Insulation Construction Research Articles

Date palm wood-derived cellulose aerogel dissolved in ionic liquids as a green thermal insulation construction material

Heat insulation materials used in the construction industry are essential for energy conservation. Nonetheless, the majority of current commercial heat insulators are fossil-fuel derived materials; thus, it is vital to provide sustainable, biodegradable, and environmentally friendly alternatives. In this work, an innovative method for producing cellulose II aerogels extracted from date palm waste and from microcrystalline lab-grade cellulose, targeting thermal insulation applications in the construction industry was introduced. A key aspect of the investigated approach is the use of a co-solvent system that combines 1-butyl-3-methylimidazolium chloride (Bmim)Cl and dimethylformamide (DMF), chosen for its efficiency in dissolving cellulose. The cellulose (at 3, 5, 7, and 9 wt%) was dissolved in a co-solvent system of 70 wt% (Bmim)Cl ionic liquid and 30 wt% DMF, saving costs associated with using purely ionic liquid solvents. The prepared aerogels exhibited low thermal conductivity (0.033–0.065 W/m⋅K), low densities (0.08–0.15 g/cm3), high porosity (89.85–94.69 %) and good thermal diffusivity (0.06–0.022 mm2/s). Furthermore, the developed insulators required a compressive strength of 75 kPa to reach 50 % strain and exhibited a sound absorption coefficient of 0.9. Structural characterization of the materials, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis, highlights the prospect of cellulose extracted from date palm wood in aerogel preparation and the potential for the (Bmim)Cl/DMF co-solvent system in dissolving cellulose.

Subwavelength acoustic topology frequency band regulation based on symmetric site-space folded resonant cavities

Acoustic topological insulators, as a type of acoustic metamaterial, possess special acoustic wave manipulation capabilities. However, an acoustic topological insulator based on Bragg scattering requires its lattice constant to be equivalent to the wavelength. This means that constructing acoustic topological insulators efficiently in the low-frequency range is a challenge. To this end, this paper proposes a method to construct sub-wavelength acoustic topological insulators by adding spatially folded resonant cavities at symmetric locations. It can easily reduce unidirectional transmission frequency bands with topological protection to subwavelength scales. On this basis, it is even possible to realize effective control of the unidirectional transmission band over a great range by adjusting the length parameter of the folded resonant cavity. The control range can reach more than 4000Hz. Experimental results from finite element simulations further verify that this approach does not affect the topologically protected edge states and the topologically unidirectional acoustic transmission properties. This work provides a method for the construction of low-frequency acoustic topological insulators, as well as an efficient method for the accurate regulation of unidirectional transmission frequency bands over a wide range of frequencies.

Developing fired clay bricks by incorporating scrap incinerated waste and river dredged sediment

The global extraction of several billions of clean clay resources, which destroy millions square meters of land, is triggering environmental problems. Incorporating different dosages of incinerated waste or dredged sediment in bricks production has been studied by many researchers. Research articulating the combined effect of incinerated waste material (IWM) and river dredged sediments (RDS) addition on the performance of bricks is scarce. This paper aims to present findings on the engineering performance of fired bricks developed with the addition of IWM and RDS. In this regard, bricks were made with 5 wt% IWM and different dosages of RDS (i.e., 0 – 15 wt%). Physical, durability, mechanical, thermal and microstructure of the developed bricks is examined. Bricks’ shrinkages were found meeting quality performance criterion in the 1.42 – 4.11% range. The highest bulk density of 1.85 g/cm3 permit to classify bricks obtained as lightweight. Water absorptions were mostly within the acceptable 20% tolerance level postulating the developed bricks high durability standard. Compressive strength reductions, which were confined within 5.28 and 21.57 MPa, showed the developed bricks applicability to structural weight-supporting construction as well as specialized engineering construction works. The 40.5% thermal conductivity reduction in WB15 bricks (at 800 °C) theorized its suitability for thermal insulation construction. Mineralogical and morphological analyses of fired bricks clearly showed kaolinite polymorphic phase transformation, which contributed to the different morphologies in the brick matrices. Consequently, reuse of IWM and RDS offered a chance to advance sustainable use of scarce clay resources in lightweight and thermal insulation brick production.

