Thermal Insulation Efficiency Research Articles

ผลิตภัณฑ์คอนกรีตบล็อกมวลเบาผสมเศษเซรามิกเหลือทิ้งจากโรงงานอุตสาหกรรม สำหรับการก่อสร้างอาคารเขียว

The objectives of this research are to study the production step, proper ratio, physical properties, mechanical properties and thermal insulation of concrete blocks mixed with waste ceramic powder. The ratios of concrete block mixed with waste ceramic powder include Portland cement type1: quarry dust: waste ceramic powder equal to1: 6.8: 0.2, 1: 6.7: 0.3, 1: 6.6: 0.4, 1: 6.5: 0.5 and1: 6.4: 0.6 by weight. Water per cement ratio are 0.6 by weight. The concrete block samples were casted by the general production as same as the ordinary concrete blocks and were tested follow TIS.58. From the results, the best amount of waste ceramic powder which put into concrete block is 1: 6.7: 0.3 of ratio. The proper ratios of waste ceramic powder can decrease the density or weight, and increase the thermal insulation efficiency of concrete blocks. However, the high volume of waste ceramic powder effects to decrease the mechanical properties of concrete blocks to lower than TIS.58 standard.

Directing the pore size of rigid polyurethane foam via controlled air entrainment

The interest in polyurethane rigid (PUR) foams as potent thermally insulating materials for a wide range of applications continues to grow as the minimization of CO2 emissions has become a global issue. Controlling the thermal insulation efficiency of PUR foams starts with the control of their morphology. Although the presence of micrometric air bubbles originating from air entrainment during the blending of the PU reactive mixture has been shown to influence the final PUR foam morphology, detailed experimental investigations on how exactly they affect the final PUR foam pore size are still lacking. To fill this gap, we use a double-syringe mixing device, which allows to control the number of air bubbles generated during a first air entrainment step, before using the same device to blend the reactive components in a sealed environment, avoiding further air entrainment. Keeping all experimental parameters constant except for the air bubble density in the reactive mixture, we can correlate changes of the final PUR foam morphology with the variation of the air bubble density in the initially liquid reactive mixture. Our results confirm recent findings which suggest the presence of two different regimes of bubble nucleation and growth depending on the presence or absence of dispersed air bubbles in the liquid reactive mixture. Our study pushes those insights further by demonstrating an inverse relation between the air bubble density in the liquid reactive mixture and the final pore volume of the PUR foam. For example, at constant chemical formulation and blending conditions, we could vary the final pore size between 400–1600 μm simply by controlling the amount of pre-dispersed air bubbles within the system. We are confident that the presented approach may not only provide a valuable model experiment to scan formulations in R&D laboratories, but it may also provide suggestions for the optimization of industrial processes.

Antibiotics tetracycline adsorption and flame-retardant capacity of eco-friendly aerogel-based nanocellulose, graphene oxide, polyvinyl alcohol, and sodium bicarbonate

This study presents a new approach in aerogel based on nanocellulose, graphene oxide, and its application as a novel adsorbent in water treatment and opening up a new potential material of thermal insulation. The eco-friendly aerogel materials were prepared by combining cellulose nanofibers (CNFs), graphene oxide (GO) sheets, polyvinyl alcohol (PVA), and sodium bicarbonate (NaHCO3) through a simple mixing and freeze-drying method. The structure of eco-friendly aerogel was also analyzed by scanning electron microscope (SEM) images, X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. The specific surface area and average pore diameter of the aerogel were also measured using Brunauer-Emmett-Teller (BET) analysis. The results showed that the presence of NaHCO3 played a role as a green flame retardant in CNF/GO/PVA/NaHCO3 aerogel. It significantly improved the thermal stability, 20 times higher in combustion characteristics, and thermal insulation efficiency better 3 times than those without NaHCO3. In addition, the NaHCO3 played as an effective additive to improve not only the thermal characteristics but also the removal ability of antibiotic TC of this aerogel material. The CNF/GO/PVA/NaHCO3 aerogel has the equilibrium TC adsorption capacity of 71.34 mg×g−1 which is about 28% higher than that of CNF/GO/PVA after approximately 60 min. The pseudo-second-order kinetic model showed an agreement with the adsorption model of this type of aerogel with a correlation coefficient (R2) of more than 99%.

