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In hilly regions, the average ambient temperature during summers and winters typically ranges from 297 to 307 K (24 to 34 °C) and 277 to 293 K (4 to 20 °C). Therefore, this paper aims to describe the development and evaluation of an insulated Himshakti biogas plant (plant 2) for hilly regions and its comparison with the conventional biogas plant (plant 1). In terms of gas production, plant 1 generated an average of 0.614 m3 (614.18 L), while plant 2 produced significantly more gas, i.e., 0.775 m3 (775.23 L) due to its insulation which generates more income. Henceforth, the results indicated that the biogas production rate in the insulated plant was highest (820 L or 0.82 m3) when the temperature was at 307 K (34 °C) in the month of May. The comparative economic analysis showed that the insulated plant model is the most feasible for hilly regions, covering the total expenditure in less than 3 years and giving returns within the next 22 years. The developed biogas plant is favorable for its temperature, greater life span, more income, and reduced daily expenses (in terms of LPG). [ABSTRACT FROM AUTHOR]

Power transformer insulating oil is essential to the transformer's usable life. Mineral base transformer insulation oil is the most commonly used type; however, biodegradable alternatives have been developed due to safety and environmental concerns. This paper improves the insulation properties of power system transformers through the utilization of natural liquid-based insulation with additives. This work aims to enhance the functionality and dependability of transformer insulation-based vegetable seed oil for power system analysis. Here, vegetable seed oil-based natural liquid is used, which includes soybean oil, maize oil, mustard oil, and rice bran oil, which are chosen for analysis together with artificial and natural antioxidants like propyl gallate and citric acid. Blending vegetable seed oil with mineral oil of different compositions and adding additional 0.5 g and 1 g of additives allows for the analysis of the property improvement. The different properties, both with and without the influence of additives, are assessed in accordance with IEC/ASTM standards for breakdown voltage, water content, flash point, fire point, acidity, viscosity, and interfacial tension. The results demonstrate that the proposed natural liquid-based insulation with additives exhibits superior electrical and thermal properties compared to conventional insulation systems. It shows enhanced dielectric strength, improved thermal conductivity, and better resistance to ageing effects. These improvements give the reliability and efficiency of power system transformers. The findings indicate that the proposed insulation system offers significant environmental benefits compared to traditional mineral oil-based insulation. [ABSTRACT FROM AUTHOR]

Functional energy-saving materials with coupled cooling effect have become particularly urgent because traditional cooling systems require high industrial energy inputs and high labor costs. Biomass-derived materials are highly desirable for the environment and energy-related applications, but raw biomass materials cannot satisfy cooling demands for more environment and energy-efficient processes. Herein, inspired by the transpiration of natural plants and radiation cooling of metal materials, this study presents the silver nanoparticles–coated wood with a coupled cooling effect for dual-mode cooling. The silver nanoparticles–coated wood with a natural hollow ordered pore structure can achieve the cooling effect by the capillary phenomenon where water absorption and evaporation. The results revealed that silver nanoparticles with high infrared reflectivity were firmly embedded in the surface of the wood by magnetron sputtering, which empowers the wood with high infrared heat dissipation properties. Compared to the bare porous wood, the surface temperatures of silver nanoparticles coated wood were decreased from 34.6–35.8 to 30.3–31.2 °C. In addition, by combining with the evaporative and radiative heat dissipation, the silver-coated wood obtained the coupled cooling effect under simulated solar radiation, which further improves the cooling effect. Owing to the silver coating, the material possesses an excellent antibacterial property which extends durability. Therefore, the tree-inspired water vapor evaporation and radiation cooling show good harmony and can be well combined by the directional structure design of the material. This dual-mode cooling mechanism provides a novel design concept of cooling materials and further promises to benefit the sustainability of society in many aspects, from health to economy. [ABSTRACT FROM AUTHOR]

Numerous studies are exploring methodologies to enhance flame resistance and minimize the emission of toxic gases and chemicals from building materials in the event of a fire, aiming to mitigate risks and save lives. To that end, this study produced an insulation material using stabilized fiber based on polyacrylonitrile (PAN). Stabilized fiber provides flame retardancy by forming aromatic bonds in existing PAN fiber through heat treatment. To manufacture an insulation material with fiber, a separate adhesive is needed to maintain the shape, and cellulose was selected as the adhesive. Cellulose is an environmentally friendly material that can be obtained from natural sources and has the additional advantages of excellent stability and heat resistance. For this study, PAN-based stabilizing fiber (PSF) insulation was prepared and further processed using cellulose adhesive (PSF-C). Combustion experiments and gas analysis were performed to assess the combustion risks of the developed PSF insulation, and the contents of the hazardous gases and smoke generated were measured. The hazardous gases and smoke released during combustion were considerably reduced, and the heat resistance of the insulation was improved. Furthermore, the pyrolysis reaction and thermal stability were investigated. The results demonstrated a substantial reduction in the combustion hazards associated with the PSF when cellulose was used, i.e., PSF-C was used. The findings of this study are expected to substantially contribute to advancing the practical applicability of PSF-C insulating materials and the development of safe building and fire prevention systems. We developed PAN-based stabilized fiber insulation to enhance fire safety and minimize human casualties. We utilized an eco-friendly cellulose adhesive for structural integrity and studied its fire-safety properties, including HCN emissions. The developed insulation with cellulose adhesive (PSF-C) significantly reduced HCN emissions compared with a PAN insulator alone (PSF). PSF-C reduces human casualties [ABSTRACT FROM AUTHOR]

By using 6,6-((sulfonylbis (4,1-phenylene)) bis (azanediyl)) bis (thiophen-2-ylm- ethylene)) bis (6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-N) as phosphorus-nitrogen flame retardant, the polyurea (PUA) with flame retardant properties (PUA/DOPO-N) was prepared. In addition, organically modified montmorillonite (OMMT) and magnesium hydroxide (MH) were used as co-effectors respectively, and the flame retardant PUA (PUA/DOPO-N/OMMT and PUA/DOPO-N/MH) were also prepared. Thermal properties, flame retardant properties, flame retardant mechanism and mechanical properties of PUA/DOPO-N, PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric (TG) analysis, limiting oxygen index (LOI), UL 94, cone calorimeter test, scanning electron microscopy (SEM), and tensile test. The results show that the LOI value of PUA/20%DOPO-N, PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%, 27.7%, and 28.3%, respectively, and UL 94 V-0 rating is attained. Compared with PUA, the peak heat release rate (pk-HRR), total heat release (THR) and average effective heat combustion (av-EHC) of PUA/20%DOPO-N, PUA/18% DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease significantly. SEM results indicate that the residual chars of PUA/20%DOPO-N, PUA/18%DOPO-N/2%OMMT and PUA/15% DOPO-N/5%MH are completer and more compact. The complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame retardancy. The mechanical properties of PUA can be improved by the addition of DOPO-N, DOPO-N/OMMT and DOPO-N/MH, respectively. The insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×1016 Ω.cm. Furthermore, by using modified boron nitride (MBN) as heat dissipating material, the complex of PUA/MBN was prepared, and the thermal conductivity of PUA/MBN was investigated. The thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K), which is a 163% improvement over pure PUA. [ABSTRACT FROM AUTHOR]

