Wrong expectation of superinsulation behavior from largely-expanded nanocellular foams

Nanoscale ◽  
2020 ◽  
Vol 12 (24) ◽  
pp. 13064-13085 ◽  
Author(s):  
Piyapong Buahom ◽  
Chongda Wang ◽  
Mohammed Alshrah ◽  
Guilong Wang ◽  
Pengjian Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Cellular Structure ◽  
Thermal Insulating ◽  
Insulating Properties

This work aims to predict the thermal conductivity of microcellular and nanocellular thermal insulation foams to explore the correlation between the cellular structure and the thermal insulating properties.

scholarly journals Using of Aerogel to Improve Thermal Insulating Properties of Windows

2018 ◽  
Vol 14 (1) ◽  
pp. 2-11 ◽  
Author(s):  
Denisa Valachova ◽  
Nada Zdrazilova ◽  
Vladan Panovec ◽  
Iveta Skotnicova
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Building Structures ◽  
Insulating Materials ◽  
Insulating Material ◽  
Composite Systems ◽  
Thermal Insulating ◽  
Technical Requirements ◽  
Technical Properties ◽  
Insulating Properties

AbstractFor the best possible thermal-technical properties of building structures it is necessary to use materials with very low thermal conductivity. Due to the increasing thermal-technical requirements for building structures, the insulating materials are developed. One of the modern thermal insulating materials is so-called aerogel. Unfortunately, this material is not used in the field of external thermal insulation composite systems because of its price and its properties. The aim of this paper is to present possibilities of using this insulating material in the civil engineering - specifically a usage of aerogel in the production of windows.

THE EFFECT OF VERTICAL AIR GAPS TO THERMAL TRANSMITTANCE OF HORIZONTAL THERMAL INSULATING LAYER

2009 ◽  
Vol 15 (3) ◽  
pp. 309-315 ◽  
Author(s):  
Jolanta Šadauskienė ◽  
Andrius Buska ◽  
Arūnas Burlingis ◽  
Raimondas Bliūdžius ◽  
Albinas Gailius
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Thermal Insulation ◽  
Standard Method ◽  
Mineral Wool ◽  
Insulating Layer ◽  
Air Gaps ◽  
Thermal Transmittance ◽  
Thermal Insulating ◽  
The Impact

