Performance of Thermal Insulation of Different Composite Walls and Roofs Materials Used for Energy Efficient Building Construction in Iraq

This study numerically involves the performance of thermal insulation of different types of composite walls and roofs to demonstrate the best model that can be used for energy-efficient building construction in Iraq.The mathematical model is solved by building its code using the Transmission Matrix Method in MATLAB software.The weather data of 21st July 2022 in Baghdad City/Iraq is selected as a test day.The wall types are selected:the first type consists of cement mortar,brick,and gypsum,the second type consists of cement mortar,brick,gypsum,and plaster and the third type consists of cement mortar,brick,gypsum,air cavity,and sheathing timber.The roof types are chosen:the first type consists of reinforced concrete,gypsum,and plaster,and the second type consists of the precast concrete flag,river sand,tar,reinforced concrete,gypsum,and plaster.The obtained solutions are compared with previous studies for the same city but with different types of walls and roofs.The findings display that the second and third types of walls reduce the entry heat flux by 4%and 10%as compared to the first type of wall.Also,the results indicate that the second type of roof reduces the entry heat flux by 21%as compared to the first type of roof.The results confirm that the best models of walls and roofs in Iraq are the third and second types,respectively,as compared to other models and hence,the performance of insulation material strongly depends on the materials used while building them.

Composite Panels from the Combination of Rice Husk and Wood Chips with a Natural Resin Based on Tannins Reinforced with Sugar Cane Molasses Intended for Building Insulation: Physico-Mechanical and Thermal Properties

The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.

Fiber Bragg grating monitors for thermal and stress of the composite insulators in transmission lines

Running composite insulators are prone to failure due to their harsh surrounding work environment, which directly affects the safe operation of transmission lines. This paper puts forward the method of using fiber Bragg grating(FBG) as the monitors to parameters correlated with thermal and stress of the composite insulators in transmission lines at working status. Firstly, monitoring points are found out by the mechanical test on composite insulator samples. Secondly, based on the monitoring theory, this paper introduces the feasibility design frame of the composite insulator with FBG implanted in the rod and the online monitor system. At last, it describes applications of this monitor system in the field of transmission lines.

Edge Detection of Composite Insulators Hydrophobic Image Based on Improved Canny Operator

The detection of hydrophobicity is an important way to evaluate the performance of composite insulators, which is helpful to the safe operation of composite insulators. Image processing technology is used to judge the hydrophobicity of composite insulators, which makes detection results more accurate and overcomes the subjective drawbacks of traditional detection methods.?As the traditional Canny operator requires manual intervention in selecting the variance of the Gaussian filter and the threshold, the paper presents a method of edge detection based on improved Canny operator. First, the adaptive median filter replaces the Gaussian filter, which can eliminate the impact from the variance of Gaussian filter and remove noise according to the characteristics of the image itself. Then the Ostu threshold method is used to select the best threshold automatically, which makes the edge detection be more continuous and reduce the presence of fake edges. The results show that the operator is applicable to all hydrophobic images.

Aging Characteristics and Influencing Factors of the Sheds of Composite Insulators in Karst Regions of China

In recent years,more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China.This type of special landform seems to have an adverse effect on the aging of the sheds of the line suspension composite insulators,which may lead to unexpected flashover and line tripping.In order to find out the particularity of the aging characteristics of insulators operating in the karst regions,samples in operation were selected from both the karst regions and the flatlands.Hydrophobicity,amount of surface contamination,and contaminant composition of the sheds were studied,then a comparison of performance between the two was made,and the possible influencing factors that cause such differences were discussed.The results show that the overall aging of the sheds of the composite insulators operating at the karst regions is more aggravated,which is caused by the combined influence of factors including the special topography,climate,and pollution in the area.The strong wind crossing the col will bring about the mutual scraping on the edges and stress concentration at the root of the sheds,leaving scratches and root cracks;the infiltration from these rupture of acid liquid,if any,will accelerate the aging and corroding of the internal silicone rubber material;moreover,the carbonates enriched on the surface of the sheds will gradually transform into more corrosive sulfates in an acidic environment,leading to further deterioration and chalking of the sheds of the insulators.The research work in this paper can provide guidance for the current operation and maintenance of composite insulators in the karst areas,as well as having important reference values for the layout design and insulation configuration of transmission lines to be built across karst landforms in the future.

