Hollow Insulation Research Articles

High-strength, thermal-insulating, fire-safe bio-based organic lightweight aerogel based on 3D network construction of natural tubular fibers

Petrochemical-based foam materials are extensively used in insulation and energy storage fields. However, their non-degradability and high flammability have caused great pressure on energy, environment and human life and property safety. It is urgent to carry out research on biodegradable and fire safety alternative biomaterials. Herein, inspired by the natural hollow insulation animal hair, the 3D network structure of tubular aerogel was constructed by using the hollow kapok fibers (KF), the binder polyvinyl alcohol (PVA) and the flame retardant crosslinker biguanide phosphonate (BGP). The multifunctional tubular aerogel integrating thermal insulation, high strength and fire safety was successfully prepared by freeze-forming and freeze-drying. Due to the intermolecular hydrogen bonding and the high viscosity of binder, KF maintained a high filling, full component and high value utilization. Compared to pure KF, the thermal conductivity of KF-PVA-BGP aerogel was reduced to 0.0531 W m−1K−1 and its compressive strength was improved to 1.64 MPa. Meanwhile, the incorporation of flame retardant cross-linker BGP promoted the degradation and charring of KF-PVA aerogel and released lots of inert gases during decomposition process, which effectively exerted the flame retardant effect in condensed and gas phases. Besides, compared with commercial PS insulation boards, KF-PVA-BGP composites are recyclable, sustainable and biodegradable in addition to their excellent thermal insulation and fire safety performance. This KF-PVA-BGP aerogel showed good application prospects for replacing traditional petrochemical-based materials in thermal insulation, energy storage and new energy fields.

Atmospheric water harvesting with scale‐up potentials using natural sunlight and passive cooling

AbstractSorption‐based atmospheric water harvesting (SAWH) is a promising technology that can potentially alleviate global shortages of water, especially in arid regions. However, current SAWH devices are difficult to scale up and exhibit significant disadvantages in terms of their cost, portability and efficiency. Herein, we report a portable and efficient atmospheric water‐harvesting device with scalable and low‐cost high‐performance lithium‐containing membrane‐encapsulated composite sorbents. We use the thermodynamic framework for moist air states to develop the device with a structure featuring hollow insulation grid that harnessed the large temperature difference between the sorbent and the condenser, and thus, the water yield of SAWH device was increased by 20.5%. In outdoor experiments, it achieved an ultra‐high water productivity of 34.8 gwater/kgdevice and 1399.28 gwater/(m2 day) and an exceptionally low water‐extraction cost of $2.65/kgwater per cycle. Thus, this scalable and efficient passive SAWH device demonstrates the possibility of achieving low‐cost and reliable water production in real scenarios and paves the way for practical applications of SAWH.Key points Water harvesting cost‐efficient sorbent Heat and moisture transfer optimization

Effect of hollow insulation riser on shrinkage porosity and solidification structure of ingot

Effect of hollow insulation riser on shrinkage porosity and solidification structure of ingot

Comparative Study on Thermodynamic Characteristics of Composite Thermal Insulation Systems With Liquid Methane, Oxygen, and Hydrogen

Abstract Composite passive insulation technology has been proved to be an effective method to reduce heat leakage into the cryogenic storage tank. However, the current related research mainly focused on liquid hydrogen (LH2). The thermophysical properties of different cryogenic liquids and the thermal insulation materials at different temperatures are significantly different, so whether the results related to LH2 are applicable to other cryogenic liquids remains to be further determined. In fact, the insulation technology of LH2 itself also needs further study. In this paper, a thermodynamic calculation model of a composite insulation system including hollow glass microspheres (HGMs), multilayer insulation (MLI), and self-evaporating vapor cold shield (VCS) has been established. The accuracy of the calculation model was verified by the experimental results, and a comparative study on thermodynamic characteristics of the composite thermal insulation system with liquid methane, liquid oxygen (LO2), and LH2 was carried out. The results show that the heat leakage reduction of the proposed system for liquid methane, LO2, and LH2 is 25.6%, 29.7%, and 64.9%, respectively, compared with the traditional SOFI + MLI system (1 × 10−3 Pa). The type of liquid and the insulation system structure has a relatively large influence on the VCS optimal position. While for a specific insulation system structure, the insulation material thickness, storage pressure, and hot boundary temperature have a weak influence on the VCS optimal position.