In order to reduce the amounts of work at the construction site, single‐ply dual density thermal insulating roofing boards are used with increasing frequency for thermal insulation of flat roofs. In this case, the joints between boards are not overlapped by the other ply over it; therefore gaps of varying width form between the sides of the boards through the entire thickness of the insulating layer, whose effect on the effective thermal conductivity of the thermal insulating layer must be evaluated. The aim of this project was to assess the reliability of standard method, used to determine the impact of such air gaps on the effective thermal conductivity of the thermal insulating layer by comparing the results of calculations and the results of measurements of thermal conductivity, also to determine the correction factors for thermal transmittance of horizontal thermal insulation layers due to the forming vertical air gaps between the single‐ply mineral wool boards. After measurements of thermal resistances of 50 mm thick thermal insulation board with the air gaps which width varied from 3 mm to 20 mm, it was determined that the thermal conductivity value of the air gaps increases with the increment of the width of air gaps. After completion the experimental measurements of thermal conductivity it was determined that the height of closed and unventilated or partly ventilated air gaps has no effect on the properties of effective thermal conductivity of the thermal insulation layer when the air gap width is up to 5 mm. When wider unventilated or partly ventilated air gaps occur, the effective thermal conductivity coefficient increases proportionally as the height of the air gaps increases. Calculated according to the standard method the affix to the thermal transmittance is overly general and not always appropriate. In some cases it is 6 times higher or 4 times lower than the measured one. In this paper a method to evaluate the effects of air gaps by the use of correction factor to the thermal transmittance of the horizontal thermal insulating layer is proposed. Santrauka Nornt sumažinti darbų apimtis statybos vietoje, stogams šiltinti vis dažniau naudojamos vienu sluoksniu klojamos dvitankės termoizoliacinės plokštės. Šiuo atveju plokščių sandūros neperdengiamos, todėl tarp plokščių kraštinių susidaro įvairaus pločio plyšių, kurių įtaka termoizoliacinio sluoksnio šilumai perduoti turi būti įvertinta. Šio darbo tikslas yra įvertinti standartinio metodo, taikomo tokių plyšių poveikiui sluoksnio šilumos laidumui, patikimumui nustatyti lyginant skaičiavimo ir šilumos laidumo matavimų rezultatus, nustatyti horizontaliojo termoizoliacinio sluoksnio šilumos perdavimo koeficiento pataisas dėl vertikaliųjų oro plyšių susidarymo. Apskaičiavus 50 mm storio termoizoliacinio sluoksnio oro plyšių šilumines varžas, kai plyšių plotis yra nuo 3–20 mm, nustatyta, kad oro plyšių šilumos laidumo koeficiento vertė didėja didėjant oro plyšio pločiui. Atlikus eksperimentinius šilumos laidumo matavimus, nustatyta, kad susidarančių uždarų ir nevėdinamų arba iš dalies vėdinamų oro plyšių aukštis neturi įtakos termoizoliacinio sluoksnio šilumos laidumo savybėms, kai oro plyšys yra iki 5 mm pločio. Esant platesniems uždariems ir nevėdinamiems oro plyšiams, šilumos laidumo koeficientas proporcingai didėja didėjant oro plyšių aukščiui. Pagal standartinį metodą skaičiuotas šilumos perdavimo koeficiento priedas yra per daug apibendrinantis ir ne visada tinkamas. Kai kuriais atvejais jis yra 6 kartus didesnis arba 4 kartus mažesnis už išmatuotąjį. Šiame darbe pasiūlytas horizontaliojo termoizoliacinio sluoksnio šilumos perdavimo koeficiento priedo, naudojamo plyšių įtakai įvertinti, skaičiavimo metodas.

Influence of Air Entraining Agent on Performance of Inorganic Thermal Insulating Mortar

2011 ◽  
Vol 71-78 ◽  
pp. 490-493 ◽  
Author(s):  
Zhi Min He ◽  
Jun Zhe Liu ◽  
Tian Hong Wang
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Apparent Density ◽  
Thermal Conductivity Coefficient ◽  
Operating Performance ◽  
Drying Shrinkage ◽  
Test Results ◽  
Thermal Insulating ◽  
Excessive Consumption

This paper presents a laboratory study on the effect of air entraining agent on the performance of thermal insulating mortar with glazed hollow bead. The test results show that with the dosage of air entraining agent increases, the consistency of thermal insulating mortar increases, apparent density, thermal conductivity and drying shrinkage decline, However, the compressive strength greater losses owing to excessive consumption of air entraining agent; air entraining agent within a certain dosage can significantly improve the operating performance of thermal insulation mortar, increase its consistency and reduce its apparent density, thermal conductivity coefficient and drying shrinkage. Due to excessive addition of air entraining agent, the apparent density, thermal conductivity and compressive strength of thermal insulation mortar all increase. For a specific insulation mortar, there will exist the best mixing amount of air entraining agent.

