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Go to Editorial ManagerHigh-performance polymer nanocomposites utilizing different-sized nanofillers had a lot of interest recently. Due to their distinct structural, and thermal characteristics. Multi-wall carbon nanotubes (MWCNT) and nanoclay (NC) have the most interest among the numerous types of reinforcing as filler elements for a polymer. The formation of hybrid from MWCNT and NC at various loadings (0.5%, 1%, and 2wt%) on the characteristics of epoxy polymer have been assessed in this work. The specimens have been created using solution blending procedures with the addition of solvent ethanol at a ratio of 1:1 for dispersed nanofillers, and then they have been re-mixed with epoxy. Tests like X-Ray diffraction (XRD), and thermal conductivity were used to identify properties of epoxy. According to the test results, the thermal conductivity rise as the filler content rises at 1wt%, then start to decrease after 1wt%. The sample with the hybrid filler loading of 1 wt% produced the best performance. Since hybrid epoxy exhibits the best result of the thermal conductivity 135% over MWNT and NC nanocomposites of 1 wt.% reached 0.3568 W/m.K in the increased thermal conductivity property. By examining the EP nanocomposites XRD pattern. The hybrid of epoxy nanocomposites exhibits all of the NC and MWCNT characteristic peaks. Since interactions between the filler and the epoxy cause a shift in the peak location of 1wt%. Due to the homogeneity of the nanofillers entire epoxy matrix, there may be changes in the intensity or location of the peaks at 1% for 2θ= 20.13°, which corresponds to an interlayer distance of d=0.461nm.
Particles filled polymer composites started to be essential because of their wide applications in addition to reducing the cost of polymer, which is a main problem. The aim of this work is studying the insulation of particulate composites resulting from the addition of filler (glass or porcelain) waste powder to reinforced epoxy matrix. Samples with and without filler were exposed to some tests to decide the influence of the filler contents on the characteristics of epoxy. Epoxy is synthesized with filler particles having (90 micron) particle sizes as reinforcement. Composites of epoxy with varying percentage (0 to 40 weights %) of filler were prepared by using hand lay-up method. The nondestructive tests consist of thermal conductivity; ultrasonic test and water absorption test have been investigated. The composite showed an improvement in physical properties with the addition of filler according to their percentages. The result show the addition of the filler in all proportions to the epoxy increased the density of the composite, leading to the ultrasonic pulses velocity ranges between 2100 m/s and 2800 m/s. Increase glass and porcelain percentage cause increase in density which increases the acoustic impedance. While the thermal conductivity decrease with glass powder percentages in the composite increase, unlike the increase in porcelain percentage which causes an increase in thermal conductivity. The 40% percentage of glass in the epoxy had higher effect on reduce the thermal conductivity. As well as from the results the epoxy reinforced by porcelain powder would have lower water absorption than epoxy reinforced by glass powder.
An investigation of thermal conductivity enhancement, melting and solidification processes of Phase Change Materials (PCMs) by using metal foams has been carried out. Two models have been used in the experiments, model I for measuring the effective thermal conductivity of metal foam embedded in paraffin wax, and model II used as a small scale thermal energy storage device with and without metal foam for investigating melting and solidification processes of the PCM under different cooling conditions (natural and forced convection). The theoretical investigation involves analytical solution of two models, the semi-infinite medium for calculating the thermal conductivity, and the thermal energy storage system TESS has been analyzed including several assumptions for determining the convective heat transfer coefficient and the factors that controlling forced convection and solidification of the PCM. The experimental results show that the thermal conductivity of wax with 10 PPI metal foam increased by (37-39) times that of pure wax. Effects of pore density (10 and 40 PPI), metal foam, and mass flow rate on solidification process have been studied and the effects of pore density and metal foam on the melting process have also been investigated. The present experimental results have been compared with the available previous studies and gave a good agreement.
The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted to simulate the conventional solar heating system, multipurpose solar water heater (MPSWH), and multipurpose solar air heater (MPSAH). The commercial computational fluid dynamics (CFD), AVL Fire ver. 2009.2 was used to solve and investigate the temperature distributions in the absorber plate and riser tube of both solar water and air heater during summer and winter seasons. The RNG k -turbulence model was employed for this CFD study. The present paper was to provide a good understanding of thermal performance for the solar collector at different operating conditions. The experimental setup and physical data of Venkatesh, R. and Christraj, W. [15] were employed as geometric parameters and initial boundary conditions to model and to validate the predicted numerical values. Comparing to the values of temperatures for the conventional SWH and SAH, the predicted results of the MPSWH and the MPSAH showed a good improvement on the thermal performance. These enhancements on the temperature may have been due to the new design adopted in the multipurpose solar heating systems by using riser tubes and headers to the original design of the thermal systems. Additionally, the thermal performance of solar collectors increases with increasing the mass flow rates and thermal conductivity of absorber plate. For validation aspect, the predicted results of all cases examined showed a good agreement against the measured results in terms of temperature distribution levels and thermal efficiencies.
Concrete is considered the most important and widely used building material in the world of construction and building due to its durability, high efficiency in shaping, and relatively reasonable cost. The main component of concrete is cement, and one of the most important problems related to cement is the environmental problems associated with cement manufacturing, as the cement manufacturing process releases a large amount of carbon dioxide. Despite the essential role of concrete in construction, we cannot ignore its environmental impact. Some claim that exploring alternative materials or innovative building techniques would reduce the carbon footprint and enhance sustainability in the industry. Partial cement replacement with pozzolanic materials like zeolite is a key technique to reduce carbon dioxide emissions. Zeolite, which reduces permeability, is a typical concrete ingredient that strengthens and lasts. Recently, natural zeolite has become a prominent concrete pozzolanic component. For environmental preservation and sustainable development, various experiments were done on concrete with pozzolanic components partially substituting cement and compared to ordinary concrete. A partial replacement of cement with zeolite improves the properties of concrete up to a certain age and mixing ratio. More than 44 relevant articles from 2004–2024 were selected from 762 papers evaluated for this paper. This paper reviews natural zeolite research in real applications. Additionally, it provided a cutting-edge review of natural zeolite literature through a critical analysis of various previous investigations. It also helped to understand how zeolite influences concrete mixture workability, strength, and durability. Since zeolite is a major concrete ingredient, it should be promoted as a sustainable resource.