Numerical Simulation of Contamination Accumulation Characteristics of Composite Insulators in Salt Fog Environment

To investigate the fouling characteristics of the composite insulator surface under the salt fog environment,the FXBW-110/120-2 composite insulator was taken as the research object.Based on the field-induced charge mechanism,the multi-physical field coupling software COMSOL was used to numerically simulate the fouling characteristics,explored the calculation method of ESDD,and demonstrated its rationality.Based on this method,the pollution characteristics of the composite insulator under the pollution fog environment were studied,and the influence of wind speed,droplet size,and voltage type on the pollution characteristics of the composite insulator was analyzed.The results showed that:with the increase in wind speed,the amount of accumulated pollution of insulator increases in the range of droplet size,and the relationship between wind speed and accumulated pollution is approximately linear;at the same wind speed,the amount of accumulated pollution increases with the increase of droplet size under the action of DC voltage;when there is no voltage,the amount of dirt on the upper surface of the insulator is more than that on the lower surface,while it is the opposite under DC voltage.

Shed Hydrophobic Cycloaliphatic Epoxy （S-HCEP）- a New Cost-efficient Housing Material for Composite Insulators

Araldite S-HCEP,a new cost-efficient alternative housing material for composite insulators is briefly presented.Main topics of this paper are the results of two new studies on this material:①UV-weathering resistance in terms of hydrophobicity,roughness increase,surface resistance and flexibility.②Leakage current behavior under salt fog conditions in comparison to other materials.

Fabrication and Thermal Insulating Properties of ITO/PVB Nanocomposites for Energy Saving Glass

Chemical co-precipitation method was used to synthesize tin-doped indium oxide（ITO）nanoparticles,and the subsequent solution co-blend was employed to fabricate ITO/PVB nanocomposites.UV（Ultra-violet）-Vis（Visible）-NIR（Near Infrared） spectra show that the addition of ITO nano particles can significantly enhance the thermal insulating efficiency of ITO/PVB nanocomposites.With increasing ITO content,the thermal insulating efficiency is increased.UV is almost fully absorbed by all ITO/PVB nanocomposites.Vis transmittance-haze spectra reveal that ITO/PVB nanocomposites exhibit higher Vis transmittance over 71.3%and lower haze below 2%when ITO content is in the range of 0.1 wt%-0.7 wt%.The UV-Vis-NIR spectroscopy shows that,under the premise of over 70%transmittance to the visible light,the screening effect of the NIR can be enhanced by 80%with 0.7%ITO/PVB nanocomposite membrane compared with the undoped PVB.The thermal insulating tests indicate that,in comparison with the pure PVB film,nanocomposite films with 0.1 wt%-0.9 wt%ITO can reduce temperature by 3-8 ℃.The results show that this novel nanocomposite can be used for energy-saving glass.

Fabrication and Thermal Insulating Properties of ATO/PVB Nanocomposites for Energy Saving Glass

The pechini method was used to synthesize antimony-doped tin oxide （ATO） nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the addition ofATO nano particles can significantly enhance the thermal insulating efficiency of ATO/PVB nanocomposites. With the increase of ATO content, the thermal insulating efficiency is increased. Uv is almost fully absorbed by all ATO/PVB nanocomposites. Vis transmittance-haze spectra reveal that ATO/ PVB nanocomposites exhibit higher Vis transmittance of over 72.7% and lower haze of below 2% when ATO content is in the range of 0.1 wt%-0.5 wt%. The thermal insulating tests indicate that in comparison with the pure PVB film, nanocomposite films with 0.1 wt%-0.5 wt% ATO can reduce temperature of 1-3 ℃, suggesting that this novel nanocomposite can be used for energy-saving glass.

