scholarly journals Study of Industrial Grade Thermal Insulation at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4613
Author(s):  
Amalie Gunnarshaug ◽  
Maria Monika Metallinou ◽  
Torgrim Log
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Heat Fluxes ◽  
Inorganic Materials ◽  
Scanning Calorimetry ◽  
Industrial Grade ◽  
Heat Treated ◽  
In Fire

Thermal insulation is used for preventing heat losses or heat gains in various applications. In industries that process combustible products, inorganic-materials-based thermal insulation may, if proven sufficiently heat resistant, also provide heat protection in fire incidents. The present study investigated the performance and breakdown temperature of industrial thermal insulation exposed to temperatures up to 1200 °C, i.e., temperatures associated with severe hydrocarbon fires. The thermal insulation properties were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and by heating 50 mm cubes in a muffle furnace to temperatures in the range of 600 to 1200 °C with a 30 min holding time. The room temperature thermal conductivity was also recorded after each heat treatment. Upon heating, the mineral-based oil dust binder was released at temperatures in the range of 300 to 500 °C, while the Bakelite binder was released at temperatures in the range of 850 to 960 °C. The 50 mm test cubes experienced increasing levels of sintering in the temperature range of 700 to 1100 °C. At temperatures above 1100 °C, the thermal insulation started degrading significantly. Due to being heat-treated to 1200 °C, the test specimen morphology was similar to a slightly porous rock and the original density of 140 kg/m3 increased to 1700 kg/m3. Similarly, the room temperature thermal conductivity increased from 0.041 to 0.22 W/m∙K. The DSC analysis confirmed an endothermic peak at about 1200 °C, indicating melting, which explained the increase in density and thermal conductivity. Recently, 350 kW/m2 has been set as a test target heat flux, i.e., corresponding to an adiabatic temperature of 1200 °C. If a thin layer of thermally robust insulation is placed at the heat-exposed side, the studied thermal insulation may provide significant passive fire protection, even when exposed to heat fluxes up to 350 kW/m2. It is suggested that this is further analysed in future studies.

Glass-Oxide Nanocomposites as Effective Thermal Insulation Materials

2013 ◽  
Vol 1558 ◽  
Author(s):  
Qing Hao ◽  
Minqing Li ◽  
Garrett Joseph Coleman ◽  
Qiang Li ◽  
Pierre Lucas
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Material Composition ◽  
Insulation Materials ◽  
Atomic Structures ◽  
Porous Nanocomposites ◽  
Theoretical Minimum

ABSTRACTWith extremely disordered atomic structures, a glass possesses a thermal conductivity k that approaches the theoretical minimum of its composition, known as the Einstein’s limit.1 Depending on the material composition and the extent of disorder, the thermal conductivity of some glasses can be down to 0.1-0.3 W/m∙K at room temperature,2,3 representing some of the lowest k values among existing solids. Such a low k can be further reduced by the interfacial phonon scattering within a nanocomposite that can be used for thermal insulation applications. In this work, nanocomposites hot pressed from the mixture of glass nanopowder (GeSe4 or Ge20Te70Se10) and commercial SiO2 nanoparticles, or pure glass nanopowder, are investigated for the potential k reduction. It is found that adding SiO2 nanoparticles will instead increase k if the measured k values for usually porous nanocomposites are converted into those for the corresponding solid (kSolid) with Eucken’s formula. In contrast, pure glass nano-samples always show kSolid data significantly reduced from that for the starting glass. For a pure GeSe4 nano-sample, kSolid would beat the Einstein’s limit for its composition.

Measurement of the Absorption of Microwave Power by Corroded Metals

1988 ◽  
Vol 124 ◽  
Author(s):  
Ralph W. Bruce ◽  
R. A. Quar
Keyword(s):  
Stainless Steels ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Surface Conductivity ◽  
Metallic Alloys ◽  
Metal Alloys ◽  
Electrical Measurements ◽  
Organic Mixture ◽  
Heat Treated ◽  
Microwave Signals

ABSTRACTMetal alloys, when exposed to a salt/organic environment at elevated temperatures, corrode resulting in a decrease in the surface conductivity. This decrease can be monitored and assessed via the measurement of the incident and reflected microwave signals impinging upon the corroded surface. Several metallic alloys, stainless steels and inconels, were treated with a salt/organic mixture (proprietary) and heat treated at 1100 F. Periodically, the metals were removed from the furnace, allowed to cool to room temperature, and measured electrically. The samples were re-coated with the salt/organic mixture and re-heat treated. The electrical measurements showed a generally increased power absorption as corrosion thickness increased.

