• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.76-84
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• 2011

The effect of inlet velocity profile on the heat transfer coefficient in a rotating smooth channel was investigated experimentally. Three simulated inlet flow conditions of fully developed, uniform, and distorted inlet conditions were tested. The Reynolds number based on the channel hydraulic diameter was ranged from 10,000 to 30,000 and the transient liquid crystal technique was used to measure the distribution of the heat transfer coefficient in the rotating channel. Results showed that the overall heat transfer coefficient increased as the Reynolds number increased. Also, the distribution of the heat transfer coefficient was strongly affected by the inlet flow condition. Generally, the fully developed flow simulated condition showed the highest heat transfer coefficient.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.536-547
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• 1997

For various angular velocities of crucible and crystal, the characteristics of melt flows, temperatures and concentrations of oxygen are numerically studied in the Czochralski furnace with a uniform axial magnetic field. Buoyancy effect due to the heating of crucible wall and thermocapillary effect due to the temperature gradient at the free surface, can be differentiably suppressed by the centrifugal forces due to the rotations of the crucible and crystal. The most important factor which yields the centrifugal forces is the rotation velocity of the crucible, that influences the fields of velocities, temperatures and concentrations. In the case that the crucible rotation velocity is not high, the rotations of the crystal gives rise to the centrifugal forces effectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.46-56
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• 1994

The characteristics of flows, temperatures, concentrations of the boron are numerically studied when uniform axial magnetic fields are applied in the Czechralski crucible. The to governing factors to the flow regimes are buoyancy, thermocapillarity, centrifugal forces, magnetic forces, diffusion coefficient and segregation coefficient of the boron. Since the concentration of the boron is so low that buoyancy effects are negligible, it cannot affect the flow and temperature fields. From the fact that the flow fields are rotationally symmetric, two velocity components in the meridional plane and the circumferential velocity are calculated together with the temperature in the steady state. Based on the known velocity and temperature distributions the unsteady concentration distributions of the boron are calculated. As the strength of the magnetic is increased, the flow velocities are decreased. Circumferential velocities are large near the crucible side-wall and in the region below the rotating crystal. Steep temperatures gradient near the edge of the rotating crystal causes the Marangoni convection. It has been found out that the convection characteristics affects the unsteady transport phenomena of the boron.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.3
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• pp.210-222
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• 1994

The characteristics of flows, temperatures, and concentrations of oxygen are numerically studies in the Czochralski furnace with a uniform axial magnetic field. Important governing factors to the flow fields include buoyancy, thermocapillarity, centrifugal force, magnetic force, diffusion and segregation coefficients of the oxygen, evaporation coefficient in the form of SiO, and ablation rate of crucible wall. With an assumption that the flow fields have reached the steady state, which means that two velocity components in the meridional plane and circumferential velocity, temperatures, electric current intensity become non-transient, then unsteady concentration field of oxygen has been analyzed with an initially uniform oxygen concentration. Oxygen transports due to convection and diffusion in the Czochralski flow field and oxygen flux through the growing crystal surface has been investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1509-1520
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• 1998

An experiment was carried out for the fully developed turbulent flow of water in tube coils on the condition of uniform heat flux. The present work was conducted for various ranges for Dean number(1794~1321), Prandtl number (2.5~4.5), curvature ratio parameters (22~60). Heat transfer to steady viscous flow in coiled tubes of circular cross section was studied for fully developed velocity and temperature fields under the thermal boundary condition of uniform heat flux. The peripherally local Nusselt number correlated as a function of Dean and Prandtl numbers. We studied the flow in heat coiled tubes under the influence of both centrifugal and buoyancy forces in order to gain insight into the flow pattern. In the present study, we obtained three emperical formulas, $Nu_v=0.0231Re^{0.84}Pr^{0.4}(a/R)^{0.13}$ (vertical) $Nu_c=0.0241Re^{0.86}Pr^{0.4}(a/R)^{0.08}$ (corrugated) $Nu_h=0.0227Re^{0.84}Pr^{0.4}(a/R)^{0.09}$ (horizontal).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.18-30
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• 1993

A numerical analysis has been carried out on the Czochralski flow fields when uniform and nonuniform magnetic fields are applied. Czochralski flow fields are governed by buoyancy forces, thermocapillarity, centrifugal forces, and applied magneic fields. In this analysis, pressure and three components of velocity vectors are obtained, and circumferential electrical currents are calculated. When a uniform magnetic field is applied, all the velocity components are decreased and the circumferential electric currents near the crystal surface are increased as the magnetic field intensity is increased. In the case of a nonuniform field, the flows in a meridional plane are suppressed and the circumferential velocity is increased as the non uniformity is increased. The understanding on the Czochralski flow fields under the influence of magnetic fields can lead to the study on the behavior of the concentration of the solute and impurities.

• Composites Research
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• v.36 no.2
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• pp.69-79
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• 2023

Oil-water separation is a critical process for several industrial applications, including oil production, wastewater treatment, food processing, and environmental area such as marine oil spills. The separation efficiency of oil-water mixtures can be influenced by various factors such as mixture composition, oil and water conditions, and the separation technology used. Over the years, various technologies have been developed to separate water and oil by physical, chemical and biological methods. This paper presents an overview of the various methods and technologies available for oil-water separation, including gravity separation, centrifugal separation, and separation using adsorbents, filters. The strengths and limitations of each method are discussed, along with recent research trends and future prospects. Furthermore, this paper aims to provide direction for future research and industrial application of sustainable and environmentally friendly oil-water separation technologies. In conclusion, we provide a comprehensive overview of recent oil-water separation technologies that will be beneficial to researchers and industrialists in the field of oil-water separation.