Papers by Keyword: Thermal Insulation

Abstract: This study presents the modelling of heat loss and mass transfer through the walls, using Ubakus program, of a block of flats built in 1978 and thermally rehabilitated after 1990. The objective of the study is to present the thermal and mass transfer parameters before and after thermal rehabilitation. Thus, the benefits obtained after the rehabilitation consist in improving the comfort and health conditions for the residents, as well as reducing the expenses for heating/cooling the house and for renovating the degradation caused by humidity in the walls.

Abstract: Today, the solid waste problem is expanding at an alarming rate, and considering the scale of production and consumption, the textile industry contributes significantly to this waste. An indispensable component of fast fashion, polyamide-containing pantyhose are included in the disposable product group and cause irreversible loss of a very valuable raw material. The waste of this product group constitutes a hidden waste group that does not decompose in nature and has not yet been recycled. This study focuses on recycling polyamide-containing pantyhose waste and evaluating them in thermal insulation panel production. In this context, the process of opening the fibers of the pantyhose is carried out in a carding machine, and a hot press technique is utilized with the addition of low melting temperature polypropylene fibers as a binder, for panel production. Rice husk, which is a commonly known agricultural waste, is also introduced into the panels in different forms (granule and powder) for better air encapsulation. The effect of ply number (two and four) and the form of rice husk added as an additive on thermal and air permeability properties is examined within the framework of a full factorial experimental design plan. The findings obtained reveal that the variables affect both thermal insulation and air permeability properties both individually and in binary interactions. The lowest thermal insulation coefficient is obtained in the two plied, granule form rice husk added sample group (0.02117 W/mK), which also has the highest air permeability values (442.57 l/m²/s) and the results are found to be competitive with commercial products. This suggests that it is possible to use this waste group in sustainable panels for construction, and the findings reveal that it may create value in terms of both solid waste management and exploring new resources for polyamide-based fibrous products.

Abstract: This research investigates the influence of the quantity and type of flame retardants and blowing agents on the thermal insulation properties of foam prepared using STR 20 block rubber. Supercell DPT was employed as a blowing agent, and aluminium trihydroxide (ATH) and chlorinated polyethylene (CPE) functioned as flame retardants, with their concentrations adjusted to 10 and 20 parts per hundred rubber (phr). All rubber compound formulations were prepared via a semi-EV sulphur vulcanization system. The expansion ratio in a compression mould and curing properties of the rubber compounds were determined at 170 °C. The experimental results revealed that increasing the amount of blowing agent from 3 to 8 phr led to a maximum increase of 110% in the pore size within the foam structure. Both ATH and CPE at a concentration of 10 phr are sufficient to make all insulating foam formulations pass the UL-94 HBF flammability test. The natural rubber foam applied with 8 phr of blowing agent and 10 phr of ATH flame retardant exhibited the lowest water absorption at 0.46%. It also demonstrated good durability at a maximum temperature of 84 °C for 7 days, and the lowest thermal conductivity (K-value) of 0.0648 W/m·K according to ASTM C518-10.

Abstract: The growing amount of textile waste presents a significant environmental challenge, requiring creative and sustainable methods for management and repurposing. Recycled and reused textiles are increasingly being utilized in the building industry, particularly as thermal and sound insulators. Effective thermal insulation is crucial for creating comfortable and energy-efficient buildings, especially in light of climate crisis and increasing energy expenses. In this study, the production of thermal insulation panels is achieved using textile waste through sustainable and innovative techniques. Cotton denim and polyester label selvedge waste are first converted into fibers and carded, then arranged into sandwich structures and formed into panels using a hot press method. The study involves experimental evaluations to determine the thermal performance of panels, with the aim of developing insulation panels that improve energy efficiency and reduce heat loss in buildings. The research also emphasizes the environmental and economic benefits of using textile waste for insulation, highlighting the thermal properties of these panels. The results show that double-layer cotton panels have the lowest thermal conductivity ranges between 0.026 and 0.028 W/mK among tested configurations, suggesting a superior insulation capability that could lead to significant energy savings in buildings.

Abstract: Waste amount in the textile industry is rising in tandem with rising production and consumption levels. Reusing waste is always the best option, but for some textile products, this isn't the case. A ruptured pair of pantyhose is among the one of the best examples. Due to their delicate structure, these products are easily punctured, so they are disposed of in solid waste sites after 2-3 times use. In this study, it is aimed to recycle these pantyhose waste (polyamide/elastane), and use it in the production of thermal panels, and to statistically examine the effects of varying thickness and elastane content on the thermal insulation and air permeability of this material. In order to create nonwoven structures with varying thicknesses and elastane ratios, the pantyhose wastes converted into fiber form and then into carded web by using a carding machine. Then, a needle punching technology is used for the web formation process. The Minitab software program is used to analyze changes in air permeability and thermal conductivity coefficient between the samples using a full factorial experimental design. The findings indicate that while both factors affected air permeability, only the changing thickness had a statistically significant impact on the thermal conductivity coefficient.

