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

Kosiński, Piotr; Brzyski, Przemysław; Duliasz, Barbara

doi:10.1080/15440478.2018.1477086

Cited by 27 publications

(13 citation statements)

References 33 publications

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“…Although the guarded hot plate method for testing thermal conductivity is more time-consuming than using a heat flow meter, it produces high precision measurements with excellent repeatability. Therefore, we obtained the experimental bulk density–thermal conductivity curves as precisely as possible to minimize the deviation by measurement, which is often present when measuring natural fibers [ 59 ]. Reducing the measurement deviation is essential because raw fibers naturally differ slightly, but these measurements served both for calibration (Type-1 straw) and for model validation (Type-2 straw); therefore, we wanted to keep the standard deviation of the measurements as low as possible and originated only from the stems, not from the measurement itself.…”

Section: Methodsmentioning

confidence: 99%

Heat Transfer in Straw-Based Thermal Insulating Materials

2021

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An analytic-empirical model was developed to describe the heat transfer process in raw straw bulks based on laboratory experiments for calculating the thermal performance of straw-based walls and thermal insulations. During the tests, two different types of straw were investigated. The first was barley, which we used to compose our model and identify the influencing model parameters, and the second was wheat straw, which was used only for validation. Both straws were tested in their raw, natural bulks without any modification except drying. We tested the thermal conductivity of the materials in a bulk density range between 80 and 180 kg/m3 as well as the stem density, material density, cellulose content, and porosity. The proposed model considers the raw straw stems as natural composites that contain different solids and gas phases that are connected in parallel to each other. We identified and separated the following thermal conductivity factors: solid conduction, gas conduction in stem bulks with conduction factors for pore gas, void gas, and gaps among stems, as well as radiation. These factors are affected by the type of straw and their bulk density. Therefore, we introduced empirical flatness and reverse flatness factors to our model, describing the relationship between heat conduction in stems and voids to bulk density using the geometric parameters of undisturbed and compressed stems. After the validation, our model achieved good agreement with the measured thermal conductivities. As an additional outcome of our research, the optimal bulk densities of two different straw types were found to be similar at 120 kg/m3.

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Section: Methodsmentioning

confidence: 99%

Heat Transfer in Straw-Based Thermal Insulating Materials

2021

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“…Thus, they are found in a wide variety of usage areas that have fire protection requirements and high fire-resistance standards. As a result of their research on hemp fiber, cellulose fiber, and mineral stone wool as thermal insulation materials, Kosiński et al (2020) reported that mineral stone wool exhibited a strong hydrophobic property and had the highest contact angle. However, water infiltration into inorganic fibrous materials affects their properties.…”

Section: Introductionmentioning

confidence: 99%

Hybrid composite board produced from wood and mineral stone wool fibers

Akkus

2022

BioRes

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Wood fiberboards are used extensively, mainly in the fields of furniture production, interior fittings, construction, etc. Mineral stone wool materials are used for heat and sound insulation in the construction industry. This study aimed to produce a new hybrid-based composite material by mixing fibers obtained from wood and mineral stone wool. For this purpose, hybrid fiberboards with 50, 40, 30, and 20% stone wool addition and a fiberboard group consisting of 100% pine and beech fibers (control sample) were produced in a hot press using thermoset-based urea formaldehyde and phenol formaldehyde resins. Statistical comparisons of the results were made for values of density, thickness swelling, and water absorption extents after 24 h immersion, bending strength and modulus of elasticity in bending, tensile strength perpendicular to the board surface (internal bond strength), and time to ignition (TTI) analysis. Additionally, percentage of mass loss (PML), average heat release rate (A-HRR), average effective heat of combustion (A-EHC), and mass loss rate (MLR) were studied. The results showed that as the stone wool content in the produced boards increased, the mechanical properties and thickness swelling decreased. The combustion results showed that the combustion resistance of the boards increased with increasing stone wool ratio.

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“…The fiber thickness was regular, in the range of 40-90 µm. The commercial mineral wool used in the study was characterized by a fiber diameter of 1-11 µm and the commercial wood wool by a diameter of 1-40 µm [38].…”

Section: Description Of Materialsmentioning

confidence: 99%

Heat Losses Caused by the Temporary Influence of Wind in Timber Frame Walls Insulated with Fibrous Materials

et al. 2020

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The paper presents the results of research concerning three fiber materials—mineral wool, hemp fiber and wood wool—as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest.

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

Cited by 27 publications

References 33 publications

Heat Transfer in Straw-Based Thermal Insulating Materials

Heat Transfer in Straw-Based Thermal Insulating Materials

Hybrid composite board produced from wood and mineral stone wool fibers

Heat Losses Caused by the Temporary Influence of Wind in Timber Frame Walls Insulated with Fibrous Materials

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