Carbonation Resistance Performance and Micro-Structure Analysis of Glazed Hollow Bead Insulation Concrete

In this paper, the carbonation depths of glazed hollow bead insulation concrete (GHBC) and normal concrete (NC) at different carbonation ages are tested. The microstructure of GHBC and NC before and after carbonation were observed and compared by mercury intrusion porosimetry (MIP), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The results showed that NC had better carbonation resistance than GHBC, and GHBC had a carbonation depth of 1.61 times than that of NC at 28 days accelerated carbonation experiment. The microstructural analysis showed that with the decrease of porosity of the samples, the carbon content and CaCO3 content increased after carbonation. The porosity of NC decreased from 14.36% to 13.53%, the carbon content increased from 4.42% to 5.94%, and the CaCO3 content increased from 18.5% to 56.0%. The porosity of GHBC decreased from 22.94% to 20.71%, the carbon content increased from 4.97% to 5.31%, and the CaCO3 content increased from 70.0% to 82.0%. The above results showed that carbon reacts with hydration products 3CaO·SiO2, 2CaO·SiO2, and Ca(OH)2 to produce a large amount of CaCO3 which causes a large amount of pores to be filled and refined hence the porosity and pore size were reduced leading to increase in the compactness of the material. From the results obtained, the carbonation depth prediction formula of glazed hollow bead insulation concrete was developed, and carbonation life was predicted.

Hysteretic Behavior and Restoring Force Model of Reinforced Glazed Hollow Bead Insulation Concrete (GIC) Columns

Based on the research of mix ratio and mechanical properties of glazed hollow bead thermal insulation concrete (GIC), the quasi-static tests of six GIC frame columns and one normal concrete (NC) frame column are carried out. The stress of frame columns under earthquake is simulated by applying a constant vertical load and cyclic horizontal load, and the hysteresis behavior, skeleton curve, ductility coefficient, stiffness degradation, and energy dissipation capacity of frame columns are studied. Contrast variables include axial compression ratio, stirrup reinforcement ratio and concrete material. The results show that the seismic performance of GIC frame columns is similar to that of ordinary concrete frame columns and frame columns. The stiffness degradation rate and ductility of GIC column are higher than that of NC column with the same parameter; higher axial compression ratio can increase the initial stiffness of GIC and reduce ductility; higher reinforcement ratio can increase ductility, but can limit plastic hinge development and reduce energy dissipation capacity of GIC column. The results can provide theoretical basis for elastic-plastic analysis of GIC column under earthquake action.

The optimal decision of insulation in cladding structures for energy efficient buildings

Execution of thermal insulation for enclosing structures of residential properties is a sophisticated part of the thermal protection. The choice of insulation materials for external walls is one of the main ways to increase the performance of heat insulation. This article contains thermo-technical calculations of two enclosing structures due to conditions of Saint-Petersburg. According to the results, the thickness of the insulating layer and a total wall thickness of the exterior walls composed of concrete, insulation and sand-cement rendering are smaller than the same characteristics of wall construction of hollow tile, insulation and sand-cement rendering.

Flexural performance of glazed hollow bead reinforced concrete beams

Flexural static tests are conducted on glazed hollow bead reinforced concrete beams (referred to as GBLs) with a range of properties. The test variables included concrete material type and cross section depth as well as longitudinal reinforcement ratio of the flexural beams. The test results were analyzed in terms of damage mechanism, ductility, stiffness, and energy dissipation in the flexural beam. The addition of the glazed hollow bead as the lightweight aggregate was to obtain higher ductility and slower degradation of strength and stiffness. It was shown in the tests that the mechanical properties of the GBLs were better than that of normal concrete beams. A finite element model was developed for the beams and the lateral force–displacement curves obtained from analyses were compared with the experimental data. The results of this study are useful in the design and application of glazed hollow bead insulation concrete bending members.

Study on Preparation and Properties of Foam Glazed Hollow Bead Thermal Insulation Mortar

This paper is the result of research on preparation and properties of foam glazed thermal insulation mortar by means of orthogonal experiment method, the influence of main preparation process parameters on mortar’s dry density and compressive strength, and the optimum combination was obtained. The micro-structure of foam glazed hollow bead insulation mortar was analyzed by scanning electron microscope (SEM), and the mechanism of glazed hollow bead and foaming agent was preliminarily discussed.

