Mineral Insulation Research Articles

Development of a Predictive Model for the Thermal Conductivity of Natural Fiber Insulation: A Novel Approach for Quality Control

ABSTRACT Natural fiber insulation materials can offer a sustainable alternative to mineral and petrochemical-based insulation materials when suitable raw materials and appropriate production processes are considered. Within the scope of our research, natural fibers like cotton, flax, hemp, wool, and coir, as well as regenerated cellulose fiber, were processed into insulation materials and examined concerning their thermal conductivity. We demonstrate that simple test methods for fiber fineness measurement with air-flow methods such as Airflow and Shirley can facilitate incoming inspection and process monitoring for insulation manufacturers. Based on these measurements, a simple model was developed to estimate the thermal conductivity based on the fineness measurements of the raw materials. The model developed on the natural fibers for lower densities was tested on a glass fiber insulation material to check its suitability. The slight deviations achieved between the experiment and the calculation verify the practicability of the concept.

Fabrication and characterization of lignocellulosic coconut and energy reed straw-reinforced methylene diphenyl diisocyanate-bonded sustainable insulation panels

The use of renewable environmental resources and plastics that can be returned to the biological cycle shows a new direction in the application of composite building materials. This study investigated the potential and strengthening effects of developing composite panels from coconut materials (CM) and reed straw (RS) particles in the presence of methylene diphenyl diisocyanate (MDI). Five composite panels with 100:0, 60:40, 50:50, 40:60, and 0:100% proportions were produced. The nominal density was 600 kg/m3 and the dimensions were 400 × 400 × 8 mm3. The panels were produced by hot-pressing for a total of 10 min at a maximum pressure of 7.2 MPa and at 135 degrees, and then slowly cooled at room temperature. The following experiments were performed: mechanical, physical and morphological properties, thermal conductivity, FTIR (Fourier transform infrared spectroscopy), and EDX (Energy disruptive X-ray). The study gave the following results: the thermal conductivity of the coir and reed panels is competitive with the thermal insulation capacity of similar natural-based insulation materials, and is close to the values of other mineral and plastic-based insulation materials. The values of thermal conductivity coefficient ranged from 0.08 to 0.10 W/(mK). Only reeds (MDI_1) boards have better results than coconut materials. Among the mechanical properties, flexural strength and internal bonding strength increased proportionally with the increase in the amount of coconut. The Young's modulus reached its maximum in the case of a 50–50% coir-reed mixture. The best values of the panels are: 6.33 MPa for flexural strength, 1.83 GPa for Young's modulus and 0.36 MPa for internal bonding strength. The morphological recordings confirmed the proper mixing and binding of the lignocellulosic materials in the composite. FTIR tests proved the successful chemical interactions. The findings support the possibility of creating a promising, environmentally friendly building material.

Characterization of mineral insulated cables at the WWR-K reactor: First results

At the WWR-K reactor, studies were started on the radiation resistance of signal cables with two types of mineral insulation (MgO and Al2O3). It is planned to accumulate fluence of fast neutrons ∼ 1020 cm−2 in cables. The irradiation temperature will be 500 ± 50 °C. The in-situ study of the degradation of the electrical properties of the insulation of signal cables will be carried out. This paper presents a capsule design, the results of complex calculations for the development of the capsule design, the expected neutron fluences, the dpa in steel, the technique for in-reactor measurement of electrical characteristics, and a work plan for the further studies. It is shown that the developed capsule forms the necessary conditions for irradiation. In particular, the temperature control range is 400–600 °C. The cable irradiation time until the target neutron fluence is reached will be about 100 effective days.

