost optimum of each measure. In a sensitivity analysis, we analyze the cost optimum retrofit measures under different economic and DH supply scenarios. The retrofit costs and primary energy savings vary somewhat between non-renewable and wood-based retrofit measures but do not influence the cost optimum levels significantly, as the economic parameters do. The lifecycle primary use of wood fiber insulation is about 76% and 80% less than for glass wool and rock wool, respectively. A small-scale DH system gives higher primary energy and cost savings compared to larger DH systems. The optimum final energy savings, in one of the economic scenarios, are close to meeting the requirements in one of the Swedish passive house standards.

An analytical and numerical investigation into conductive-radiative energy transfers in evacuated honeycombs. Application to the optimisation and design of ultra-high temperature thermal insulation

Ultra-high temperature thermal and latent energy storage technologies offer a potential solution to the decarbonisation of the energy sector. However, uneconomical thermal energy losses are a barrier to their development and where significant, their minimisation requires knowledge about the different modes of thermal transport and their interaction in a given structure. In this paper, evacuated rectangular honeycomb structures are investigated as candidates for efficient ultra-high temperature thermal insulation.First, a theory is laid out along with its numerical implementation for the modelling of coupled non-linear conduction and radiation in three-dimensional cuboid multi-media structures with rarefied gaseous and opaque or semi-transparent solid media. The model is then applied to the study, optimisation and design of efficient ultra-high temperature thermal insulation based on rectangular honeycomb structures.A dimensionless number Nrc is defined and an analytical thermal analysis of rectangular honeycombs is developed which correlates Nrc to the optimal geometry and equivalent thermal conductivity of a honeycomb insulator. A numerical optimisation procedure is then presented and the correlations are validated, and thus constitute simple practical design tools for honeycomb insulators. Finally, it is shown that with an appropriate choice of geometry and materials, thin-walled honeycombs have the capacity to outperform existing high-temperature thermal insulation technologies with thermal conductivities lower than 0.01 W/m/K at 1600 K. In particular, a wall thickness of 50μm on a titanium alloy honeycomb would suffice to outperform ceramic fibre insulation over its entire range of operating temperatures.

Natural Fibre Insulation Materials: Use of Textile and Agri-food Waste in a Circular Economy Perspective

Fibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.

Increasing the Uniformity of the Heat Treatment of a Layer of Fibrous Heat Insulation on a Horizontal Conveyor with a Side Supply of the Heat Carrier

Increasing the Uniformity of the Heat Treatment of a Layer of Fibrous Heat Insulation on a Horizontal Conveyor with a Side Supply of the Heat Carrier

Thermal insulation and anti-vibration properties of MoSi2-based coating on mullite fiber insulation tiles

Thermal protection materials with excellent thermal insulation properties and high reliability are crucial for aerospace vehicle. Mullite fiber insulation tiles coated with MoSi2-borosilicate glass ([email protected]2) were prepared by a simple slurry method. Results shown that the surface temperature rapidly reached 1043.1 °C under the heat flux of 450 kW/m2, while the cold-surface remained at room temperature. The adjusting effects of MoSi2-based coating on the thermal response and transfer properties of MFIT were investigated systematically. Compared with MFIT, the surface and internal temperatures of [email protected]2 were obviously suppressed, due to the existence of MoSi2-based coating with high emissivity, which effectively enhanced the thermal radiation of the surfaces. Finally, the structural reliability under coupled environment of heating (q0 = 450 kW/m2) and random vibration with high magnitude (20–2000 Hz, Grms = 20 g) was also investigated. Destructive cracking and peeling of the coating were not observed, due to the excellent bonding strength between the coating and the substrate. The results provided an important basis for the potential application of insulation tiles with mullite fibers in aerospace vehicles and the design of lightweight thermal protection systems.

