جستجوی مقالات مرتبط با کلیدواژه « Environment » در نشریات گروه « مواد و متالورژی »

Tire recycling or tire recycling is a process in which car tires are no longer worn out or are no longer suitable for use because of a rupture or unrepairable failure. These tires are among the most significant waste that is very problematic. This problem is due to the persistence and persistence of tires and their high volume of production. It is estimated that 259 million tires are discarded each year. In this research, the Preparation stages of production of activated carbon nanofibers produced from the recycling of worn tire rubber with different percentages of different solvents of potassium hydroxide, ethanol, and toluene were studied and tested. To achieve a solution for worn tire tires, a certain amount of scraped rubber fragments was dissolved in potassium hydroxide, ethanol, and toluene solvents, and electrospinning solutions were determined and prepared and to produce nanofiber layers, Electrospinning operations are performed. By scanning electron microscopy images, the mean diameter of nanofibers obtained in potassium hydroxide solvent was the lowest, and scanning electron microscopy images confirmed the absence of willow in the produced nanofibers. The efficiency of carbon production was determined as 37.2%. To confirm the formation of activated carbon, FTIR spectra were used, which confirmed the presence of spike related to the aromatic ring formation of activated carbon nanofibers after activation.

Aggressive environment reduces the mechanical and durability-related properties of concrete. In this study, the effects of exposing the concrete containing crumbed tire rubber (CTR) to aggressive environmental conditions, including hydrochloric acid (HCl) is investigated. For this purpose, 5, 10, and 15% of the fine aggregate of the mixing design were partially replaced with the CTR, and then at the age of 7 days, when the concrete reached almost 70% of the initial strength, the samples were placed in water containing 2% HCl for 28 and 90 days. In this study, the effect of using Nano-SiO2(NS) in the rubberized concrete and its behavior in acidic environments by replacing 5 and 10% by weight of cement with NS was also studied. Compressive strength and mass loss were evaluated at 28 and 90 days after casting. The results showed that the detrimental effects of HCl on the compressive strength of concrete significantly increased with an increasing in CTR content of concrete. The results also indicated that the impact of HCl acid on mass loss is improved by increasing the percentage of CTR so that the sample with the 15% crumbed tire showed a 7% lower weight reduction than the control sample.

Each year, production of ceramic materials causes many environmental repercussions including air and soil pollution. In addition, due to their nature, industrial environments are susceptible to serious damages and risks that can be potentially exacerbated with the increasing growth of technology. In this regard, the current study aims to evaluate the policies on the prosperity of the domestic production of advanced ceramics with the approach to environmental protection. The current research is among the mixed and exploratory researches that was carried out in two qualitative and quantitative stages. The statistical population includes the senior and executive managers of the "advanced ceramics production industries" in the Ministry of Industry, Mining, and Trade, Iran. This study used the document review tools and semi-structured interviews with 14 academic and executive experts in this industrial field. Based on the "theme analysis" method in this research, the results and consequences of industrial policy assessment were extracted according to the environmental protection approach and finally, these policies were evaluated. The results of this evaluation showed that although some of the production processes of ceramic materials have been modified based on the environmental policies, some other processes are still inconsistent with environmental policies and requirements; therefore, the extent of pollutants in the industrial processes is not accurately monitored and measured, and the level of pollutants in most industrial places is more than the standard level.

Heaters are one of the central parts of natural gas reduction stations using turboexpanders to prevent the formation of hydrate and corrosion failure. This study intends to design a fired heater by applying a combustion sub-model to derive an optimal model for this kind of application. This model is developed to accurately consider all subsections of the fired heater namely radiation, convection, and shield sections, as well as flue gas composition, and its volume. Within this context, a multi-objective optimization is employed to identify the optimal design of the gas-fired heater in the natural gas reduction station for the Ramin power plant case study. The total economic and environmental costs, together with modified exergy efficiency, are selected as objective functions. Multi-criteria-decision-making-method is employed on Pareto frontiers optimal curve to suggest the optimal solution. Results show that the developed model can outperform previous models in thermal efficiency with relatively similar costs. Besides, the optimal point in Pareto suggested by the decision-making-method accounts for a higher modified exergy efficiency (1.3%) than the counterpart, which thermal efficiency is regarded as an objective function. At the same time, its total cost remained almost constant. The effects of changes in each of the design parameters on the objective functions are also evaluated.

The field of nanomaterial has greatly advanced in the last decade following a wider range of applications in the fields of electronics, automobiles, construction, and healthcare due to its extraordinary and ever-evolving properties. Synthesis of the nanomaterial plays a crucial role in redefining the current engineering and science field. At the same time, procuring an environment-friendly end product through eco-friendly solutions and sustainable processes is the key to many global problems. Green synthesis of nanomaterials like graphene and its derivatives involves mild reaction conditions and nontoxic precursors because it is simple, cost-effective, relatively reproducible, and often results in more stable materials. This paper primarily focuses on the green synthesis of graphene and its derivatives (graphene oxide & reduced graphene oxide) and geopolymers; a green technology for preparing graphene reinforced geopolymer composites. Various methods used globally for green synthesis of graphene and geopolymer are briefly discussed and this paper tries to integrate these two areas for a green end product. Possible applications of these green composites are also discussed to provide insights on the current growth and developments.

