Alternative Thermal Insulation Research Articles

Thermal Insulation Properties of Delignified Balsa and Paulownia Wood “Foams” with Polylactic Acid Coverings

The energy-conserving performance of a building, normally realized by a variety of insulation materials, needs to be carefully considered, from the design to construction operations. Traditional mineral or chemically synthesized insulation materials are facing severer environment or health challenges. Hence, this work aims at developing an alternative thermal insulation material from wood. Two species, balsa and Paulownia, were chosen for their naturally low densities. Lignin and hemicellulose components were removed to create a “foamed” structure with more air induced. Polylactic acid (PLA) was applied to cover the delignified wood samples to further improve the hydrophobicity. The microstructure, physical properties, thermal conductivity and insulation properties of the treated wood samples were assessed. After lignin and hemicellulose removal, the original porous micro skeleton of balsa and Paulownia wood was retained, along with an increased porosity to 96.6% and 94%, respectively. Meanwhile, the thermal conductivity was successfully decreased by 22% to 0.053 W/(m·K) for balsa wood and by 27% to 0.067 W/(m·K) for Paulownia wood. PLA-covering treatment further enhanced the water resistance of the delignified wood samples without an evident change in the thermal conductivity. The above findings demonstrated the feasibility of applying delignified wood as a potential insulation material in modern construction operations, which may help set up a new pathway for a low-carbon and energy-saving construction industry.

Research on fire resistance and economy of basalt fiber insulation mortar

The construction sector has become the most critical source of carbon emissions, but the existing thermal insulation materials such as thermal insulation mortar have obvious limitations, so it is urgent to develop building thermal insulation materials with superior performance and low cost. Aiming at the problem of poor bond strength of foam thermal insulation mortar, this research team selected basalt fiber as admixture to verify the influence of basalt fiber content on its performance and the economic feasibility of thermal insulation mortar. The main finding is that basalt fiber as an additive can obviously improve the crack resistance of thermal insulation mortar. When the content of basalt fiber increases from 0 to 2.5%, the compressive strength of mortar increases at first and then decreases, and the bond strength increases nonlinearly, but the thermal conductivity and dry density also increase. Therefore, the optimal content of basalt fiber is 1.5%. The improvement effect of fire resistance of thermal insulation mortar with 1.5% basalt fiber content is better. After curing for 28 days, the mass loss rate of the sample is reduced by about 11.1% after high temperature, and the relative compressive strength is increased by about 9.71% after high temperature. The raw material cost of the new fireproof thermal insulation mortar improved by basalt fiber is lower, and the cost of the finished product is reduced by 16.98%, 28.18%, 33.05% and 38.96%, respectively, compared with the four types of thermal insulation mortar already used in the market. More importantly, the economic recovery period of the new fireproof and thermal insulation mortar is undoubtedly shorter than that of alternative thermal insulation or energy storage materials, which not only achieves low emission and environmental protection, but also satisfies the economic feasibility.

"Alternative thermal insulation building material manufactured by expanding the glass waste with anthracite under the effect of microwave radiation"

"Alternative thermal insulation building material manufactured by expanding the glass waste with anthracite under the effect of microwave radiation"

Experimental, numerical and theoretical study on heat transfer in paper honeycomb structure

The fabrication of most current thermal insulation materials from polymeric foams has created an unfavorable impact on the environment. With the aim of reducing the use of foam plastic, this paper focuses on honeycomb paperboard, an alternative thermal insulation material which is recyclable and cost-effective, and evaluates its heat transfer performance under different conditions. The experimental results show the effective thermal conductivity of honeycomb paperboard increases as the honeycomb height or the side length increases. This paper also establishes a novel theoretical model based on a newly developed convective heat transfer correlation to predict the effective thermal conductivity under different conditions. The model's results conform well to the experimental results, and the effect of convective heat transfer is investigated quantitatively using this model. As the vertical adiabatic boundary surfaces are replaced by honeycomb walls, the convection heat transfer strictly depends on the thermal boundary condition of the honeycomb walls and highly depends on honeycomb height and side length.

Chemical compatibility of hollow ceramic cenospheres as thermal insulation for high-temperature thermal energy storage applications with molten nitrate salt