Analysis of the compliance of windows with up to day energy efficiency requirements

Due to the consequences of the energy and environmental crises, reducing energy consumption in buildings is an urgent task, both globally and nationally. It is this goal that causes a constant increase in the requirements for resistance to heat transfer of the external enclosing structures of buildings in climatic conditions, where the design temperature of the outside air is at the level of -20ºС. Increasing the resistance of non-transparent enclosing structures is achieved by available means that allow guaranteed achievement of the designated resistance to heat transfer. Increasing the heat transfer resistance of transparent (or translucent) enclosing structures has limitations that limit the maximum values. The analysis of window designs that are offered on the construction market of Ukraine in the context of the requirements of DBN V.2.6.31-2021 "Thermal insulation and energy efficiency of buildings" was carried out. To increase the resistance to heat transfer of windows, the manufacturer has (today) three constructive means - an increase in the number of chambers, the use of selective coatings and filling the chambers with an inert gas argon. It should also be taken into account that the production of windows is a multicriteria task, in which the achievement of a certain level of resistance to heat transfer is one of the factors among others, no less important. The results of the analysis show that the fulfillment of the requirement Rqmin≥0.9 m2•ºС/W for the first temperature zone of Ukraine requires the use of all technical means available from manufacturers. A sample of eighty-two window designs that are actually offered on the Ukrainian construction market was analyzed. Compliance with the requirements for the second temperature zone was achieved for forty-three percent of window designs. Compliance with the requirements for the first temperature zone was achieved for seventeen percent of window designs. The complexity and increased cost of such structures may necessitate additional control measures at the completion of construction and during the operation of buildings.

Rejuvenating the Market for Earth-Based Building Construction Materials in a Developing Economy

Earth-based materials are useful in building and engineering construction projects globally, but they have largely remained unextracted and wasted, and their use has been limited to rural areas and avoided in modern buildings in the cities. The sustainability market in developing countries is still largely unsaturated and undertapped. This situation is blamed on lack of knowledge of the potential, benefits, and characteristics of green and sustainable building materials. This study aimed at determining the benefits of earth-based materials that could lead to the rejuvenation of the market for their adoption in building construction projects in the urban areas of a developing economy. The study adopted a structured questionnaire administered via electronic means to construction experts using the snowball sampling technique in Nigeria. With a response rate of 62.94% and a reliability index of over 0.90, the gathered data were analysed using frequency, percentage, and exploratory factor analysis (EFA). The study revealed that the main clusters of benefits of earth-based materials that can stimulate the market for these materials in urban areas are "cost and pollution-related benefits," "emissions and environmental benefits," "waste and workability benefits," "sound and fire-related benefits," and "thermal insulation and resource efficiency." The study recommended that housing investors, clients, and stakeholders should capitalise on the availability of large quantities of earthen materials to improve the quantity of housing provisions in cities and urban areas.

Thermal Insulation and Compressive Performances of 3D Printing Flexible Load-Bearing and Thermal Insulation Integrated Lattice

Structurally and functionally integrated materials usually face the problem of serious functional degradation after large deformation or fracture, such as load-bearing and thermal insulation integrated lattice. In this work, the lattice with a big width-thickness ratio, which empowered the flexibility of the lattice by reducing the rod deformation during compression, was proposed. The structure of the lattice almost kept integrality after large deformation or fracture, and the decay of thermal insulation performance was less. Compared with the conventional lattice, the big width-thickness ratio lattice obtained favorable thermal insulation performance. On this basis, two kinds of flexible load-bearing and thermal insulation integrated hourglass lattices with big width-thickness ratios (BWR lattice) were prepared by SLM, and the thermal insulation and compressive performances were measured. The thermal insulation efficiency could reach 83% at 700 °C. The lattice would recover after large deformation or fracture, and the thermal insulation efficiency of the fracture lattice was 75%. This work provides a new way of designing load-bearing and thermal insulation integrated lattice and achieves the functionality preservation of load-bearing and thermal insulation integrated lattice after large deformations and fractures.

