The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform

Albert J Shih - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of the dry and near dry electrical discharge milling processes
    Journal of Manufacturing Science and Engineering-transactions of The Asme, 2008
    Co-Authors: Albert J Shih, Jun Ni
    Abstract:

    This study investigates the dry and near-dry electrical discharge machining (EDM) milling to achieve a high material removal rate (MRR) and fine surface finish for roughing and finishing operations, respectively. Dry EDM uses gas and near-dry EDM applies a Liquid-Gas Mixture as the dielectric medium. Experimental studies leading to the selection of oxygen gas and copper electrode for high MRR dry EDM and the nitrogen-water Mixture and graphite electrode for fine surface finish near-dry EDM are presented. Near-dry EDM exhibits the advantage of good machining stability and surface finish under low discharge energy input. A 2 5-1 fractional factorial design is applied to investigate the effect of discharge current, pulse duration, and pulse interval on the MRR and surface finish in dry and near-dry EDMs. Lower pulse duration and lower discharge current are identified as key factors for improving the surface finish in near-dry EDM.

  • near dry electrical discharge machining
    International Journal of Machine Tools & Manufacture, 2007
    Co-Authors: Albert J Shih
    Abstract:

    Abstract This study investigates the near dry electrical discharge machining (EDM) process. Near dry EDM uses liquid–gas Mixture as the two phase dielectric fluid and has the benefit to tailor the concentration of liquid and properties of dielectric medium to meet desired performance targets. A dispenser for minimum quantity lubrication (MQL) is utilized to supply a minute amount of liquid droplets at a controlled rate to the gap between the workpiece and electrode. Wire EDM cutting and EDM drilling are investigated under the wet, dry, and near dry conditions. The Mixture of water and air is the dielectric fluid used for near dry EDM in this study. Near dry EDM shows advantages over the dry EDM in higher material removal rate (MRR), sharper cutting edge, and less debris deposition. Compared to wet EDM, near dry EDM has higher material removal rate at low discharge energy and generates a smaller gap distance. However, near dry EDM places a higher thermal load on the electrode, which leads to wire breakage in wire EDM and increases electrode wear in EDM drilling. A mathematical model, assuming that the gap distance consists of the discharge distance and material removal depth, was developed to quantitatively correlate the water–air Mixture's dielectric strength and viscosity to the gap distance.

Felipe Bastos De Freitas Rachid - One of the best experts on this subject based on the ideXlab platform.

  • modeling of release and absorption of gas in liquid gas flows within a consistent thermodynamic framework
    International Journal of Engineering Science, 2013
    Co-Authors: Agnaldo Borges Silva, Felipe Bastos De Freitas Rachid
    Abstract:

    Abstract This work presents a consistent thermodynamic model to describe the gas release and gas absorption phenomena in homogeneous liquid–gas flows undergoing isothermal transformations. The liquid–gas Mixture is regarded as a pseudo-fluid whose constitutive behavior is obtained from two thermodynamic potentials: the Helmholtz free energy and a pseudo-potential of dissipation. Thanks to the inclusion of the concentration of dissolved gas in the liquid in the list of state variables, along with the gas volume fraction and the mass densities of the liquid and gas constituents, a suitable and simple expression for the rate of mass transfer of gas is derived. Besides of unconditionally satisfying the Second Law of the Thermodynamics, the proposed expression is capable to properly describe experimental data available in the literature with great accuracy for a relatively wide range of saturation pressures. Numerical simulations carried out for an water–air Mixture, subjected to a single expansion and cyclic expansion–contraction loadings, illustrate the influence of the gas release on the mechanical response of the fluid, which exhibits dispersion and attenuation and also hysteresis.

Agnaldo Borges Silva - One of the best experts on this subject based on the ideXlab platform.

