Heat Insulation Applications Research Articles

Synthesis, Activation, and Characterization of Carbon Fiber Precursor Derived from Jute Fiber.

Activated carbon (AC) fiber is a carbonaceous material with a porous structure that has a tremendous scope of application in different fields. Conventionally, AC is derived from fossil fuel-based raw materials like polyacrylonitrile (PAN) and pitch. In this work, AC was synthesized from eco-friendly, renewable, and ubiquitous jute fiber. Systematically, the jute fiber was washed and pretreated with NaOH. Raw jute and NaOH-treated jute were carbonized/pyrolyzed at 500 °C for 1 h in presence of N2 gas. The carbonized carbon was activated with H3PO4 and KOH and again pyrolyzed at 650 °C for 1.5 h maintaining the inert condition. The different features of activated carbons were characterized with field emission-scanning electron microscope, energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis. The average yield of carbonized and activated carbons was recorded at 19 and 13.8%, respectively. The scanning electron microscopic images confirmed a honeycomb-like porous structure. It was observed that KOH-activated carbon exhibited a more porous structure than the H3PO4-activated carbons. The average pore diameter of activated carbons was noted to be 1.3 μm. The pore density was higher in case of KOH-activated carbons accounting for 2.15 pore/μm. The EDX analysis showed that H3PO4-activated carbons had more than 90% carbon atoms indicating a significant carbon content. The TEM images revealed that AC particles were in the nanoscale range. The average particle sizes of H3PO4-activated carbon and KOH-activated carbon were 36.38 and 32.8 nm, respectively. The XRD study demonstrated the highly disordered and low level of crystallinity of AC. It was detected that the AC showed much higher thermal resistance than the jute fiber. The H3PO4-activated carbon obtained from NaOH-treated jute remained at 84% even after 500 °C. A higher thermal resistance was achieved with H3PO4-activated carbon since it contains 0.56% phosphorus, which was confirmed by EDX investigation. It was found that a higher carbon yield was obtained from NaOH-treated jute. The porous structure of the material showed that it could be used as an adsorbent. Due to its high thermal stability, it is recommended for flame retardants and heat insulation applications as well.

Prediction of thermal conductivity for polyimide nanofiber aerogel based on three 3D FEM models

Polyimide (PI) nanofibrous aerogels (NFAs) have garnered significant attention for their exceptional mechanical and thermal properties, making them promising materials for heat insulation applications. However, there is a lack of comprehensive research on heat transfer of PI NFAs on the modeling and prediction. Therefore, three modified unit cells with the features of PI NFA backbone were constructed for the finite element simulation. Subsequently, the comparisons of our results with experimental data from available literature were conducted. It indicated that the cubic unit cell fitted well with the experimental values when the density was lower than [Formula: see text], while the Weaire–Phelan unit cell demonstrated good agreement when the density was higher than [Formula: see text]. A series of parametric studies were performed and indicated that the thermal conductivity is proportional to the nanofiber diameter, whereas inversely proportional to the pore size and porosity. Our research will provide novel insights to the selection of parameters for industrial manufacturing of thermal insulation materials in aerospace, energy, protection, etc.

Development of ultralight, tough and hydrophobic polymethylmethacrylate/polyvinylidene fluoride shape memory foams for heat insulation applications

Thermal insulation is vital for achieving efficient thermal management, energy conservation, and emission reduction. However, the existing polymer foams still have some performance limitations and cannot meet the application demands in a wider range of situations. Accordingly, herein, an innovative strategy based on polyvinylidene fluoride (PVDF) melt blending and CO2 microcellular foaming was proposed for the fabrication of lightweight high-performance polymethylmethacrylate (PMMA) foams for heat insulation, and ultralight, tough, and hydrophobic foams with outstanding heat insulation and shape memory performances were successfully prepared. Because of the plasticization of PVDF and nucleation of PVDF microcrystals, the foaming temperature window of PMMA substantially descended, and the cellular structure of PMMA became refined. Blend foams with expansion ratios of 36.2, cell sizes of 15.8 μm, and foam densities of 0.0357 g∙cm−3 were obtained at 130 °C. Due to higher porosity and strong infrared absorption ability of PMMA, the resulting foams exhibited thermal conductivities of less than 32 mW∙m−1∙K−1. Owing to the hydrophobicity and incombustibility of PVDF and its microcrystals, the blend foams demonstrated better hydrophobicities, shape memory properties, and flame retardancies. This study provides an effective way for the green and mass production of high-performance polymer foams with appropriate thermal insulation performances.