The consumption of poly(ethylene terephthalate) (PET) has experienced a surge in recent times, owing to the widespread use of single-use plastic bottles, particularly in the context of beverages and drinking water. PET, a thermoplastic polymer, is known for its recyclability, and the recycled variant is referred to as rPET. The incorporation of rPET in fiber manufacturing is favored due to its cost-effectiveness, and the functionalized rPET fibers present an innovative product that can be used in a variety of applications. This study aimed to functionalize rPET fibers using the spun-bond technique, imparting antibacterial and flame-retardant properties, which are commonly employed in thermal insulator products. Nano zinc oxide (nano-ZnO) was used to confer antibacterial functionality, while phosphorus flame retardant (PFR) was used to impart flame-retardant properties. The core-sheath bicomponent fiber structure was employed to achieve the desired outcomes. The extrusion process was used to incorporate PFR and ZnO as the core and sheath components, respectively, at various ratios. The presence of nano-ZnO on the fiber shell was confirmed by the EDX data. The flame retardant study was utilized to observe the level of burning damage. The findings of the study demonstrated that increasing the percentage of PFR (maximum 8%) resulted in a significant decrease in the damage distance of the nonwoven material, with reductions of up to 60% was observed. Furthermore, the results of the antibacterial test indicated that the inclusion of an additional 3 wt% of ZnO resulted in a considerable reduction of the bacteria S. aureus and K. pneumoniae by about 99.96 and 98.79%, respectively. Based on the results obtained, it was determined that the most effective functionalized fiber was synthesized by including 3 wt% of ZnO and 5 wt% of PFR. Moreover, the incorporation of varying proportions of additives resulted in modifications to the mechanical and thermal characteristics of the fibers. This work highlights the potential of functionalized rPET bicomponent fibers as viable candidates for thermal insulator products. The utilization of functionalized rPET bicomponent fibers as a sustainable alternative for thermal insulator products showcases the commitment to environmentally friendly solutions, contributing to the overall goal of sustainability in the manufacturing industry. [ABSTRACT FROM AUTHOR]

Following the invasion of Ukraine and the associated energy policy tensions with Russia, the EU began looking at how it could replace Russian energy sources. One of the proposed solutions is to decrease energy consumption. Buildings have been the principal target, owing to their high energy usage – especially of natural gas, which the EU is particularly keen on reducing. This literature review article summarises existing knowledge on the potential energy savings that can be made through energy efficiency improvements to existing buildings in Central and Eastern Europe. The countries in this region share common traits due to their Communist past and associated legacy of poor energy efficiency, both generally and in buildings in particular. At the same time, Central and Eastern Europe contains a range of geographical and climatic regions, and so, the findings of this paper are applicable to other regions. This bibliometric analysis identifies three main areas (insulation, heating source and policy) in which the academic literature has identified potential for energy efficiency improvements to buildings. On the basis of these findings, this paper looks at the policy implications for reducing energy consumption in buildings and thus helps the EU to become less dependent on energy supplies from Russia. [ABSTRACT FROM AUTHOR]

The paper is devoted to an overview of the development of insulating materials and media used in high-voltage equipment over the past 150 years. The transition from traditional dielectrics such as air, porcelain, and glass to modern developments based on polymers and polymeric composites is considered. The increase in the use of synthetic liquids such as silicone and specialty oils is discussed, and the emergence of alternatives, such as liquid nitrogen for technological applications of superconductivity, is considered. Special attention is paid to the use of different gases, for example, fluoronitriles and ketones at different pressure values as an alternative to air and gas for gas insulation of high-voltage equipment. [ABSTRACT FROM AUTHOR]

The main application of silica aerogel is as an insulating material. However, basic forms of silica aerogel have limited application. Silica aerogel can be embedded in fibrous materials to achieve a mechanically reinforced and continuous form. This aerogel blanket can be easily used in many applications. In this study, a silica aerogel blanket has been fabricated through sol–gel process. Aerogel precursors undergo the synthesis steps within the fibreglass matric. The thermal conductivity of the fabricated aerogel blanket was 0.021–0.077 W m−1 K−1 over 20–600°C. The blankets were hydrophobic with a contact angle of 138°. The linear length shrinkage and linear width shrinkage were obtained at 0.12 and 0.22%, respectively. Values of compressive resistance of blankets were 149, 549 and 1700 kPa for 30, 50 and 70% deformation, respectively. The results of hot surface performance, flexibility or rigidity, maximum exothermic temperature rise, and resistance to vibration analyses confirm the excellent thermal and mechanical performance of the fabricated aerogel blankets. [ABSTRACT FROM AUTHOR]

Interactions of solar radiation with mammal fur are complex. Reflection of radiation in the visible spectrum provides colour that has various roles, including sexual display and crypsis, i.e., camouflage. Radiation that is absorbed by a fur coat is converted to heat, a proportion of which impacts on the skin. Not all absorption occurs at the coat surface, and some radiation penetrates the coat before being absorbed, particularly in lighter coats. In studies on this phenomenon in kangaroos, we found that two arid zone species with the thinnest coats had similar effective heat load, despite markedly different solar reflectances. These kangaroos were Red Kangaroos (Osphranter rufus) and Western Grey Kangaroos (Macropus fuliginosus). Here we examine the connections between heat flow patterns associated with solar radiation, and the physical structure of these coats. Also noted are the impacts of changing wind speed. The modulation of solar radiation and resultant heat flows in these coats were measured at wind speeds from 1 to 10 m s−1 by mounting them on a heat flux transducer/temperature-controlled plate apparatus in a wind tunnel. A lamp with a spectrum like solar radiation was used as a proxy for the sun. The integrated reflectance across the solar spectrum was higher in the red kangaroos (40 ± 2%) than in the grey kangaroos (28 ± 1%). Fur depth and insulation were not different between the two species, but differences occurred in fibre structure, notably in fibre length, fibre density and fibre shape. Patterns of heat flux within the species' coats occurred despite no overall difference in effective solar heat load. We consider that an overarching need for crypsis, particularly for the more open desert-adapted red kangaroo, has led to the complex adaptations that retard the penetrance of solar radiation into its more reflective fur. [ABSTRACT FROM AUTHOR]

