• Journal of Electrochemical Science and Technology
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• v.15 no.2
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• pp.299-313
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• 2024

Electrochemical machining (ECM) is an effective manufacturing method for difficult-to-machine materials and is widely used in the precision manufacturing of aerospace components. In recent years, the requirements for the machining accuracy and surface integrity of ECM have become increasingly stringent. To further improve the machining quality, this work investigated the intricate laws between electrolyte filtration accuracy and machining quality. Electrolytes with different filtration accuracies were compared, and a numerical simulation was used to evaluate the change in temperature and bubble rate of the flow field in the machining area. Experiments were conducted on ECM of Ti-6Al-4V (TC4) alloy workpieces using electrolytes with different filtration accuracy. The workpiece machining accuracy and surface quality were analyzed, and the repetition accuracy of the workpiece was evaluated. The intricate laws between electrolyte filtration accuracy and machining quality were explored. It was found that when the electrolyte filtration accuracy is improved, so too is the machining quality of the ECM. However, once the filtration accuracy has reached a certain value, the machining quality has extremely limited improvement. By evaluating the repetition accuracy of processed workpieces in electrolytes with different filtration accuracies, it was found that when the filtration accuracy reaches a certain value, there is no positive correlation between the repetition accuracy and filtration accuracy. The result shows that, for the workpiece material and conditions considered in this paper, an electrolyte with 0.5㎛ filtration accuracy is suitable for the wide application of precision ECM.

• Structural Engineering and Mechanics
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• v.62 no.2
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• pp.163-170
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• 2017

This study presents a particle-wall filtration model for predicting the particle motion behavior in a typical rotational flow field-filtration in blower system of cooker hood. Based on computational fluid dynamics model, air flow and particles has been simulated by Lagrangian-particle/ Eulerian-gas approaches and get verified by experiment data from a manufacturer. Airflow volume, particle diameter and local structure, which are related to the particle filtration has been studied. Results indicates that: (1) there exists an optimal airflow volume of $1243m^3/h$ related to the most appropriate filtration rate; (2) Diameter of particle is the significant property related to the filtration rate. Big size particles can represent the filtration performance of blower; (3) More than 86% grease particles are caught by impeller blades firstly, and then splashed onto the corresponding location of worm box internal wall. These results would help to study the micro-particle motion behavior and evaluate the filtration rate and structure design of blower.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.127-136
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• 2006

Prediction of diesel particulate filtration is typically made by virtue of modeling of particulate matter(PM) collection. The model is closed with filtration parameters reflecting all small scale phenomena associated with PM trapping, and these parameters are to be traced back by inversely analyzing large-scale empirical data-the pressure drop histories. Included are soot cake permeability, soot cake density, soot density in the porous filter wall, and percolation constant. In the present study, a series of single channel DPF experiment is conducted, pressure histories are inversely analyzed, and the essential filtration parameters are deducted by DPF filtration model formulated with non-linear description of soot cake regression. Sensitivity analyses of model parameters are also made. Results showed that filtration transients are significantly altered by the extent of percolation constant, and the soot density in the porous filter wall is controlling the filtration qualities in deep-bed filtration regime. In addition, effect of soot particle size on filtration quality is distinct in a period of soot cake regime.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.115-120
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• 2023

The design theory for nanoporous filtration membranes needs to be established. The present study shows that the performance and technical advancement of nanoporous filtration membranes are determined by the fundamental parameter I (in the unit Watt^1/2) which is formulated as a function of the shear strength of the liquid-pore wall interface, the radius of the filtration pore, the membrane thickness, and the bulk dynamic viscosity of the flowing liquid. This parameter determines the critical power loss on a single filtration pore for initiating the wall slippage, which is important for the flux of the membrane. It also relates the membrane permeability to the power cost by the filtration pore. It is shown that for biological cellular membranes its values are on the scale 1.0E-8Watt^1/2, for mono-layer graphene membranes its values are on the scale 1.0E-9Watt^1/2, and for nanoporous membranes made of silica, silicon nitride or silicon carbonized its values are on the scale 1.0E-5Watt^1/2. The scale of the value of this parameter directly measures the level of the performance of a nanoporous filtration membrane. The carbon nanotube membrane has the similar performance with biological cellular membranes, as it also has the value of I on the scale 1.0E-8Watt^1/2.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.84-91
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• 2010