Performance improvement of Fe-6.5Si soft magnetic composites with hybrid phosphate-silica insulation coatings

Fe-6.5Si soft magnetic composites(SMCs)with hybrid phosphate-silica insulation coatings have been designed to improve their comprehensive property via chemical coating combining sol-gel method in this work.The microstructure and magnetic performance of the Fe-6.5Si SMCs with hybrid phosphate-silica insulation coatings were investigated.The hybrid phosphate-silica coatings with high heat resistance and high withstand pressure,formed on the surface of the Fe-6.5Si ferromagnetic powders,were found stable in the composites.Compared with Fe-6.5Si SMCs coated by single phosphate or single silica,Fe-6.5Si SMCs with hybrid phosphate-silica show much higher permeability and lower core loss.The work provides a new way to optimize the magnetic performance of soft magnetic composites.

Surface Structure of Aged Composite Insulator Studied by Slow Positron Beam

Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.

Preparation and characterization of carbonyl iron soft magnetic composites with magnesioferrite insulating coating layer

Spherical carbonyl iron(Fe)powders were coated with magnesioferrite(MgFe2O4)insulating coating layer and then mixed with epoxy-modified silicone resin(ESR).Soft magnetic composites(SMCs)were fabricated by compaction of the coated powders and annealing treatment.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS)revealed that the MgFe2O4 layer was coated on the surface of the iron powders.The magnetic properties of SMCs were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials.The results showed that the SMCs prepared at 800 MPa and 550℃ exhibited a significant core loss of 167.5 W/kg at 100 kHz and 50 mT.

Experimental study on axial compressive behaviors of prefabricated composite thermal insulation walls after single-side fire exposure

The axial bearing capacity of prefabricated composite walls composed of inner and outer concrete wythes,expandable polystyrene(EPS)boards and steel sleeve connectors is investigated.An experimental study on the axial bearing capacity of four prefabricated composite walls after fire treatment is carried out.Two of the prefabricated composite walls are normal-temperature specimens,and the others are treated with fire.The damage modes and crack development are observed,and the axial bearing capacity,lateral deformation of the specimens,and the concrete and reinforcing bar strain are tested.The results show that the ultimate bearing capacity of specimens after a fire is less than that of normal-temperature specimens;when the insulation board thicknesses are 40 mm and 60 mm,the decrease amplitudes are 20.8%and 16.8%,respectively.The maximum lateral deformation of specimens after a fire is greater than that of normal-temperature specimens,and under the same level of load,the lateral deformation increases as the insulation board thickness increases.Moreover,the strain values of the concrete and reinforcing bars of specimens after a fire are greater than those of normal-temperature specimens,and the strain values increase as the thickness of insulation board increases.

Sodium Nitrate Passivation as a Novel Insulation Technology for Soft Magnetic Composites

Sodium nitrate passivation has been developed as a new insulation technology for the production of FeSiAl soft magnetic composites (SMCs). In this work, the evolution of coating layers grown at different pH values is investigated involving analyses on their composition and microstructure. An insulation coating obtained using an acidic NaNO_(3) solution is found to contain Fe2O_(3), SiO_(2), Al2O_(3), and AlO(OH). The Fe2O_(3) transforms into Fe3O4 with weakened oxidizability of the NO_(3)– at an elevated pH, whereas an alkaline NaNO_(3) solution leads to the production of Al2O_(3), AlO(OH), and SiO_(2). Such growth is explained from both thermodynamic and kinetic perspectives and is correlated to the soft magnetic properties of the FeSiAl SMCs. Under tuned passivation conditions, optimal performance with an effective permeability of 97.2 and a core loss of 296.4 mW∙cm−3 is achieved at 50 kHz and 100 mT.