Characterization of the Hygrothermal Properties of Wood Fibre Insulation Board for a Cold Climate

Characterization of the Hygrothermal Properties of Wood Fibre Insulation Board for a Cold Climate

ENERGY EFFICIENT BUILDING DESIGN: TIMBER FRAME CONSTRUCTION BASED IN HEMP FIBER INSULATION

Energy efficient building concerns to the structure and using the process that is environmental liable and material efficient all around a building lifecycle. The basic principle of this building to minimize the energy consumption for heating and cooling system. The paper investigates the thermal behavior of hemp fiber insulation in timber framed wall panels for which timber framed structures will be experimented. Steps to enhance the energy performance were applied to building structure, window area, window glazing, lightning, heating ventilation and air conditioning (HVAC) system. We were measured the U-values of timber walls, hemp fiber insulation and window glazing. Results showed that energy efficient building enjoy the benefits of saving 40-50% energy by reducing greenhouse gases emissions into atmosphere. We have discussed about the rating system of energy efficient building or green building. In this paper, information pertaining to building life cycle and detailed explanation regarding fundamentals of building energy will be provided.

Features of thermal operation of bath regenerative furnaces for production of mineral melt

The most common in the production of fibrous thermal insulation using fine raw materials (up to 10‒15 mm) or fragile easily crumbling rocks are bath furnaces. Their operation at horseshoe-like movement of gases in working space is characterized by considerable unevenness of temperature field of liquid bath due to limited range of gas flares. The combustion of natural gas in the working space of the furnace is carried out with a high coefficient of air consumption with the complete absence of chemical malaise. As flue gases are transported from the regenerator to the pipe, the number of suckers increases by 44,85 %. The exhaust gases from the regenerator are characterized by a relatively high temperature of 570‒600 ° C and a significant heat reserve up to 2022,09 kW, which requires their further disposal. The thermal efficiency of the regenerative furnace bath is 39,04 %.

농촌주택 및 목조주택 표준모델 구조체의 습·열 환경 성능 개선 방안

The purpose of this study was to investigate whether the standard models for rural housing and wooden housing model have performance for hygrothermal and to propose a way of improvement relevant to hygrothermal performance for those models. All of the models to be analyzed were found to have some parts that were absent of stability in terms of performance for hygrothermal. In the process of analyzing the causes and proposing improvement measures, the following conclusions were derived. Fist, The exterior surface of the structure should be composed of a structure with good moisture permeability, and for the interior surface, a variable vapor retarder paper should be applied in consideration of the reverse condensation phenomenon in summer. Second, in terms of performance for hygrothermal, applications of external insulation plaster finish to the exterior wall or of ventilation method using a rafter vent on the roof should be avoided. Third, a rain screen method with a ventilation layer should be applied to the exterior wall, and a method of constructing ventilation layer separated from the insulation layer with a vapor retarder paper should be applied to the roof. Fourth, the application of insulation materials having capillary action, such as wood fiber insulation board or cellulose insulation board, contributes to more stable performance for hygrothermal.

Thermal Protection by Integration of Vacuum Insulation Panel in Liquid-Cooled Active Thermal Management for Electronics Package Exposed to Thermal Radiation

Abstract Thermal management systems (TMSs) working for electronics packages under harsh environments like intense thermal radiation are challenging due to external thermal interactions. Thermal insulation protection for TMS is very critical in these harsh conditions. An experimental setup was developed to analyze the effect of insulation protection against thermal irradiation over a pumped liquid-cooling active thermal management system (ATMS) with varying heat dissipation rate (0–4.2 kW/m2), thermal irradiation (0.85–3.80 kW/m2), and coolant temperature (15–25 °C). Three configurations of ATMS are considered in the experimental study: ATMS without thermal insulation protection, ATMSs integrated with Cellulose Fibre Insulation (CFI), and Vacuum Insulation Panel (VIP). The effect of insulation on each parameter in all three ATMS configurations over the temperature of the electronics component, cooling load, and nature of heat flow in ATMS was analyzed. VIP outperformed CFI on achieving a significant reduction in the temperature of electronics systems (35.67%) and cooling load (45.64%) experienced by the ATMS. VIP effectively reduced the impact of temperature and cooling load change in ATMS against change in thermal irradiation. The study concluded that thermal insulation protection was most effective at high thermal irradiation and low heat dissipation rate. Heat Flow Direction Index (HFDI) concept was developed to find the nature of heat transfer direction in ATMS without temperature distribution trend. Heat generation rate and irradiation possess significant influence over the nature of heat flow direction.