• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.51-52
• /
• 2006

This study was progressed on the freezing behavior of waste water in relation to freeze concentration method useful to waste water treatment system of small and middle size and which can re-use purified water. The object of this experiment is comparing a pollutant contain of the frozen layer and of an aqueous solution by cooling wall temperature, a flow field effect and a initial thickness of frozen layer.

• Journal of Navigation and Port Research
• /
• v.37 no.2
• /
• pp.129-135
• /
• 2013

Recently, waste water treatment system is developed in small and middle size to get more economic advantage. Freeze concentration system has high thermodynamic efficiency and low energy consumption, can re-use purified water and cold energy obtained from ice. This study was experimentally performed to investigate pollution containment in frozen layer by cooling wall temperature, air-bubble flow methods, initial ice-lining thickness of frozen layer in NaCl aqueous solution and the representative heavy metals, Pb and Cr aqueous solution. As the result, a decrease in the cooling wall temperature bring a higher growth rate of ice front and the more solute was involved in frozen layer. The method to inject directly air-bubble into ice-liquid interface through ring shape nozzle gave high purity of ice compared to indirect method. Ice lining in 5mm thickness resulted in frozen layer with higher purity than 1mm thickness.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.9 no.4
• /
• pp.435-445
• /
• 1997

It was studied the phenomena of transient freezing of an inclined water-saturated enclosure. One side of the test section was cooled and the other sides were insulated. The effects of the initial temperature, the inclination angle on the temperature field and the shape of the ice-water interface were observed. In the beginning of freezing, with increasing the inclination angle the freezing rate was increased and in the stable density layer centered $4^{\circ}C$, the freezing was fast as the convective fluid flow became small. When the initial temperature was above the $4^{\circ}C$, the frozen thickness in the upper part of inclined surface was thinner than that in the lower part, but with time the frozen thickness of upper part was thicker than that of lower part, below the $4^{\circ}C$, the frozen thickness in the upper part was thicker than that of lower part from the begining, and above the $8^{\circ}C$ in the beginning upper part was thinner with concave, but with time thicker the upper part, vanishing concave.

• Journal of Advanced Marine Engineering and Technology
• /
• v.19 no.1
• /
• pp.36-44
• /
• 1995

Melting characteristics of unrestrained liquid ice in a rectangular vessel with heated top wall were investigated experimentally. The liquid ice, a mixture of ice particles and ethylene-glycol aqueous solution, was adopted as a testing material. During the melting process the liquid ice was drawn by buoyancy to the heated top wall of the rectangular vessel where close-contact melting occured. The melting behavior and melting rate of the liquid ice as well as local/mean heat-transfer coefficient at the heated top wall were observed and measured under a variety of conditions of heat flux and various initial concentration of the aqueous binary solution. It was found that the heat transfer of the heated top wall is remarkably promoted by the close-contact melting, and that the dendritic frozen layer at the lower interface of the liquid ice is formed. Photographic evidence demonstrated that plumes containing solute-rich liquid issued from isolated chimneys within the liquid ice layer where segregation of interstitial channel took place.

• Solar Energy
• /
• v.13 no.2_3
• /
• pp.53-64
• /
• 1993

This study investigated heat transfer phenomena during the freezing of an initially superheated or non-superheated liquid in a cooled cylinder tube. Numerical and experimental method were performed to obtatin the temperature and velocity distribution, the shape of interface. Natural convection effects in the superheated liquid were confined and moderated a short freezing time. After natural convection ceases, heat conduction dominated in the whole paraffin, so Crystal and much-zone were found out in PCM. Initial superheating of liquid tended to morderatly diminish the frozen layer thickness at short freezing times but little effect on the these quantities at longer times. On the amount of frozen mass, Iintial liquid superheating is less affected than tube wall subcooling.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.11-12
• /
• 2016

The contemporary buildings are becoming super-taller gradually as the industry evolves. Accordingly, winter concrete also became an important element for the year-round construction since shortening of a construction duration became important. Accordingly, this research team once developed a double bubble sheet as concrete cover curing compound during winter. But since there is no proper countermeasure for the exposed reinforcement bars, it is worried that the concrete can be damaged by exposed frozen reinforcement bars at a low temperature during the initial period. Therefore, in this study, it is intended to review the temperature history of the reinforcement bars depending on changes of the covering methods of the exposed reinforcement bars by using bubble sheets.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.3
• /
• pp.413-422
• /
• 1996

Freezing of water in von-$K{\acute{a}}rm{\acute{a}}n$ swirling flow is considered. The transient behavior of the temperature distribution in both solid and liquid phases and freezing rate are determined. The fluid flow induced by the rotation of solid strongly inhibits the freezing process. The thickness of frozen layer is inversely proportional to the square root of the angular velocity of solid. As the angular velocity or initial liquid temperature becomes larger, the freezing process is more strongly inhibited by the fluid flow. When phase change is present, the transient heat transfer rate is greater than the case with no phase change.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.10a
• /
• pp.13-14
• /
• 2016

In the modern construction industry, since numerous skyscrapers have been built, there have been sought for developing various kinds of methods for shortening a construction period. Therefore, many kinds of studies on some kinds of cold-weather concrete have been conducted actively for the purpose of a year-round construction. Accordingly, this research team once developed a double-layered bubble sheet as a surface-coated curing material for winter. And there have been raised some worries that some initial damages to frozen concrete caused by low temperature of reinforcing bars which are exposed out of the wall areas of a wall-type apartment during winter. Therefore, in this study, it is intended to find out clearly whether it is possible for concrete to be damaged initially or not by analyzing the temperature characteristics of the exposed reinforcing bars of the wall areas under the temperature conditions during winter.

• Journal of Powder Materials
• /
• v.21 no.3
• /
• pp.191-195
• /
• 2014

This study reports a simple way of fabricating the porous Cu with unidirectional pore channels by freeze drying camphene slurry with Cu oxide coated Cu powders. The coated powders were prepared by calcination of ball-milled powder mixture of Cu and Cu-nitrate. Improved dispersion stability of camphene slurry could be achieved using the Cu oxide coated Cu powders instead of pure Cu powders. Pores in the frozen specimen at $-25^{\circ}C$ were generated by sublimation of the camphene during drying in air, and the green bodies were sintered at $750^{\circ}C$ for 1 h in $H_2$ atmosphere. XRD analysis revealed that the coated layer of Cu oxide was completely converted to Cu phase without any reaction phases by hydrogen heat treatment. The porous Cu specimen prepared from pure Cu powders showed partly large pores with unidirectional pore channels, but most of pores were randomly distributed. In contrast, large and aligned parallel pores to the camphene growth direction were clearly observed in the sample using Cu oxide coated Cu powders. Pore formation behavior depending on the initial powders was discussed based on the degree of powder rearrangement and dispersion stability in slurry.