Method of arrangement of internal thermal insulation of external protective structures of the room

This article aims to discuss the conditions of insulation and avoidance of moisture condensation in the enclosing structures of buildings whose facades cannot be insulated from the outside due to historical and cultural value. The paper presents a study of the energy-efficient design of the facade of a residential building, which uses insulating materials that are suitable for internal thermal insulation of historical buildings. The analysis of domestic and European literary sources regarding the improvement of the level of thermal protection of buildings shows that the improvement of energy efficiency is important for ensuring a sustainable, affordable and safe energy system. The paper presents the results of a study aimed at increasing energy efficiency in residential buildings, as well as an analysis of the humidity state and the possibility of condensation when using internal insulation. Numerical simulations were performed to confirm the results. The obtained results indicate that the use of mineral insulation "BETOL®" and aluminium foil as a vapour barrier, applied from the inside, contributes to the improvement of thermal insulation of the walls and reduces the risks of condensation. Computer simulations have shown that under the considered conditions, condensation does not occur. The relative humidity in the structure does not reach 90%. The same structure without the vapour barrier causes condensation because the relative humidity exceeds 100 % in whole thickness of the brickwork, which will cause destruction of the historical structure. This research makes an important contribution to the development of energy-efficient solutions for the construction industry, as it will ensure the minimum permissible value of the heat transfer resistance of the enclosing structures and extend the service life of them and buildings as a whole.

METHOD OF ARRANGEMENT OF INTERNAL THERMAL INSULATION OF EXTERNAL PROTECTIVE STRUCTURES OF THE ROOM

The paper presents the results of a study aimed at increasing energy efficiency in residential buildings, as well as an analysis of the humidity state and the possibility of condensation when using internal insulation. Numerical simulations were performed to confirm the results. The obtained results indicate that the use of mineral insulation "BETOL®" and aluminum foil used as a vapor barrier, applied from the inside, contributes to the improvement of thermal insulation of the walls and reduces the risks of condensation. Computer modeling showed that under the formed conditions, condensation is not observed. This research has an important contribution to the development of energy-efficient solutions for the construction industry, as it allows to ensure the minimum permissible value of heat transfer resistance of external enclosures, to extend their service life.

Some features of air pollution monitoring as a component of the microclimate of the premises

The quality of living space largely depends on the quality of indoor air. The physical and chemical properties of the air people breathe can affect their health and comfort. Indoor air pollution in residential and workplace environments can occur due to various activities of occupants or employees, such as cooking, smoking, and using electronic devices, as well as emissions of pollutants from building materials and the use of certain products. Pollutants that can be present indoors include carbon monoxide, formaldehyde, volatile organic compounds, particulate matter, aerosols, biological contaminants, and more. To effectively monitor the quality of atmospheric air, it is necessary to determine the main sources of air pollution, which is the purpose of this study. Naturally, the quality of indoor air cannot be clearly separated from the ambient air quality. The first factor affecting the microclimate is the level of air pollution near the building. Air from the street enters the room through windows, doors, or the building's ventilation system. If the state of the surrounding environment is unfavorable, the concentration of harmful substances indoors may also exceed the norm. However, indoor sources of air pollution in any building can have a much greater impact on the health and comfort of the people inside it. Materials used in construction, such as concrete or mineral insulation, may contain ammonia, formaldehyde, and other substances that are released from building structures over time and deteriorate indoor air quality. Ensuring control and monitoring of indoor air quality is an extremely important task. This includes measuring concentrations of pollutants and identifying their sources. It is also important to adhere to standards and recommendations developed by health and environmental organizations to ensure safety and comfort indoors. To reduce indoor air pollution, various measures can be implemented, such as selecting appropriate building materials, and ventilation, installing purification systems, controlling sources of pollution, and limiting the impact of human activity. Keywords: air pollution, microclimate parameters, air quality monitoring, harmful substances.

Market of Finishing and Thermal Insulation Materials in 2023

The 15th annual conference of the Construction Information company took place in St. Petersburg on October 12–13, 2023. More than 120 representatives from 72 organizations from three countries took part in its work – commercial directors, heads of marketing departments, dealer centers, supply and sales specialists. Traditionally, the conference examines the results of the work of the Russian construction complex as a whole over the past year, as well as a number of sub-sectors of the building materials industry. The main results of the work of the industry of dry building mixtures, gypsum finishing materials, mineral and polymer-based thermal insulation materials, facade systems, paint and varnish materials, voiced in the reports of conference participants, are presented. The forecast for the development of these sub-sectors for the short term is also shown.

