• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.4
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• pp.255-265
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• 2008

This paper presents the optimization process of evaporator for a vapor compression cooling system for high heat flux CPU. The CPU thermal capacity was given by 300W. Evaporating temperature and mass flow rate were $18^{\circ}C$ and 0.00182kg/s respectively. R134a was used as a working fluid. Channel width(CW) and height(CH) were selected as design factors. And thermal resistance, surface temperature of CPU, degree of superheat, and pressure drop were taken as objective responses. Fractional factorial DOE was used in screening phase and RSM(Response Surface Method) was used in optimization phase. As a result, CW of 2.5mm, CH of 2.5mm, and CL of 484mm were taken as an optimum geometry. Surface temperature of CPU and thermal resistance were $33^{\circ}C\;and\;0.0502^{\circ}C/W$ respectively. Thermal resistance of evaporator designed in this study was significantly lower than that of other cooling systems such as water cooling system and thermosyphon system. It was found that the evaporator considered in this work can be a excellent candidate for a high heat flux CPU cooling system.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.258-263
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• 2007

The performance of louver-finned flat-tube radiators for computer CPU liquid cooling were experimentally investigated. In this study, 5 samples of louver-finned flat-tube radiators with different width size (19mm, 24mm), tube hole (1, 9) and pass number (1, 2, 5) were tested in a wind tunnel. The experiments were conducted under the different air velocity ranging from 1 to 5 m/s. The water flow rate through a pass was 1.7 LPM. Inlet temperatures of air and water were $20^{\circ}C$ and $30^{\circ}C$ respectively. The results showed that the best performance in the 24mm sample considering pressure drop and heat transfer coefficient.

• Journal of ILASS-Korea
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• v.19 no.1
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• pp.19-24
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• 2014

In this study, the cooling performance of a liquid CPU cooler using the water/propylene glycol(PG)-based $Al_2O_3$ nanofluids is experimentally investigated. Water/PG-based $Al_2O_3$ nanofluids are manufactured by two-step method with ultrasonic energy for 10 hours. The volume fractions of the nanofluids are 0.25% and 0.35%. Thermal conductivity and viscosity of the nanofluids are measured to theoretically predict the thermal performance of the liquid CPU cooler using performance factor. Performance factor results indicate that the cooling performance of the liquid CPU cooler can be improved using the manufactured nanofluids. To evaluate the cooling performance of the liquid CPU cooler experimentally, temperature differences between ambient air and heater are measured for base fluid and nanofluids respectively. Based on the results, it is shown that performance of the liquid CPU cooler using $Al_2O_3$ nanofluids is improved maximum up to 8.6% at 0.25 Vol.%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.417-422
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• 2002

The experiments have been carried out to evaluate the cooling performance of a fan-aluminum foam heat sink assembly in comparison with a conventional CPU cooler. In terms of the dimensionless surface temperature of the heater, the cooling performance of the aluminum foam heat sink is similar to that of the conventional one with much reduced weight. The optimum fin height is found to be strongly dependent on the fin height of the heat sink and flow characteristics of the cooling fan.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.821-828
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• 2012

Increasing heat generation in CPUs can hamper effective recirculation and by-pass because of the large temperature difference between the exhaust and the intake air through a server room. This increases the overall temperature inside a data center and decreases the efficiency of the data center's cooling system. The purpose of the data center's cooling system is to separate the intake and exhaust air by controlling the computer room air-conditioner(CRAC). In this study, ICEPAK is used to conduct a numerical analysis of a data center's cooling system. The temperature distribution and the entire room are analyzed for different volumetric flow rates. The optimized volumetric flow rate is found for each CPU power. The heat removal and temperature distribution for CPU powers of 100, 120, and 140 W are found to be the best for a volumetric flow rate of $0.15m^3/s$. The numerical analysis is verified through RTI indicators, and the results appear to be the most reliable when the RTI value is 81.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.173-175
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• 2012

