Performance Of Thermal Insulation Materials Research Articles

Multiphase-Thermal Flow Simulation in a Straight Vacuum-Insulated LH2 Pipe: Fuel Gas Supply System in a LH2-Fueled Ship

Hydrogen, stored as a liquid at cryogenic temperatures to enhance transport efficiency, is susceptible to boiling due to thermal fluctuations, underscoring the importance of investigating thermal insulation for liquid hydrogen piping. Evaluating their suitability and effectiveness for hydrogen ship piping remains critical. This study conducted numerical simulations to analyze insulation and phase-change impacts on the multiphase thermal flow of piping systems used for the Fuel Gas Supply System (FGSS) of hydrogen-fueled ships. The accuracy of the adopted phase-change model was validated against selected experimental cases of boiling phenomena, demonstrating agreement with experimental results. We applied the validated phase-change model to simulate multiphase thermal flow in an LH2 pipe and evaluated the thermal performance of insulation materials. The insulation material considered in this study is a composite insulation system with various filling materials. Specifically, we observed that the insulation performance was superior when utilizing a combination of vacuum insulation along with MLI Mylar nets. Additionally, we evaluated the safety within the pipe by comparing the amount of vapor generated inside with the Lower Flammability Limit (LFL). Our results indicate that a safety assessment of the insulation is necessary when no filling material is used. Quantitatively, we found that pipes with composite vacuum and MLI Mylar net insulation reduced vapor generation by 45% compared to vacuum-only insulation, highlighting the effectiveness of the proposed insulation method.

High -temperature duct thermal insulation debonding analysis for civil aircraft

The paper focuses on the problem of the composite thermal insulation of High-temperature Pneumatic ducts for civil aircraft debonding phenomenon. The performance of thermal insulation material is tested to explain the reason why debonding. A model based on the test and thermal kinetic analysis is proposed to quantify the life of the insulation. Based on the model, a certain duration of thermal insulation is calculated. This methodology can predict the life of thermal insulation.

Performance Research and Application Progress of Thermal Insulation Materials for Cold Storage

The thermal insulation performance of thermal insulation materials for cold storage has a great influence on the energy saving of cold storage, so many scholars have done a lot of research on it. This paper summarizes the production, application, and performance analysis of Polyurethane foam plastics (PU), Expanded polystyrene (EPS), Extruded polystyrene (XPS), and rock wool for cold storage, and summarizes the thermal insulation application of civil-type cold storage, steel structure cold storage, prefabricated cold storage and cold storage pipeline, as well as the cold storage anti-cold bridge measures.

Examining the performance of thermal insulation materials used in buildings for noise insulation

Urbanization is spreading throughout the world as a result of rising population. Accordingly, airway, seaway, road, and railway transportation networks are expanding. Advancements in transportation and population growth result in significant increases in environmental noise. Increased noise levels have a negative impact on people's health and cause a variety of issues such as sleep disorders and communication problems. Consequently, various noiseproofing (insulation) regulations and codes have appeared in various countries. However, studies conducted recently have shown that in order for providing sustainable quality of life, it is recommended that the noise level should not exceed certain values. On maximum noise levels for comfortable living places have revealed that adequate and enough insulation levels should be satisfied using the criteria specified in specifications. Nowadays, building energy savings have increased significantly with the use of thermal insulation materials used in buildings. This study investigates the performances of commonly used thermal insulation materials in buildings on noise insulation. Namely, the effects of various wall thicknesses and thermal insulation materials on noise insulation performance were studied. Outdoor and indoor noise levels were measured in a heavily trafficked workplace area of Konya, Turkey, which is identified as sample noise noise source of this study. It was found out in the study that while some thermal insulation materials provide adequate noise insulation in a specific noise frequency range, some others not adequate.

Performance of Thermal Insulation Material Produced from Lithuanian Sheep Wool

ABSTRACT In the current paper, the thermal insulation material from the wool of sheep grown in Lithuania is analyzed. Three types of thermal insulation material were produced: horizontal orientations, corrugated from the individual layer obtained, and corrugated from individual mats. The 50 mm thick products were prepared and their main performance characteristics were evaluated: thickness changes, thermal conductivity, tensile strength, short-term water absorption, and flammability. Changes in the thickness of the materials were determined under different loads, and dependences on the density of the material were obtained. Thermal conductivity was measured for products of different densities, evaluated separately for horizontal orientation and corrugated products, and density dependences were obtained. Tensile strength was determined along and across the direction of formation for relatively different types of products. For all types of products, the short-term water absorption of the specimens was determined by partial immersion in water, and the results were compared. During the flammability tests, the flame propagation time on the specimen surface and the fact of incineration after removal of the flame source were determined for all types of specimens.

Analysis of Sheep Wool-Based Composites for Building Insulation.