The increasing attention towards wearable materials with excellent thermal insulation properties stems from their potential to save energy and fulfill the requirement for smart clothing, thereby addressing the fundamental need to maintain human body temperature. In this work, the multifunctional Cu nanoparticles/cellulose fibers aerogels (Cu-NPs/CFAs) composites with functional integration were prepared via simple in-situ deposition and freeze-drying process using sisal cellulose as starting material for thermal insulation applications. During this process, sisal cellulose was extracted to obtain cellulose aerogel, which was then in-situ deposited with copper nanoparticles through redox reactions. The subsequent freeze drying resulted in the formation of porous Cu-NPs/CFAs with high infrared reflection and self-cleaning properties. The SEM images showed that the Cu nanoparticles were tightly anchored on surface of cellulose aerogel, forming the high infrared reflection coating. The reflectivity of copper nanoparticle coating is approximately 0.85 to 0.95 in the ranging from 2 to 14 μm, indicating the high thermal insulation for human warmth in the cold environment. Besides, obtained Cu-NPs/CFAs material shows a self-cleaning property with a stable water contact angle of 150.5°, which can provide a stable infrared performance on the surface of the material. The present results indicate that Cu-NPs/CFAs are promising candidates as insulation material for human thermal management, energy regulation and other facility applications. Highlights: Aerogel composites were fabricated using sisal cellulose as starting material. Copper nanoparticles had been successfully deposited on the surface of the CFAs. Aerogel composites have a high infrared reflectivity. Cu-NPs/CFAs showed excellent stable hydrophobic performance. Cu-NPs/CFAs are promising candidates as insulation material for thermal management application. [ABSTRACT FROM AUTHOR]

In this research, a vegetable-based oil blend has been subjected to thermal ageing for different time periods before and after being dispersed with graphene oxide nanoparticles and its dielectric breakdown is investigated and compared with the newly developed unaged samples. Results show that at peak values, the ac breakdown voltage of nanofluids decreases by just 2.6% after ageing when compared to the base oil for which the ac breakdown voltage decreases by 8.4% after ageing. Similarly, at peak value, the impulse breakdown voltage of nanofluid decreases by just 2.9% after ageing as compared to the base oil for which the impulse breakdown voltage decreases by 7.3%. Thus, the developed nanofluid can be potentially used in transformers with successful operation after analyzing the physio-thermal properties. [ABSTRACT FROM AUTHOR]

Design models are commonly used in fire safety design of light timber frame assemblies. Parameters for use in the models are available for rectangular members with mineral wool, wood fibre or cellulose insulation and for assemblies with I-joists and mineral wool. For assemblies where I-joists and combustible insulations are combined, design parameters are missing. Five fire experiments with two I-joist types and four combustible insulation products have been conducted. The aim was to study charring of I-joist flanges and recession rates of combustible insulations and in addition, to compare their behaviour to the new and existing models of Eurocode 5. Charring rates for the flanges were 0.40–0.76 mm/min and 0.54–1.72 mm/min for the protected and post-protected phase, respectively. Rates decreased with increasing flange size. Charring rates for flanges of solid wood and LVL were comparable. The results show that lateral charring of I-joist flanges can be significant in the protected phase. The tested insulation products showed a lower recession rate than values reported for glass wool insulation, with a more pronounced difference for wood fibre and cellulose insulations. The low recession rates compared to previously reported generic values can possibly be explained by better product-specific properties, negligible shrinking and slightly different test set-up. The insulation stayed well in place after gypsum board fall-off and best-practice for keeping the insulation in place is given. The results, completed with future loaded full-scale tests, can give basis for further development of design models for assemblies with I-joists and combustible insulations. [ABSTRACT FROM AUTHOR]

Developing alternative eco-friendly construction materials is an important factor in sustainable development. Besides, one of the main ways to achieve this goal is the use of earthen materials in construction. In this respect, this study aims to investigate the feasibility of using Alfa fibers (Stipa tenacissima L.) and brick waste in the production of compressed earth blocks (CEB). Hence, the effects of Alfa fibers on the mechanical and thermal performance of CEB containing brick waste are analyzed. Brick waste content was fixed at 20% after an optimization study based on plasticity requirements, while Alfa fibers content varied from 0 to 0.5% of the dry weight of the block. Plain (unreinforced) CEB and fiber-reinforced CEB were tested for physical properties (density and absorption), compressive strength, and thermal behavior (conductivity and diffusivity). The results showed that Alfa fibers lightened the CEB. Also, adding Alfa fibers with a concentration of 0.5% increases the capillary absorption and the compressive strength by 40% and 111.25%, respectively. In terms of thermal properties, it is observed that using Alfa fibers improves the insulation aspect of the composite. Specifically, the thermal conductivity reduced by 13%. In all, using Alfa fibers and waste brick materials in CEB could be a promising solution to produce sustainable material with improved mechanical and thermal properties, contributing to the circular economy. [ABSTRACT FROM AUTHOR]

The eventual aim of this research work was to develop a new low-cost synthesis route to produce ultralight aluminum oxide ceramic fibers for high temperature insulation. This paper mainly focuses on the application of Al2O3 fibers as insulation materials in space vehicles. The study extended to check the fibers during the launch and in the conditions of space by a satellite test. The materials were monitored by thermo-vacuum and vibration tests before the launch. The long-term stability, the daily maximum and minimum temperature, and the temperature fluctuation were investigated in the satellite test. The data derived from satellite was collected in about 9 months. The other focus of this study was the characterization of fibers at high temperature. Al2O3 fibers were prepared by a new solution method and electrospinning technique. The developed Al2O3 fibers can be characterized by 0.035–0.037 W⋅mK−1 thermal conductivity, excellent heat resistance (up to 1600 °C), and good flexibility. [ABSTRACT FROM AUTHOR]

The present research aimed to investigate a charging of the cylindrical insulation layer of wires for space applications under the influence of isotropic electron radiation with an electron injection uniform in the volume of the dielectric. An analytical solution of the first-order differential equation resulting from the proposed charging model is obtained. A software has been developed and received state registration that allows for a complete calculation of the physical parameters of space-application wires resistant to electrification effects. The obtained results are proposed to be used for modeling and testing of wires for space applications in order to completely exclude the physical possibility of the occurrence of electrostatic discharges (ESR) of the "insulation–core" type during the operation (of the spacecraft) in orbit during geomagnetic disturbances in the Earth's magnetosphere. [ABSTRACT FROM AUTHOR]

Results are presented of an investigation of an ADSS optical cable for resistance to tracking. This cable is intended for a zonal communication line that is mounted on the supports of high-voltage power lines. This cable design differs from similar ones in lacking conductive elements. The outer insulating sheath of such a cable is made of polymers that are resistant to electrical discharges that damage the sheath surface. Test methods for evaluating the cable for tracking resistance are considered, and experimental research results using one of these methods are presented. [ABSTRACT FROM AUTHOR]

An electrical insulation made as a hollow circular cylinder with unlimited length is considered under a constant difference of electric potentials on cylindrical surfaces. The cylinder material is a composite with a polymer matrix modified by heat-conducting dispersed granules improving characteristics of the electrical insulation. The nonlinear mathematical model of the temperature state of the electrical insulation is constructed for given density of the heat flow on the inner surface of the cylinder and the heat exchange conditions specified on its outer surface. Results of the quantitative analysis of this model allow us to determine the maximal potential difference just before the thermal explosion of the electrical insulation and to find out possible applications of polymer composites with heat-conducting dispersed inclusions as dielectrics in various high-voltage electrical and electro-physical devices, among others, as electrical insulation of conducting strands of high-voltage DC cables. [ABSTRACT FROM AUTHOR]