Observation of nonlinear disclination states

Introduction of controllable deformations into periodic materials that lead to disclinations in their structure opens novel routes for construction of higher-order topological insulators hosting topological states at disclinations. Appearance of these topological states is consistent with the bulk-disclination correspondence principle, and is due to the filling anomaly that results in fractional charges to the boundary unit cells. So far, topological disclination states were observed only in the linear regime, while the interplay between nonlinearity and topology in the systems with disclinations has been never studied experimentally. We report here on the experimental observation of the nonlinear photonic disclination states in waveguide arrays with pentagonal or heptagonal disclination cores inscribed in transparent optical medium using the fs-laser writing technique. The transition between nontopological and topological phases in such structures is controlled by the Kekulé distortion coefficient r with topological phase hosting simultaneously disclination states at the inner disclination core and spatially separated from them corner-I, corner-II, and extended edge states at the outer edge of the structure. We show that the robust nonlinear disclination states bifurcate from their linear counterparts and that location of their propagation constants in the gap and, hence, their spatial localization can be controlled by their power. Nonlinear disclination states can be efficiently excited by Gaussian input beams, but only if they are focused into the waveguides belonging to the disclination core, where such topological states reside. Our results open new prospects for investigation of nonlinear effects in topological systems with disclinations and are relevant for different areas of science, including Bose-Einstein and polariton condensates, where potentials with the disclinations can be created.

Waste corn husk fibers for sound absorption and thermal insulation applications: A step towards sustainable buildings

In the last decade, noise pollution and global warming and their effects on human health and the environment have received much attention. Building sectors are one of the most important areas for potential improvements. To this end, sound-absorbing and thermal insulation construction materials are being used effectively. Recently, a great deal of interest has arisen in using various natural fibers as sound-absorbing and/or thermal insulation materials. In line with these studies, this work investigates the acoustic absorption and thermal insulation characteristics of corn husk fiber (CHF). The results showed that the samples enjoy excellent noise reduction coefficients of 0.36–60 and effective thermal conductivities of 0.038–0.042 W/mK. It was found that the thermal insulation properties of CHFs are not significantly influenced by the moisture content. The Dunn and Davern (DD) model and a modified model of DD based on the Nelder-Mead simplex algorithm were also used to predict the acoustic behavior of the samples. It was found that the proposed model provides very excellent prediction accuracy.

Hyperbolic band topology with non-trivial second Chern numbers

Topological band theory establishes a standardized framework for classifying different types of topological matters. Recent investigations have shown that hyperbolic lattices in non-Euclidean space can also be characterized by hyperbolic Bloch theorem. This theory promotes the investigation of hyperbolic band topology, where hyperbolic topological band insulators protected by first Chern numbers have been proposed. Here, we report a new finding on the construction of hyperbolic topological band insulators with a vanished first Chern number but a non-trivial second Chern number. Our model possesses the non-abelian translational symmetry of {8,8} hyperbolic tiling. By engineering intercell couplings and onsite potentials of sublattices in each unit cell, the non-trivial bandgaps with quantized second Chern numbers can appear. In experiments, we fabricate two types of finite hyperbolic circuit networks with periodic boundary conditions and partially open boundary conditions to detect hyperbolic topological band insulators. Our work suggests a new way to engineer hyperbolic topological states with higher-order topological invariants.

