• 한국기계가공학회지
• /
• 제8권4호
• /
• pp.83-89
• /
• 2009

This study investigates two-phase cooling system of close-loop by using FC-72 and PCM(Phase change material). The cooling system consists of evaporator, cold plate, micro pump, and condenser. The heat input on the performance of evaporator is appreciated by visualizing the boiling on the evaporator. The heat performance of cooling system is investigated to determine the effects of volume fill ratio change at working fluid, pump flow rate change, and volume fill ratio change at PCM in cold plate. Experimental results show the ideal condition when the volume ratio of working fluid, the pump flowing, and the volume ratio of PCM are 60%, 6ml/min, and 60% respectively.

• 한국추진공학회지
• /
• 제9권3호
• /
• pp.92-100
• /
• 2005

로켓엔진 연소기의 분사면 냉각성능을 개선하기 위한 연료 매니폴드의 최적형상을 제시하였다. 매니폴드의 형상은 분사균일성을 최대한 유지하면서 분사면 중심의 냉각성능을 높일 수 있어야 한다. 이를 위하여 7가지 후보 형상에 대하여 냉각성능을 비교한 결과 분사기 2-3열과 9-10열 사이에 분리판이 설치된 형상이 최적인 것으로 판단되었다. 분사균일성은 설계원형과 유사한 수준이며 분사면의 최고온도는 27$\%$ 감소하였다. 또한 매니폴드의 형상 변화에 의한 추가적인 압력강하는 거의 없을 것으로 예측되었다.

• 한국주조공학회지
• /
• 제29권3호
• /
• pp.144-149
• /
• 2009

In this study, we investigated optimum condition of cooling plate method to obtain semi-solid AM100A Mg alloy with fine and globular morphology. AM100A Mg alloy were hot extruded at $380^{\circ}C$ extrusion temperature under extrusion ratio of 25 : 1 and ram speed of 2.4 mm/sec. Vickers hardness test, optical microscopy, scanning electron microscopy, and image analyzer were performed to identify the optimum conditions of cooling plate method. Optimum conditions of cooling plate method to fabricate semi-solid AM100A Mg alloy with fine and globular microstructures were achieved at a pouring temperature of $602^{\circ}C$ and the angle of cooling plate of 60 degree.

• 한국생산제조학회지
• /
• 제20권1호
• /
• pp.81-85
• /
• 2011

Recently, the electronic parts are to be thinner plate, smaller size, light weight material and CPU, HDD and DRAM in all the parts have been produced on the basis of the high speed and greater capacity. Also, conventional goods have replaced a LED (Light-Emitting Diode) in lighting products so; such industry devices need to have cooling. To maximize all the performance on the heat-radiated products, the area of heat-radiated parts is required to be cooled for keeping the life time extension and performance of product up. Existing cooling systems are using radiant heat plate of aluminum, brass by extrusion molding, heat pipe or hydro-cooling system for cooling. There is a limitation for bringing the light weight of product, cost reduction, molding of the cooling system. So it is proposed that an alternative way was made for bringing to the cooling system. EP (Engineering Plastic) of low-cost ABS (Acrylonitrile butadiene styrene Resin) and PC (Polycarbonate) was coated with brass and the coating made the radiated heat go up. The performance of radiant heat plate is the similar to the existing part. We have studied experimentally on the radiated heat plate for the light-weight, molding improvement and low-cost. From now on, we are going to develop the way to replace the exiting plate with exterior surface of product as a cooling system.

• 한국태양에너지학회 논문집
• /
• 제27권4호
• /
• pp.11-17
• /
• 2007

The purpose of this study is to check whether the plate temperature could be lower than the surrounding air by using the radiant cooling during the day time in summer at Seoul. Without an insolation shield as this experiment was performed, a few cases were found. The temperatures of the black painted plate are lower than those of the aluminium film coated plate if the following condition exist; no or small insolation over the plate, the wind velocity less than around 2 m/s, and clear sky However if there are insolation over the plate, the temperatures of the aluminium coated plate are lower than the black painted plate. Also, as the wind velocity increases, the plate temperature decreases faster. The temperature response of the small system is much faster than the large system.