Design of Economical and Achievable Aluminum Carbon Composite Aerogel for Efficient Thermal Protection of Aerospace.

Insulation materials play an extremely important role in the thermal protection of aerospace vehicles. Here, aluminum carbon aerogels (AlCAs) are designed for the thermal protection of aerospace. Taking AlCA with a carbonization temperature of 800 °C (AlCA–800) as an example, scanning electron microscopy (SEM) images show an integrated three-dimensional porous frame structure in AlCA–800. In addition, the thermogravimetric test (TGA) reveals that the weight loss of AlCA–800 is only ca. 10%, confirming its desirable thermal stability. Moreover, the thermal conductivity of AlCA–800 ranges from 0.018 W m−1 K−1 to 0.041 W m−1 K−1, revealing an enormous potential for heat insulation applications. In addition, ANSYS numerical simulations are carried out on a composite structure to forecast the thermal protection ability of AlCA–800 acting as a thermal protection layer. The results uncover that the thermal protective performance of the AlCA–800 layer is outstanding, causing a 1185 K temperature drop of the structure surface that is exposed to a heat environment for ten minutes. Briefly, this work unveils a rational fabrication of the aluminum carbon composite aerogel and paves a new way for the efficient thermal protection materials of aerospace via the simple and economical design of the aluminum carbon aerogels under the guidance of ANSYS numerical simulation.

Reduced Graphene Oxide/MXene Composite Foam with Multilayer Structure for Electromagnetic Interference Shielding and Heat Insulation Applications

The electromagnetic interference (EMI) shielding performance of reduced graphene oxide (rGO) foam is restricted to its poor conductivity and macro‐monotonic structure. In this work, highly conductive MXene nanosheets are introduced into graphene oxide (GO) solution and multilayer structures were designed to improve the EMI shielding performance of graphene foam. The multilayer rGO/MXene composite foam shows an excellent EMI shielding effectiveness of more than ≈28 dB in C and ≈35 dB in X band. Meanwhile, it reveals an outstanding heat insulation performance equaling to air (0.025 W m−1 K). The macro multilayer and microporous structure plays a prominent role in the EMI shielding and heat insulation performance. This work provides valuable ideas for designing multifunctional EMI shielding materials for the next generation of smart electronic devices.

Experimental investigation of heat conduction characteristics of density-layered stone wool materials

This work presents an experimental study to investigate the heat conduction coefficient of the density-layered stone wool plates insulation materials used in heat insulation applications. The stone wools, which have 70, 100, and 150 kg/m3 of densities, have been combined in different thicknesses to 60 mm. The aim of this layer combination is to benefit from lower heat conductivity and lightness of the lower density stone wools and the better strength of higher density stone wools. First, the single-layer stone wools with 60 mm of thickness, which is in the insulation market, have been tested. Then, they have been combined in different thicknesses, with a total thickness of 60 mm. A total of 18 samples have been produced, and the thermal conductivity of samples has been measured experimentally. Consequently, the heat conduction coefficient of density-layered stone wools and their weights have been compared experimentally. At the end of the present study, it is observed that density-layered stone wool plates play a critical role in improving the heat conductivity and lowering the weight of high-density plates. When combining 10 mm thick 150 kg/m3 density stone wool with 50 mm thick 70 kg/m3 density stone wool, the heat conductivity has been improved by 3.52% and the weight of the 1 m2 plate has reduced by 4 kg (44%) according to the stone wool with 150 kg/m3 of density.

Reduced Graphene Oxide/Mxene Composite Foam with Multilayer Structure for Electromagnetic Interference Shielding and Heat Insulation Applications

The electromagnetic interference (EMI) shielding performance of reduce graphene oxide (rGO) foam was restricted to its poor conductivity and macro monotonic structure. In this work, highly conductive MXene nanosheets were introduced into graphene oxide solution and multilayer structures were designed to improve the EMI shielding performance of graphene foam. The multilayer reduced graphene oxide/MXene composite foam shows an excellent EMI shielding effectiveness of more than ~28 dB in C and ~35 dB in X band. Meanwhile, it reveals an outstanding heat insulation performance equaling to air (0.025 W/m·K). The macro multilayer and microporous structure play a prominent role in the EMI shielding and heat insulation performance. This work provides valuable ideas for designing multifunctional EMI shielding materials for the next generation of smart electronic devices.