Simulation and Optimization of Insulation Wall Corner Construction for Ultra-Low Energy Buildings

Approximately 40% of the overall energy consumption of society is consumed by buildings. Most building energy usage is due to poor envelope performance. In regions with cold winters, the corners of structures typically have the lowest interior surface temperature. In corners, condensation, frost, and mold are common. This has a substantial effect on building energy usage and residents’ comfort. In this study, the heat loss of corner envelopes is evaluated, and a suitable insulation construction of wall corners is constructed to increase the surface temperature of the envelope interior. Computational Fluid Dynamics simulation has been used to examine the heat transmission in a corner of an ultra-low energy building in this study. By comparing the indoor surface temperature to the soil temperature beneath the building, the insulation construction of wall corners has been tuned. The study results indicate that the planned insulation construction of wall corners can enhance the internal surface temperature in the corner and the soil temperature under the structure by approximately 8.5 °C, thereby decreasing the indoor–outdoor temperature differential and the heat transfer at ground level. In extremely cold places, the insulation horizontal extension belt installation can help prevent the earth beneath the building from freezing throughout the winter.

Barrier effect of insulation against harmful chemical substances according to the wall surface construction of layered building materials

Energy consumption by buildings can be reduced by increasing thermal efficiency by improving insulation. Phenolic foams (PFs) are stable and economical insulation materials with low thermal conductivity. However, chemical-containing building materials can pollute indoor air in residential spaces. Indoor air quality, related to PF construction in interior walls, was investigated using discharge chamber tests and a test bed simulating construction. Concentration changes of harmful chemicals following insulation construction in the test bed and empirical research results can guide legal management standards for indoor air quality in terms of insulation materials and the effective construction of insulation materials.

Optimization of regenerator operating parameters and thermal insulation construction for rotary regenerative thermal oxidizer (r-RTO) based on thermal-fluid coupling method and quadratic regression model

Rotary regenerative oxidiser ( r -RTO), an effective VOCs treatment equipment, needs to be operated for a long time under actual working conditions, resulting in excessive temperatures on the outer wall of the r -RTO furnace, which causes production accidents. In order to avoid production accidents, the heat transfer process of airflow inside r -RTO regenerator should be clarified. Computational Fluid Dynamics (CFD) method is applied to analyse the temperature and pressure distribution in r -RTO regenerator. The temperature distribution of regenerator is analysed in order to find the main thermal dissipation path based on thermal-fluid coupling method. In temperature distribution, the outlet temperature T outlet is decreased with the increase of regenerator height h . However, T outlet is increased with the increase of gas flow rate v gas pore size D p , respectively. In pressure distribution, the pressure drop P drop is increased with the increase of h and v gas . However, P drop is decreased with the increase of D p . The results of the temperature distribution analysis are shown that the main pathway for thermal dissipation is along the partition dividers to insulation material where thermal dissipated through the insulation material. Quadratic regression method is used to design multivariate simulation experiments. Genetic algorithm is used to find optimal operating parameters. In addition, partition divider material and thermal insulation thickness are used as optimization parameters to optimize the thermal insulation construction. The present study reveals that thermal-fluid coupling method and quadratic regression method are satisfactory for the optimization of regenerator operating parameters and thermal insulation construction for r -RTO regenerator.

Real-space construction of crystalline topological superconductors and insulators in 2D interacting fermionic systems

The construction and classification of crystalline symmetry protected topological (SPT) phases in interacting bosonic and fermionic systems have been intensively studied in the past few years. Crystalline SPT phases are not only of conceptual importance, but also provide great opportunities towards experimental realization since space group symmetries naturally exist for any realistic material. In this paper, we systematically classify the crystalline topological superconductors (TSC) and topological insulators (TI) in 2D interacting fermionic systems by using an explicit real-space construction. In particular, we discover an intriguing fermionic crystalline topological superconductor that can only be realized in interacting fermionic systems (i.e., not in free-fermion or bosonic SPT systems). Moreover, we also verify the recently conjectured crystalline equivalence principle for generic 2D interacting fermionic systems.

Discussion on Key Technical Points of Exterior Wall Insulation Construction of High-rise Building

Discussion on Key Technical Points of Exterior Wall Insulation Construction of High-rise Building

Mechanical Properties of Lightweight Cementitious Cellular Composites Incorporating Micro-Encapsulated Phase Change Material.