Circuit Integrity Assessment of Fire-Resistant Cables

In the electrical industry, fire accidents may happen due to overheating of electrical equipment, short circuit faults and any external source of fire. Polymeric Electrical Cables are prone to spread fire along the cable run as the insulation and sheathing materials are of flammable nature. Hence various flame retardants and low-smoke polymers are being used so that the flame spread and toxic gas release can be controlled. There are some special application cables called Fire Resistant cables which need to maintain the circuit integrity of the cable even during fire conditions. The construction of these fire-resistant cables requires fire-resistant insulation to achieve the fire-resistance property. They are such as Glass- Mica tape, Silicone Rubber, mineral insulation, metal insulation and fire retardant coating. There is various International and National standard assessing methods to assess these special cables. In this paper, the fire-resistant insulating materials and their performance during the assessment in achieving the required fire-resistant property are discussed.

Breaking the cycle of excessive conservatism: Evaluating the γ-radiation dose from building materials

Radionuclide content in building materials is regulated in most European countries by calculating the activity concentration index. The I-index does not account for the properties nor the application of the material but provides a conservative evaluation of the annual γ-radiation dose. Using a Monte Carlo toolkit, EGSnrc, this study calculated doses from building materials in less conservative set-ups by focusing on materials with a potential for recycling NORM residues, such as Portland cement, ceramics, gypsum, and mineral insulation. It was observed that proper consideration of building material geometry strongly affected the indoor dose rate. Regulating low-density materials and finishing materials such as gypsum and insulation under the same framework as high-density and high-bulk materials proved problematic because the doses differ by orders of magnitude. The current reference values for radionuclide concentrations used in calculating the I-index do not apply to most construction materials. For many types of building materials, higher radionuclide concentrations in the material could be allowed without contradicting the annual effective dose reference for the public. This illustrates the potential for boosting the use of NORM residues in various construction applications.

Research and development of copper joint for ITER In-Vessel Coils

The ITER In-Vessel Coils (IVCs) are crucial components of the Tokamak fusion reactor. They are located within the vacuum vessel (VV) behind the blanket shield modules and are responsible for compensating for fast perturbations of the plasma. There are a total of 176 joints used to connect the IVCs, feeders and feedthrough. The joint structure consists of a central copper conductor, a mineral (MgO) insulation layer, and an outer stainless-steel jacket. Given the inaccessibility of the IVCs once the blanket modules are installed, the highest level of quality is required for the joints. One key item is the welding of the copper conductor which has to be done inside the VV. To address the high thermal conductivity of copper conductor and the challenging constraints working inside the VV, a preheating method by the arc of the welding head has been developed. Macro- and micro-structure examination were performed on the welding cross sections, and tensile tests were carried out to check the strength of the copper joint, which demonstrated that arc preheating does not have a significant impact on the heat-affected zone. After more than 40 welding attempts and several design updates, the copper joint has been successfully developed and can be repeatedly and successfully welded.

Assessment of acute and chronic ecotoxicological effects of aqueous eluates of stone wool insulation materials