High strength glass foams recycled from LCD waste screens for insulation application

This paper has reported a sustainable way of producing high strength glass foam using scrap LCD panel of TVs as the glass source and manganese dioxide from scrap alkaline battery and sodium carbonate as foaming agents, respectively. This work demonstrates the feasibility of producing foamed ceramic from the waste alumino-borosilicate glass with a compressive strength ranging from 28.7 to 8.7 MPa and an apparent density of 1.86–0.76 g/cm3. The prepared foamed ceramic has a high compressive strength of 18.7 MPa, the high flexural strength of 6 MPa, the thermal conductivity of 0.22 W/m‧K at the low density of 0.85 g/cm3. The demonstrated method has proposed a promising procedure for transforming -ewaste resources into a ceramic product for heat insulation applications.

Isı Yalıtım Sektöründe Maliyet Muhasebesi Uygulaması ve Bir Alan Çalışması

The rapid consumption of energy resources has shown the necessity to use energy in an efficient way. The fact that energy saving can be achieved in the buildings with heat insulation applications makes the production of heat insulation materials important. This study was conducted to evaluate the cost system of the enterprise by providing information about theproduction process and costs of XPS heat insulation boards. This study was carried out in a company which produces Extruded Polystyrene Foam (XPS) thermal insulation board in Kahramanmaras.The production process of the XPS heat insulation board has been tried to be observed in detail and also information has been obtained with the authorized persons. In addition, people in the accounting department were been interviewed and the current cost system was examined. Also the cost system applied in the enterprise and the practices carried out were examined and some shortcomings were identified and suggestions were made to eliminate these deficiencies.

Heat and sound insulation applications of pineapple aerogels from pineapple waste

Given the harmful effects of agricultural waste residues on the environment and the abundance of pineapple byproducts after harvest, converting pineapple waste into a high-engineering value product for practical applications is one of the solutions toward sustainable development in developing countries. For the first time, flexible cellulose aerogels from raw pineapple-leave fibers (PALF) are developed successfully by using an adhesive agent, polyvinyl alcohol (PVA), and deionized (DI) water as a solvent, followed by a freeze-drying process. The effects of the pineapple fiber (PF) concentration on the heat and acoustic insulation properties are also investigated. The PF aerogels show high porosities of nearly 99%, ultra-low densities of (0.013–0.033) g/cm3, and a microporous structure which are determined by FE-SEM, BET and XRD analysis. They have very low thermal conductivities of (0.030–0.034) W/mK, indicating their excellent suitability for heat insulation applications. Indeed, the thermal jacket using a PF aerogel as filler wrapped around a water bottle can maintain the water temperature below 0 °C for 6 h (initial temperature of −3 °C), and above 40 °C for 2.5 h (initial temperature of 90 °C). The heat insulation capacity of the thermal jacket is about three times better than that of a commercially available product. With the same thickness, the noise reduction coefficient of 2.0 wt% PF aerogel samples is greater than that of a commercial absorber Basmel, which demonstrates their potential in acoustic insulation applications.

Cellulose-based aerogels from sugarcane bagasse for oil spill-cleaning and heat insulation applications

A promising and economic material for various applications, such as thermal insulation in construction building and oil clean-up in marine ecosystems, is successfully developed from the by-product of the sugarcane industry. Biodegradable sugarcane bagasse aerogels are produced using polyvinyl alcohol (PVA) binder, followed by a freeze-drying method. This environmental-friendly recycled aerogel has an ultra-low density ([0.016-0.112] g/cm3), a high porosity ([91.9–98.9]%), and a very low thermal conductivity ([0.031-0.042] W/mK). Its superhydrophobicity properties and its maximum oil absorption capacity (up to 25 g/g) are measured after coating aerogel samples with methyltrimethoxysilane (MTMS). The biodegradable aerogel has a Young's modulus of 88 K Pa and can be bent without breaking, demonstrating its high flexibility.