Hybrid Concrete focused on development of buildings, highways, and other structures of civil engineering. In the current study, various mix combinations have been prepared and tested with different percentages of super-plasticizer at different levels of water reduction for obtaining the optimum mix. Further, study on different properties of hybrid concrete and replacement of ordinary portland cement (OPC) with ground granulated blast furnace slag (GGBFS), silica fume (SF) and glass fibers (GF) for obtaining highly cement replaced concrete (HCRC) and glass fiber concrete (GFC). The concrete performance was evaluated based on slump cone test, compressive strength test, split tensile strength test, flexural strength test, water absorption test and ultrasonic pulse velocity test. It was observed from the results that, the best performance of HCRC achieved at 50% GGBFS and 3% silica fume replacement. Further, in the case of GFC, 0.2% of glass fibers showed high performance in terms of split tensile and flexural strength at all ages. The optimized concrete mixtures like HCRC and GFC performed better than the control concrete (CC).

Today, with regard to population growth, there is a need for more renewable energy sources that can easily serve different human needs without harming the environment; therefore, designing energy saving buildings as well as protecting natural resources is one of the main responsibilities of the experts. One of the types of renewable energies is geothermal energy, which is one of the least costly, most beneficial of these energies and a good alternative to fossil fuels, and the generation of electricity and the heating and cooling of buildings by the heat pump are a number of its applications. This article attempts to explain the use of this energy in heating and cooling buildings and the need to use this cheap and clean energy instead of using fossil fuels.Increasing population and increasing economic prosperity on the other requires energy. The increasing need for energy has led people to increasingly use fossil fuels (coal, oil, gas) but the nonrenewable and contaminations that have emerged, such as global warming, ice melting, and the collapse of the natural ecosystem of the planet, have reduced the use of these energy sources. Therefore, the use of energy sources that are unlimited and cause the least pollution has attracted the attention of researchers in recent decades, which they call the sources of new and renewable energy. One of these sources is geothermal energy, which we will continue to explain.

Nowadays, environmental protection and efforts to reduce pollution, caused by industrial activities, on one hand, and research on finding new and improved energy supply options on the other, have become one of the major concerns of governments around the world. In recent years, photovoltaic (PV) systems, due to their proved potential are rapidly developed in most parts of the earth. The objective of this study, is to estimate the amount of CO2 emission reduction by implementing a 7 MW PV power plant. The location of this power plant is in the north of Hamedan province, Iran. Moreover, the amount of not consumed fossil fuel were measured. Finally, it is found that the total reduction of 134050 t CO2 will be achieved when PV power plant is used compared to a natural gas one, during 25 years. Moreover, in this paper, the energy payback time (EPBT) and the Energy Yield Ratio (EYR) are calculated. The results show that EPBT is about 5.5 years and EYR of mentioned PV power plant is more than 4.2.

This paper proposes an approach for improving the plant efficiency by reducing the heat rejection temperature of power cycle using Kalina Cycle System 11 (KCS11) which is integrated at the steam condenser of a 500 MWe SubC (subcritical) coal-fired power plant. It is modelled by using power plant simulation software ‘Cycle Tempo’ at different plant operating conditions. Results show that the additional net electric power of 5.14 MWe from KCS11 improves the net energy and exergy efficiencies of the power plant by about 0.302 % point and 0.27 % point, respectively at full load over the stand-alone coal-fired steam power plant. Thereby, the carbon dioxide (CO2) emission is reduced by about 2.02 t/h at full load. Combined plant efficiencies decrease with decrease in evaporator outlet temperature due to decrease in vapour quality of binary mixture at turbine inlet and higher steam turbine back pressure. Levelized Cost of Electricity (LCoE) generation and payback period of the combined cycle power plant are about Rs 1.734 and 4.237 years, respectively and the cost of fuel saving is about Rs 0.685 per kg of coal which is lower than the fuel cost.

In recent years, increasing the awareness on the environmental problems, especially global warming, has increase the concerns about the impact of emissions on the global climate. The current study was conducted to evaluate and analyze the environmental effects of rapeseed production in the form of life cycle using SimaPro software with the aim concentration on climate changes and impact of acidification. In order to perform the experiments, 1 tone rapeseed was used as operational unit. The required data was collected from 30 farms in Izeh city. Ten environmental indexes including depletion of groundwater resources, potential to acidification, potential to eutrophication, potential to global warming, ozone depletion potential, human toxicity potential, potential to toxicity of fresh water and marine fish, potential to environmental toxicity, potential to photochemical oxidation were investigated in this research. Results showed that the amount of greenhouse emissions for rapeseed was equal to 112.73 kg of carbon dioxide equivalent. It was also revealed that chemical fertilizer had the highest share among the evaluated inputs within the life cycle. Results obtained in this survey indicated that management of nutrients and pesticides can be considered as a concentration point for optimizing the environmental influences of rapeseed production in the related region.