Effect of Surface Modification Treatment on Gold Coated Zari Yarn and Its Weavability Characteristics

The Zari yarn is a three component yarn which consists of red silk thread wrapped around by a silver wire and coated with pure gold. The Zari yarn is a metalized yarn and is basically manufactured by wrap spinning technique. In this work the zari yarn components has been treated with plasma reactor using argon and oxygen medium. The zari yarn is also made by using three different silk varieties as a core material. In initial stage the silk yarn is also degummed by using enzyme and also by traditional method. The effect of plasma treatment in each stage has been examined. After plasma treatment the frictional properties of zari yarn is interpreted. The weavability factors for the zari yarn also measured in the research.

Features of interpretation of luminescence spectra of zinc oxide films on sapphire

In the presented work features of interpretation of luminescent spectral dependence properties of ZnO films on sapphire are given. For complex analysis, films of ZnO of different thickness obtained in oxygen medium at different substrate temperatures are considered using the stage of recrystallysis annealing. It is shown that only a red (650 – 1000 nm) band ZnO sapphire substrate is observed in the spectrum of cathodoluminescence of thin films obtained at low temperature of the substrate, and luminescence of the film ZnO fed by excessive defect. Prolonged recrystallization annealing results in improved quality of thin ZnO films and a broad (430 – 740 nm) band in the ZnO. With an increase the film thickness, only bands associated with ZnO appear in the cathodoluminescence spectra: the edge luminescence band (maximum 390 nm) and the red band (500 – 950 nm with a maximum in the region of 710 nm) are associated with charged zinc vacancies. Focusing the beam leads to local heating of the sample and an increase in the concentration of interstitial zinc. This is due to the displacement of the edge light band into the 410 nm region, as well as the blue mixing of the defective luminescence band.

Experimental Study of the Effect of Intake Oxygen Concentration on Engine Combustion Process and Hydrocarbon Emissions with N-Butanol-Diesel Blended Fuel

This paper summarizes a study based on a modified, light, single-cylinder diesel engine and the effects of the physicochemical properties for n-butanol-diesel blended fuel on the combustion process and hydrocarbon (HC) emissions in the intake at a medium speed and moderate load in, an oxygen-rich environment (Coxy = 20.9–16%), an oxygen-medium environment (Coxy = 16–12%), and an oxygen-poor environment (Coxy = 12–9%). The results show that the ignition delay period is the main factor affecting the combustion process and it has a decisive influence on HC emissions. In an oxygen-medium environment, combustion duration affected by the cetane number is the main reason for the difference in HC emissions between neat diesel fuel (B00) and diesel/n-butanol blended fuel (B20), and its influence increases as the intake oxygen concentration decreases. In an oxygen-poor environment, in-cylinder combustion temperature affected by the latent heat of vaporization is the main reason for the difference in HC emissions between B00 and B20 fuels, and its influence increases as the intake oxygen concentration decreases. By comparing B20 fuel with diesel/n-butanol/2-ethylhexyl nitrate blended fuel (B20 + EHN), the difference in the ignition delay period caused by the difference in the cetane number is the main reason for the difference in HC emissions between B20 and B20 + EHN fuels in oxygen-poor environment, and the effect of this influencing factor gradually increases as the intake oxygen concentration decreases.

HYDROGEN-OXYGEN STEAM GENERATOR FOR A CLOSED HYDROGEN COMBUSTION CYCLE

The paper analyzes the problems of combustion hydrogen in an oxygen medium for produce high-temperature steam that can be used to produce electricity at various power plants. For example, at the nuclear power plants, the use of a H2-O2 steam generator as part of a hydrogen energy complex makes it possible to increase its power and efficiency in the operational mode due to steam-hydrogen overheating of the main working fluid of a steam-turbine plant. In addition, the use of the hydrogen energy complex makes it possible to adapt the nuclear power plants to variable electric load schedules in conditions of increasing the share of nuclear power plants and to develop environmentally friendly technologies for the production of electricity. The paper considers a new solution of the problem of effective and safe use of hydrogen energy at NPPs with a hydrogen energy complex.Technical solutions for the combustion of hydrogen in the oxygen medium using direct injection of cooling water or steam in the combustion products have a significant drawback – the effect of “quenching” when injecting water or water vapor which leads to a decrease in the efficiency of recombination during cooling of combustion products that is expressed in an increase fraction of non-condensable gases. In this case, the supply of such a mixture to the steam cycle is unsafe, because this can lead to a dangerous increase in the concentration of unburned hydrogen in the flowing part of the steam turbine plant. In order to solve this problem, the authors have proposed a closed hydrogen cycle and a hydrogen vapor overheating system based on it, and carried out a study of a closed hydrogen combustion system which completely eliminates hydrogen from entering the working fluid of the steam cycle and ensures its complete oxidation due to some excess of circulating oxygen.The paper considers two types of hydrogen-oxygen combustion chambers for the system of safe generating of superheated steam using hydrogen in nuclear power plant cycle by using a closed system for burning hydrogen in an oxygen medium. As a result of mathematical modeling of combustion processes and heat and mass transfer, we have determined the required parameters of a hydrogen-oxygen steam generator taking into account the temperature regime of its operation, and a power range of hydrogen-oxygen steam generators with the proposed combustion chamber design.

NUMERICAL STUDY OF HYDROGEN FUEL COMBUSTION IN COMPRESSION IGNITION ENGINE UNDER ARGON-OXYGEN ATMOSPHERE

Gas emissions from automobiles are one of the major causes of air pollution in our environment today. In fact, emissions of carbon dioxide (CO2), a product of complete combustion, has become a significant factor of the global warming effect. Hydrogen, which is a renewable energy, is regarded as a promising energy to solve this problem since the final product of hydrogen (H2) combustion, is water (H2O). However, the reaction of hydrogen fuels in the air under high temperature conditions produces a high volume of harmful nitrogen oxide (NOx). Furthermore, the high auto-ignition temperature of H2 makes it difficult to ignite in a compression ignition engine in normal air. In this research, argon (Ar) is used to replace nitrogen (N2), in order to eliminate NOx and enhance combustion. Simulation for this research was conducted using Converge, computational fluid dynamics software that is based on Yanmar TF90M compression ignition engine parameters. The simulation process was initially conducted with normal air (N2-O2) as the medium of combustion; but later it was replaced with an argon-oxygen (Ar-O2) atmosphere to investigate the ignition possibility of hydrogen fuel. Hydrogen was injected at 9.95 MPa at the start of injection (SOI) at 18º BTDC. The results show that, by employing the same parameters for both simulations in normal air and argon-oxygen mediums, the combustion of hydrogen only occurred in the argon-oxygen medium. However, no combustion took place in normal air. It is therefore concluded that an argon-oxygen medium is applicable for direct hydrogen injection in a compression ignition engine.