Biomethanation is a temperature-dependent process, and in the cold regions where temperature mostly remains below 20 °C, it acts as a crucial limiting factor. The biomethanation process with efficient cold-tolerant anaerobes and other advanced techniques, including reliable digester designs, cost-effective insulation strategies, and additives, can help increase methane production efficiency under low ambient temperature. In cold regions, traditional fuel sources like forest wood, charcoal, agricultural residues, or cow dung cakes are used for cooking and heating, leading to increased greenhouse gas emissions. Thus, biogas is a promising fuel to replace traditional fuels and helps reduce the greenhouse effect to a great extent. The current review article has highlighted the role of cold-tolerant methanogens, different digester designs with a special focus on insulation techniques, co-digestion, and additives. The review also discusses different upgradation techniques to generate pure methane as a substitute for natural gas. Additionally, life cycle assessment analysis is also carried out focusing on the reduction of greenhouse gas emissions to show higher biogas production over traditional biogas systems. Overall, the importance of improved biomethanation in cold regions has been discussed in this review article. [ABSTRACT FROM AUTHOR]

Equipment installed in a power system network has to tolerate impulse overvoltage throughout its life span. Lightning impulses are one of the primary reasons of this overvoltage. Hence, insulation of the power equipment is designed and tested with standard lightning impulse. However, in reality, various complex, oscillatory non-standard lightning impulse waveforms exist in natural lightning impulses. Therefore, for the better design of insulation of the power equipment, identification of the non-standard lightning impulse waveform is essential. This article presents a comprehensive review of the effects of non-standard lightning impulse voltage on the insulation of power equipment. This article will help to classify the non-standard lightning impulse waveforms and identify the parameters, generation circuit, and analysis of non-standard lightning impulse waveforms till the present day. Hence, the information presented in the article can be helpful for the insulation design of the power equipment. [ABSTRACT FROM AUTHOR]

Buildings account for one-third of the world's energy consumption. Reducing this consumption is only possible by making buildings more energy efficient. One of the most efficient methods for increasing the energy efficiency of buildings is thermal insulation. Fuel consumption and therefore emission values can be reduced by achieving adequate thermal insulation of buildings. In this study, the optimum insulation thicknesses for cities in the various climatic regions of Turkey were determined using statistical methods. Insulation thickness, thermal conductivity, heating degree-days (HDD), and fuel type were determined as variable parameters, and the optimum insulation thickness and total heating cost for cities in four different climate zones were determined using the response surface method (RSM). The effect ratios for each parameter on total costs were also reviewed and analyzed using the RSM method. Mathematical models have been developed that estimate the total cost of natural gas, coal, and fuel oil based on thermal insulation thickness, thermal conductivity, and heating degree days. With the mathematical models presented in the study, dependent parameters (total heating cost) can be obtained as a function of independent parameters (fuel type, thermal conductivity of insulation material, and HDD). The models provide a calculation of direct costs for different types of fuels and provide a basis for various research. As a result, the optimum insulation thicknesses for İzmir (HDD: 1781), İstanbul (HDD: 2531), Ankara (HDD: 3303), and Erzurum (HDD: 5393) are 0.059 m, 0.066 m, 0.075 m, and 0.080 m, respectively; reductions in annual total costs were found to be 40.7%, 39.7%, 41.9%, and 50.1%, respectively. [ABSTRACT FROM AUTHOR]

Heat stress is a significant concern to firefighter health and is largely affected by the heat release properties of protective clothing. Air gaps exist in multi-layer firefighter clothing and have a great impact on body heat dissipation. In this study, the effect of air gap size on heat loss through firefighter turnout composites in different ambient environments was explored with a specially designed hotplate system. Three firefighter turnout composites with different moisture barriers were tested in mild (25 °C) and hot environments (35 and 45 °C). Study findings showed the air layer's thermal insulation and evaporative resistance increased up to a critical air gap size of about 15 millimeters when tested in mild condition due to the occurrence of natural convection. When tested in hot environments, the insulation and evaporative resistance of air gap kept increasing. The most significant finding was that air gaps together with ambient conditions affected the amount of moisture absorption inside moisture barriers, which further influenced the evaporative resistance and evaporative heat loss of firefighter composites containing bi-component moisture barriers. In contrast, for fabric composites with microporous moisture barrier, their evaporative resistance was relatively independent of air gap size and ambient conditions. The results from this study are useful for the modeling of heat transfer through firefighter clothing and are of great importance for the design of firefighter composites. [ABSTRACT FROM AUTHOR]

To prevent the migration of energetic plasticizers in propellants, Graphene oxide (GO) was added as filler to the ethylene propylene diene monomer (EPDM) insulation composite by mechanical mixing. Then, the anti-migration performance was analyzed by investigating the diffusion of dioctyl sebacate using immersion tests at different temperatures. The diffusion coefficient is in the range of 10–14-10–12 m2/s, and the migration activation energy is about 60 kJ/mol. Compared with pure EPDM, the anti-migration effects of EPDM/GO-5 are increased by 15.68%, 9.23%, 8.81%, and 5.69% at 25 °C, 40 °C, 60 °C, and 80 °C, respectively. Moreover, the composite shows a 58% increase in tensile strength and a 132% improvement in the elongation at break by the addition of 5 phr filler of GO. Meanwhile, the thermal stability of the EPDM insulation is also improved with the addition of GO. [ABSTRACT FROM AUTHOR]

From the perspective of reducing the carbon footprint, yield improvement is seeing global interest. One possibility to achieve this goal is to influence the volume of feed metal in the molds to achieve a sound casting. The largest volumes of risers are used in steels, so the research has focused on carbon steels for castings. Typically, to reduce the amount of molten metal in the riser, sleeves are used, such as exothermic and insulating ones. However, this is no longer sufficient, and therefore, blends of sleeves have been developed that perform both exothermic and insulating functions. The use of a new and innovative two-layer sleeves, combining the advantages of both layers (inner layer exothermic, outer layer insulating), proves to be highly effective. The conducted experiment compares this new approach with commonly used sleeves (exothermic, insulating, and exothermic—insulating). The utilization of riser metal using the new two-layer sleeve showed to be 8–10% higher compared to standard exo—iso mixed sleeves, and compared to single-layer inserts, the utilization of molten metal was 18–20% higher. [ABSTRACT FROM AUTHOR]