A Study on Impervious and Heat-Insulating Performance of Geomembrane Composites Within Breakwater

This paper investigates the performance of geomembrane composites used as impervious and heat-insulating lining within a breakwater for a power station. The seepage field, distribution of stress-strain contour and seepage discharge of hot water which has been treated as the inner thermal source in the calculation of heat-insulation, have been given by three-dimensional calculation method coupling seepage with stress. The results indicate that the impervious and heat-insulation effect of geomembrane composites is significant.

The Origin of the Giant Hall Effect in Metal-Insulator Composites

Near the metal-insulator transition, the Hall coefficient R of metal-insulator composites (M-I composite) can be up to 104 times larger than that in the pure metal called Giant Hall effect. Applying the physical model for alloys with phase separation developed in [1] [2], we conclude that the Giant Hall effect is caused by an electron transfer away from the metallic phase to the insulating phase occupying surface states. These surface states are the reason for the granular structure typical for M-I composites. This electron transfer can be described by [1] [2], provided that long-range diffusion does not happen during film production (n is the electron density in the phase A. uA and uB are the volume fractions of the phase A (metallic phase) and phase B (insulator phase). β is a measure for the average potential difference between the phases A and B). A formula for calculation of R of composites is derived and applied to experimental data of granular Cu1-y(SiO2)y and Ni1-y(SiO2)y films.

Application of Mullite Composite Lining Plates in Rotary Coke Tanks for Coke Dry Quenching Equipment

To reduce the burning loss and the spalling and to improve energy efficiency,the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment.The results show that:the dense mullite composite lining plate in the cone part has the density of 2.20 g·cm^(-3) and the wear test,s volume loss of 4.08 cm^(3),and the light weight mullite composite lining plate in the straight cylinder part has the density of 1.95 g·cm^(-3) and the wear test,s volume loss of 17.6 cm^(3).After using,there is no shrinkage gap,no burn loss or holes in the plates,indicating good sealing of the mullite composite lining plates.The lining plate for the cone part has low burning loss,without spalling for more than half a year.The outer surface temperature of coke tanks adopting the cast steel or the alloy lining is 480 to 570℃,while that of the ones adopting mullite composite lining plates is 120 to 170℃,showing a largely improved insulating property.Adopting mullite composite lining plates on the basis of the current coke tank cage,the lining plates can be timely treated and wholly replaced,improving the service life and reducing the maintenance workload.

Preparation and Characterization of Alumina-coated Hollow Quartz Fiber Reinforced Al_(2)O_(3)-SiO_(2) Aerogel Composite

Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.

Hollow glass microspheres/silicone rubber composite materials toward materials for high performance deep in-situ temperaturepreserved coring

Deep petroleum resources are stored under high temperature and pressure conditions,with the temperature having a significant influence on the properties of rocks.Deep in-situ temperature-preserved coring(ITP-coring)devices were developed to assess deep petroleum reserves accurately.Herein,hollow glass microspheres(HGMs)/silicone rubber(SR)composites that exhibit excellent thermal insulation properties were prepared as thermal insulation materials for deep ITP-coring devices.The mechanism and process of heat transfer in the composites were explored,as well as their other properties.The results show that the HGMs exhibit good compatibility with the SR matrix.When the volume fraction of the HGMs is increased to 50%,the density of the HGMs/SR composites is reduced from 0.97 to 0.56 g/cm^(3).The HGMs filler introduces large voids into the composites,reducing their thermal conductivity to 0.11 W/m·K.The addition of HGMs into the composites further enhances the thermal stability of the SR,wherein the higher the HGMs filler content,the better the thermal stability of the composites.HGMs significantly enhance the mechanical strength of the SR.HGMs increase the compressive strength of the composites by 828%and the tensile strength by 164%.Overall,HGMs improve the thermal insulation,pressure resistance,and thermal stability of HGMs/SR composites.