scholarly journals MINERAL WOOL COMPOSITE WITH THE USE OF SAPONITE-CONTAINING MINING INDUSTRY WASTE

2020 ◽  
Vol 3 (3) ◽  
pp. 21-27 ◽  
Author(s):  
T. Drozdyuk ◽  
Arkadiy Ayzenshtadt ◽  
M. Frolova ◽  
Rama Shanker Rama Shanker Verma
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Mining Industry ◽  
Basalt Fiber ◽  
Linear Increase ◽  
Mineral Wool ◽  
Basalt Fibers ◽  
Thermal Insulating ◽  
Coefficient Of Thermal Conductivity

the paper shows the possibility of producing a thermal insulating composite based on basalt fibers and sapo-nite-containing mining waste. A method for manufacturing thermal insulating composites from hydro-mass with different contents of the mixture components is proposed. Basalt fibers were used as a filler, and pre-mechanoactivated saponite-containing material (SCM) was used as a binder. It was found experimentally that depending on the composition of composites, the coefficient of thermal conductivity varies from 0.1109 to 0.1342 W/(m•K), and the compressive strength – from 0.45 to 0.93 MPa. In addition, it was found that thermal modification of composites at temperatures up to 1200°C significantly (up to 3 times) increases the compressive strength of composites, while not affecting the coefficient of thermal conductivity. The ex-periments to determine the conductivity of the composite “basalt fiber – SСM” depending on its moisture content showed that the obtained composite is characterized by intense and linear increase in the values of conductivity when the humidity of the sample to 12% and further increase in humidity practically does not change the values of the coefficient of thermal conductivity. Comparison of the studied thermal insulation composite with known structural thermal insulation materials in terms of its thermal insulation and strength characteristics showed that it is comparable to gas and foam blocks. It should also be noted that this material is environmentally safe and can withstand high temperatures without collapsing.

scholarly journals Influence of Particle Size on the Properties of Boards Made from Washingtonia Palm Rachis with Citric Acid

2020 ◽  
Vol 12 (12) ◽  
pp. 4841
Author(s):  
Maria Teresa Ferrandez-Garcia ◽  
Antonio Ferrandez-Garcia ◽  
Teresa Garcia-Ortuño ◽  
Clara Eugenia Ferrandez-Garcia ◽  
Manuel Ferrandez-Villena
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Citric Acid ◽  
Thermal Insulation ◽  
Single Layer ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Plant Fibers ◽  
Thermal Insulating ◽  
Ecological Resources

The manufacture of technical materials of mineral and synthetic origin currently used for thermal insulation in buildings consumes a large amount of energy and they are not biodegradable. In order to reduce the environmental problems generated by their manufacture, an increasing amount of research is being carried out on the use of renewable and ecological resources. Consequently, the use of plant fibers and natural adhesives in the development of new thermal insulating products is increasing worldwide. Palm trees were used as a replacement for wood in some traditional constructions in places with scarce wood resources. This paper discusses the use of palm pruning waste in the manufacture of particleboards, using citric acid as a natural binder. Five particle sizes of Washingtonia palm rachis were used as the raw material for manufacturing the boards and the citric acid content was set at 10% by weight, in relation to the weight of the rachis particles. Single-layer agglomerated panels were made, applying a pressure of 2.6 MPa and a temperature of 150 °C for 7 min. Twenty panels were produced and their density, thickness swelling, water absorption, modulus of rupture, internal bonding strength and thermal conductivity properties were studied. Smaller particle size resulted in better mechanical properties. The boards had an average thermal conductivity of 0.084 W/m·K, meaning that these boards could be used for thermal insulation in buildings.

Sustainable materials with high insulation capacity obtained from wastes from hemp industry processed by wet-laid

2021 ◽  
pp. 004051752110460
Author(s):  
O Gutierrez-Moscardo ◽  
M Canet ◽  
J Gomez-Caturla ◽  
D Lascano ◽  
E Fages ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Textile Industry ◽  
Areal Density ◽  
Absorption Capacity ◽  
Thermal Insulating ◽  
Viscose Fibers ◽  
Sustainable Materials ◽  
The One ◽  
Insulating Properties