Wandering of Crosslinks in Rubber at High Temperature

1959 ◽  
Vol 32 (3) ◽  
pp. 696-700
Author(s):  
M. J. Voorn ◽  
J. J. Hermans
Keyword(s):  
Stress Relaxation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Crosslinking Density ◽  
Heat Treated Sample ◽  
Equilibrium Degree ◽  
Heat Treated ◽  
Before And After ◽  
Final Stress ◽  
Different Temperatures

Abstract There are strong reasons to believe that on heating a crosslinked rubber crosslinks are broken and new ones formed. This has been established by the well-known work on stress relaxation of Tobolsky and his school, and others. In the following we will discuss some experiments which give further support to these views, both of a qualitative and quantitative nature. In the first place, we carried out a few preliminary experiments on stress relaxation at elevated temperatures. This stress relaxation may be due to either or both of two effects : (a) a displacement of the crosslinks, (b) a change in the number of crosslinks per unit of volume (crosslinking density p). A measure of ρ can be obtained from the equilibrium degree of swelling at room temperature, and this gives us a means of comparing changes of ρ in a stretched sample with those occurring in the unstretched state. To this end commercial rubber strips were heated in the stretched state in the absence of oxygen at three different temperatures (80, 106, 122° C) for times varying from 2 to 72 hours. The degree of stretch, i.e., the length of the stretched rubber divided by the original length was α=1 (unstretched) in one series, and α=3 in a second series. The initial stress τ0 (for α=3) and the final stress τ at the end of the heating period were read from the stress-strain diagrams, taking into account that for the heat-treated strips there was a permanent set. In other words, τ is the stress needed to give the heat-treated sample at room temperature a length 3 times the length of the original untreated sample; the ratio τ/τ0 is therefore essentially the ratio between the moduli of elasticity. The cross-linking densities ρ0 and ρ before and after heating were derived from swelling experiments (for details see the sections on swelling).

scholarly journals The effect of heat treatment on thermal conductivity of paulownia wood

2019 ◽  
Vol 78 (1) ◽  
pp. 205-207
Author(s):  
Z. Pásztory ◽  
S. Fehér ◽  
Z. Börcsök
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Treatment ◽  
Thermal Insulation ◽  
Insulation Materials ◽  
Heat Treated ◽  
Paulownia Wood

AbstractThe thermal conductivity properties of wood of Paulownia Clones in Vitro 112 were investigated after heat treatment at temperatures of 180 °C, 200 °C and 220 °C. After the treatment, the density decreased by 5.6, 8.9, and 14.1% for the samples heat-treated at 180 °C, 200 °C and 220 °C, respectively. The decrease in the thermal conductivity was 0, 2.6 and 15.7%, respectively. The thermal conductivity of kiri wood after thermal treatment at 220 °C was 0.064 W/mK, which is almost the same as that of thermal insulation materials.

Characterization of stone wool properties for fire safety engineering calculations

2018 ◽  
Vol 36 (3) ◽  
pp. 202-223 ◽  
Author(s):  
Karlis Livkiss ◽  
Blanca Andres ◽  
Abhishek Bhargava ◽  
Patrick van Hees
Keyword(s):  
Elevated Temperatures ◽  
Reaction Kinetic ◽  
Mass Loss Rate ◽  
Organic Content ◽  
Product Development Process ◽  
Kinetic Properties ◽  
Scanning Calorimetry ◽  
Bomb Calorimetry ◽  
Stone Wool ◽  
In Fire

Prediction of the insulating capability of building products in fire conditions would support the product development process. Stone wool insulation is a widely used material in fire barrier constructions. Due to the combustion of its organic content, the temperature inside stone wool can rise above the temperature of the exposed boundary. This temperature rise is difficult to predict. An extensive test program was performed to obtain the thermal and reaction kinetic properties of stone wool. The test methods included modified slug calorimeter, thermogravimetric analysis, differential scanning calorimetry, micro-scale combustion calorimetry and bomb calorimetry. The thermal conductivity in elevated temperatures was similar for all the investigated products. Two positive mass loss rate and heat release rate peaks were observed in temperatures between 20°C and 700°C. Reaction kinetic parameters were obtained and used in a finite difference model predicting the temperature increase in stone wool upon linear heating.

Thermal Performance Evaluation of Textile Waste as an Alternative Solution for Heat Transfer Reduction in Buildings

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Ayoub Gounni ◽  
Mohamed El Wazna ◽  
Mustapha El Alami ◽  
Abdeslam El Bouari ◽  
Omar Cherkaoui ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Temperature ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Air Permeability ◽  
Heat Fluxes ◽  
Insulation Material ◽  
Potential Applicability ◽  
Building Walls ◽  
Wall Surface Temperature