Mechanical Strength and Microstructure Analysis of Cementitious Wheat Straw Composite

Wheat straw alkali treatment has impacts on the strength of cement mortar and glazed hollow beads insulation mortar. The results show that the bending strength and bending strength of cement mortar specimen with 4% wheat straw are respectively 58.3% and 40.9% of the benchmark specimen, but bending-press ratio of the latter is 1.42 times of the former. The SEM images reflect the straws influences on the cement hydrate morphology, status and the influence of the number on cement mortar and glazed hollow beads insulation mortar. Compared with the latter, the former C-S-H gel is loose fibrous, failure to form a good network. In the thermal insulation mortar consistency and stratification of the same circumstances, with straw dosage increased, strength first increases, then declining. And folding pressure than in straw dosage is less than 24% more ideal. The SEM pictures show that network C-S-H gel decrease and loose fibrous C-S-H gel increased. At the same time, AFt gradually become attenuate and curly.

Preparation and Study on the Performance of Glazed Hollow Beads Thermal Insulation Materials

The glazed hollow beads thermal insulation board was made of glazed hollow beads and perlite by selecting cement and fly ash as cementitious materials, and adding appropriate amount of VAE emulsion and fibers, in the compression molding process. In this paper, the influence of different dosages of perlite replacing vitrified beads, VAE emulsion and fiber on the material properties were studied. Besides, the internal morphology of the sample was observed by scanning electron microscopy, and the action mechanism of the insulation material was explored.

Uniaxial Compression Tests Research on C25 Glazed Hollow Bead Insulation Concrete

With the growing global energy crisis, development of economic and land-efficient construction structural system became an significant subject in Civil Engineering field. Under this context, material and structural test and theoretical analysis research is meaningful on new energy-saving building material, glazed hollow bead insulation concrete. In this paper, one mix design that meet insulation requirements of the energy-saving project on coefficient of heat conductivity and compressive strength have been chosen. Under the uniaxial status, prism samples of above mix design have been selected to do compression strength and deformation tests; Systemic analysis of the relationship between the strength and deformation for glazed hollow bead insulation concrete has been carried through, and some results have been provided, including the stress-strain constitutive relationship of glazed hollow bead insulation concrete with grade c25, prism compressive strength, strain, initial elastic modulus, residual strength, ductility, etc.

Uniaxial Compression Tests Research on C35 Glazed Hollow Bead Insulation Concrete

With the growing global energy crisis, development of economic and land-efficient construction structural system became an significant subject in Civil Engineering field. Under this context, material and structural test and theoretical analysis research is meaningful on new energy-saving building material, glazed hollow bead insulation concrete. In this paper, one mix design that meet insulation requirements of the energy-saving project on coefficient of heat conductivity and compressive strength have been chosen. Under the uniaxial status, prism samples of above mix design have been selected to do compression strength and deformation tests; Systemic analysis of the relationship between the strength and deformation for glazed hollow bead insulation concrete has been carried through, and some results have been provided, including the stress-strain constitutive relationship of glazed hollow bead insulation concrete with grade c35, prism compressive strength, strain, initial elastic modulus, residual strength, ductility, etc.

Energy Saving Measures of Building Integration and Cost Analysis Based on 65% Standard

It is difficult to reach the request that 65% standard of building energy in china and the goal of China’s science and technology development in 2020 using traditional outer insulation technology. The several combinations of ordinary concrete (1) and bearing ceramsite concrete (2), styrofoam board of external thermal insulation for external wall (3) and cement-based glazed hollow bead insulation system (4) are made thermal calculations and cost analysis separately in this paper based on a practical project of Jiaozuo city. The results indicate that the combination of (2)+(4) is the best one, which reduces the energy saving rate, labor intensity, transportation weight, project cost by 74%, 20%, 30%-40% and 10% respectively.

Characterization of Polyurethane Foam Dielectric Strength

Internal flashovers in hollow insulation systems can produce serious damage. Frequently, SF6 or N2 is used to eliminate this problem, but possible gas leakage may endanger the insulation. This paper proposes the use of polyurethane foams to fill the hollow spaces in insulation systems. Thus far, few publications deal with the dielectric properties of foams. This paper demonstrates the dielectric strength of three different foams which are investigated using ac and lightning impulse voltages under different humidity and temperature conditions. The results show that polyurethane foams have 2-3 times better dielectric strength than air. The breakdown strength decreases with the thickness of the foam; temperature and humidity have negligible effects on the breakdown voltage. The major parameter is the size of the voids in the foam. Reducing the size of the voids increases the breakdown strength. This can be achieved by improving the manufacturing technology.