• 한국전산유체공학회지
• /
• 제21권2호
• /
• pp.90-98
• /
• 2016

A numerical study is conducted on thermal performance of a large-area hot plate specially designed as a heating and cooling tool for thermal nanoimprint lithography process. The hot plate has a dimension of $240mm{\times}240mm{\times}20mm$, in which a series of cartridge heaters and cooling holes are installed. The material is stainless steel selected for enduring the high molding pressure. A numerical model based on the ANSYS Fluent is employed to predict the thermal behavior of the hot plate both in heating and cooling phases. The PID thermal control of the device is modeled by adding user defined functions. The results of numerical computation demonstrate that the use of cartridge heaters provides sufficient heat-up performance and the active liquid cooling in the cooling holes provides the required cool-down performance. However, a crucial technical issue is raised that the proposed design poses a large temperature non-uniformity in the steady heating phase and in the transient cooling phase. As a remedy, a new hot plate in which heat pipes are installed in the cooling holes is considered. The numerical results show that the installation of heat pipes could enhance the temperature uniformity both in the heating and cooling phases.

• International Journal of Ocean System Engineering
• /
• 제1권1호
• /
• pp.46-51
• /
• 2011

In a line heating process for hull forming, the phase of the steel transforms from austenite to martensite, bainite, ferrite, or pearlite depending on the actual speed of cooling following line heating. In order to simulate the water cooling process widely used in shipyards, a heat transfer analysis on the effects of impinging water jet, film boiling, and radiation was performed. From the above simulation it was possible to obtain the actual speed of cooling and volume percentage of each phase in the inherent strain region of a line heated steel plate. Based on the material properties calculated from the volume percentage of each phase, it should be possible to predict the plate deformations due to line heating with better precision. Compared to the line heating experimental results, the simulated water cooling process method was verified to improve the predictability of the plate deformation due to line heating.

• 설비공학논문집
• /
• 제19권11호
• /
• pp.797-802
• /
• 2007

The effects of window cover on the performance of the plate type radiant cooling test system are studied. The cover materials tested are 2mm, 1mm, 0.7mm glass, Cokin 007 filter, and PVC film. The measurements are performed during the September nights of 2005 at the rooftop of the building in Seoul. The equivalent height of the building is about a building with twelve floors. The radiant cooling performance of the black painted and aluminum film coated plate are compared under no cover condition. Also the results are compared when the system has cover over the plate. In general, the covers reduce the radiant cooling temperature differences during the nighttime. Among these covers, the PVC film cover shows the best performance. In some cases, the plate with PVC film cover shows lower temperatures than the system without cover.

• 한국태양에너지학회 논문집
• /
• 제28권5호
• /
• pp.49-55
• /
• 2008

The radiant cooling(RC) effects are studied during the winter night. The plate was viewing the nighttime sky. The data were collected at the rooftop of the Engineering building at the Dongguk University in Seoul, Korea. As observed during the summer night, the plate temperature was lower than ambient temperature under the RC favorable conditions. The parameters under study are the wind velocity, cloud index, and visibility for given system size and surface condition. The results follow the same tendency with these parameters as observed from the previous study for the summer night. As long as the wind velocity is less than around 2 m/s, the radiant cooling was observed with the system under study. In some cases, the radiant cooling temperature differences (RCTD) are higher than those for the summer night. The larger the RCTD as the wind velocity decreases and as the sky becomes clear.

• 대한기계학회논문집
• /
• 제12권5호
• /
• pp.952-958
• /
• 1988

본 연구에서는 폭방향 불균일 냉각에 따른 열응력이 판변형 및 잔류응력의 주 요원인이라는 고려하에 냉각중에 압연판의 온도분포 및 열응력을 예측할 수 있는 수치 해석 모델을 구성하였다. 온도와 응력 계산에 상변태 현상을 고려하였으며, 판변형 은 압축성분 열응력에 의한 좌굴현상으로 고려하여 해석하였다.