The potential applicability of a developed recycled textile material, based on acrylic spinning waste, as thermal insulation is conducted. The prepared acrylic spinning waste (AS) is thermo-physically characterized in terms of density, air permeability, and thermal conductivity. The results show that the density and air permeability are 10.583 kg/m3 and 1100 L/m2/s, respectively. In addition, the thermal conductivity is found to be 38.27 mW/(m K). The developed thermal insulator is then tested in a thermally controlled reduced scale cavity. Two walls of the cavity are outfitted with AS at two different locations and compared to the walls without AS. The comparison is made based on the wall surface temperature and heat flux. A reduction in surface temperature is observed in the walls outfitted with AS, compared to wall without AS. Indeed, compared to a control wall, the peak heat fluxes are reduced by 27.23% and 18.67%, respectively, related to the walls with AS at location 1 and location 2. The obtained results show that the AS is a competitive thermal insulation material and can increase the thermal performance of the building walls.

scholarly journals Electrical resistivity measured by millisecond pulse-heating in comparison to thermal conductivity of the hot work tool steel AISI H11 (1.2343) at elevated temperature

2020 ◽  
Vol 49 (1-2) ◽  
pp. 75-87
Author(s):  
ERHARD KASCHNITZ ◽  
PETER HOFER-HAUSER ◽  
WALTER FUNK
Keyword(s):  
Thermal Conductivity ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Electrical Resistivity ◽  
Tool Steel ◽  
Room Temperature ◽  
Pulse Heating ◽  
Scanning Calorimetry ◽  
Hot Work Tool Steel ◽  
Steel Aisi

Selected thermophysical properties of the hot work tool steel AISI H11 (1.2343) were measured in the temperature range from room temperature to the melting temperature. Thermal diffusivity was measured by the laser-flash method; heat capacity by differential scanning calorimetry; linear thermal expansion by push-rod dilatometry; and density at room temperature by an Archimedean balance. From these experimentally obtained data, thermal conductivity was calculated. Additionally, electrical resistivity of AISI H11 (1.2343) was measured by millisecond pulse-heating in the above mentioned temperature range. The measurement results of electrical resistivity as a function of specific enthalpy was combined with results of specific heat capacity measurements by differential-scanning calorimetry to obtain the relation between resistivity and temperature. Based on measured electrical resistivity and thermal conductivity, a Smith-Palmer-plot for the hot work tool steel AISI H11 (1.2343) is obtained for the ferritic and austenitic phases. No linear behaviour – as expected by the Wiedemann-Franz law – is observed in the ferritic phase region. In the high temperature austenitic region, the thermal conductivity can be computed from electrical resistivity using empirical constants of similar austenitic steels or superalloys.

scholarly journals Effect of Surrogate Aggregates on the Thermal Conductivity of Concrete at Ambient and Elevated Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Tae Sup Yun ◽  
Yeon Jong Jeong ◽  
Kwang-Soo Youm
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conduction ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Aggregate Size ◽  
Building Design ◽  
Normal Concrete ◽  
Coarse Aggregates ◽  
Thermal Data ◽  
High Thermal Resistance

The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100°C during heating to ~800°C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m−1K−1. The surrogate aggregates effectively reduce the conductivity to ~1.25 W m−1K−1at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

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 Study of Industrial Grade Thermal Insulation as Passive Fire Protection up to 1200 °C

Safety ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 41
Author(s):  
Joachim Søreng Bjørge ◽  
Amalie Gunnarshaug ◽  
Torgrim Log ◽  
Maria-Monika Metallinou
Keyword(s):  
Thermal Insulation ◽  
Fire Protection ◽  
Heat Sink ◽  
Temperature Increase ◽  
Steel Plate ◽  
Steel Plates ◽  
Scanning Calorimetry ◽  
Plate Temperature ◽  
Industrial Grade ◽  
Passive Fire Protection

It has recently been demonstrated that 50 mm thick industrial grade thermal insulation may serve as passive fire protection of jet fire exposed thick walled steel distillation columns. The present study investigates the performance of thermal insulation in conjunction to 3 mm, 6 mm, 12 mm and 16 mm steel walls, i.e., where the wall represents less heat sink, when exposed to 350 kW/m2 heat load. Regardless of the tested steel plate thicknesses, about 10 min passed before a nearly linear steel temperature increase versus time was observed. Thereafter, the thinnest plates systematically showed a faster temperature increase than the thickest plates confirming the wall heat sink effect. To study thermal insulation sintering, 50 mm thermal insulation cubes were heat treated (30 min holding time) at temperatures up to 1100 °C. No clear sign of melting was observed, but sintering resulted in 25% shrinkage at 1100 °C. Thermogravimetric analysis to 1300 °C revealed mass loss peaks due to anti-dusting material at 250 °C and Bakelite binder at 460 °C. No significant mass change occurred above 1000 °C. Differential scanning calorimetry to 1300 °C revealed endothermic processes related to the anti-dusting material and Bakelite mass losses, as well as a conspicuous endothermic peak at 1220 °C. This peak is most likely due to melting. The endothermic processes involved when heating the thermal insulation may to a large part explain the 10 min delay in steel plate temperature increase during fire testing. Overall, the tested thermal insulation performed surprisingly well also for protecting the thin steel plates.

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