Thermal comfort parameters of knitted fabrics such as thermal resistance and liquid transfer can be enhanced by combining hydrophilic and hydrophobic functional yarns as double-face fabrics. This study aims to investigate thermal conductivity (Alambeta Parameters), permeability (air permeability and Permetest Parameters) and liquid management characteristics of double-face knitted fabrics for which functional yarns such as Thermosoft®, Nilit Heat®, Viloft® and wool were combined with standard polyester (PET) and polypropylene (PP) by a false rib structure. According to the results of 11 fabrics-s is necessary, Nilit Heat®/PP (inner/outer) fabric has advantages for breathability, warmer sensations as a result of its minimum thermal absorption, conductivity and diffusion. Wool/PET can be suggested more for liquid management properties with its branched structure besides its higher thermal resistance and air permeability values. Both structures including hydrophilic or functional inner surfaces touching the skin can be suggested for a cold protective clothing to enable stable insulation and dryness. [ABSTRACT FROM AUTHOR]

Shipping containers are increasingly adapted for modern modular construction of both permanent and mobile low-cost civilian-use structures, with the diversity and interchangeability of their uses suggesting the need for container-based modular structures to conform to standard fire safety requirements, notably insulation and integrity. Multi-storey structures in city centres consisting entirely of modified shipping containers, or shipping containers fitted into structural frames, are becoming more commonplace. Full-scale fire tests are generally rather expensive and can be complemented with systematic numerical studies of fire resistance times offered by a range of passive protection configurations and thermal transport properties. Noting that standardised fire resistance ratings have three components (structural, insulation, integrity), this study specifically considers fire resistance times offered by passive fire protection configurations, by performing a series of time-dependent finite element heat transfer analyses of passively protected side panel configurations. A set of reference curves with which to determine insulation resistance times in the context of the ISO 834–1 standard fire curve is presented, specifically for use in the rational fire safety design of modular structures constructed from shipping containers. Negligible literature is currently available on fire resistance ratings of shipping container structures. [ABSTRACT FROM AUTHOR]

Polyimide nanocomposites have drawn much attention as mechanical, thermal, and electrical insulation materials due to its superior dielectric, thermal stability, and corona resistance properties. The polyimide nanocomposites are defined as substance of polyimide matrix reinforced with certain weight percent of nanofillers. Researchers have demonstrated the usage of polyimide nanocomposites in mechanical, thermal, and electrical insulation application. However, the nanocomposites are noted to face interfacial bonding issues, which have affected their mechanical performance for thermal and electrical insulation properties. The dielectric behaviour and corona resistance lifetime of the polyimide nanocomposites are reportedly degraded over a long-term exposure to high-temperature environment. Although, there have been an advancement on improving the mechanical, thermal, and electrical properties of polyimide nanocomposites for multifunctional insulations. This review summarises the effects of nanofillers, such as silica (SiO2), titania (TiO2), alumina (Al2O3), graphene's, nanotubes, boron nitride and some other fillers on the mechanical, thermal, and electrical properties of polyimide nanocomposites for insulation application. The authors concluded the review with advancement, challenges and recommendations for future improvement of polyimide nanocomposites as an insulation material. Thus, the review study offers discernment into the improvement and selection of polyimide nanocomposites material for mechanical, thermal, and electrical insulation. More so, the review will also give a way for further research. [ABSTRACT FROM AUTHOR]

This paper is proposing an machine learning based expert system for preliminary prediction of the insulation fire resisting performance of shallow floor systems when subject to exposure to the ISO 834 Standard Fire Curve. The proposed system is a digital tool which incorporates a machine learning algorithm trained on the outcomes of pre-run two-dimensional finite element heat transfer analyses of shallow floor system details. The algorithm predicts the insulation performance of similar details with a measurable accuracy of 96% (i.e the insulation rating band was predicted correctly in 96% of the cases) without the requirement for an explicit deterministic analysis. The paper presents the challenges and prerequisites to build such an expert system and acts as a proof of concept for the use of machine learning for the assessment of the insulation performance of shallow floor system under the guidance of BS EN 1363-1:2012. A Support Vector Machine machine learning algorithm is adopted in this work. The required processes that were needed for the development of the expert system include the stages of data acquisition, exploratory data analysis, choice of machine learning algorithm, model training, tuning, and validation. This expert system is useful for practitioners to rapidly assess the feasibility of different construction details at early stages of the design process. [ABSTRACT FROM AUTHOR]

The improvement of energy efficiency in buildings is pivotal for mitigating climate change and its repercussions on weather patterns, such as raised average temperatures and extreme weather events, which are expected to become an increasingly frequent occurrence. In addition, it is continuously impacting ecosystems and causing biodiversity loss through the proliferation of non-native invasive species, such as Typha domingensis, which can entail significant direct human health impacts. This research puts forth the use of this aquatic plant as thermal insulation material, which would consequently aid in controlling its spreading. Along with a context-tailored manufacturing method, five types of thermal insulation boards were developed, each with a different dosage of cement, ranging from 0 to 80%. Out of these, the boards with 60% of fibre content were found to be optimal due to their low thermal conductivity and their balanced mechanical strength, swelling and hydric performance. Furthermore, transient simulations developed for the Nigerian context and sub-Saharan Africa area showed that the optimal thickness for the boards would be 80 mm. With the implementation of Typha boards, indoor temperatures no longer exceeded 35 °C and the number of comfortable occupied hours increased by 70% compared to the baseline situation. [ABSTRACT FROM AUTHOR]

Polymer/conductor composite dielectrics easily have high permittivity, high conductivity, and high dielectric loss, limiting large increase of energy storage density in them. The relationship between high permittivity and low conductivity is coordinated to achieve high energy density. In this study, polyvinyl alcohol (PVA)/V2C MXene/cellulose ternary composites with high permittivity and low dielectric loss were prepared. Due to good water solubility of PVA and high water dispersibility of V2C, PVA and V2C have good interfacial compatibility. That reduces the interface electric leakage conductance, which is conducive to the lower conductivity and dielectric loss in the composite materials. The high interfacial polarization between PVA and V2C improves the dielectric response of the composite materials, improving the permittivity of the composite materials. Compared with binary PVA/V2C composites, ternary PVA/V2C/cellulose composite materials use the high insulation of cellulose filler to increase the insulation of composites. Thus, the conductivity and dielectric loss are reduced in ternary composites. Good synergy of conductive V2C and insulating cellulose fillers is important to obtaining the balance of high dielectric response and high insulation trait in ternary composites. Best ternary composite with 6 wt% V2C has a high permittivity of ca. 40, low dielectric loss of ca. 0.25 at 100 Hz, and high breakdown strength of ca. 40 MV m−1. This work enables a facile preparation of promising composites for dielectric energy storage. Relevance summary: • Novel ternary composite dielectric films with V2C MXene and cellulose were fabricated. • Good synergy of V2C and cellulose can lead to optimization of overall electric properties. • This work might provide ideas for preparing bio-dielectric materials employing cellulose. [ABSTRACT FROM AUTHOR]