BackgroundStone wool is an inorganic mineral insulation material increasingly used to reduce the climate impact of buildings. The acute and chronic ecotoxicological potential of stone wool eluates have been studied in a battery of standardized laboratory ecotoxicological tests. The experiments were conducted with stone wool test materials in fibrous and milled form, with and without the presence of organic binder. For the preparation of eluates, the OECD protocol on the transformation/dissolution of metals and metal compounds was applied. The resulting eluates were used in acute tests, i.e., bioluminescence test with Aliivibrio fischeri (DIN EN ISO 11348-1:2009), algae growth test with Desmodesmus subspicatus (OECD No. 201) and immobilization test with Daphnia magna (OECD No. 202), as well as chronic tests, i.e., the Daphnia magna reproduction test (OECD No. 211) and the nematode growth and reproduction test with Caenorhabditis elegans (ISO 10872:2010).ResultsWhile no acute or chronic ecotoxicological effects of the eluates were observed for fibrous stone wool material, the milled test materials showed some chronic effects on aquatic invertebrates. Depending on the test materials and concentrations of milled stone wool used in the eluate preparation, these chronic effects included significant stimulation or inhibition of daphnid reproduction and nematode growth. The chemical analysis conducted in parallel to the ecotoxicological assessment indicated no leaching of organic substances from the applied binder or mineral oils and no formation of nanoparticles by the milling of stone wool. Furthermore, ICP-MS and ICP-OES analysis of eighteen elements revealed that only aluminum and nickel could be quantified in the eluates, at concentrations of approximately 750 µg/L and 7 µg/L, respectively.ConclusionsBased on the present ecotoxicological assessment, eluates from stone wool fibers cannot be considered as chemically hazardous to the aquatic environment. However, additional investigations of the ecotoxicological potential of the milled material and the environmental exposure of stone wool products are necessary for a complete evaluation of potentially negative effects of stone wool insulation materials.

Full-scale installation trial of ITER's in-vessel and marshalling area loom prototypes

The in-vessel components of the ITER Diagnostics are located all over the inner shell of the Vacuum Vessel, in the Ports and on the Divertor Cassettes as well. The electrical transmission lines which transmit the signals from the sensors across the vacuum boundaries are Mineral Insulated Cables. These cables will be arranged into looms, which will be fixed to the vacuum vessel with different kinds of attachments.The ITER tokamak is at a stage where manufacturing and testing of each component are becoming more and more important. For this reason, to allow IO to assess feasibility, gain experience and obtain feedback with respect to the suitability of the current designs regarding handling and installation of in-vessel signal cables and loom components, GEMS Engineering has carried out a series of installation trials on full-scale mockups of in-vessel and divertor looms, upper and lower port marshalling area looms. Beside of installation trials, the scope of the work also covered the manufacturing and testing of cable clamps and clips for in-vessel and divertor looms and marshalling areas.This paper outlines the results of the manufacturing of prototypes and assembly trials of the above-mentioned components.

Life cycle assessment of post-demolition autoclaved aerated concrete (AAC) recycling options

Autoclaved aerated concrete (AAC) is a widely used building material for masonry units, prefabricated reinforced components, and lightweight mineral insulation boards. Its low thermal conductivity and good fire resistance increase its popularity in residential buildings. Thus, post-demolition wastes are expected to increase in the future. However, post-demolition AAC (pd-AAC) is mainly disposed in landfills while landfill capacities decrease and legal framework conditions in Europe are tightening. This study performed life cycle assessments (LCA) of different pd-AAC recycling options and compared them to each other and to current landfilling to identify the best end-of-life handling of pd-AAC from an ecological perspective. The functional unit was 1 kg pd-AAC, and the system boundaries included pd-AAC at the demolition site, transports, pd-AAC treatment, and secondary production processes. Final products of the recycling process gained environmental credits/rewards for avoiding primary production using system expansion. Providing primary resources, primary production, and use phase were not in the scope of this study. Results show that especially closed-loop recycling of pd-AAC in AAC production has a high potential of improving environmental impacts. In the best recycling option (high substitution in AAC-0.35), potential savings per kg pd-AAC compared to landfilling reach up to 0.5 kg CO2-Eq, 7 MJ fossil resources, 0.005 mol H+-Eq (acidification), 0.17 CTU (freshwater ecotoxicity), 0.2 g P-Eq (freshwater eutrophication), 5.2 × 10-9 CTUh (carcinogenic effects), 4.4 × 10-8 CTUh (non-carcinogenic effects), 2.5 × 10-5 g CFC-11-Eq (ozone layer depletion), and 1.6 g NMVOC-Eq (photochemical ozone creation). Despite data uncertainties, recycling of pd-AAC is advantageous for several recycling options, including the production of AAC, light mortar, lightweight aggregate concrete, and shuttering blocks made from concrete without fine fractions (no-fines concrete). In Germany, up to 280,000 t CO2-Eq could have been saved in 2022 by pd-AAC recycling using different recycling options instead of landfilling.

