Investigation of the thermal insulation performance of fibrous aerogel samples under various hygrothermal environment: Laboratory tests completed with calculations and theory

Lakatos, Ákos

doi:10.1016/j.enbuild.2020.109902

Cited by 31 publications

(26 citation statements)

References 21 publications

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“…Laboratory testing of the above-mentioned parameters is widely discussed by both domestic and foreign research groups [5][6][7]12,14,16,18,19]. This paper complements previous research studies executed on the fiber-reinforced aerogel insulation [10,11].…”

Section: Introductionsupporting

confidence: 64%

“…Several models exist to describe the total or effective thermal conductivity (λ t ) of inhomogeneous (fibrous or cellular) thermal insulation materials described as Equation (1), one of which is the most appropriate. After the examination of the results in scientific literature [11,13] and from our research, we can also conclude that this is the most appropriate model for defining the thermal conductivity of the insulation materials. It is a basic fact that in a porous, fibrous or cellular (gas-filled) thermal insulation material, the heat propagation is divided into six members: (λ c,g ), which describes the thermal conductivity of the gas; (λ c,s ), as well as (λ r ), defining the radiative part; and the member defining the gas convection (λ conv ), the latter being more typical for fibrous materials.…”

Section: Thermal Conductivity Of Insulation Materialsmentioning

confidence: 61%

“…The total or effective thermal conductivity of the whole block material can be measured under laboratory conditions (e.g., by heat flow meter, calibrated chamber method or guarded hot plate method). The total thermal conductivity (λ t ) is thus simplified to four terms as Equation (2) represents [10,11]:…”

Section: Thermal Conductivity Of Insulation Materialsmentioning

confidence: 99%

“…To produce a monolith aerogel takes time, while creating the special circumstances for production is expensive. As such, the economical production of these flexible insulation aerogels remains a challenge [10][11][12][13][14][15]. One of the important topics of the present research is the investigation of the thermomechanical properties of the mentioned materials, including the determination of the physical properties, paying special attention to the thermal insulation performance of fibrous silica aerogel.…”

Section: Introductionmentioning

confidence: 99%

“…Regarding insulating materials, we often do not have complete information on how they behave under external influences, such as humidity, temperature or time. These might change their properties and possibly their structures, and they may lose their good thermal insulation properties that are already present during production [3,11,12,[14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Exceeding the Applicability Limit of Aerogel Super Insulation Materials in Different Environmental Conditions

Lakatos

2020

Applied Sciences

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Newly designed and constructed buildings are subjected to increasingly strict regulations which emphasize the minimization and, where possible, the elimination of wasteful energy consumption, thus resulting in a decrease in emissions. Thermal insulation materials have an important role in making better use of the primary energy delivered to consumer systems, be it by an industrial process or building services systems or in residential and commercial buildings. It is well declared that buildings account for about 30% of total energy consumption, while they contribute to about 20% of greenhouse gas emissions. High-performance insulation has great potential to achieve the European Commission’s ambitious goals for reducing the thermal loss of buildings. A new class of super insulation materials (SIMs) could play an important role in the future of insulations (e.g., fiber-reinforced silica aerogel). This material is grouped with super insulation materials by the sixty-fifth annex of the International Energy Agency. However, due to their short presence on the market, we do not know much about their long-term performance, and if their properties change with time, the question is how and in which direction they do. This is why their artificial aging is so important through thermal annealing, in addition to exposing them to high humidity and low temperatures. In this paper, the application of measurement results after the artificial aging of fiber-reinforced silica aerogel will be discussed. In order to see the changes in the thermal insulation capability of the materials, 13 different cases of environmental exposures are discussed. These cases will be presented to see possible changes in the thermal insulation performance of the aerogel after treating it in different climatic conditions. Firstly, samples were exposed to humidity treatments at 296 K with different relative humidities (0, 35, 50, 65, 80 and 90%) until they reached equilibrium moisture contents. Secondly, the samples were heat treated once for 6 weeks at 343 K, then for 1 day at 373, 423, 453 and 483 K. Moreover, we wanted to see the effects of frost, and thus we executed a freeze–thaw cycle on the samples for 25 days between 258 and 303 K. After these curing procedures, the thermal conductivities of the samples were measured with a heat flow meter, according to the ISO 8301 standard. The measured thermal conductivity values after heat treatment, wetting and freezing were used for building energetics calculations, with a special focus on the thermal transmittance of two different hypothetical building structures (brick- and concrete-based walls) covered with the mentioned insulation.

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