An effective insulation material that is both thermally and chemically stable in molten salts could transform the design of molten-salt-based thermal energy storage (TES) tanks. Most current molten salt TES tanks hold the metallic tank structure in direct contact with hot salt inventory, a design which leads to thermal expansion of the tank and triggers stresses that can lead to thermomechanical failures. With an internal insulation to lower the temperature at the tank structure, the extent of thermal expansion can be reduced, thereby reducing expansion-induced stresses and allowing for consideration of lower-cost tank structure materials. Conventional insulation materials are either 1) too porous and allow molten salts to permeate into the matrix, which significantly increases the thermal conductivity or 2) too dense and have a thermal conductivity that cannot provide sufficient thermal insulation. This paper presents an alternative thermal insulation concept using cenospheres which have an alumino-silicate structure. The cost analysis suggests that the low-density cenospheres can be one of the cheapest materials to provide cost-effective thermal insulation. The chemical compatibility of cenospheres is investigated in molten 60 wt% NaNO 3 /40 wt% KNO 3 salt which is close to industrial-grade Solar Salt. This paper shows that diffusion of the sodium and potassium cations from the salt into the cenospheres occurs based on weight analysis, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The cation diffusion breaks the bridging oxygen bonds and causes volume expansion of the microstructure which is responsible for the failure of the cenosphere particles. The chemical composition of the cenospheres is found to affect their compatibility with molten nitrate salt. A cenosphere product with low iron content showed the best compatibility with an average survival rate of 77.9% ± 9.8% after 7 days of immersion in the molten nitrate salt. While even the low-iron cenospheres appear to require protection from direct molten salt contact, their slow degradation rate, closed-cell porosity, and low cost hold potential for effective use as internal tank insulation. • Hollow cenospheres are investigated as insulation for molten nitrate salt storage. • Low level of impurities in cenospheres should improve chemical stability. • Cenospheres can provide cost-effective insulation. • Cenospheres can be fail-safer than conventional materials.

Research on the use of silica aerogels

Silica aerogels are alternative thermal insulation materials for external wall structures. They have a minimum density and water resistance, which in a period of global warming and in a hot climate allows you to get the necessary protective shell of the building. High technologies contribute to a significant improvement in the quality of insulation through the use of aerogel structures. A promising direction in the field of research is to improve the technical characteristics of the insulation used and reduce the costs of its manufacturing process. The aim of the work was to conduct an experiment on a room model and evaluate the possibilities of using silica aerogels as a light thermal insulation material. Within the framework of the study, the tasks were solved using numerical computer modeling. The stages of obtaining aerogels with the specified parameters are reduced into a clear technological sequence, which allows us to justify their physical and thermal properties. Based on the experience of conducting research, the indicators of the use of aerogels in construction are analyzed. An experiment was conducted on a model of a room with aerogel insulation and the radiation from mutually located surfaces was determined. According to the results of the work, a predictable and regular decrease in temperature was obtained over time. Aerogel sheets turned out to be rational materials for walls and other elements of buildings, because along with low density, they have a high thermal insulation ability. The practical benefit of the study lies in the fact that the obtained dependencies allow us to recommend the use of aerogel insulation not only for load-bearing and enclosing structures, but also for individual elements of buildings and can be used to develop methods to increase thermal protection.

Characterization of an alternative thermal insulation material using recycled expanded polystyrene

Thermal insulations help to reduce household energy demand and extend the periods of thermal comfort generated by heating and cooling systems. Conventional isolations may not be economically accessible to all social sectors, despite their benefits. This paper presents and evaluates an alternative low-cost insulating material and its variants, based on the mechanical reuse of expanded polystyrene (EPS) waste packaging, cementitious binder, plastic additives, and water. These materials show comparable performance to commercially available insulations (thermal conductivity range 0.0603–0.0706 W/m K) and provide an environmentally-safe and cost effective alternatives for house isolation for the low income population living in settlements worldwide.

Parametric Cost Optimization of Solar Systems with Seasonal Thermal Energy Storage for Buildings

In combination with seasonal thermal energy storage (STES), solar energy offers a vast potential for decarbonizing the residential heat supply. In this work, a parametric optimization is conducted to assess the potential of reducing the costs of water-based STES through the use of alternative thermal insulation materials and the integration of an underground storage outside the building. The investigated configurations include: a hot-water tank, a solar collector installation, and a multifamily building with a solar fraction of 100%. The storage is either integrated inside the building or buried underground in its direct vicinity. A simulation-based analysis shows that if the tank is integrated inside an existing building (as part of a retrofitting action) – where costs are primarily driven by the loss of living space – vacuum-insulation panels can lead to significant savings in living space and a cost advantage compared to the use of conventional glass wool. Nevertheless, storage integration inside an existing building is a more expensive option compared to an external integration due to the high costs associated to the internal building modification and loss of living space. Despite the high excavation costs and increased heat losses, the concept of burying the storage underground is a promising option to allow the integration of large-volume seasonal storage systems in new and existing buildings.