This work focuses on combining digitally architected cellular structures with cementitious mortar incorporating micro-encapsulated phase change material (mPCM) to fabricated lightweight cementitious cellular composites (LCCCs). Voronoi structures with different randomness are designed for the LCCCs. Aided by the indirect 3D printing technique, the LCCCs were prepared with a reference mortar (REF) and a mortar incorporating mPCM. The compressive behavior of the LCCCs was studied at the age of 28 days, by experimental and numerical methods. It was found that the highly randomized Voronoi structure and the mPCM have minor negative influence on the compressive properties of the LCCCs. The mPCM incorporated LCCCs have high relative compressive strength compared to conventional foam concrete. Furthermore, the critical role of air voids defects on the compressive behavior was identified. The highly randomized porous Voronoi structure, high mPCM content and good compressive strength ensure the LCCCs’ great potential as a novel thermal insulation construction material.

Thermal performance assessment of cold chain chamber with vacuum insulation panel envelope layer

As one of the super thermal adiabatic materials nowadays, Vacuum Insulation Panel has slim thermal conductivity, which can be no more than 0.0040 W/(m·K) at an internal pressure of less than 10Pa. the excellent thermal performance makes it prosperous in cold chin experiments. Actually, Vacuum Insulation Panel is normally installed with other insulation materials as multilayer envelope in practice. However, influenced by the fluctuation of environmental factors and the difference of thermal & physical properties of materials, the overall thermal performance of multilayer insulation systems with Vacuum Insulation Panel different arrangement sequences is significantly various. A reasonable Vacuum Insulation Panel location plays an important role on the thermal performance. In this paper, the thermal insulation performance of multilayer under unsteady state condition was studied. Three chambers, with the same exterior size, that is, 300 × 300 × 300 mm3, were employed for the innovation purpose. The multi-layer insulation construction involves a 10 mm layer of Vacuum Insulation Panels and a 10 mm layer of polyurethane. And three different envelope structures, namely, internal insulation, sandwich insulation and external insulation were built according to the Vacuum Insulation Panel's location. The numerical heat transfer model and physical model were established. The simulative and experimental results were comprised and analyzed. The results implied that, to maintain the constant temperature in cold\hot chamber, the vacuum insulation panels are located on the face of temperature fluctuation side, i.e. the ambient side, and have a better overall insulation performance.

Promotion and suppression of single-molecule conductance by quantum interference in macrocyclic circuits

Promotion and suppression of single-molecule conductance by quantum interference in macrocyclic circuits

Hazard evaluation of indoor environment based on long-term pollutant emission characteristics of building insulation materials: An empirical study

Insulation materials are essential components in construction, and their main objective is to increase the efficiency of thermal energy by minimizing internal and external thermal exchange. Accordingly, research and development studies are being actively conducted to increase the thermal resistance of insulation materials, and high-performance insulation materials that use organic chemicals have been developed after industrialization. However, thermal insulation comprising chemicals poses a potential risk of pollutant emissions and can cause health problems. In this study, five types of insulation materials and the contaminants generated from the building materials used in insulation construction were quantitatively analyzed. In addition, an empirical study on the discharge of pollutants was conducted using a test bed, and the effects of the pollutants discharged from the insulation material on the indoor environment were examined by analyzing the pollutant concentration for 90 days. In addition, we analyzed the effect of an insulation material on an indoor environment through the standard specifications. Moreover, the necessity of legal management of the emission of contaminants from insulation materials was proposed based on the empirical research results.

ОЦІНКА ЕФЕКТИВНОСТІ ЕКСПЕРИМЕНТАЛЬНИХ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ СХЕМ ТЕПЛО- ТА ЗВУКОІЗОЛЯЦІЇ БУДИНКІВ

This work is devoted to solving an important issue regarding the sound insulation of floors in residential buildings, namely from impact noise. The article considers the structural and technological schemes of floor sound insulation of three types, using different materials to achieve regulatory requirements for sound insulation from impact noise. Field tests were conducted in the building under construction. The technology of execution of each type of a floor, and in the future and comfort of inhabitants of the apartment will depend on the chosen constructive-technological scheme. Comparison of structural and technological schemes in the future will allow to investigate and develop a modern and highly effective structural and technological scheme of sound insulation of the floor. It was determined that the most effective structural and technological solution for the construction of sound insulation of the floor, and one that meets regulatory requirements, is the design - Type 1, based on materials "Izolkap Fine" and "Akuflex".