The aim of this paper is to propose ecological thermal insulation materials that meet the goals of sustainability but also fulfill the imposed thermal performance requirements. This paper studies new composite materials based on sheep wool from the perspective of thermal conductivity. The composites were prepared using two types of binder: acrylic-polyurethane resin and natural rubber latex, which were applied to the wool fibres through different methods and percentages. Based on the obtained results of thermal conductivity, two types of samples were selected for further analysis, which aimed to determine the microstructure, chemical composition, water absorption, attack of microorganisms, water vapour permeability, hygrothermal adsorption characteristics and sound absorption of the samples. In order to analyse the variation of thermal conductivity, the following parameters were taken into account: thickness, density, type of binder and percentage of binder. Following the obtained results, it was observed that the value of the thermal conductivity of the samples varies between 0.0324 and 0.0436 W/mK. It was found that all the samples prepared and analysed in this study fulfil the national criteria for the thermal performance of thermal insulation material. After conducting the in-depth analysis of the two selected sample types, it was concluded that both materials have good sound absorption characteristics over the considered frequency range. In addition, as it was expected from the natural fibres, the samples had low resistance against the attack of microorganisms and water-related tests.

Evaluation of environmental impact on the formaldehyde emission and flame-retardant performance of thermal insulation materials

Thermal insulation material, an essential building material, is used to preserve heat or block heat gains in buildings. Insulation material is currently attracting significant attention, and thermal conductivity, i.e., thermal insulation performance, is expressed at a very low value. Therefore, since the era of industrialization, several chemicals have been used to secure thermal insulation performance in each sector; therefore, the resulting hazards have increased. To date, researches have been mainly conducted to secure the low thermal conductivity of insulating material; however, the hazards remain unaddressed. Therefore, this study quantitatively evaluates 18 building construction products and the emission of pollutants and harmful gas during combustion events. Pollutant emission was conducted using the 20-L small chamber method according to the ISO 16000, and formaldehyde, total volatile organic compounds, and five volatile organic compounds were analyzed. Gas hazard evaluation during combustion was evaluated by KS F 2271: Fire Retardant Testing Method of Interior Finishes and Structures as the average behavioral stop time of rats under thermal insulation combustion conditions.

Moisture absorption characteristics and thermal insulation performance of thermal insulation materials for cold region tunnels

Laying thermal insulation is one of the common thermal insulation measures to prevent frost damage of tunnels in cold regions and the performance of thermal insulation material directly determines the effectiveness of freeze-proofing and insulation of thermal insulation layer. As an important parameter for evaluating the performance of thermal insulation materials, thermal conductivity is generally affected by density, humidity, temperature and other factors, therefore this paper will mainly focus on when the air humidity in the tunnel is too high, the moisture absorption of insulation materials may occur in the humid environment for a long time, which will lead to the increase of moisture content of insulation materials. Hence tunnels in cold regions, generally exhibit lower temperature conditions, thus the water inside the insulation material is easy to freeze, which will greatly improve the thermal conductivity of the material and reduce its thermal insulation effect. Therefore, it is of great significance to study the thermal insulation performance of cold-regions tunnel thermal insulation materials after moisture absorption and complete freezing.

Effect of built-in mineral wool insulations durability on its thermal and mechanical performance

Energy efficient buildings are unimaginable without highly insulating thermal envelopes. Mineral wool among others is a popular material for thermal insulation. Architects and engineers usually use the data given by the manufacturer in the specification of the material for their building physical design. Such data are obtained from laboratory measurements, carried out on non-aged, and dry samples. However, moisture could affect the thermal performance of insulation materials and may affect the durability too. In the research, we examined stone mineral wool hardboard thermal insulations, which were obtained from a flat roof. The samples looked differently: some of them were in good condition and maintained their load bearing capability, but some were spoiled and soft. We measured and compared the used samples’ thermal conductivity, sorption isotherm and deformation under compressive force to new etalon samples. We also investigated the reason behind the lack of load bearing durability of the built-in and spoiled mineral wool boards using scanning electron microscopy and derivatography. In our study, we show how built-in conditions changed the thermal and mechanical properties and thermal performance of the mineral wool insulation layer, which could degrade by up to 40% in terms of thermal resistance under built-in conditions due to certain spoiling and production mistakes of mineral wool.

Porosity distribution optimization of insulation materials by the variational method

Heat transfer performance of thermal insulation materials is determined by many independent parameters, it is hard to optimize the internal structures of such materials through constructing a mathematical relation between the independent parameters and the optimization objective. In this paper, we theoretically analyze such factors as temperature, pressure and porosity influencing the heat transfer performance of porous materials, establish a mathematical model by using the entransy theory with such constraints as fixed mass and thickness of the porous material, and finally apply the variational principle to derive the governing equations for optimizing the porosity/solid fraction distribution in porous materials. Meanwhile, a 1-D and a 2-D physical model are taken as examples to show the applications. When the surface temperatures as well as the total mass and thickness of the high-porous structure are given, we get the optimal porosity distribution through solving the newly derived governing equations. The results show that both heat flux and the effective thermal conductivity of the optimized structure is the minimal. That is, the thermal insulation performance is optimal.