Solid Media Thermal Energy Storage System for Heating Electric Vehicles: Advanced Concept for Highest Thermal Storage Densities

The integration of thermal energy storage systems enables improvements in efficiency and flexibility for numerous applications in power plants and industrial processes. By transferring such technologies to the transport sector, existing potentials can be used for thermal management concepts and new ways of providing heat can be developed. For this purpose, technology developments for solid media high-temperature thermal energy storage systems are taking place for battery-electric vehicles as part of the DLR Next Generation Car (NGC) project. The idea of such concepts is to generate heat electrically, to store it efficiently and to discharge it through a bypass concept at a defined temperature level. The decisive criterion when using such solutions are high systemic storage densities which can be achieved by storing heat at a high temperature level. However, when storing high temperature heat increasing dimensions for thermal insulation are required, leading to limitations in the achievable systemic storage density. To overcome such limitations, an alternative thermal insulation concept is presented. Up to now, conventional thermal insulations are based on sheathing the storage containment with efficient thermal insulation materials, whereby the thickness results from safety restrictions with regard to the permitted maximum surface temperature. In contrast, the alternative concept enables through the integration of the external bypass into the thermal insulation systemic advantages during the charging and discharging period. During discharging, previously unused amounts of heat or heat losses within the thermal insulation can be integrated into the bypass path and the insulation thickness can be reduced during loading through active cooling. Using detailed models for both the reference and the alternative thermal insulation concept, systematic simulation studies were conducted on the relevant influencing variables and on the basis of defined specifications. The results confirm that the alternative thermal insulation concept achieves significant improvements in systemic storage densities compared to previous solutions and high potentials to overcome existing limitations.

The Formation of a Comfortable Habitat and the Economic Feasibility of Using Alternative Thermal Insulation Technologies

The pace of construction and renovation of buildings is increasing every year. This encourages the search and introduction of new materials and technologies to improve the comfort of housing. An important problem is also the need to ensure the energy efficiency of buildings. A peculiarity of the Russian natural conditions is a significant daily and annual difference in atmospheric temperatures. The use of various thermal insulation materials in the construction process will significantly reduce the cost of maintaining buildings and provide comfortable conditions for people, regardless of natural events. In addition, the use of certain facade treatments solves the aesthetic problem and can protect against precipitation and industrial emissions. Therefore, the purpose of this study is to find additional possibilities for thermal insulation of buildings using non-traditional technologies and materials. Modern approaches to the aesthetics of buildings involve the use of expensive mineral thermal insulation materials. Reducing the cost of their manufacture is possible through the use of industrial waste. Wastes from non-ferrous metallurgy are suitable for the production of slag wool or for the production of slag glass-ceramics. A wide range of possibilities allows the use of various wastes in the manufacture of bricks to increase porosity, strength and frost resistance. The use of a number of additives also provides an increase in economic efficiency and environmental friendliness of production. The use of special coatings for gypsum finishing materials could increase their strength and water resistance. The quality of facade paints is significantly increased when using aluminum silicate liquid sodium glass. Fine-dispersed waste of metallurgical enterprises will allow to lower the cost of production of liquid glass and aluminosilicate glue. The use, obtained from waste, astringent, provides for the production of heat-insulating materials the production of bright colors without the use of pigments. High strength and water resistance of materials can ensure the use of magnesian waste. Keywords: thermal insulation, energy efficiency, industrial waste, building materials, finishing materials, paints.

Environmental impact assessment of building envelope components for low-rise buildings

The selection of building envelope components has a high impact on all the lifecycle phases of a building, from the environmental and energy perspectives, and plays a significant role in the design of sustainable buildings. This paper presents an environmental impact comparison of four different building structural systems widely used in the construction of energy efficient houses in Central Europe: reinforced concrete, brick, cross-laminated timber, and timber-frame panel construction. The basic properties of wall and roof components were determined according to the thermal transmittance equivalent, where their environmental performance using a lifecycle approach was assessed. The study reveals the environmental impacts of individual structural systems and alternative thermal insulation materials, as well as their impact share on environmental performance of building envelopes.Based on the comparison of selected components, this study demonstrates that there is a significant potential for improving the environmental potential of low-rise buildings, by selecting suitable components and materials, sustaining the energy performance of the building. The comparison of envelope components draws attention to the critical materials, representing guidelines for the optimization of environmental impacts of building envelope components for sustainable low-rise buildings, especially considering the design phase.

Experimental Analysis of MOC Composite with a Waste-Expanded Polypropylene-Based Aggregate.

Polypropylene (PP) is one of the most widely produced types of plastic worldwide, but its recycling is limited. This work presents a study of the utilization of expanded polypropylene (EPP) waste in a magnesium oxychloride cement (MOC) composite usable in the building industry. MOC is formed by mixing magnesium oxide powder and a concentrated solution of magnesium chloride and is characterized by excellent bonding ability to large quantities of different types of aggregates. A developed air-cured MOC composite, where an EPP-based aggregate was used for the full replacement of natural aggregate, was investigated in terms of its basic physical, mechanical, thermal and water resistance properties. The results demonstrate that incorporation of EPP waste greatly improved the thermal insulation properties, while the mechanical resistance was reduced to an acceptable level. The developed MOC composite containing EPP waste can be considered as an alternative thermal insulation material applicable for the construction of floor or envelope construction systems.