The Mechanical Analysis of ELM Joint under Coupling Field

The Edge Localized Mode coil is the key component to prohibit the phenomena of disruptive instability occur-ring in the edge of Tokamak plasma. And the coil is made of Stainless Steel Jacketed Mineral Insulated Con-ductors. The different pieces of conductor are connected by joints. During the normal operation of Tokamak device, the joint will be shocked by electromagnetic and thermal loads. Thus, it is necessary to perform the mechanical analysis to verify whether or not the ELM joint has sufficient safety margin to resist the impact of coupling field. In order to obtain the load boundary condition for mechanical analysis, the electromagnetic and thermal analysis are launched first. Then the temperature and electromagnetic force density are inserted into the mechanical analysis model. And the equivalent stress is calculated. The analysis results indicate there is stress intensity at the component of supporting rail. To mitigate the stress intensity, the local structural optimi-zation design is employed. Finally, the stress evaluation is carried out based on analytical design. The assess-ment results demonstrate the optimized model has sufficient safety margin to withstand the combined action of multiple loads.

Partial Discharge Detection in Pressboards Immersed in Mineral Insulation Oil With Quantum Well Hall Effect Magnetic Field Sensors

Insulation degradation may cause inefficient and faulty operation of transformers. The insulation failures in transformers mostly start with a Partial Discharge (PD) event. For both operational and cost reasons to ensure the best performance and functionality of transformers, early detection of PD events is of great importance. In this paper presents a novel PD detection technique by using a highly sensitive Quantum Well Hall Effect (QWHE) magnetic field sensor and compare the findings with an off-the-shelf silicon magnetic field transducer. The investigation of the QWHE for high voltage engineering problem such as PD detection is given first time in this paper. The aim of the study is to detect PD activity in pressboards immersed in mineral insulation oil experimentally using a new QWHE sensor. The measured experimental data from both sensors are decomposed by Empirical Mode Decomposition (EMD) and Wavelet Decomposition (WD) methods, and PD signals are analyzed comparatively. The results show that QWHE sensors provide more accurate and noise free measurements allowing early and more accurate PD detections.

Condition Monitoring of High Voltage Transformer using Dissolved Gas Analysis Methods

Power transformer plays a significant role in the entire power transmission network; thus, transformer protection requires more attention for fault free electric supply. when the mineral oil and insulation inside the transformer is subjected to high thermal and electrical stresses, gases are created by the decay of mineral oil and cellulose. Different gases create different faults, Identification of faults inside the power transformer before they occur reduces its failure rate during its service period. For Knowing the fault condition of power transformer, Dissolved Gas Analysis (DGA) is proven to be as accurate method based on combination of concentration of gases like CO, CO2, H2, C2H6, C2H4, C2H2 etc., Dissolved gas analysis is the most important test in determining the fault condition of a transformer and it is the first indicator of a problem and can identify deteriorating insulation and oil, overheating hot spots, partial discharge and arcing. For developing this DGA Techniques, the MATLAB GUIDE interface can be used for making easy interaction between the user and software developed. This software is designed using some conditional statements and logical functions to get the type of faults in transformers based on the concentration of gases in transformer oil. The faults in transformer using dissolved gases analysis are detected using methods such as key gas, Roger’s methods, IEC ratio, Doernenburg ratio, Duval triangle and the Combined DGA methods. In this paper, these four methods of dissolved gas analysis (DGA) are presented and explained briefly.