  • modeling of release and absorption of gas in liquid gas flows within a consistent thermodynamic framework
    International Journal of Engineering Science, 2013
    Co-Authors: Agnaldo Borges Silva, Felipe Bastos De Freitas Rachid
    Abstract:

    Abstract This work presents a consistent thermodynamic model to describe the gas release and gas absorption phenomena in homogeneous liquid–gas flows undergoing isothermal transformations. The liquid–gas Mixture is regarded as a pseudo-fluid whose constitutive behavior is obtained from two thermodynamic potentials: the Helmholtz free energy and a pseudo-potential of dissipation. Thanks to the inclusion of the concentration of dissolved gas in the liquid in the list of state variables, along with the gas volume fraction and the mass densities of the liquid and gas constituents, a suitable and simple expression for the rate of mass transfer of gas is derived. Besides of unconditionally satisfying the Second Law of the Thermodynamics, the proposed expression is capable to properly describe experimental data available in the literature with great accuracy for a relatively wide range of saturation pressures. Numerical simulations carried out for an water–air Mixture, subjected to a single expansion and cyclic expansion–contraction loadings, illustrate the influence of the gas release on the mechanical response of the fluid, which exhibits dispersion and attenuation and also hysteresis.

Jun Ni - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of the dry and near dry electrical discharge milling processes
    Journal of Manufacturing Science and Engineering-transactions of The Asme, 2008
    Co-Authors: Albert J Shih, Jun Ni
    Abstract:

    This study investigates the dry and near-dry electrical discharge machining (EDM) milling to achieve a high material removal rate (MRR) and fine surface finish for roughing and finishing operations, respectively. Dry EDM uses gas and near-dry EDM applies a Liquid-Gas Mixture as the dielectric medium. Experimental studies leading to the selection of oxygen gas and copper electrode for high MRR dry EDM and the nitrogen-water Mixture and graphite electrode for fine surface finish near-dry EDM are presented. Near-dry EDM exhibits the advantage of good machining stability and surface finish under low discharge energy input. A 2 5-1 fractional factorial design is applied to investigate the effect of discharge current, pulse duration, and pulse interval on the MRR and surface finish in dry and near-dry EDMs. Lower pulse duration and lower discharge current are identified as key factors for improving the surface finish in near-dry EDM.

Yang Yang - One of the best experts on this subject based on the ideXlab platform.

  • a cost effective production of hydrogen peroxide via improved mass transfer of oxygen for electro fenton process using the vertical flow reactor
    Separation and Purification Technology, 2020
    Co-Authors: Yang Chen, Yuwei Pan, Yang Yang
    Abstract:

    Abstract This study has investigated a novel jet-type reactor (vertical flow reactor) in order to improve the oxygen utilization for enhanced production of hydrogen peroxide (H2O2). In vertical flow electro-Fenton (EF) system, the effects of current density, water flow rate, Fe2+ concentration and initial pH were investigated for the removal of tetracycline hydrochloride. The efficient removal of tetracycline hydrochloride could reach 100% within 60 min under the current density of 24 mA cm−2, water flow rate of 10 L h−1 and pH of 3. The vertical flow reactor was relatively stable and reusable for the removal of pollutants. The removal rates of tetracycline hydrochloride and total organic carbon (TOC) were maintained at about 95% and 80%, respectively in a 5-time continuous runs. Moreover, the vertical flow reactor could efficiently remove a wide type of organic pollutants, and the TOC removals of acid magenta, rhodamine B, alizarin yellow R, orange Ⅳ and diclofenacdium were 75.96, 77.90, 61.27, 72.11 and 82.89%, respectively after 3 h of reaction time. Cathodic adsorption, anodization, and H2O2 oxidation played minor roles in the removal of tetracycline hydrochloride, while the OH radicals are the most pivotal oxidizing substance in the system. As compared with the traditional aeration, the vertical flow reactor has a high-speed jet flow state, which makes the Liquid-Gas Mixture homogeneous, and renders it high oxygen absorption rate, cost effectiveness and high power efficiency for the degradation of pollutants.