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Graphene-based nanocomposites and nanohybrids for the abatement of agro-industrial pollutants in aqueous environments 全文
2022
Farhan, Ahmad | Rashid, Ehsan Ullah | Waqas, Muhammad | Ahmad, Haroon | Navāz, Shāhid | Munawar, Junaid | Rahdar, Abbas | Varjani, Sunita | Vēlāyutan̲, T. A.
Incessant release of a large spectrum of agro-industrial pollutants into environmental matrices remains a serious concern due to their potential health risks to humans and aquatic animals. Existing remediation techniques are unable to remove these pollutants, necessitating the development of novel treatment approaches. Due to its unique structure, physicochemical properties, and broad application potential, graphene has attracted a lot of attention as a new type of two-dimensional nanostructure. Given its chemical stability, large surface area, electron mobility, superior thermal conductivity, and two-dimensional structure, tremendous research has been conducted on graphene and its derived composites for environmental remediation and pollution mitigation. Various methods for graphene functionalization have facilitated the development of different graphene derivatives such as graphene oxide (GO), functional reduced graphene oxide (frGO), and reduced graphene oxide (rGO) with novel attributes for multiple applications. This review provides a comprehensive read on the recent progress of multifunctional graphene-based nanocomposites and nanohybrids as a promising way of removing emerging contaminants from aqueous environments. First, a succinct overview of the fundamental structure, fabrication techniques, and features of graphene-based composites is presented. Following that, graphene and GO functionalization, i.e., covalent bonding, non-covalent, and elemental doping, are discussed. Finally, the environmental potentials of a plethora of graphene-based hybrid nanocomposites for the abatement of organic and inorganic contaminants are thoroughly covered.
显示更多 [+] 显示较少 [-]Thermal, hygric, and environmental performance evaluation of thermal insulation materials for their sustainable utilization in buildings 全文
2021
Wi, Seunghwan | Park, Ji Hun | Kim, Young Uk | Yang, Sungwoong | Kim, Sumin
As energy use in the building sector is increasing worldwide, building materials with characteristics that save energy are becoming increasingly important; in addition, there is an emerging need for high-performance insulation materials with low thermal conductivity. However, thermal insulation should consider thermal conductivity, which is the main performance parameter, in addition to the water adsorption rate, acidity, and deformation and expansion due to drying conditions. This study evaluated the main performance of 21 insulation materials used at construction sites to objectively and clearly evaluate their overall performance, including their thermal conductivity. Thermal conductivity was measured by the heat flow meter method according to ASTM C518 and ISO 8301 standards; it was also evaluated according to the drying conditions. The water absorption rate was evaluated by ISO 2896 to ensure the sustainability and long-term thermal conductivity performance of the material. Acidity was evaluated with ASTM E861 to reduce the environmental load of the buildings and soil. The results of this study reviewed an appropriate method to measure the main performance according to the type of insulation.
显示更多 [+] 显示较少 [-]Ignitability of crude oil and its oil-in-water products at arctic temperature 全文
2017
Ranellone, Raymond T. | Tukaew, Panyawat | Shi, Xiaochuan | Rangwala, Ali S.
A novel platform and procedure were developed to characterize the ignitability of Alaska North Slope (ANS) crude oil and its water-in-oil products with water content up to 60% at low temperatures (−20–0°C). Time to ignition, critical heat flux, in-depth temperature profiles were investigated. It was observed that a cold boundary and consequent low oil temperature increased the thermal inertia of the oil/mixture and consequently the time to sustained ignition also increased. As the water content in the ANS water-in-oil mixture increased, the critical heat flux for ignition was found to increase. This is mainly because of an increase in the thermal conductivity of the mixture with the addition of saltwater. The results of the study can be used towards design of ignition strategies and technologies for in situ burning of oil spills in cold climates such as the Arctic.
