Papers by Keyword: Pressure

Abstract: This research focused on noise reduction in jets using chevron passive control method, the nozzle designs with varying chevron types were subjected to CFD analysis and experimental analysis to understand pressure distribution patterns in the far field. This research distinctively analysed chevron performance through pressure distribution in the far field and not based on nozzle acoustic power dis-tribution, a surface phenomenon. Four models of nozzles namely base, chevron, wave and tabular were designed, manufactured and extensive analysis in both computational and experimental approaches was carried out. The sound pressure level (SPL) was calculated along with its percentage reduction for three models by taking the base model as reference model. The scientific results showed that among all models, wave is the least noisy with reduction of 3.3% and 1.16% SPL in computation and experiment respectively. On the other hand, the base model found to be the highest noisy model both computationally and experimentally.

Abstract: The study focuses on optimizing the design of respirator filter cartridges against particles to minimize their impact on ergonomic performance. The aim is to determine the uniformity of airflow distribution in the filter. Numerical analysis in SolidWorks Flow Simulation was applied to assess the effect of design parameters. Covers with a round inlet, smooth edges and an inner surface ensured the most uniform flow and reduced pressure drop. Cartridges with a central outlet showed higher velocity (by 10 %) and pressure (by 15 %) variation than those with an offset outlet, as air moves directly to the centre. Increasing airflow from 30 l/min to 95 l/min improved uniformity, reducing velocity variation to 25 % and pressure to 30 %. The outer cover and geometry of the cartridge were proven to influence airflow distribution, ensuring efficient use of the entire filter surface. With elliptical and square inlets, velocity variation increased from 30 % to 50 % compared to round inlets, due to asymmetrical pressure distribution. The scientific value lies in identifying the influence of inlet/outlet geometry on airflow velocity and pressure distribution, while the practical outcome is defining optimal inlet dimensions for efficient, comfortable respirators.

Abstract: Porous Titanium (Ti) is one of the leading biomedical materials with high biocompatibility, durability, high stability, and non-toxic to the human body. In this study, highly porous Ti have been fabricated by spark plasma sintering process using NaCl as a pore former (70% wt.), and then, NaCl was dissolved in water. All the samples were sintered at 625 °C and held there for 10 min under applied pressure ranging from 20 to 50 MPa with heating rate of 100 °C/min in vacuum. The results suggested that NaCl is a proficient porogen, the porosity of all samples was in the range of 66.95 - 68.8%. When the pressing pressure increased from 20 - 50 MPa, the porosity of the samples decreased but the size of the pores increased. The pore size concentrated in the range of 300 - 350 µm. This implies that the compression pressure plays a crucial role in influencing both the porosity and pore size of the titanium material produced using the SPS technique. The compressive strength is 18.42 - 25.23 MPa, and the elastic modulus is 0.35 - 1.05 GPa, which matches the strength and the modulus of elasticity of biological implants.

Abstract: High-temperature oxidation is a widely studied topic in the field of Solid Oxide Fuel Cells as it commonly affects the steels used in stacks and other system components. Considering the targeted lifetime of systems using this technology (> 60kh), long-term testing is required to certify material properties throughout the life cycle. The design of accelerated testing is often cited as a way to speed the development and validation of materials for these components. In this work, the effect of pressure (1 to 4 bar) at various operating temperatures (750 to 850°C) on the oxidation kinetics and electrical properties of AISI 441 steel was investigated. While oxide growth was affected by pressure at all test temperatures, electrical properties showed significant changes only at 850°C. The results were supported by theoretical calculations of the oxidation and chromium evaporation kinetics of the steel.