3D-printed SiC lattices integrated with lightweight quartz fiber/silica aerogel sandwich structure for thermal protection system

A lightweight thermal protection/insulation integrated sandwich structure for the aerospace thermal protection system (TPS) was developed with the aim of achieving superior mechanical strength and thermal insulation properties. On the one hand, the lattice frameworks of silicon carbide (SiC) ceramic thermally insulated components with body-centered lattice core (BCLC) were fabricated by selective laser sintering (SLS) 3D printing technology; on the other hand, the sol–gel process was applied to fill quartz fibers reinforced silica (Qf/SiO2) aerogel into the hollow parts of the BCLCs to form a sandwich structure, thus further enhancing the mechanical and thermal insulation properties. To explore the impact of lattice core structure gradient on performance, we designed two types of BCLCs, single-layer one and double-layer one. By comparing the properties of the sandwich structures with the BCLCs, it was found that after the hot surface temperature was kept at 1000℃ for 1500 s, the backside temperature of the single-layer and double-layer sandwich structures decreased by 69.15℃ and 112.73℃, respectively, implying that the thermal insulation efficiency increased by 8.75 % and 13.85 %, respectively. Remarkably, it was precisely due to the filling of the Qf/SiO2 aerogels that the compressive strength of the single-layer and double-layer sandwich structures reached 119.41 MPa and 35.16 MPa, respectively, which were successfully improved by 238.56 % and 256.23 %, respectively, in comparison with the BCLCs structures. Consequently, this study provides an efficient and reliable method for the preparation of thermal protection/insulation integrated components by using 3D printing technology combined with the sol–gel method, which has broader significance among academic and industrial communities.

Temperature-adaptable pressure sensors based on MXene-coated GO hierarchical aerogels with superb detection capability

With the broader application of intelligent sensors in various complex conditions, sensing materials with better mechanical and conductive properties as well as higher temperature adaptability are required. For this purpose, a GO/PVA/MXene (GPM) composite aerogel was designed and prepared via a two-step strategy, including self-assembly and vacuum-assisted dip-coating processes. The as-prepared GPM has a unique structure composed of hierarchical GO network skeleton and MXene coating, endowing it with high Young's modulus (11.2 kPa) and compressibility (90%). Demonstrated with the finite element (FE) simulation, the elasticity and toughness of the GPM are originated from the hierarchical microstructure and the improved thickness of shells. Besides, the GPM exhibits a long-term durability of 5,000 compression cycles at 50% strain, a high sensitivity of 1.744 kPa−1, and a rapid response time of 4.5 ms. Further application examples reveal that the pressure sensor based on GPM has superior physiological signal capture capability, realizing fingertip pulse and temporal artery detections. Moreover, the GPM aerogel possesses high thermal insulation efficiency, resulting in good temperature adaptability in harsh environments from −196 °C to 300 °C. The sensitive pressure sensors should have the potential application in many fields of intelligent factories, complex militaries, and space discoveries.

Producing sustainable concrete with plastic waste: A review

Plastics are cheap, lightweight, versatile, and readily accessible material. The utilization of plastic has become a necessary facet of our day-to-day lives, and its production has risen exponentially in the last 50 years. As a result, there is an increase in the generation of waste related to plastic that leads to undermining the environment. This encourages researchers to use this waste in concrete manufacturing as a sustainable material. However, this paper reviews recent research on how the utilization of recycled plastic in concrete is an effective solution to enhance sound and thermal insulation. The aggregate comprises the largest and heaviest portion of concrete, which accounts for 85% of its weight. Besides, the plastic has a low density compared to the aggregate. As a result, the use of plastic waste as a partial replacement (50% to 75%) for the total aggregate significantly boosts the efficiency of thermal and sound lightweight concrete insulation. In addition, the cost of its manufacturing is drastically diminishing in comparison to that of ordinary concrete, and plastic can be installed and utilized quickly with less labor due to its lightweight nature. Plastic waste may be considered a typical material for the production of lightweight green concrete that can be used as a non-structural component in building construction.

Numerical investigation of water curtain for smoke blocking and heat insulation in urban underground road

• New variables for evaluating the smoke blocking efficiency and water curtain momentum ratio are introduced. • The effect of water spray intensity and momentum ratio(R) on smoke blocking efficiency are analyzed. • The reasonable conditions for safe evacuation of the trapped people are analyzed. With an appropriate air supply, smoke can be controled by water curtain system effectively in an urban underground road. In this study, smoke blocking efficiency and water curtain momentum ratio are newly introduced. These parameters are used to quantitatively characterize the effects of smoke control and thermal insulation. Numerical simulation method is used in this paper. The results indicate the following: the smoke efficiency decreases as water spray intensity increases, and when the water spray intensity is 0.5L/(m·s), increasing the water spray intensity by 0.5L/(m·s) may be beneficial to increase the smoke blocking performance. The smoke blocking efficiency and the thermal insulation efficiency decrease first and then increase along with the increase in the momentum ratio R. Better smoke blocking and heat insulation performance occured when R ≤ 2. In this condition, the visibility at the 2 m above the floor is above 10 m,and the temperature is lower than 60 °C. It can ensure the safe evacuation of the trapped people.

Study on the Protection Effect of Sprinklers on Glass by Fire Scale in Building Fires

Window sprinklers are commonly used to protect glass, but there is a lack of research on the effect of fire scale on protection. In this study, full-scale experiments on sprinkler-protected glass in building fires were carried out. The experimental process was simulated using CFD numerical simulation software (FDS), and the effect of the heat release rate on the protection effect was revealed based on the glass surface temperature and heat insulation efficiency. It was found that in a full-size compartment fire, the window sprinkler was able to protect the glass from being damaged by high-temperature smoke. The numerical simulation could effectively simulate the spray distribution pattern of a window sprinkler as well as the gas temperature evolution, and the simulation results matched well with the full-size experiments. The window surface temperatures all decreased rapidly and increased linearly with the HRR after the window sprinkler was activated. The steady-state window center temperatures were 40 °C, 60 °C and 76 °C when the HRR was 2 MW, 4 MW and 6 MW, respectively. The window center temperature was less than the critical temperature of glass breakage, indicating that the window sprinkler could protect the glass from fire damage well, within the fire scale of 6 MW. The thermal insulation efficiency in the edge region was slightly lower than that in the center of the window. In the range of 2 to 6 MW, there was no significant correlation between the thermal insulation efficiency and the HRR, and the thermal insulation efficiency was in the range of 54% to 59%.

Layer-by-layer self-assembly of sodium alginate and zinc ions on the surface of graphene oxide to improve the fire protection ability of intumescent waterborne epoxy coatings

In this study, polyethyleneimine (PEI) was first adsorbed on the GO surface, resulting in a positively charged GO/PEI composite. Afterwards, SA and Zn2+ were loaded on the surface of GO/PEI through a facile route to obtain an organic-inorganic hybrids (GPS@Zn). Among them, the gas phase products of SA delayed the progress of the combustion reaction, while the catalytic carbonization of zinc oxide and the high barrier effect of GO effectively improved the thermal insulation efficiency of the char layer. The fire performance test results showed that the backside temperature of GPS@Zn/EP decreased to 161.2 °C after burning for 60 min. The swelling height and swelling ratio of GPS@Zn based EP remained at the highest value compared to the other samples. In addition, the residual char content of EP loaded GPS@Zn was as high as 31.2 %, which lays the foundation for its high thermal insulation performance. The PHRR, THR, SPR and TSP values of GPS@Zn/EP were 420.2 ± 13 kW/m2, 13.2 ± 0.6 MJ/m2,0.078 ± 0.05 m2/s and 1.87 ± 0.05 m2, respectively, which were significantly lower than the other samples, thus proving its best flame retardant and smoke suppressing properties. The carbon residue analysis confirmed that zinc oxide remained in the char layer, which was beneficial to the improvement of its thermal insulation performance and strength.