显示更多 [+] 显示较少 [-]Effects of Corn Straw Biochar, Soil Bulk Density and Soil Water Content on Thermal Properties of a Light Sierozem Soil 全文
2023
Y. Q. Li, L. J. Li, B. W. Zhao, Y. Zhao, X. Zhang and X. Dong
This research aimed to quantify the effects of biochar derived from corn straw on soil thermal conductivity, capacity, and diffusivity. Firstly, the amount of biochar application (w/w) added to light sierozem soil was 0% to 5%, and the mixtures were packed into soil columns at a consistent bulk density (1.20 g.cm-3). Secondly, soil columns with a consistent biochar addition rate (5%) were packed to different bulk densities of 1.30, 1.25, 1.20, 1.15, and 1.10 g.cm-3. Soil thermal characteristics were measured under the control of soil moisture content from 0% to 40%. Under consistent bulk-density conditions, biochar could significantly reduce soil thermal conductivity and diffusivity. Still, there wasn’t a significant influence on soil heat capacity in most soil moisture content levels. With the decrease of soil bulk density, soil thermal conductivity, capacity, and diffusion coefficient reduced significantly. As soil water content increased, all the indexes of thermal properties largely improved, and the effects were much more significant than those of biochar amendment and bulk density change on soil thermal performances. This research could supply an implication to evaluate the influence of biochar amendment on soil thermal performances.
显示更多 [+] 显示较少 [-]Recycling of marble cutting waste additives in fired clay brick structure: a statistical approach to process parameters [Erratum: October 2022, v.29(47); p.71948] 全文
2022
Erdogmus, Ertugrul | Yaras, Ali | Sutcu, Mucahit | Gencel, Osman
Within the scope of the present study, the marble cutting waste, which is an industrial waste of different sizes (< 75 µm and < 150 µm), was incorporated into the clay structure at various rates and a total of 36 series bricks were produced. The brick mixtures were prepared by the semi-dry molding method and the brick specimens were sintered for three temperatures (850 °C, 950 °C, and 1050 °C). The fired bricks containing marble cutting waste with a lower particle size (75 µm) have higher compressive strength. However, all samples produced can meet the relevant standard requirements in terms of compressive strength. Thermal conductivity decreased from 1.008 to 0.775 W/mK with the incorporation of marble cutting waste, a decrease of approximately 23.11%. The effects of grain size, firing temperature, and marble cutting waste concentration on the quadratic model were statistically determined by variance analysis (ANOVA). According to statistical findings, the order of importance of design factors for brick properties (except for compressive strength) is marble cutting waste > firing temperature > particle size. For compressive strength, the most dominant factor is amount of marble cutting waste, followed by particle size and firing temperature, respectively. Consequently, the results suggest that marble cutting waste does not need to be reduced to smaller particle sizes to improve the fired clay brick properties.
显示更多 [+] 显示较少 [-]Physical, mechanical, and thermal properties of concrete roof tiles produced with vermiculite 全文
2022
Viana, Queilla Santos | Eugênio, Tony Matheus Carvalho | Sabino, Ticyane Pereira Freire | Scolforo, José Roberto Soares | Mendes, Rafael Farinassi
This study aimed to evaluate the effect of using expanded vermiculite and its impact on the production of concrete roof tiles. The control treatment and replacement of 12.5, 25, 37.5, and 50% sand by vermiculite were evaluated. The concrete roof tiles were moulded by the simultaneous pressing and extrusion mechanical process. The control trace was comprised by 21.95% CPV-ARI cement, 65.85% sand, and 12.20% limestone. After production, the concrete roof tiles were cured for 28 days. The physical (roof tiles classification, samples dry weight, water absorption, and porosity), mechanical (splitting tensile strength), and microstructural properties were evaluated. All treatments were assessed before and after accelerated ageing. The thermal properties of the modification in the concrete roof tiles’ composition were also analysed. The evaluated amounts of vermiculite significantly affected the physical, mechanical, and thermal properties of concrete roof tiles. The use of vermiculite in concrete roof tiles reduced their dry weight and thermal conductivity, not impairing their durability. The use of 31.0% vermiculite in concrete roof tiles was suggested for better thermal insulation optimization (20.29% reduction) and weight reduction (7.92% and 7.94% at 28 days of curing and after accelerated ageing, respectively), along with adequate physical, mechanical, and durability properties.
显示更多 [+] 显示较少 [-]A comprehensive review on experimental, numerical and optimization analysis of EAHE and GSHP systems 全文
2022
Noman, Syed | Tirumalachetty, Harinarayana | Athikesavan, Muthu Manokar
Geothermal energy is one type of renewable source of energy that can be used as shallow geothermal system for the use of cooling and heating of residential and commercial buildings. In this paper, an intense review is carried out on geothermal heating and cooling for air conditioning with a focus on Earth-Air Heat Exchanger (EAHE) and Ground Source Heat Pump (GSHP) systems. The study is carried out to understand the factors which have a significant effect on the performance of the EAHE and GSHP systems. This paper also focuses on the hybrid work of geothermal heating and cooling system with other forms of energy and provides benefits for designing efficient GSHP and EAHE systems. This study indicates that the important parameters for EAHE and GSHP systems are the thermal conductivity of soil, the water content present in the ground will significantly improve the performance of the systems, and further benefits are discussed in this study.
