• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.451-464
• /
• 2008

Three-phase inverse fluidized bed has been widely adopted with its increasing demand in the fields of bioreactor, fermentation process, wastewater treatment process, absorption and adsorption processes, where the fluidized or suspended particles are small or lower density comparing with that of continuous liquid phase, since the particles are frequently substrate, contacting medium or catalyst carrier. However, there has been little attention on the three-phase inverse fluidized beds even on the hydrodynamics. Needless to say, the information on the hydrodynamics and transport phenomena such as heat and mass transfer in the inverse fluidized beds has been essential for the operation, design and scale-up of various reactors and processes which are employing the three-phase inverse beds. In the present article, thus, the information on the three-phase inverse fluidized beds has been summarized and reorganized to suggest a pre-requisite knowledge for the field work in a sense of engineering point of view. The article is composed of three parts; hydrodynamics, heat and mass transfer characteristics of three-phase inverse fluidized beds. Effects of operating variables on the phase holdup, bubble properties and particle fluctuating frequency and dispersion were discussed in the section of hydrodynamics; effects of operating variables on the heat transfer coefficient and on the heat transfer model were discussed in the section of heat transfer characteristics ; and in the section of mass transfer characteristics, effects of operating variables on the liquid axial dispersion and volumetric liquid phase mass transfer coefficient were examined. In each section, correlations to predict the hydrodynamic characteristics such as minimum fluidization velocity, phase holdup, bubble properties and particle fluctuating frequency and dispersion and heat and mass transfer coefficients were suggested. And finally suggestions have been made for the future study for the application of three-phase inverse fluidized bed in several available fields to meet the increasing demands of this system.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.5
• /
• pp.856-866
• /
• 1987

In the present paper a statistical method using probability density function has been applied to investigate experimentally the flow patterns and fluctuations of time-averaged local void fraction in air-water two-phase mixtures which flow vertically upwards in concentric annuli. This study was carried out using three vertical concentric annuli. The annular test section consists of a lucite outer tube whose inside diameter is 38mm and a stainless steel inner rod. The rod diameter is either 12mm, 16mm or 20mm. The two-phase flow patterns observed in the experiment were bubbly, slug, annular and each transition patterns. It was first demonstrated that the variance, coefficients of skewness and kurtosis calculated from probability density function on time-averaged local void fraction can be used to identify the flow patterns in the annular passage, and the fluctuation of time-averaged local void fraction varies with the radial position in annular gap and the flow pattern.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.3
• /
• pp.7-12
• /
• 2007

Friction welding is a welding method to use frictional heat of a couple of materials. In this paper object is that design the welding part shape with the flow gallery part which there is no effect in flow. Decided the welding part design parameter and doing the friction welding analysis used the rigid-plastic FEM program DEFORM-2D. To do friction welding analysis must input necessary flow stress data, friction coefficient by temperature change, upset pressure and Revolution per minute etc. According to analysis result, it decided the optimal shape of welding part with no effect in flow.

• Solar Energy
• /
• v.15 no.3
• /
• pp.105-117
• /
• 1995

Heat transfer coefficients on a single spiral coil tube in the furan foundry sand fluidized bed have been investigated. Heat transfer coefficients(ho) to an immersed single spiral coil tube were measured in the bed. The bed diameter was 0.21 m. The following quantities were varied: (l)bed temperature, (2)mean particle diameter, (3) fluidization rate, (4)the ratio of heated coil tube pitch to diameter(p/Do), and (5)the ratio of heated coil tube pitch to mean particle diameter(p/dp). In addition, the experimental values of maximum Nusselts number were compared with the values of maximum Nusselts number predicted by the existing correlations. The values of heat transfer coefficient increase with the increase in bed temperature and fluidization rate, but decrease with increase in particle diameter. An empirical formulus of maximum Nusselts number which is applicable in the furan foundry sand fluidization bed is as follows: $$Nu_{max}=1.01\;Re^{0.48}Prg^{0.4}(p/dp)^{0.28}(p/Do)^{0.05}$$.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.1
• /
• pp.61-69
• /
• 2015

The objective of this study is to experimentally investigate the mixed flow behaviors and oxygen transfer characteristics of a vertical orifice ejector. The experimental apparatus consisted of an electric motor-pump, an orifice ejector, a circulation water tank, an air compressor, a high speed camera unit and control or measurement accessories. The mass ratio was calculated using the measured primary flow rate and suction air flow rate with experimental parameters. The visualization images of vertically injected mixed jet issuing from the orifice ejector were qualitatively analyzed. The volumetric oxygen transfer coefficient was calculated using the measured dissolved oxygen concentration. At a constant primary flow rate, the mass ratio and oxygen transfer coefficient increase with the air pressure of compressor. At a constant air pressure of the compressor, the mass ratio decreases and the oxygen transfer coefficient increases as the primary flow rate increases. The residence time and dispersion of fine air bubbles and the penetration of mixed flow were found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.6
• /
• pp.1415-1427
• /
• 1988

The effect of injection angle and blowing rate on a film-cooled flat plate has been investigated experimentally. Three cases of 90.deg. injection, 35.deg. streamwise injection and 35.deg. spanwise injection are employed. The naphthalene sublimation technique in used to obtain local mass transfer coefficients. Thus heat transfer coefficients are evaluated using heat-mass transfer analogy. Schlieren photographs are taken to visualize the trajectory of injection fluid by introducing carbon dioxide gas through injection tubes. The experiments indicate that due to the injection the heat transfer coefficients increase significantly in the neighborhood of the infection holes, so the design of film cooled component must be based on the heat transfer coefficient with injection as well as film cooling effectiveness.

• The Journal of Engineering Geology
• /
• v.9 no.2
• /
• pp.101-118
• /
• 1999

The pumping test analysis on 28 pumping test data in Duksan hot-spring area was performed using the fractal model, the leaky fractal model, and the steady-state dual-porosity fractal model. The fractional flow dimension 1.9 or 2.0 was determined in the central put of the hot spring and the fractional flow dimension 1.5-1.7 in the marginal area. For the flow dimension 2.0, the correlation between the transmissivity and the productivity index by the aquifer loss was much better than that between the transmissivity and the specific yield by the total drawdown. On the other hand, for the flow dimension 1.9, the correlation between the generalized transmissivity and the productivity index was very similar to that between the generalized transmissivity and the specific yield.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.6
• /
• pp.1372-1380
• /
• 1988

A heat transfer model for a pulse combustion water heater is developed, and an associated computer simulation is conducted to determine the temperature distribution as well as heat transfer rate. Parametric studies are performed to examine the effects of the operating and design variables on the thermal performance and heat transfer rate. They are found to be influenced mainly by energy input rate, the amount of excess air, the volume of combustion chamber, and the diameter of flue tube.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.84.2-84.2
• /
• 2005

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.10
• /
• pp.817-824
• /
• 2015

Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles.