• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1346-1351
• /
• 2004

This study is concerned with the thermal analysis during the cool-down period of 135,000 $m^3$ class GT-96 membrane type LNG carrier under IMO design condition. The cool-down is performed to cool the insulation wall and the natural gas in cargo tank for six hours to avoid the thermal shock at the start of loading of $-163^{\circ}C$ LNG. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls clown from $-40^{\circ}C$ to $-130^{\circ}C$ and the spraying rate for the insulation wall cooling increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the 1 st barrier and 1st insulation, which are among the insulation wall, especially in the top side of the insulation wall. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted.

• Land and Housing Review
• /
• v.11 no.3
• /
• pp.75-82
• /
• 2020

The urban heat island phenomenon that accelerates global warming has always been controversial when summer heatwaves have occurred since it was first investigated and described by Luke Howard in the 1810s. In Korea, since 2014, government have been interested in Cool Roof and painted white coating on the rooftops of the aging and weak buildings, and the cool roof business has expanded nationwide. However, the roof occupies 20-25% of the entire city surface, much less than 37-45% of the pavement area consisting of roads, parking lots and sidewalks, there is a need to expand the policy of Cool Pavement as a way to reduce the urban heat island phenomenon. Domestic cities are high-rise buildings centered on apartments, and the area occupied by outer walls is larger than that of rooftops compared to foreign low-rise buildings. Therefore, as a way to reduce the urban heat island phenomenon, there is a need for a policy to expand the Cool Roof in buildings and use Cool Wall in parallel. Therefore, this study aims to present the expansion of Cool Wall in buildings and Cool Pavement in urban areas, expanding the installation range of Cool Roof, by comparing and reviewing the thermal characteristics of eco-friendly ceramic coating with excellent thermal proof performance and coatings used for roof waterproofing.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.11
• /
• pp.1390-1397
• /
• 2004

This study is concerned with the thermal analysis during the cool-down period of 135,000㎥ class GT-96 membrane type LNG carrier under IMO and USCG design condition. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls down from -4$0^{\circ}C$ to -l3$0^{\circ}C$, and the spraying rate for the cooling of the insulation wall increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the first barrier and the first insulation, which are among the insulation wall, especially in the top side of the insulation wall under IMO and USCG design condition. Also, as the NG temperature distribution is fixed, the outer temperature condition under the design condition has influence on the temperature variation at the insulation. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted under IMO and USCG design condition. From the comparison between two conditions; IMO design condition shows more severe temperature gradient than USCG design condition, therefore, it provides the conservative estimation of the BOG.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.1
• /
• pp.125-134
• /
• 2003

The present paper is concerned to the thermal analysis during the cool-down period of 138,000 m$^3$class GTT MARK-III membrane type LNG carrier servicing with LNG from the Middle East to Korea. It is the cool-down period that cools the insulation wall and the gas in LNG tank to avoid the thermal shock as the start of loading of -162$^{\circ}C$ LNG. For six hours of the standard cool-down period, the temperature of NG falls down from -4$0^{\circ}C$ to -13$0^{\circ}C$ and especially the mean temperature of the 1st barrier in the top side insulation wall falls down from -38.38$^{\circ}C$ to -122.42$^{\circ}C$ in case of IMO design condition. By the 3-D numerical calculation about the cargo tank and the cofferdam, the temperature variation in hulls and insulations is precisely predicted in this paper. And the mean temperature variation of gas is calculated as the function of the spraying rate by the heat balance model during the cool-down period.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.5
• /
• pp.22-28
• /
• 2010

A study has been made of cool-down process on an incompressible fluid contained in a periodically oscillating cylinder when an abrupt cooling of wall temperature is imposed. Characteristics of flow and heat transfer are investigated along the variations of oscillating frequency and amplitude. One found the flow regimes are divided into 4-modes : 1 thermal island mode, 2 thermal island mode, 4 thermal island mode and asymmetry mode. Comprehensive analysis for each mode are given with a physical mechanism on cool-down process.

• Transactions of Materials Processing
• /
• v.15 no.1 s.82
• /
• pp.15-20
• /
• 2006

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.09a
• /
• pp.9-12
• /
• 2005

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filing difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation fur both the conventional molding and the RTR molding processes

• Computational Structural Engineering
• /
• v.10 no.4
• /
• pp.155-164
• /
• 1997

A reactor pressure vessel, which contains fuel assemblies and reactor vessel internals, has the thermal stress resulting from the cool-down and heat-up of the vessel wall in combination with the pressure stress from system pressure resulting in large stresses. The combination of the pressure stress and thermal stress along with a decrease in fracture toughness may cause through-wall propagation of a relatively small crack. Therefore, it is necessary to define the relations between operating pressure and temperature during cool-down and heat-up. In this study, theory of fracture mechanics for a pressure/temperature limit curve is investigated and a numerical procedure for generating it is developed. Plant-specific limit curves for the Kori unit 1 plant, the oldest nuclear power plant in Korea, have been obtained for several cooling and heating rates and their results are discussed.

• Progress in Superconductivity and Cryogenics
• /
• v.10 no.4
• /
• pp.33-37
• /
• 2008

The main objective of this study is to identify the pressure drop characteristics of coolant flow passages of 154kV/1GVA High Temperature Superconducting (HTS) power cable, experimentally. The passages were consisted of two parts, the one is the circular path with spiral ribs in the core to cool the cable conductor layer and the other is annular path with spirally corrugated outer wall to cool the shield layer. Thus the experiments to acquire the pressure drop data were performed with two types of circular spiral tubes and eight types of the concentric annuli in various range of Reynolds number. The pressure drops in the core tubes and the annuli were much higher than those in the tubes with smooth surface. Therefore, modified correlations to present the experimental results in each flow passage were suggested.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.3
• /
• pp.25-32
• /
• 2006

The objective of this study is to investigate the effect of building integrated PV application method on power generation. PV modules were integrated to a hypothetical apartment building facade in Seoul, Korea. Three different design options of PV panel mounted on exterior wall were developed for the analysis of cooling effects through ventilation. Numerical simulations using TRNSYS coupled with COMIS were executed to evaluate the design options. Their facade configurations are such as vertically installed PV panels with or without air gap between PV rear surface and exterior wall surface, and the tilted PV panels attached to the exterior wall at an angle of to the horizontal. Parametric results show that there is little difference regardless of the air 9ap width between PV rear surface and exterior wall surface. Special strategies which could effectively cool a PV panel to increase the electric power are required if we prefer to a vertical facade configuration in a building integrated PV installation. Consequently, it is expected that there is no reason for architect to install vertically PV panels with air gap unless active strategies are considered.