显示更多 [+] 显示较少 [-]Possibility of producing thermal insulation materials from cementitious materials without foaming agent or lightweight aggregate 全文
2022
Rashad, Alaa M.
Due to the high increase in the consumption of building energy in the world, it is urgent to develop and use thermal insulation materials to limit the demand of energy. In this article, the possibility of producing thermal insulation plasters from common cementitious materials such as fly ash (FA), metakaolin (MK), and silica fume (SF) without employing any foaming agent or lightweight aggregate was investigated. Either cement or gypsum was used as a binder material. Eight different types of plaster based on different pozzolanic materials were investigated and compared with the traditional cement mortar plaster (TC). The compressive strength, bulk density, total porosity, thermal conductivity, and thermal resistance were measured. The results showed that it is possible to produce thermal insulation plasters based on pozzolanic materials without including foaming agent or lightweight aggregate. The obtained insulating plasters exhibited low density (888.75-1575.63 kg/m³), high porosity (39.5-57.75%), low thermal conductivity (0.30-0.48 W/mK) and suitable compressive strength. Using gypsum as a binder material was better than cement for insulation purposes. SF showed the highest insulation efficiency followed by FA and MK.
显示更多 [+] 显示较少 [-]Thermal insulation materials in architecture: a comparative test study with aerogel and rock wool 全文
2022
Danaci, Hacer Mutlu | Akin, Neslihan
Thermal insulation has great potential to reduce energy consumption in buildings. This study aims to provide a general perspective by addressing the thermal insulation materials used throughout the history of the construction industry and to understand the current situation with developing technology. The literature review was used as a method in the study. The insulation values of current thermal insulation products were investigated and compared. An energy loss and gain analysis were carried out on the Revit-2019 model to understand the difference between the widely used rock wool and a nanotechnology product, aerogel-added thermal insulation material. In addition, the effect of the use of these products on the building cost is emphasized. The results of the study show that thermal insulation materials produced with nanotechnology examined have lower thermal conductivity coefficients compared to other thermal insulation materials. According to the analysis carried out on the Revit-2019 (Autodesk Revit Architecture/3D) model, the thermal insulation material with aerogel provides 8% savings in cooling loads compared to the use of rock wool. As a result of the analysis made on the Revit-2009 model, it was concluded that 8% savings were achieved in cooling loads in the use of aerogel-added materials compared to the use of rock wool, but the initial investment cost was high. Developing competitive and sustainable materials is of the utmost importance. The literature review suggests that new composite insulators can be produced by combining suitable materials.
显示更多 [+] 显示较少 [-]Lignocellulosic materials as soil–cement brick reinforcement 全文
2022
Sabino, Ticyane Pereira Freire | Coelho, Nayane Pereira Freire | Andrade, Nayhara Camila | Metzker, Stefânia Lima Oliveira | Viana, Queilla Santos | Mendes, Juliana Farinassi | Mendes, Rafael Farinassi
The need for environmental preservation requires civil engineering to reach new concepts and technical solutions aiming at the sustainability of its activities and products. In this context, this study aimed to evaluate the effect of using different types and percentages of vegetable particles on the physical, mechanical, and thermal properties of soil–cement bricks. Bamboo, rice husk, and coffee husk particles at 1.5 and 3% percentages and a control treatment not using the particle were evaluated. The chemical properties, shrinkage, compaction, consistency limits, and grain size were characterized for the soil; and the anatomical, chemical, and physical properties for the lignocellulosic particles. The bricks were produced using an automatic press and characterized after the curing process for density, water absorption, porosity, loss of mass by immersion, compressive strength, durability, and thermal conductivity. The increase in the lignocellulosic waste percentage caused a mechanical strength decrease and bricks’ porosity and water absorption increase. However, it caused a decrease in density and an enhancement in loss of mass and thermal insulation properties. The bricks produced with rice husk obtained the best results in terms of mechanical and thermal properties, and were still among the best treatments for physical properties, standing out among the lignocellulosic waste as an alternative raw material source for soil–cement brick production.
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