Modelling and predicting the generation of post-demolition autoclaved aerated concrete (AAC) volumes in Germany until 2050

Autoclaved aerated concrete (AAC) has a porous structure and excellent thermal properties. Therefore, it is a frequently used building material for masonry units, prefabricated reinforced components and lightweight mineral insulation boards with increasing popularity. Post-demolition AAC is currently mainly disposed of in landfills. Decreasing landfill capacities, the legal framework, and protection of primary resources require developing recycling options for AAC. However, so far, no overall recycling of post-demolition AAC has been established yet. Only AAC primary process waste is recirculated or discharged, for example as an absorbent for chemicals or animal bedding. For high-quality post-demolition AAC recycling, only minimal information about recyclable volumes and their regional distribution is available. Therefore, a new dynamic retrospective and prospective AAC quantification model on a national level using AAC production, construction activity, AAC popularity, and buildings’ lifetimes is developed to assess geographically distributed current and future post-demolition AAC volumes. This new model is applied to quantify post-demolition AAC volumes in a case study for Germany in the period between 1950 and 2050. For validation, the results are compared with two different approaches and with data from the literature. The AAC quantification allows decision support for the circular management of AAC during its life cycle and along its value/supply chain regarding design, location planning, logistics, production, and recycling.

Experimental and Numerical Study on the Heat Transfer Characteristics of a Newly-Developed Solar Active Thermal Insulation System

A newly-developed solar active thermal insulation system (SATIS) is introduced with the main objective to accomplish a highly-dependent total solar transmittance on the irradiation angle. SATIS is also designed to obtain the maximum transmittance at a prescribed design irradiation angle and to reduce it remarkably at higher irradiation angles. A purely mineral thermal insulation plaster with micro hollow glass spheres is applied to manufacture the investigated SATIS prototype. Light-conducting elements (LCEs) have been introduced into SATIS and suitable closing elements have been applied. The SATIS prototype has been investigated both experimentally and numerically. It turned out that the contributions of conduction, radiation and convection to the effective thermal conductivity of SATIS, without the closing elements (49 mWmK), amount to 86.2%, 13.2% and 0.6%, respectively. The angle-dependent short-wave radiation exchange within the LCE has been investigated via ray tracing. At the incidence angle of 19% (design angle), 27% of the radiation within the LCE is absorbed by the absorber plate, resulting in measured and computed total solar energy transmittances of 11.2%/11.7%, respectively. For a typical summer irradiation angle of 60%, 98% of the incident radiation is absorbed by the surfaces at the entrance of the LCE. The corresponding total solar energy transmittance amounts to 2.9%.

Improving the quality of pipeline insulation with high-density Calcium Silicate material

The problem currently being faced is the occurrence of pipe leakage due to corrosion under insulation. The purpose of this study is to provide an overview of the specifications and ways of applying high-density calcium silicate insulation material as a substitute for rock wool mineral insulation material that has been used since the beginning of the refinery construction. This research method used the application research method with the case study approach method, which is a case study of pipe leakage problems due to corrosion under insulation. The results showed that the emergence of corrosion problems under insulation was due to rock wool mineral material storing and depositing water in the insulation. The observations also showed that after the insulation was replaced, the temperature of the steam fluid in the piping increased by 9-14°C and the results of observation through widow inspection revealed that the calcium silicate condition remained dry and the piping condition did not indicate corrosion. The results of this study indicated that high-density calcium silicate material was suitable and also recommends corrosion control under insulation by replacing rock wool mineral material into high-density calcium silicate.

Rešavanje problema eksploatacije transformatora sa korozivnim sumporom desulfurizacijom ulja primenom jake neorganske baze i organskog rastvarača

Most power transformer failures are associated with the presence of corrosive sulfur compounds in mineral insulating oil, of which dibenzyl disulfide (DBDS) is the best known and most widespread corrosive sulfur compound. The oil of failed transformers usually contained DBDS, a compound with a pronounced affinity for the formation of copper (I) sulfide (Cu2S). Copper (I) sulfide is a compound that does not dissolve in oil, conducts electricity, and can be deposited on the paper insulation or copper conductor of the transformer. Created conductive paths between the windings can initiate turn-to-turn breakdown and failure of the transformer. Several technological procedures have been developed as a solution to oil corrosivity. The application of desulfurization technology developed by the Electrical Engineering Institute "Nikola Tesla" enables the efficient removal of DBDS and aging products from mineral insulation oils.