In this paper, the optimization of transmission insulation and grounding is performed considering two backflashover rate (BFR) evaluation procedures widely applied in the industry. The optimization approach is based on the Lagrange formulation introduced by Hileman in late sixties. This method used the old AIEE procedure to evaluate the BFR of transmission lines. Since then a number of BFR evaluation are available to determine BFR rates outperforming legacy procedures. Recently, the Hileman's optimization method was updated using the EPRI two-point method to evaluate the BFR. However, despite the step-by-step EPRI method being still widely used in industry, stochastic simulation with specialized programs is becoming standard. Thus, in this paper, the insulation and grounding optimization methodology is updated using more adequate and recent BFR evaluation procedures such as the IEEE Std. 1243-97 and the Monte Carlo EMTP-based methods. Technical and economic results were compared with the existing optimization approach based on the EPRI two-point method using the EPRI 345 kV transmission line as test system. Results show that IEEE and EPRI methods yield equivalent results. The stochastic-based method (MC-EMTP) is more optimistic showing total and marginal insulation and grounding costs below the IEEE/EPRI methods. [ABSTRACT FROM AUTHOR]

Composites based on a homogeneous mixture of low-density polyethylene (LDPE) with powdered natural zeolite (clinoptilolite and heulandite of Agdag deposits, Azerbaijan) in the form of films 140–200 μm thick and 20 mm in diameter have been obtained by hot pressing at a temperature of 403–413 K and pressure of 15 MPa, followed by quenching in a mixture of ice and water. The dielectric parameters (the real part of the dielectric constant (ε'), the tangent of the dielectric loss angle (tan δ), and the electrical conductivity (σ)) of the composite samples of 60 vol % LDPE/40 vol % zeolite and 40 vol % LDPE/60 vol % zeolite have been examined at frequencies of 25–106 Hz and in a temperature range of 293–403 K. On the basis of the temperature dependence of the electrophysical parameters of composite samples, it has been revealed that tanδ and σ increase with an increase in the filler content and this is associated with an increase in the concentration of charge carriers and their mobility. The study of the frequency dependences ε′ = f(log ν), tan δ = f(log ν), and log σ = f(log ν) has shown the presence of two linear regions of the frequency dependences of electrical conductivity, which change according to the law σac(ν) ∼ ν0.73, and this is more consistent with the hopping mechanism of electrical conductivity of LDPE/zeolite composites. [ABSTRACT FROM AUTHOR]

The silane cross linking of polyethylene and the parameters affecting the structure and degree of cross linking of the polymer have been studied; as well as the optimal conditions for the processing of cross-linked polyethylene have been established. The influence of the content of ethylene vinyl acetate on the technological properties, thermal deformation and the degree of cross linking of silane-based cross-linked polyethylene is investigated. [ABSTRACT FROM AUTHOR]

An energy audit was realized for a building group located on a university campus to measure the environmental sustainability and efficient usage of natural resources. As a result of energy audit, exterior insulation and double-glazing application were came to the front for energy-saving options. Although energy audit provides energy-saving options as output, it is not enough to provide information about how environmental impacts will change if the defined options are used. To determine the improvements in terms of environmental indicators, these options were assessed with life cycle assessment (LCA). LCA was realized for 50 years life span for 1 m3 of the building. CML-IA method was used to conduct LCA analyses. Ecovalue08 was applied as a monetary weighting method since the used CML-IA method has no weighting function. Results show that there are significant improvements (> 5%) on ADPff (11–12.5%) and GWP100 (8.5–9.7%) impacts provided by both of the energy-saving options. Additionally, double glazing would provide a 10.5% improvement on ODP. On the other hand, the exterior insulation application would increase the ODP value of EB by 34%. The impact category of GWP100 is found as the most dominant impact according to Ecovalue08. The ranking of the other impact categories from higher to lower value is HTP, ADPff, and AP. [ABSTRACT FROM AUTHOR]

In the present study, long-term multi-stress aging performance of silicone-based polymeric insulators was investigated for possible use on high-voltage alternating current transmission lines in Pakistan. One neat sample of high-temperature-vulcanized silicone rubber and four silica and alumina trihydrate filled hybrid composites were studied for 5000 h under accelerated multi-stress aging simulating environment of Karachi. Several measurements and diagnostic techniques such as hydrophobicity assessment, leakage current measurement, scanning electron microscopy, Fourier transform infrared spectroscopy, tensile testing and shore-A hardness were deployed to better establish a reliable comparison of resistance-to-aging among the investigated samples. Through extensive analysis of all measured data, it was established that among the investigated five samples, the specimen representing silicone hybrid composite containing 2% nano-silica and 20% micro-silica showed the most superior performance. Expanding grid in Pakistan which has been facing several challenges in terms of pollution-related flashovers maybe made more reliable through use of silicone rubber hybrid insulators. [ABSTRACT FROM AUTHOR]

Using data from a survey of solar adopters in the USA, the present paper examines the effect of adding insulation on electricity bill savings. We identify whether solar adopters added insulation to their house close to the time of rooftop photovoltaics (PV) installation as a bundling strategy, and examine whether such decisions are correlated with higher electricity bill savings. We find that only 7% of solar adopters in the sample ended up bundling their PV installation with additional insulation. About 58% of solar adopters in the sample have not added insulation at all. The evidence in the present study suggests that solar adopters who choose the bundling strategy have larger, older houses, located in counties with higher electricity prices than those adopters who did not add insulation at all. Results show that while all solar adopters who choose the bundling strategy have a higher average dollar amount of savings, only those with high initial bills end up with a higher percentage of savings. The results of the present study provide some insights into the energy decision-making of households and provide some input for policies focused on combining renewable energy with efficiency standards. [ABSTRACT FROM AUTHOR]

Optimization of insulation on subsea oil and gas equipment can lead to significant cost and weight reduction. A judicious combination of commercially available Finite Element Analysis (FEA) software with evolutionary optimization algorithms can efficiently serve this purpose. In the present study, the optimization of insulation on a gate valve has been presented with due emphasis on the methodology adapted. A parameterized model of the gate valve with several dimensions of interest has been chosen for the numerical experiment. Of the various Design of Experiment (DOE) techniques, the Optimal Space Filling (OSF) method has been considered for generating the samples owing to its robustness and the associated computational cost. The insulation in subsea systems is usually supposed to satisfy two contradicting constraints, it must be ensured that the temperature of the production fluid remains above the Hydrate Formation Temperature (HFT) and at the same time the production fluid temperature cannot be too high, as to create structural damage of the seals in High Pressure High Temperature (HPHT) applications. The sample cases are run simultaneously in a cluster and a response surface is created using genetic aggregation using the various samples those are generated by OSF. The resulting response surface is finally subjected to optimization using the calculus based/gradient based methods. In the present investigation, the optimization is performed using the NonLinear Programming with Quadratic Lagrangian (NLPQL) and Adaptive Single Objective (ASO) Methods. The results obtained show that almost two thirds of the insulation can be effectively removed without compromising on the thermal efficiency of the system. Similar savings have been witnessed in several other cases/subsea geometries that the authors are aware of. The presented case is truly representative of a wide class of subsea applications and the proposed methodology can be suitably adjusted to customer specific requirements to provide suitable results. [ABSTRACT FROM AUTHOR]