Superelastic and robust carbonaceous nanofibrous aerogel with high pressure-sensitivity, excellent thermal insulation and high photothermal-conversion efficiency

Carbonaceous aerogels have attracted extensive research interest due to their impressive physical properties such as high porosity, high electrical conductivity, low thermal conductivity, and low density. However, the low durability of the aerogels under compression is a concern. In this work, superelastic, multimodal porous, chitin-derived carbonaceous nanofibrous aerogel (CAs) whose mechanical properties were tunable were prepared by a facile and cost-efficient carbonization method. The CAs exhibited remarkable elasticity and stability under compression, even under extreme temperatures. After the CAs had been subjected to one loading-and-unloading cycle under the compressive strain (ɛ) of 50%, the CAs exhibited a very low energy-loss coefficient (0.15). Moreover, the CAs maintained their structural integrity with little deterioration of mechanical properties after 1000 cycles. The structural stability and the superelasticity of the CAs conferred the materials a fast and accurate piezoresistive response, which renders it promising for the fabrication of pressure sensor with a high gauge factor (GF, 14.24) under low ɛ (up to 2%). Furthermore, the biomass-derived cost-efficient CAs demonstrated high photothermal-conversion efficiency of solar energy (96.4%) and excellent thermal insulation. Therefore, the CAs exhibit potential applications in the fabrication of pressure sensors, the production of thermal-insulation materials, and the desalination of seawater.

Analysis of the efficiency of thermal insulation of high-pressure hoses of the drilling rig URB-2A2 based on mathematical modeling

Analysis of the efficiency of thermal insulation of high-pressure hoses of the drilling rig URB-2A2 based on mathematical modeling

Hydrothermally-calcined waste paper ash nanomaterial as an alternative to cement for clay soil modification for building purposes

It has been observed that clay soil cannot be used for building design, unless it is modified by firing or with cement. Either method of stabilization can adversely affect the environment and public health just like indiscriminate dumping or open burning adopted in developing countries as the prevalent disposal technique for waste papers. This paper sought to examine the feasibility of using assorted waste papers to derive an alternative stabilizer to Portland Limestone Cement for modification of clay soil into composite materials suitable for building design. Specifically, clay-based composites were fabricated at 0 %, 5 %, 10 %, 15 %, and 20% replacement levels by weight with cement, and then hydrothermally-calcined waste paper ash nanomaterial (HCWPAN). Water absorption, sorptivity, bulk density, thermal conductivity, specific heat capacity, thermal diffusivity, flaking concentration, flexural strength, and compressive strength were investigated for each of the fabricated samples. Irrespective of the stabilizing agent utilized, 10% loading level was found to be the optimum for possession of maximum mechanical strength by the samples. Only samples with the HCWPAN content were found to be capable of reducing building dead loads and improving thermal insulation efficiency over un-stabilized clay material, if applied as walling elements in buildings. Generally, it was revealed that the cement and HCWPAN have comparable influences on the properties of clay soil, thus indicating that HCWPAN could be utilized as an alternative stabilizer to cement. In addition, the preparation of HCWPAN was found to be more energy-saving than that of the cement.

Experimental Study of the Thermal Behavior of Perforated Bricks Wall Integrated with PCM