Toward transparent composite films with selective solar spectral, flame retardant and thermal insulation functions

Optical films with high visible (vis) wavelength transparency as well as high ultraviolet (UV) light/high-energy visible (HEV) light/near-infrared (NIR) blocking properties are desired for applications as glass films in building/automotive, and protective films for color printing or culture relics. Herein, the above multi-functions were achieved by preparing the PVC with plasticizer, UV absorbers, pigment yellow and NIR blockers. The prepared transparent films keep high transmittance in visible region (74.53%) and low transmittance in UV region (0.35%), HEV region (52.80%) and NIR region (28.11%). Meanwhile, the flame retardancy was considerably high as verified by its high limiting oxygen index (LOI) value (31%). Moreover, a decrease of about 14.1 °C can also be observed in temperature test using a solar simulator, indicating their outstanding heat insulation/cooling properties. No loss in mechanical performance was observed with the addition of functional additives. All these suggest the potential of using PVC films for outdoor heat-insulation applications.

Synthesis and applications of MANs/poly(MMA-co-BA) nanocomposite latex by miniemulsion polymerization.

We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)–poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure. Owing to the uniformity and hydrophobicity of MANs, the MANs-embedded PMB latex nanocomposite can be tailored more precisely than other nanoparticles-embedded nanocomposites. Films incorporating 10 wt% of MANs in the MAN/PMB latex nanocomposite exhibit good transmittance in the visible region, and excellent opacity in the near infrared region. The MANs/PMB nanocomposite film also appears suitable for heat insulation applications.

The Production of Thermal Insulation by Waste Animal and Vegetable Fibres

World energy consumption refers to the total energy used by all of human civilization. Since the heating costs in winter, the cooling costs in summer are very high in Turkey, insulation is made to the buildings to reduce these costs. A great part of the raw materials of insulation materials have been imported. Rapid increase in the population, developments in the technology everyday bring rapid consumption of energy resources with them. Today, the energy consumption has reached serious proportions and precautions have already been started to be taken all over the world. Most of the energy in Turkey is spent in industry and in housings. Energy savings potential is available up to annual $ 7.5 billion by the dissemination of heat insulation applications in Turkey. Energy efficiency should be supported in buildings via heat insulation in order to prompt this potential. In the present study, animal and vegetable fibre doped insulation material has been produced at specified rates. Set out in the findings, research materials waste animal and vegitables fibers shows that it is possible to produce insulation materials enough to mix it with plaster. The thermal insulation coefficient of the obtained samples conforms to the TS EN standards

Development of Thermal Insulation for Textile Wet Processing Machinery Using Needlepunched Nonwoven Fabrics

In textile manufacturing, many fiber manufacturing, dyeing and finishing processes require temperatures in the range of 100oC to 200oC. A substantial amount of energy is needed to produce the desired temperature, and part of this energy is wasted when heat from the process escapes to the environment. Many of the processes are batch processes requiring frequent reheating and restarting. Most process equipment is constructed from stainless steel, which is a good conductor of heat. In addition to this, because of the cost involved in installation and regular maintenance of insulation, many manufacturers do not insulate their process equipment. The heat and moisture loss to the environment makes the manufacturing facilities environmentally uncomfortable for employees. This reduces their productivity and is a health risk. Due to the energy wasted in the textile wet processing industry, there is a need to develop suitable insulating materials specifically for these applications. For commercial applications, both the cost of the insulating material as well as its effectiveness, ease of installation and durability are important. Needlepunched fabrics have the potential to meet these demands [1]. Since low density needled felts with good heat blocking capacity can be made from durable fibers, they are ideal for heat insulation applications [1,2]. This research focuses on identifying suitable fibers and the manufacturing technology which will yield the desired results. After testing of prepared samples, the data was analyzed to determine the fabric and fiber parameters which influence heat transfer. An economic analysis was also conducted to optimize both cost and effectiveness. The important factors contributing to the transfer of heat through needlepunched nonwoven fabrics were found to be the bulk density of the batt and the surface area of the fibers. Incorporation of low denier fibers (meltblown web) in the needlepunched structure led to a significant decrease in the apparent thermal conductivity of the batt. A cost analysis of this insulation (incorporating the meltblown web) determined the optimum thickness of such an insulation to be 10.1 mm.