Wood waste as an alternative thermal insulation for buildings

Current insulation materials in the construction market, which are predominantly inorganic materials, have a high performance in relation to heat transfer, i.e. high R-values, but the environmental impacts in their production processes are significant. The use of bio-based natural fibre materials such as cork, cotton, wood fibre, hemp, etc. with their lower embodied energy, moisture buffering capacity and, consequently, improved Indoor Environmental Quality have received increasing focus in both research and application, particularly amongst environmentally-conscious clients and designers.In this study a natural fibre material in the form of wood waste is examined experimentally to assess its suitability for use as a thermal insulation material, without the addition of any binder, within a timber frame wall construction. The wood waste is from primary production sources using untreated material. According to our experimental results, the thermal conductivity values of wood waste with different densities, ranged from 0.048 to 0.055 W/mK. These values are slightly higher than commonly used inorganic based insulation materials, although comparable to other natural insulation materials in the market, but have the economic advantage of being a low-cost by-product. The values relating to the material hygric performance including the water vapour diffusion resistance factor, water vapour permeability, and water absorption coefficient were also determined and presented, which will help facilitate future hygrothermal modelling.

Performance Evaluation and Research of Alternative Thermal Insulation Based on Waste Polyester Fibers

In the production of building materials the emphasis is put on the utilization of waste materials generated in various industrial processes. The production of secondary raw material increases annually with the increase in production volume that is highly dependent on increasing demand. Based on material properties of harmless raw material the utilization in civil engineering is being search. This paper deals with laboratory examination of fundamental material characteristics such as composition, size, shape and thermal and acoustical properties. This paper is subsequently dedicated to the complexity of making a thermal insulation from polyester fibers and bi-component fibers. The research aims to eliminate the amount of waste going to landfills and expand manufacturing industry of producer. The tests results show that the thermal insulation from waste polyester fibers has comparable characteristic with mineral/rock wool.

Verification of the thermal insulation properties and determination the optimal position of the reflective thermal insulation layer in the wood based envelope

Abstract To achieve thinner wood based envelope is necessary look for an alternative thermal insulation material, which will have the best possible thermal insulation properties while maintaining affordability. One such material is also reflective thermal insulation layer, but it is necessary to verify the thermal insulation properties and determine the optimal position in the wood based envelope.

Prediction of the effective thermal conductivity of microsphere insulation

Since glass microsphere has high crush strength, low density and small particle size, it becomes alternative thermal insulation material for cryogenic systems, such as storage and transportation tank for cryogenic fluids. Although many experiments have been performed to verify the effective thermal conductivity of microsphere, prediction by calculation is still inaccurate due to the complicated geometries, including wide range of powder diameter distribution and different pore sizes. The accurate effective thermal conductivity model for microsphere is discussed in this paper. There are four mechanisms which contribute to the heat transfer of the evacuated powder: gaseous conduction (kg), solid conduction (ks), radiation (kr) and thermal contact (kc). Among these components, kg and ks were calculated by Zehner and Schlunder model (1970). Other component values for kc and kr, which were obtained from experimental data under high vacuum conditions were added. In this research paper, the geometry of microsphere was simplified as a homogeneous solid sphere. The calculation results were compared with previous experimental data by R. Wawryk (1988), H. S. Kim (2010) and the experiment of this paper to show good agreement within error of 46%, 4.6% and 17 % for each result.

Textile waste as an alternative thermal insulation building material solution

The adoption of more sustainable behaviors, particularly in what concerns to the reduction of energy consumption and the emissions of greenhouse gases, is nowadays a priority. The construction sector is one of the key areas of intervention, which carries a high consumption of resources such as materials, energy, and water. Thus, it is essential to adopt more efficient actions during all stages of the construction process, including the use of more sustainable materials. The reuse of different types of waste in the construction or rehabilitation of buildings can contribute significantly to sustainability.In this research work, the potential applicability of woven fabric waste (WFW) and a waste of this residue, named woven fabric subwaste (WFS), as thermal insulation building material was studied. Experimental work was conducted using an external double wall, with the air-box filled with these two types of waste, to determine their thermal characteristics. Two heat flowmeters and four surface temperatures sensors were placed on the wall surface to determine the thermal conductivity of the wastes.The obtained results show that the application of the WFW and WFS in the external double wall increases its thermal behavior in 56% and 30%, respectively.The thermal conductivity value of the WFW is similar to the values obtain for expanded polystyrene (EPS), extruded polystyrene (XPS) and mineral wool (MW). The value of this parameter for the WFS is approximately equal to the values for granules of clay, vermiculite or expanded perlite. Therefore, applying these wastes as a possible thermal insulation material seems to be an adequate solution. Environmental, sustainable and economical advantages may result from this practice.