The increasing need to provide standard comfort requirements inside buildings has made the construction sector one of the dominant energy consumers and a contributor to greenhouse gas emissions. Improving the thermal insulation efficiency of the building envelope by improving the thermal behaviour of the walls leads to giving an impetus towards reducing energy consumption. In this paper, an experimental embedding of Phase Change Materials (PCM) with perforated bricks wall. For PCM (Paraffin wax) packaging purposes, two configurations are used; capsules were manufactured to fit the size of the holes inside the bricks and a square thin container. Both packages are made from iron and filled with Paraffin (147 kJ/kg latent heat, 38℃ solid phase and 43℃ liquid phase) and closed in a way that prevents leakage. The experiments included constructing a cube-shaped zone from the sandwich panels material with a square hole (0.5m×0.5m) was made in one of its walls to place the test samples in it. The indoor test proceeded with 900W/m2 light intensity applied directly on the sample external surface. Four different samples named C1, C2, C3, and C4 have been used in this study. When compared to a traditional wall C1, the results showed that the heat flow was reduced by 35.7%, 17.4%, and 13.9% for C2, C3, and C4 respectively. All the models that included PCM got a reduction in temperature increases and a slowdown of thermal diffusion. Placing the PCM layer inside the brick holes achieved a maximum reduction in the heat flux compared to the reference model.

Performance of Thermal Insulation Covering Materials to Reduce Postharvest Losses in Okra

The efficiency of different thermal insulation covers in minimizing temperature fluctuations in cool chain management was investigated to reduce postharvest loss and maintain okra quality during storage and transportation. The four thermal insulation covering materials: (1) heat reflective sheet with thin nonwoven (HRS + TNNW), (2) heat reflective sheet with thick nonwoven (HRS + TKNW), (3) metalized Tyvek® (MTyvek) and (4) metalized foam sheet (MFS) were studied and compared with perforated linear low-density polyethylene (P-LLDPE) as the typical handing package for okra distribution alongside no covering as the control. The material properties, transpiration rate, vital heat, temperature profiles (air and pulp temperatures), relative humidity, mass loss and incidence of decay were determined throughout a simulated supply chain. Results exhibited that HRS + TNNW and HRS + TKNW covers had the lowest thermal heat energy (Qx) and moderate R-value. These two covers maintained low temperature fluctuation with the lowest rate of air and pulp temperature changes, reflecting in lowest mass loss and decay in okra. The HRS + TNNW cover yielded less decay (1%) in okra, compared to commercial covers; MTyvek (16%) and MFS (9%). Results showed that HRS + TNNW exhibited great potential as a thermal insulation cover to reduce postharvest loss in okra (5%) compared to typical handling (11–18%) and could be considered as alternative material to reduce the use of foam sheets in cool chain management distribution packaging of okra under ambient environment conditions.

Эффективность применения теплоизоляции в подземных сооружениях криолитозоны

In continuation of the previously published research results (Energy Safety and Energy Economy, iss. 1, 2021), the current study investigates thermal insulation efficiency for underground structures in permafrost conditions. Thermal insulation experiences the influence of various factors affecting its efficiency. For the purpose of this research, said efficiency was evaluated by intensity of heat flow from air to the ground. The non-stationary heat transfer coefficient, the so-called Kirpichev number, reflects for heat flow intensity. The 3D diagrams show the results of the study with a large data coverage for proper evaluation of thermal insulation efficiency of underground structures in permafrost. The results confirm that thermal insulation can be considered effective both for short-term and long-term underground workings.

Higher thermal insulation and energy efficiency of buildings and prevention of diseases and long-term care

Higher thermal insulation and energy efficiency of buildings and prevention of diseases and long-term care

Effects of Metal Fasteners of Ventilated Building Facade on the Thermal Performances of Building Envelopes

Thermal bridging in the building envelope is one of the main causes of energy losses, even in high-efficiency ventilated building façades. In this study, the effects of point-thermal bridges attributed to metal fasteners on the heat transferred through different types of bricks were predicted. All the structural details of the substrate wall were included as well. This was accomplished with a multi-scale, finite element modelling approach used to enhance the thermal insulation efficiency of the building envelope. The effects of the metal fastener length, diameter, density and location were examined to elucidate any opportunity to minimize the heat losses caused by thermal bridging. The results demonstrated that increases in the lengths of fasteners yielded higher energy losses compared with those generated when the diameter increased. Additionally, metal fasteners caused higher energy losses by up to 30% when fixed on mortar, compared with the energy losses incurred when they were fixed on bricks.