In this paper, we present a study of products obtained using various technological processes of forming laminated insulation by the winding method. The description of technological processes, the experimental setup, and methods for determining the dielectric strength of samples is given. A comparative analysis of samples obtained by different winding methods was performed, and the best method for manufacturing insulation was revealed. [ABSTRACT FROM AUTHOR]

The passive house concept specifically improves insulation of exterior building components, utilisation of passive solar gains, airtightness and heat recovery from ventilation air. Reducing also heat losses from thermal bridges, the energy balance is improved significantly resulting in net heating demands lower than 15 kWh/(m2a) which is less than one-tenth of the typical heating energy in the average of existing buildings. The design concept can be used for every new building, and many thousand examples have so far been built for different use, in several climates and based on different construction type (e.g. concrete, timber, mixed). The very first prototype is a terraced house with four dwellings built 1990/1991 in Darmstadt. This building uses typical masonry external walls, concrete floors and a timber roof and can be seen as a representative example for highly energy-efficient construction. By monitoring all relevant energy flows through the building's envelope during a period of more than 25 years, it has been confirmed that the energy consumption is as extraordinarily low as designed and stable over the whole period. This article especially investigates how this has affected the indoor climate, the indoor air quality and the durability of all components. By thorough investigation, an assessment of the maintenance cycles is given, which are representative for this construction type. The main characteristics of the components and the ventilation system after 25 years of performance of the pilot building have been determined; these are typical for passive house quality components; therefore, the results are indicative for the concept. The passive house concept turns out to be not only energy-saving but also most notably very durable and extraordinarily low-maintenance. [ABSTRACT FROM AUTHOR]

Background: Adhesion formation is a major problem when a mesh is exposed to intraabodminal viscera, with potential severe complications (bowel occlusion, fistulas or abscesses). New methods for preventing adhesions from a polypropylene mesh placed intra-abdominally or to solve difficult situations, such as when the peritoneum cannot be closed during a TAPP repair for an inguinal hernia, are still being seeked. This study mimics in an animal model a situation that can be found in clinical practice during laparoscopic inguinal hernioplasty. A polypropylene mesh could be exposed to the intra-abdominal cavity even when the peritoneum is closed due to different circumstances, with no options to guarantee the prosthetic material of being exposed to the intrabdominal viscera. Different options have been suggested to solve these situations, being proposed in this study to cover the visceral surface of the mesh with an absorbable sponge containing thrombin, fibrinogen, and clotting factors (Tachosil®, Nycomed, Takeda, Osaka, Japan), to assess its use as a barrier to prevent postoperative adhesion formation. Material and methods: Thirty Wistar white rats (300–450 mg) were included in this study as experimental animals, being randomized into three groups (A, B, and C). We performed a bilateral prosthetic repair with conventional polypropylene mesh (2 × 2 cm, 82 kD). Prosthesis fixation was performed as follows. Group A: absorbable suture; group B: metal staples; group C: metal tackers. A piece of insulating absorbable sponge (Tachosil® 5 × 5 cm) was placed to cover the visceral surface of mesh placed at the right side of each animal. After 10 days, we performed a gross examination (by laparoscopy and laparotomy), measuring the quantity and the quality of the adhesions. Samples were taken for histopathological analysis. Results: Tachosil®-treated prostheses showed a statistically significant decrease in the quality of the adhesion found (p < 0.05). In addition, a smaller quantity of adhesions was identified in barrier-treated animals, although this lacked statistical significance. The histologic analysis showed no significant differences: more edema with the untreated mesh and increased angiogenesis and a lower degree of necrosis in mesh covered with Tachosil®. Conclusions: The use of Tachosil® as a barrier material led to the absence of strong adhesions as it prevented direct contact between the mesh and the internal organs, preventing major problems associated with strong adhesions. [ABSTRACT FROM AUTHOR]

Post-earthquake fires occur after earthquakes and have commonly been encountered throughout history. The fires are particularly deadly and threaten the stability of buildings as possible structural damages caused by seismic loading can be exacerbated by temperature loading. Moreover, damage to insulation during seismic events causes accelerated heating in portions of members experiencing large bending moments. A method is proposed for evaluating the stability and deflection of a semi-braced structural steel frame subjected to post-earthquake fire conditions. The proposed method adopts the interstorey drift concept and assumes that each member in the frame has three segments of differing temperatures, modelling the damage to insulation near moment connections and/or midspans of flexural members. The method is presented in the form of a deflection equation, which indicates the instability of the frame when the lateral stiffness in the denominator reaches zero. The proposed method is demonstrated via a numerical example, and the duration of fire until the given frame becomes unstable is computed, with the results validated via finite element analysis. The degrees of structural and insulation damage are also varied in parametric analyses, showing that the lateral stiffness and critical temperatures of a frame subjected to post-earthquake conditions can be severely reduced. [ABSTRACT FROM AUTHOR]

Composite dielectrics and insulators are emerging as replacement of neat epoxy because of their superior characteristics. However, methods of composite preparation, type and size of filler and stresses such as temperature and mechanical stresses influence these characteristics. In addition, inorganic oxides-based epoxy composites are expected to have good dielectric characteristics. In this work, effect of compression and silica on the dielectric properties of epoxy composites with reference to neat epoxy is explored. Epoxy microcomposite (15% by weight silica loading) and nanocomposites (2.5% and 5% by silica loadings) are prepared, and their dielectric properties are investigated before and after compression at 15 MPa. Overall epoxy nanocomposites with 5% nanosilica performed best having 0.09 dissipation factor and dielectric constant of 6.23. After compressing the samples at 70 °C and 15 MPa, dramatic increase in the dissipation factor of microcomposites was recorded where the average κ increased by a factor of 1.53–8.27 in comparison with 5.40 in the uncompressed form. [ABSTRACT FROM AUTHOR]

The influence exerted by the composition of ceramics with imitators of radioactive wastes (Nd, U) on their stability against leaching in water at 90 and 150°C has been studied. Raising the content of TiO2 in a ceramic with Nd led to an increase in the fraction of perovskite and decrease in the amount of murataite. Samples with perovskite have the lowest stability in solution, especially at 150°C. Making smaller the fraction of perovskite lowers the rate of Nd leaching by a factor of 2 (90°C) and 5 (150°C). The weaker influence exerted by temperature on the U leaching from the samples is observed because more stable pyrochlore or zirconolite appear in the samples instead of perovskite. [ABSTRACT FROM AUTHOR]

