• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2609-2614
• /
• 2007

Shell & Tube type Oil Cooler is widely used for hydraulic presses, die casting machines, generation equipments, machine tools and construction heavy machinery. Temperature of oil in the hydraulic system changes viscosity and thickness of oil film. They have a bad effect to performance and lubrication of hydraulic machinery, so it is important to know exactly the heat exchanging efficiency of oil cooler for controlling oil temperature. But most Korean manufacturers do not have test equipment for oil cooler, so they cannot carry out the efficiency test of oil cooler and it is impossible to verify its performance. This paper includes information of construction of necessary utilities for oil cooler test and design and manufacture of test equipment. One can select the optimum product by obtaining performance data through tests of various kinds of oil coolers. And also the paper developed a program which can be easily used for design of 2D and 3D drawings of oil cooler.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.93-93
• /
• 2012

반도체 생산 공정은 고청정 환경을 요구하며, 이를 위해 반도체 생산 장비에서 고진공 펌프는 핵심 장비이다. 크라이오 펌프는 극저온 냉동기에 의해 냉각되는 냉각판에서의 응축 또는 흡착에 의해 기체를 제거하여 고진공 환경을 조성하는 고진공 펌프의 일종이다. 특히, 기존의 상용화된 크라이오 펌프에 적용되어온 GM 극저온 냉동기에 비해 본 연구에서 개발하는 맥동관 냉동기는 저진동 및 고신뢰성의 장점을 갖기 때문에 반도체 생산 장비의 공정 정밀도 및 유지보수 주기 향상에 도움이 될 것으로 기대된다. 하지만, 맥동관 냉동기는 저온부에 움직이는 부분이 없어 많은 장점을 갖지만, GM 극저온 냉동기에 비해 성능이 낮은 단점이 있다. 때문에, 맥동관 냉동기 적용 크라이오 펌프가 기존의 상용 제품에 대해 경쟁력을 갖기 위해서는 맥동관 냉동기의 성능 향상이 요구된다. 본 연구에서는 형상 설계 및 작동 조건 최적화 등을 포함하여 크라이오 펌프용 GM 맥동관 냉동기의 성능 향상 방안에 대한 연구를 수행한다.

• 한국기계가공학회지
• /
• 제19권6호
• /
• pp.36-42
• /
• 2020

Nowadays, the touch screen panel (TSP) cover glass for mobile smart devices is being developed with a curved glass shape due to different design requirements. Because the sizes of mobile smart devices continue to increase, there has also been a great increase in the demand for large-area curved glass greater than 20 inches. In this study, heat and fluid flow analysis using CFD was performed to optimize the heating surface temperature distribution of the large curved glass formation system. Five cooling water flow paths in the cooling block were designed and analyzed for each case. A function that can quantitatively calculate the temperature uniformity of the heating surface was proposed and these values were obtained for the five models. The temperature distributions of the heating surface and the energy consumption of the heating system were also compared and comprehensively analyzed. Based on the analysis results of the five different cooling channel path models, the optimal path design could be presented.

• 대한기계학회논문집B
• /
• 제21권1호
• /
• pp.1-14
• /
• 1997

Natural convection cooling of discrete heaters located in a two-dimensional vertical open top cavity is investigated experimentally. The five discrete heaters with same heat generation are located on the wall of the cavity. The heaters are arranged in two configurations; flush-mounted on a vertical wall and protruding from the wall about 4.5 mm. The materials used for the vertical walls are copper and epoxy-resin, and air is used as the cooling fluid. The temperature and flow fields in the cavity were visualized by means of Mach-Zehnder interferometer and smoke-method. Also, local temperature measurements are made along the vertical wall. Results are obtained for cavity aspect ratios of 4.6, 7.5 and 9.5 and modified Rayleigh numbers ranging from 10$^{3}$ to 10$^{6}$ . Results indicate that the cooling efficiency for the copper wall is superior to that of the epoxy-resin. For the epoxy-resin wall, the protrusion of the heaters plays a role in decreasing the heat transfer performance. The location of maximum temperature is significantly influenced by the wall materials and heater configurations. Correlations relating the Nusselt number to the modified Rayleigh number are proposed.

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• pp.1-8
• /
• 2002

Metal surface temperatures around the combustion chamber in a gasoline engine directly affect thermal durability and performance of the engine. Metal surface temperatures are influenced by many cooling factors such as drilled water passage, deflector, combustion chamber wall thickness, pillar, and coolant flow pattern. The object of this study is to learn how the coolant passages and coolant flow pattern in an engine influence to the engine metal surface temperature at engine full load and speed. From the test result, it is suggested a plan to reinforce the engine stiffness and to reduce the thermal stress simultaneously. Also, approaches are introduced to reduce the thermal load on the engine by adjusting the discharging direction from the water pump and by optimizing the water transfer holes in the cylinder head gasket. These methods and the optimized engine cooling system, which were suggested in this paper, were adapted for an engine in progress to eliminate the exhaust valve seat wear.