This article reports on the revalorization of hemp waste from the textile industry, focusing on the development of new sustainable materials with high insulating properties. Wet-laid technology was used to manufacture nonwovens with different binding fibers, polylactic acid, and viscose fibers. The characterization of the acoustic insulating capacity was carried out using a Kundt tube, and the thermal insulating performance by measuring the heat transmission resistance ( R) and thermal conductivity ( λ). The results showed that the developed nonwovens have lower thermal conductivity values of about 0.027–0.034 W/(m K), were even lower than those of traditional thermal insulating materials, being the sample with 100 g/m2 of areal density and with a composition of 80% of hemp, 10% of polylactide and 10% of viscose the one with the lowest thermal conductivity (0.027 W/(mK). Their acoustic absorption capacity was around 0.76 at a frequency of 6 kHz, in samples containing high hemp waste (>80 wt%). However, the heterogeneous, discontinuous, and high void density structure that contributes to excellent insulating properties, lead to a decrease in their mechanical properties. This demonstrated that these materials are suitable for substituting traditional materials in insulating applications. Additionally, antifungal tests were carried out. However, hemp nonwovens proved to be inefficient against fungal proliferation.

Preparation and Properties of Expanded Vermiculite/Gypsum Thermal Insulation Boards

2010 ◽  
Vol 178 ◽  
pp. 220-225 ◽  
Author(s):  
Yong Guang Xi ◽  
Tong Jiang Peng ◽  
Hai Feng Liu ◽  
Ji Ming Chen
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Compression Molding ◽  
Preparation Methods ◽  
Casting Technique ◽  
Thermal Insulating ◽  
Expanded Vermiculite ◽  
Calcined Gypsum ◽  
Molding Methods

In this paper, thermal insulation boards comprising expanded vermiculite and gypsum were manufactured by casting and compression molding methods respectively. The effects of flake size and preparation methods of expanded vermiculite (EV), ratio of calcined gypsum/EV and molding methods on thermal and mechanical properties were discussed. The results indicated that the thermal conductivity (λ) and compressive strength of the boards decreased with the increase of flake size, and increased as the ratio of calcined gypsum/EV rose, and the density of the boards increased linearly with the increasing ratio. Compared to compression molding, casting technique can make insulating materials with higher thermal conductivity, compressive strength, and lower water content. The boards containing EV expanded by microwave chemical method presented a better thermal insulating property (λ=0.091W•m-1•K-1) relative to the ones filled with microwave exfoliated EV (λ=0.107W•m-1•K-1). The prepared materials can be used for heat, acoustical insulation and moisture adjustment.

Evaluation of Structure Influence on Thermal Conductivity of Thermal Insulating Materials from Renewable Resources

1970 ◽  
Vol 17 (2) ◽  
pp. 208-212 ◽  
Author(s):  
Jolanta VĖJELIENĖ ◽  
Albinas GAILIUS ◽  
Sigitas VĖJELIS ◽  
Saulius VAITKUS ◽  
Giedrius BALČIŪNAS
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Renewable Resources ◽  
Raw Materials ◽  
Raw Material ◽  
Barley Straw ◽  
Insulation Material ◽  
Insulating Materials ◽  
Insulation Materials ◽  
Thermal Insulating

The development of new thermal insulation materials needs to evaluate properties and structure of raw material, technological factors that make influence on the thermal conductivity of material. One of the most promising raw materials for production of insulation material is straw. The use of natural fibres in insulation is closely linked to the ecological building sector, where selection of materials is based on factors including recyclable, renewable raw materials and low resource production techniques In current work results of research on structure and thermal conductivity of renewable resources for production thermal insulating materials are presented. Due to the high abundance of renewable resources and a good its structure as raw material for thermal insulation materials barley straw, reeds, cattails and bent grass stalks are used. Macro- and micro structure analysis of these substances is performed. Straw bales of these materials are used for determining thermal conductivity. It was found that the macrostructure has the greatest effect on thermal conductivity of materials. Thermal conductivity of material is determined by the formation of a bale due to the large amount of pores among the stalks of the plant, inside the stalk and inside the stalk wall.http://dx.doi.org/10.5755/j01.ms.17.2.494

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