Experiences when employing different alternatives for envelope upgrading

The challenges of achieving the 2020 goals in terms of energy savings and improving efficiency are guiding numerous research initiatives looking for more insulated envelopes, dealing with thermal performance of insulation materials and envelope systems. Nevertheless, the envelope integrates within the building and this improvement on the insulation performance has to be properly adopted, taking into account the interrelation of main elements composing the overall system (facade, frame, slabs, openings, partitions etc.), as well as side effects originated not only for new erected buildings, but specifically in renovation and retrofitting works. This paper describes real experiences when considering various options for upgrading the facade through the increase of the insulation capacity, starting from external overcladding prefabricated panels and ventilated facades, advancing to more sustainable low carbon systems and ending with even more highly insulated solutions employing aerogels. Lessons from these cases, where energy and hygrothermal assessments have being carried out, demonstrate the influence of the design and construction phases and the relevance of disregarded effects such as minor thermal bridges, uncontrolled craftsmanship on site, and moisture transfer for the different technologies considered. Finally, possible alternatives are provided to overcome some of the detected difficulties, such as combination with non-metallic structural components and building membranes, and being prepared for future challenges and new developments when these isolative elements are combined with other technologies, as for example, renewable energy harvesting devices.

Prediction of varying thermal resistivity of organic insulation materials

Temperature, humidity and aging have significant influence on the thermal performance of insulation materials. The assumption of constant material properties frequently leads to the wrong results for simulating heat transfer through insulation materials. Therefore, the impact of hygrothermal conditions and aging on the long-term behavior of insulation materials should be investigated. The objective of this work is to evaluate the influence of coupled hygrothermal conditions and aging on the thermal resistivity of organic foamy materials. A model of aging conversion coefficient for two organic foamy materials is proposed. The thermal resistivity ratio (TRR) is calculated using the coupled heat and moisture transfer model which introduces effective thermal conductivity for expanded polystyrene and extruded polystyrene. The comparison of predicted values with experimental data shows a good agreement. This paper provides an estimation approach to the aging conversion coefficient that affects the thermal conductivity of the organic foamy materials.

Research on the Heat Exchange Performance of Thermal Insulation Material and Cooling Pipe for Concrete Dam

In the mass concrete structure construction, the thermal insulation material and cooling pipe are important temperature control materials to prevent concrete from cracking. In order to select the right materials, their heat exchange coefficients should be obtained exactly. But no proper apparatus can give the parameters through simple measure. An experiment concrete block with the dimension of 50m long and 22m wide was established near a dam construction site and the corresponding inversion calculating was applied. The experiment method is presented. The measured curves and calculated curves meet well which shows the inversed parameters reliable. Then the heat exchange coefficients of the EPE insulation materials with different thickness and the HDPE pipes with different diameters are given. The application effect shows the selected materials have achieved the goal of crack prevention. The experiment and inversion method will provide reference to other cases and the heat exchange coefficients can be used in similar structures.

EXPERIMENTS ON INFLUENCE OF MOISTURE ON THERMAL PERFORMANCE CHANGE OF INSULATIONS

In order to save energy consumption for air-conditioning of buildings throughout those lifecycle, thermal performance of insulation materials applied in buildings should be kept in required value. On the other hand, there are many factors of ageing of insulation materials such as ambient temperature, vibration and moisture etc. In the previous paper, main factors of thermal performance change were discussed and several experimental results were shown. This paper examines the influences of moisture on thermal performance of various insulations based on three kinds of experiment. In first experiment, the relationship between equilibrium moisture content and thermal conductivity of fiber insulations is obtained. Second experiment is on the influence of gaseous moisture on fiber insulations and the results show that the dimension change of fiber insulations is small even in very humid condition. Third experiment is on the reversibility of thermal conductivity after the internal dew condensation process and the dry process, and the results show that many insulation materials have reversibility except for several plastic insulation foams.

INVESTIGATION OF FACTORS OF PERFORMANCE CHANGE OF INSULATIONS AND EXPERIMENTS ON INFLUENCE OF VIBRATION ON THERMAL PERFORMANCE CHANGE

Thermal performance of insulation materials decreases with the passage of time. Such ageing of insulations should be considered in the design stage of buildings to keep insulation performance within the required one throughout the lifecycle of buildings. Firstly, this paper focused various factors that affect performances of insulations. The main factors for fiber insulations are moisture, vibration and microbe. The main factor for plastic insulation foams is ambient temperature that accelerates the diffusion of blowing agent. Secondly, real performances of sold new insulations and scraped old ones were measured and compared the required value by Japanese standard. Performances of some insulations were lower than standard values and performance change was detected. Finally, this paper discussed the influence of vibration on performance for fiber insulations based on the experimental data. The changes of insulation depth and thermal resistances were observed after the vibration test.