• 동력기계공학회지
• /
• 제13권4호
• /
• pp.56-61
• /
• 2009

In recent years, since the continuing increase in the capacity in personal computer such as the optimal performance, high quality and high resolution image, the computer system's components produce large amounts of heat during operation. This study analyzes and investigates the ability and efficiency of a cooling system inside a computer by means of central processing unit (CPU) and power supply cooling fan. This research was conducted to enhancement of efficiency of the cooling system inside the computer by making a structure which produces different air pressures in an air inflow tube. Consequently, when temperatures of the CPU and room inside computer were compared with a general personal computer, temperatures of the tested CPU, the room and the heat sink were as low as $5^{\circ}C$, $2.5^{\circ}C$ and $7^{\circ}C$ respectively. In addition to, revolution per minute (RPM) was shown as low as 250 after 1 hour operation. This research explored the possibility of enhancing the effective cooling of high-performance computer systems.

• 한국정밀공학회지
• /
• 제22권1호
• /
• pp.97-102
• /
• 2005

The procedure of semi-solid forming is composed of heating a billet, forming, compression holding and ejecting step. There are several methods to heat a billet during semi-solid forming process such as electric heating and induction heating. Usually in semi-solid forming process, induction heating has been adopted to achieve more uniform temperature of semi-solid material. Although induction heating is better method than any others, however, there is still difference of temperature between internal part and surface part of semi-solid material. Worse yet, in case of high liquid fraction of semi-solid material, liquid of the billet will flow down though solid of the billet still remains, which is very difficult to handle. In the present study, induction heating of semi-solid material with compulsive surface cooling has been performed to obtain uniform distribution of temperature. Distribution of temperature of the billets was measured and compared with that of conventional distribution of temperature. By this new induction heating method, not only temperature over the whole billet become uniform, but also control of temperature is possible.

• 한국자동차공학회논문집
• /
• 제7권6호
• /
• pp.1-7
• /
• 1999

In this study, the prediction method of coolant flow rates has been developed and applied to an engine and vehicle cooling system. The flow rate passing through each component of the system is very important parameter to evaluate the heat transfer process form the combustion gas to the coolant and the heat rejection process form the radiator /heater to the ambient air. However, the present study reveals that the measurement using the flowmeter fails to give practical flow rates due to its additive resistance. In contrast, the present method which uses the parallel and serial relationship of flow resistance proved to be a good tool to predict the real flow rates. It can be also used to design the cooling system in the incipient stage of engine/vehicle development . The procedure was coded to the computer program so as to use it flexibly and, in the future, to expand it into an independent design tool of the whole cooling system including the heat release and rejection.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.93-96
• /
• 2009

고속 비행기술의 발전과 엔진효율의 향상은 비행체와 엔진의 열적부하를 증가시킨다. 극초음속까지 비행체의 속도가 빨라지면 공기흐름을 이용한 냉각이 어렵기 때문에 항공유를 주요 냉각제로서 사용하게 된다. 연료가 열 흡수원(Heat sink)으로서 사용될 때 열분해반응 또는 촉매분해반응과 같은 흡열반응(Endothermic reaction)을 거쳐 분해가 되는데 이러한 특성을 지닌 연료를 흡열연료(Endothermic fuels)라고 한다. 흡열반응은 촉매를 통해 개선될 수 있지만, 코킹침적이 형성되기 이전까지의 온도로 제한된다. 본 연구에서는 흡열연료에 관련된 주요 기술을 조사하여 기초연구에 활용하고자 하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.465-468
• /
• 2000

The procedure of semi-solid forming is composed of heating a billet, forming, compression holding and ejecting step. There are several methods to heat a billet during semi-solid forming process such as electric heating and induction heating. Usually in semi-solid forming process, induction heating has been adopted to achieve more uniform temperature of semi-solid material. Although induction heating is better method than any others, however, there is still difference of temperature between internal part and surface part of semi-solid material. Worse yet, in case of high liquid fraction of semi-solid material, liquid of the billet will flow down though solid of the billet still remains, which is very difficult to handle. In the present study, induction heating of semi-solid material with compulsive surface cooling has been performed to obtain uniform distribution of temperature. Distribution of temperature of the billets was measured and compared with that of conventional distribution of temperature. By this new induction heating method, not only temperature over the whole billet become uniform, but also control of temperature is possible.