Abstract: Monosodium Glutamate (MSG) [1] was invented more than 100 years ago from its first invention in 1908 by Japanese biochemist Kikunae Ikeda, who was trying to isolate and duplicate the savory taste of kombu, an edible seaweed used as a base for many Japanese soups. From 2016, most MSG worldwide is produced by bacterial fermentation in a process similar to making vinegar or yogurt. Sodium is added later, for neutralization. During fermentation, Corynebacterium species, cultured with ammonia and carbohydrates from sugar beets, sugarcane, tapioca (cassava tuber) or molasses, excrete amino acids into a culture broth from which L-glutamate is isolated. In this process, Monosodium Glutamate companies buy cassava [2] pulps from farmers that contain a lot of sand and impurities. In order to increase the productivity with lowest expense, the filtration of sand and solid impurities’ is performed by separation cyclone. In this paper, we study all the measure to design a system of effective pump, cyclone to extract as much as possible all of solid impurities included sand out of cassava slurry before providing to the bacterial fermentation in a process.

Abstract: The corrosion behavior of 3Cr steel in simulated oilfield CO₂ and formation water environment at different temperature and partial pressure of CO₂ were investigated using dynamic immersion tests, scanning electron microscopy inspection and X-ray diffraction analysis. The result demonstrated that with an increasing of temperature, the corrosion rate of 3Cr steel decreased, and reached the maximum corrosion rate when the partial pressure of CO₂ was 0.5MPa. The high content of Ca²⁺ in the formation water had also played an important role in the corrosion behavior of the 3Cr steel for it can lead to a deposition of the CaCO₃ on the surface of the specimen.

Abstract: This paper studies the characteristics of white powder generation on the buffer layer of cables under the influence of humidity and pressure. After testing, the presence of white powder in the buffer layer leads to an increase in the volume resistivity (higher than the area without white powder). The denser the white powder, the more the volume resistivity rises. The current density and surface temperature is simulated in COMSOL and observed the process of white powder generation. The volume resistivity is also measured using an electrochemical impedance spectrometer with different contents of white powder in buffer layer. The test results show that the electrochemical corrosion increase on buffer layer under high water contents in the presence of large current density. The experimental results show that when the water content of the buffer layer is 2 mL, the formation rate of white powder is the fastest; when the pressure of the buffer layer in the range of 998.2 N/m²~9982 N/m², the formation rate of white powder increases first, then decreases, and finally tends to be saturated; The main component of white powder is aluminum oxide, which is formed by chemical corrosion and electrochemical corrosion of aluminum, carbon black, sodium polyacrylate, water and etc.

Abstract: It is of great interest to be able to remove residues of impregnating material from the resulting article in order to reduce the cost of manufacturing such parts. To this end, a thermodynamic calculation allows you to obtain the necessary conditions for obtaining high-quality products.

Abstract: This paper was devoted to the technological process of manufacturing a biocomposites tube made of low-density polyethylene and barley straw fibers. 50% of HDPE, 42% barley straw, 5% of shungite (mineral filler), 2% Maleid F (N, N-metaphenylenediamine) as coupling agent, and 1% Hexol CLA as lubricant were pre-mixed before compounding. The compounding of the raw materials was carried out on a co-rotating twin-screw extruder. The resulting granules were fed into the single screw extruder to obtain thermoplastic composite tubes. The temperature regime for the HDPE/barley straw composite processing was in the range of 145-160 °C and the screw rotation speed was 50 rpm. The tensile strength and modulus were found to be 27.7 MPa and 1687 MPa, respectively. The water absorption (24-h) and density of the specimens were 1.43% and 1.158 g/cm³, respectively. Based on the findings obtained from the present study, it can be said that the barley straw can be efficiently used in the production of tube formed HDPE composites.

Abstract: The work refers to the modern method of stabilizing unstable, water-saturated creeping slopes, with the combination of bulk piles and gabions. The application of the method makes it possible to ensure the stability of the slope by means of bulk piles, passing through weak soils, building semi-massive gabion walls on the piles with a stepped front edge. Bulk piles and gabions are used in modern construction for strengthening the slopes of river banks, in the preparation of protective structures to stand the rockfall, avalanche floods, in the construction of bridges, hydraulic and other facilities. The novelty of the proposed method is the stabilization and watering of the slopes organized without the construction of reinforced concrete retaining walls and land-based systems. It provides strength in depth and minimizing hydrostatic pressure.