데이터 센터와 같은 대량의 서버를 사용하는 시설이 늘어남에 따라 전력 소모 관리와 열 발생 관리는 매우 중요한 문제가 되었다. 열 관리 연구들의 경우 대부분 열관리의 목적이 시스템의 오류를 방지하는 것이다. 하지만 열 관리에는 많은 전력 소모량이 사용된다. 따라서 열관리를 잘 해주는 것은 전력 관리를 효율적으로 해주는 것이라고 할 수도 있다. 본 논문은 열 관리를 전력 관리라는 측면에서 접근했다. 즉 열 관리에 사용되는 전력과 열로 인해 발생하는 전력을 고려해서 이를 최소화하는 냉각 제어 기법을 구현하였다. 우리가 개발한 냉각 제어 기법을 실제로 실험해서 기존의 냉각 기법과 비교해본 결과 전력 소모량을 17% 감소시키는 것을 확인 할 수 있었다.

• Electronics and Telecommunications Trends
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• v.30 no.1
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• pp.144-153
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• 2015

열전소자는 열에너지를 전기에너지로, 전기에너지를 열에너지로 직접 변환하는데 사용되는 소자로 자동차 온도조절 시트(Climate Control), 반도체(순환기, 냉각판), 바이오(혈액분석기, PCR, 시료온도싸이클 테스터기), 이학분야(스펙트로포토미터), 광학분야(CCD 쿨링, 적외선센서 냉각, 레이저다이오드 냉각, 포토다이오드 냉각, SHG레이저 냉각), 컴퓨터(CPU 냉각), 가전제품(김치냉장고, 소형냉장고, 냉온수기, 와인냉장고, 쌀통, 제습기), 산업분야(폐열발전기, 리모트 파워발전) 등 다양한 분야에 적용되고 있으며 새로운 시장을 창출하고 있다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.1
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• pp.1-7
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• 2011

The performance of louver-finned flat-tube and fin and tube radiators for computer CPU liquid cooling was experimentally investigated. In this study, 7 samples of radiators with different shape and pass number (1, 2, 10) were tested in a wind tunnel. The experiments were conducted under the different air velocity ranged from 1 to 4 m/s. The water flow rate through a pass was 1.2 LPM. Inlet temperatures of air and water were $20^{\circ}C$ and $30^{\circ}C$ respectively. It was found that the best performance was observed in the louver-finned flat-tube sample considering pressure drop and heat transfer coefficient.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.744-745
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• 2008

IT기기, 통신시기, 반도체 기기 등은 점점 더 고성능화되면서 속도도 빨라지고 기능도 추가되는 추세이다. 이러한 IT기기들은 속도와 더불어 열문제는 더욱더 크게 강조되고 있는 실정이며 개인용으로 많이 사용하고 있는 PC의 경우 더 이상 속도를 높이지 못하고 있는 실정이다. 이러한 열문제는 100W까지는 Heat pipe 등으로 냉각이 가능하였으나 거의 한계수준에 도달한 상황이다. 이러한 상황에서 일부 메니아들은 빠른 속도의 통신이나 작업을 위해서 수냉식 전용 냉각기를 설치하여 현재의 기능보다 더 좋은 환경에서 사용하고자 하고 있다. 본 연구에서는 수냉식 냉각기보다 더 큰 열용량을 가진 CPU의 냉각을 위해서 냉매 압축기를 적용하고자 하였으며 냉매 압축기에 사용하기 위한 선형압축기를 개발하고자 하였다. 즉 선형압축기에 의해서 압축된 냉매를 사용하여 CPU를 냉각하기 위해서 본 연구를 시작하였다. 본 연구에서는 선형전동기를 공진구동형 스프링을 장착하여 50-100Hz로 공진구동하는 액추에이터를 제작하여 그 특성을 알아보았다. 먼저 제자과정과 제작후 추력과 공진구동 설계 및 공진구동시 전기적, 기계적 특성변화를 확인하였으며 피스톤과 실린더 및 흡입밸브와 배기밸브 등을 장착하여 선형압축기로서 시운전까지 수행하였다.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.205-209
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• 2000

The performances of cascade-type thermoelectric modules are analysed by numerical simulations. The geometrical variations are used as design parameters.