Systematic construction of square-root topological insulators and superconductors

We propose a general scheme to construct a Hamiltonian $H_{\text{root}}$ describing a square root of an original Hamiltonian $H_{\text{original}}$ based on the graph theory. The square-root Hamiltonian is defined on the subdivided graph of the original graph of $H_{\text{original}}$, where the subdivided graph is obtained by putting one vertex on each link in the original graph. When $H_{\text{original}}$ describes a topological system, there emerge in-gap edge states at non-zero energy in the spectrum of $H_{\text{root}}$, which are the inherence of the topological edge states at zero energy in $H_{\text{original}}$. In this case, $H_{\text{root}}$ describes a square-root topological insulator or superconductor. Typical examples are square roots of the Su-Schrieffer-Heeger (SSH) model, the Kitaev topological superconductor model and the Haldane model. Our scheme is also applicable to non-Hermitian topological systems, where we study an example of a nonreciprocal non-Hermitian SSH model.

Foams based on industrial waste

Substantial volumes of tailings and waste rocks placed in dumps create serious environmental and economic damage in mining areas and adjacent territories. The development of technologies for processing waste into heat-insulating building materials (foam glass) will make it possible to reduce the burden on the environment, as well as reduce the cost of finished building products. The article substantiates the possibility of obtaining block foamed materials for the production of heat-insulating materials based on man-made waste using low-temperature technology. The author investigated the ways of improving the operational properties of foam silicates by introducing modifying additives (apatite-nepheline waste, fly ash). To obtain foam silicates based on silica-containing waste, a liquid glass composition was prepared, into which additives were introduced. After molding and drying, the samples were swollen. Physical, chemical and thermal properties of foamed silicate materials made of silica-containing raw materials were determined taking into account the requirements of GOST for thermal insulation construction materials. To determine the thermal conductivity coefficient, an ITP-MG 4 electronic thermal conductivity meter was used. Microscopic studies were carried out using a SEM LEO 420 scanning microscope. The author of the article proposes the optimal compositions and conditions for obtaining foam materials that meet the regulatory requirements for materials and products for building insulation. Foamed materials with density up to 0.55 g/cm3, strength 5.5 MPa, water absorption 15–22 %, thermal conductivity 0.09–0.104 W•m/K were obtained. Foam glass materials have a wide range of properties: non-flammable, environmentally friendly, have a long service life, and are not subject to mold deterioration. The obtained materials can be recommended for use as thermal insulation in the construction and reconstruction of industrial and civil buildings and structures.

Effects of AC Electrical Stress, Oil Pressure and Insulation Construction on Time Transition of Partial Discharge Characteristics on Oil-impregnated Paper Insulation System for Oil-filled Cables

Effects of AC Electrical Stress, Oil Pressure and Insulation Construction on Time Transition of Partial Discharge Characteristics on Oil-impregnated Paper Insulation System for Oil-filled Cables

Competition and management of wood-cement compositions among light concretes in the market of construction materials

The paper describes the stages and motivation of a reasonable choice when purchasing construction materials for low-rise housing in B2C and B2B segments. Due to the optimal combination of indicators of strength, thermal conductivity, low cost in the market of construction materials for low-rise housing, light concretes took a stable position as a thermal insulation construction material. Light concretes are divided into aerated concretes and foam concretes, as well as concretes based on wood-cement compositions. The volumes of aerated and foam concrete production and consumption are hundreds times as high as the production of wood-cement compositions. The negative attitude of the consumers to the processed products and the high price of such materials are deterrence to the wide distribution of wood-cement compositions in low-rise housing. The policy of integrated use of renewable wood resources can be the basis for increasing the production and consumption of wood-cement compositions.