Abstract: The promise of transforming wastes from the Azores into building materials is the focus of this research. The insulation properties of some of these materials can be advantageous to the building construction sector. These materials are upcycled into non-structural components of the building such as panels for ceilings and walls as a factor to control thermal comfort economically. In this paper, insulation panels using cryptomeria waste from the carpentry industry were developed and experimentally evaluated in terms of conductivity for further study of their thermal properties, as well as life cycle analysis. Sodium silicate was used as a primary binding material along with these treated materials. The different composite panels made from the waste and surplus materials are expected to be analysed in Test cells that are built in Azores using this together with other wastes available in the region. These panels will be tested for longer periods in these test cells subjected to the local climatic conditions. The results of thermal conductivity are promising for the two composites sampled.

Abstract: This paper aims to study the possibility of valorizing hemp residues in order to develop new local bio-composites from Moroccan hemp shiv and epoxy. The goal is to use them as thermal and acoustical insulation panels since these hemp residues exist in large quantities in landfills and present a national concern due to a lack of waste management technologies. For this purpose, several samples were prepared for different densities and two sizes of hemp shiv; crushed shiv (CS) and fibred shiv (FS). The results revealed that the increase of density resulted in an increase in thermal conductivity and a decrease in thermal diffusivity. However, the thermal conductivity of composites is still lower than 0.1 W/mK for the most studied samples. The samples show values of acoustic absorption coefficients varying between 0.2 and 0.59 for crushed shiv composites (CSC) at the frequency range (578-1396 Hz) and between 0.2 and 0.73 at the frequency range (662-1396 Hz) for Fibred shiv composites (FSC). It has been observed that the density has a significant effect on the sound absorption coefficient. Increasing the density shifts the acoustic absorption curve towards the low frequencies. Also, decreasing the particle size enhances the sound absorption in the medium frequency range (300-600 Hz). The obtained results are satisfactory for manufacturing these new composites that can be used as thermal and acoustic insulators. Moreover, it offered the best solution for hemp waste management.

Abstract: Population growth, urbanization, industrialization, developing technology, increasing welfare level and changing consumption habits cause solid wastes to increase day by day. There are also sub-waste groups that have not yet been fully recognized among the solid waste groups in which textile wastes have a large share. One of them is pantyhose, which has been indispensable for modern life since the day it was presented to the consumer. These socks, which are made of polyamide and elastane fibers that are easily punctured, run and become unusable when worn once or several times, are generally thrown away after use. These pantyhose wastes, which are not biodegradable due to their raw materials, also pose an environmental risk. Within the scope of the study, thermal and sound insulation properties of carded and needle-punched pantyhose wastes are investigated. The results show that the thermal and acoustic properties of the developed material are at a sufficient level, and it has ensured that polyamide wastes, which have superior properties among thermoplastic polymers and have high economic value, are brought back into the economy.

Abstract: The paper presents a numerical study of thermal conductivity of porous structures using the Ansys software package. Unlike the well-known porous materials used in construction and engineering, it is proposed to use porous materials with an ordered law of cavity placement. The porous material proposed is formed by dividing the volume into cubes of equal size with a spherical cavity placed in the center of each cube. The numerical calculation of an effective thermal conductivity coefficient of a porous medium is performed using the Ansys Mechanical computer modeling tool. The values obtained are compared with solutions based on classical methods for determining the effective thermal conductivity of porous materials. A dependency graph of effective thermal conductivity in a porous material based on pores geometric parameters (distance between cavities, diameter of cavities), as well as an analytical dependence to obtain the effective thermal conductivity value is presented. Additive technologies available today provide producing the proposed porous material with an ordered law of cavity placement with any accuracy and any pore geometric parameters. Such materials open up wide opportunities for engineers, especially in the field of thermal power engineering, because it has predictable thermophysical and mechanical properties.

Abstract: The construction sector is a major contributor to total energy consumption, therefore, it is crucial to adopt energy efficiency strategies capable of reducing energy impact in buildings. Among these strategies, exterior wall insulation is one of the most cost-effective options to achieve energy savings for both newly constructed and renovated buildings. In this paper, based on an economic analysis, we aim to determine the economically optimal thickness of insulation material to be used for retrofit interventions of masonry structures. The study analyzes 10 different insulating materials and 5 masonry structures widespread in Italy. The results show that each masonry structure requires a careful evaluation of the thickness of the insulating material to be applied in retrofit operations. Moreover, varying the type of insulating material used, even if applied to the same wall structure, there are different levels of thickness to be applied in order to optimize the performance of the structure.