The centrifugal oil purifier is used in ships for purifying the engine lubrication oil. The momentum needed for the rotation of the cylindrical chamber is obtained by jet injections. The dust particles in the oil are separated by the centrifugal forces moving to the inner wall of the rotating cylindrical chamber body. The dust particles are eliminated when the particles are adsorbed onto the surface of the inner wall of the chamber body. The flow characteristics and the physical behaviours of particles in this centrifugal oil purifier have been investigated numerically and the filtration efficiencies have been evaluated. For the calculations, a commercial code has been used and the SST k-${\omega}$ turbulence model has been adopted. The MRF (Multiple Reference Frame) method has been introduced to consider the rotating effect of the flows. Under various variables, such as particle size, particle density and rotating speed, the filtration efficiencies have been evaluated. It has been verified that the filtration efficiency is increased with the increments of the particle size, the particle density and the rotating speed of the cylindrical chamber.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.13-18
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• 2015

Over the past years, many research works have been carried out to investigate the factors which govern the performance of diesel engines. The air pollutant emissions from the diesel engines are still significant concerns environmentally in many countries. In the present study, a novel smoke filtration system of diesel engine is proposed. This novel system is composed of filtering elements and vacuum pump driven by exhaust gases emitted from engine cylinders for capturing smoke. In order to verify the excellency of the novel filtration system, the differential pressure across the filtration system is investigated experimentally comparing with other systems which are used commercially in diesel vehicles. As a result it is founded that the differential pressure of the novel system is the smallest among them.

• Particle and aerosol research
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• v.20 no.2
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• pp.57-68
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• 2024

A silicon carbide (SiC) ceramic filter is an effective component for hot flue gas cleaning because of its high collection efficiency, high thermal shock resistance, and excellent mechanical strength. The effect of molding pressure in the production of SiC granular ceramic filters, on the mechanical strength and filtration performance, was investigated in this work. It was found that the ceramic filters produced at molding pressures less than 20 MPa have low mechanical strength and that this result was caused by weak physical interaction among the ceramic powders due to defects and cracks. On the other hand, the filter quality factor(q_F), which represents filtration performance of filter media, decreased with increasing the molding pressure due to the drastic increase in pressure drop. Ceramic filter performance factor(q_FM), which is the manipulation of maximum mechanical strength and q_F, was introduced to consider both mechanical strength and filtration performance in this study. As a result, molding pressure of 30 MPa was desirable to produce a SiC granular ceramic filter based on q_FM.

• Journal of Korea Foundry Society
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• v.23 no.2
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• pp.69-76
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• 2003

The present work was undertaken to investigate the mutual effect of the individual melt treatment commonly applied in aluminum foundries such as grain refining, modification, degassing and filtration on the microstructures and the mechanical properties. A357 alloys were fabricated through various melt treatments such as degassing by gas bubbling filtration, modification via the addition of Al-Sr master alloy, grain refining through the addition of Al-Ti-B master alloy and filtration before pouring of the melt. Each melt treatment was performed at its optimum condition reported in the literatures. The effects of each melt treatment and their interactions on the microstructures and mechanical properties of A357 alloy were examined.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.10-16
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• 2011

Diesel particulate filter is being recognized that it is the most effective technologies to reduce particulate matter. In this study, to determine the characteristics of the cell-open-type pDPF, we employed p-DPF to exhaust gas tunnel of diesel engine and surveyed filtration efficiency and BPT on the basis of PM which is exhausted from engine. In this paper the soot loading mass in DPF can be predicted from increase of differential pressure of DPF so that we can measure filtration efficiency and Balance Point Temperature (BPT) by soot loading mass. The result of the research showed that the filtration efficiency is 65% in ESC mode with 0.7mm hole diameter. For the results of the characteristics of filtration efficiency and BPT according to mass_exh, we found that if mass_exh increases, filtration efficiency increases and BPT decreases.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.165-177
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• 2007

Predictions of diesel particulate filtration are typically made by modeling of a particle collection, and providing particle trapping levels in terms of a pressure drop. In the present study, a series of single channel diesel particulate filter (DPF) experiments are conducted, the pressure traces are inversely analyzed and essential filtration parameters are deducted for model closure. A DPF filtration model is formulated with a non-linear description of soot cake regression. Dependence of soot cake porosity, packing density, permeability, and soot density in filter walls on convective-diffusive particle transportation is examined. Sensitivity analysis was conducted on model parameters, relevant to the mode of transition. Soot cake porosity and soot packing density show low degrees of dispersion with respect to the Peclet number and have asymptotes at 0.97 and $70\;kg/m^3$, respectively, at high Peclet number. Soot density in the filter wall, which is inversely proportional to filter wall Peclet number, controls the filtration mode transition but exerts no influence on termination pressure drop. The percolation constant greatly alters the extent of pressure drop, but is insensitive to volumetric flow rate or temperature of exhaust gas at fixed operation mode.