• 한국유체기계학회 논문집
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• 제12권2호
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• pp.24-30
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• 2009

Flow and noise analyses are conducted for examining a new design concept of impinging jet electronics cooling, and the analysis results are compared with conventional electronics cooling techniques. For the application of impinging jet electronics cooling method, the present study considers the air duct where air is supplied by axial fan and air flow from the duct is impinged vertically onto the electronic component heat source. Applying CFD simulation technique and fan noise model to the present cooling scheme, the cooling performance of the impinging jet as well as the operation condition and the noise characteristics of fan are investigated for various impinging jet nozzle conditions and fan models. Furthermore, the impinging jet electronics cooling analysis results are compared with the conventional parallel-flow cooling scheme to give the design concept and criteria of impinging jet cooling method.

• 설비공학논문집
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• 제22권9호
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• pp.614-619
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• 2010

Recently, a problem related to the thermal management in portable electronic and telecommunication devices is becoming issued. That is due to the trend of a slimness of the devices, so it is not easy to find the optimal thermal management solution for the devices. From now on, a pressed circular type cooling device has been mainly used, however the cooling device with thin thickness is becoming needed by the inner space constraint of the applications. In the present study, the silicon flat plate type cooling device with the separated vapor and liquid flow path was designed and fabricated. The normal isothermal characteristics created by vapor-liquid phase change was confirmed through the experimental study. The cooling device with 70 mm of total length showed 6.8 W of the heat transfer rate within the range of $4{\sim}5^{\circ}C/W$ of thermal resistance. In the future, it will be possible to develop the commercialized cooling device by revising the fabrication process and enhancing the thermal performance of the silicon and glass cooling device.

• Journal of Mechanical Science and Technology
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• 제19권10호
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• pp.1932-1938
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• 2005

Graphite foams consist of a network of interconnected graphite ligaments and are beginning to be applied to thermal management of electronics. The thermal conductivity of the bulk graphite foam is similar to aluminum, but graphite foam has one-fifth the density of aluminum. This combination of high thermal conductivity and low density results in a specific thermal conductivity about five times higher than that of aluminum, allowing heat to rapidly propagate into the foam. This heat is spread out over the very large surface area within the foam, enabling large amounts of energy to be transferred with relatively low temperature difference. For the purpose of graphite foam thermosyphon design in electronics cooling, various effects such as graphite foam geometry, sub-cooling, working fluid effect, and liquid level were investigated in this study. The best thermal performance was achieved with the large graphite foam, working fluid with the lowest boiling point, a liquid level with the exact height of the graphite foam, and at the lowest sub-cooling temperature.

• 설비공학논문집
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• 제25권3호
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• pp.131-136
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• 2013

The present study has conducted cycle design and control technology of a water source VRF heat pump system. Previously, study of a simultaneous heating and cooling in an air source VRF heat pump system has been conducted. However, performance data and design methods for simultaneous heating and cooling in a water source VRF heat pump system are limited in the literature, due to various system parameters and operating conditions. In this study, the operating characteristics and performances of a simultaneous heating and cooling heat pump system are carried out, in simultaneous operation modes. Control logics of an EEV are developed for flow rate control to the outdoor unit, and are verified. When the control logics are applied, the simultaneous cooling and heating performances are sufficiently achieved, and system COPs are increased by up to 23.4%.

• 한국유체기계학회 논문집
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• 제18권3호
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• pp.33-37
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• 2015

A numerical study on the IPM/Bridge Diode cooling and coil cooling has been performed. Results are presented as plots of thermal resistance, temperature drop and RPM-ratio. CFD analysis for conventional cooling system has been performed as a reference case. As the RPM-Ratio was increased, heatsink thermal resistance and coil temperature were decreased. IPM/Bridge Diode thermal resistance and temperature of the coil is tended to be trade-off. The temperature of coil closest to the AC-motor fan showed the most significant change in accordance with duct design. The temperature of coil located at the top of DC-motor fan showed the most significant variation as the cooling air passes the heatsink fin area.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 추계학술대회 논문집
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• pp.120-123
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• 2004

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 추계학술대회 논문집
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• pp.116-119
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• 2004

• 전력전자학회논문지
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• 제4권3호
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• pp.257-267
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• 1999

본 논문은 대용량 컨버터의 수냉식 방열 시스템에 관한 내용을 담고 있다. 본 논문은 수냉식 방열 시스템의 이론적 근거와 모델링을 제시하고 전력용 반도체(싸이리스터)의 열량 계산을 수학적인 모델링에 근거하여 제시하였으며 실제로 우리나라에 설치되어 있는 제주-해남 HVDC 시스템에 적용하여 타당성을 검증하였다.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.67-71
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• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.441-446
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• 2007

This present study is to evaluate the cooling performance of a water-to-refrigerant ground source heat pump system(GSHP) under actually operating condition. 1 unit is selected among 10 units of the GSHP in the building to analyze the performance. The average cooling COP of the GSHP at the part load of 64% is 8.2, overall system COP is 6.19. In the GSHP system, the cooling temperature of the condenser is lower compared to the air source heat pump system. Conclusively, the cooling performance of the GSHP is higher than the air source heat pump system by 80%.