The mineral oil (MO) in conjunction with paper is the main insulation components in oil-immersed transformers; their insulation properties play a significant role in the safe and stable operation of power transformers. To strengthen the insulation level of ultra-high voltage transformer and to reduce its size and weight, it is imminent to enhance the insulating performance of transformer oil and oil-impregnated cellulose. Recently, a unique novel effort of suspension of nanorods (NRs) into MO has been carried out and the results have exhibited improved insulation characteristics of transformer oil. The Al2O3 NRs with favorable features were prepared in our laboratory to develop transformer oil/paper insulation system with better insulation performance. The transformer oil-based nanofluids (NFs) were prepared with nanorod shape, oleic acid surface modification and 0.8 g/L concentration of NRs. The impregnated pressboards were prepared by impregnating them into dried oil and NF under vacuum beneath 1 kPa at 80 °C for almost 48 h to obtain the oil-impregnated pressboard (OIP) and nanofluid-impregnated pressboard (NIP), respectively. The interface at solid/liquid is considered weak link and is the main reason of oil-filled transformer collapse. The effect of Al2O3 NRs on creeping discharge and flashover traits of oil/pressboard (OP) interface under AC and impulse voltages were studied. Partial discharge and creeping flashover test of OIPs and NIPs were conducted. TSDC and PEA tests were applied to examine the space charge properties of OP interface before and after suspension of Al2O3 NRs. [ABSTRACT FROM AUTHOR]

Insulated polyimide (PI) composites filled with short glass fibers (SGF), polytetrafluoroethylene (PTFE), SiO2, and polyphenylene (PPL) are specially designed, prepared, and the tribological properties are systematically investigated with references to the special requirements for frictional materials used in ultrasonic motors. The hardness and thermal decomposition temperature of the insulated PI composites are comparable to that of conductive PI composites. However, these insulated materials present excellent friction and wear performance, especially under high loads and speeds. Scanning electron microscopy (SEM) analysis of the worn surface indicates that adhesive and fatigue wear dominate the wear mechanisms. [ABSTRACT FROM AUTHOR]

The aim of the present study is to produce novel developed composite materials which provide thermal insulation by using waste and natural materials in construction applications. Composite construction samples were prepared using an expanded perlite aggregate of 15 % wt., 30 % wt., and 45 % wt., which had the grain sizes of 0–3 mm, 3–5 mm and 5–8 mm, as well as waste marble dust of 5 % and 15 % filtrated from a 300 µm sieve, combined with molten tragacanth of 0 %, 0.5 % and 1 %, and CEMI 42.5 N-type portland cement. The microstructure of the composite samples was examined by the SEM analysis. Density, thermal conductivity, compressive strength, abrasion loss, water absorption, compressive strength after high temperature, and compressive strength after freeze–thaw tests were performed on these composite samples. It was found that the density values of composite materials decreased from 1.983 g·cm−3 to 0.933 g·cm−3. It was observed that their porosity ratios up to 43 % were improved by increasing the amount of waste marble dust, expanded perlite and molten tragacanth, additionally, while their compressive strengths decreased. Thermal conductivity of the porous samples decreased from 0.468 W·m−1·K−1 to 0.167 W·m−1·K−1 by raising their porosity, which corresponds to a reduction of 36%. It was observed that as the rates and sizes of the materials used in the samples, their thermal conductivity, compressive strength and density values decreased, and the abrasion loss and water absorption increased. [ABSTRACT FROM AUTHOR]

This study quantifies the results of the thermal conductivity for cement-based foam reinforced with polypropylene fibers and correlates the influence with pozzolans, porosity, moisture content, and pore parameters. Here, the mixtures were prepared for the densities range of 400–800 kg/m3 in which cement was replaced in the ratios of 10% and 20% (by weight) with fly ash, silica fume, and metakaolin. Along with pozzolan, polypropylene micro-fibers were added at the volume fraction of 0.2%. The thermal conductivity was measured variously at the hydration age of 60–210 days by using the transient plane source technique. While the porosity and the pore parameters were evaluated by using X-ray microtomography, a non-destructive technique. The results revealed that polypropylene fibers contributed to reducing the conductivity and among the three pozzolans, fly ash was the most efficient. However, the porosity increases with the inclusion of fibers but drops significantly with the addition of pozzolans, especially for lower densities mixtures. Also, it was found that D50 relates linearly with conductivity. However, based on experiment results, a modified thermal conductivity predictive model for cement-based foam reinforced with fiber was developed. [ABSTRACT FROM AUTHOR]

Many animals exhibit ontogenetic changes associated with adaptations for survival. Harp seals (Pagophilus groenlandicus) live in the Arctic and rely on thick insulation to maintain thermal homeostasis. Adult harp seals primarily use blubber for insulation, but newborn harp seals rely on a lanugo pelt while nursing, as their blubber layer develops and their first-year pelage grows. This study compared ontogenetic changes in the thermal properties of harp seal pelts in water and in air. Thermal conductivity, pelt thickness, and thermal resistance were measured in water for pelts of harp seal neonates (1 day old), thin whitecoats (4 day old), fat whitecoats (9 day old), ragged jackets (2 week old), beaters (3 week old), and adults and compared to previously published measurements made on the same pelts in air. Pelt conductivity was significantly higher in water than air for pre-molt and molting pups (P ≤ 0.031). Unlike adult pelage, which flattened underwater, lanugo hairs lifted underwater, a phenomenon that has not been reported previously. Thermal resistance of the pelt was significantly reduced in water compared to air for neonates and thin whitecoats (P ≤ 0.0001). A mathematical model of conductive heat transfer for an ellipsoid body showed volume-specific heat loss in water decreased and then stabilized as harp seals aged (P = 0.0321) and was significantly higher for neonates, thin whitecoats, and ragged jackets in water than in air (P ≤ 0.0089). Overall, pelt function is reduced in water for harp seal pups with lanugo, and this renders neonates and thin whitecoats particularly vulnerable to heat loss if submerged. [ABSTRACT FROM AUTHOR]

The way heat processes influence the structural elements of an electric motor is analyzed, and the factors determining the residual lifetime of the traction electric motor are revealed. A procedure for predicting the residual lifetime of induction traction electric motors based on the information on their heat state is presented. [ABSTRACT FROM AUTHOR]

Domestic refrigerators have become an indispensable part of the modern life. Since they are connected to the electric mains and operate throughout the day and year, they consume a lot of energy. Several experimental studies show that the addition of phase change material in the refrigerators at various locations improves the energy efficiency of the refrigerators. In this work, an experimental study was conducted to explore and reveal the improvement in energy efficiency of a small-scale refrigeration system when PCM was applied between the evaporator coil and the insulation. It was observed that the addition of PCM for a thickness of 0.03 m could reduce the heat ingress inside the evaporator by 15-19%. Moreover, the compressor ON cycle time and the temperature fluctuation inside the freezer cabinet were also relatively lesser. The per day energy consumption was reduced by 15.7-17.3% and the improvement in COP was found to be 17.4% with the addition of PCM. The refrigeration system was able to retain its desired temperature level for a period of 5 h even after the power supply was switched OFF. This idea of incorporating PCM between coil and insulation could be extended to household refrigerators so as to reduce the energy consumption. This would come handy in case of power outages which are very common in places having low grid reliability. [ABSTRACT FROM AUTHOR]