박판형 히트파이프의 모세관력 향상을 위한 구조 개발

문석환(Seok-Hwan Moon),박윤우(Yoon-Woo Park) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Considering using the heat pipe in Electronic Telecommunication Fields is in incremental increase. Especially in the electronic packaging application, the thin flat heat pipe has relatively higher applicability compared with the circular heat pipe. The thin flat heat pipe(TFHP) could be realized by pressing the circular heat pipe or welding two plates, however the envelope for the thin flat heat pipe with the total thickness of 2㎜ was obtained by the extrusion process through the present study. The thin flat heat pipe has the simple capillary wick structure consisting of rectangular cross sectional grooves built on the inner wall of that. Although the groove is simple as the capillary wick and many of that are built on the inner wall, it is difficult to realize a relatively high capillary force by the grooves. In the present study, to overcome the poor capillary force in the thin flat heat pipe with grooves, the thin flat heat pipe with wire bundle was fabricated and tested. Through the performance test, the thin flat heat pipe with the wire bundle showed the lower thermal resistance about 3.4 times and higher heat transfer rate about 3.8 times than the thin flat heat pipe with grooves as the capillary wick respectively. The possibility of the wire bundle in the thin flat heat pipe as the capillary wick was validated in the present study and the study for commercializing will be followed in the future.

히트파이프와 루프히트파이프의 성능향상에 관한 최신기술

정의국(Eui Guk Jung),권정훈(Cheong Hoon Kwon),부준홍(Joon Hong Boo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

This paper has dealt with the three latest technologies for performance improvement of heat pipe and loop heat pipe. First, a part of the liquid in the condenser is bypassed to the evaporator in order to reduce the interface flow resistance caused by the counter flow of liquid and vapor inside the heat pipe. By applying this technology, the maximum amount of heat transfer caused by dry-out of the heat pipe was increased, and the experimental results were introduced, which improved the heat transfer performance by reducing the thermal resistance. Second, a technique of bypassing a portion of the vapor generated from the evaporator to the liquid reservoir was introduced in order to overcome the operational limit of the loop heat pipe. Through the application of the vapor bypass technology, the temperature overshoot on the evaporator wall of the loop heat pipe could be eliminated, and the heat transfer performance could be improved at high heat load range. Third, a performance prediction model of the micro heat pipe was developed. In this study, a performance prediction model for micro heat pipe to which the augmented Young-Laplace equation is applied is presented. This mathematical model has the advantage of being able to predict the shape of the phase change interface created inside the micro heat pipe more precisely than the previous model. The three latest technologies mentioned above can be studied more popularly in the future and can contribute to the technological expansion of heat pipe and loop heat pipe.

히트파이프 열교환기의 열전달 성능해석 및 모사

권혁수,권정훈,정의국 대한기계학회 2023 大韓機械學會論文集B Vol.47 No.11

본 연구는 히트파이프 열교환기의 열교환 성능을 예측하기 위한 수학적 모델을 전개하고 열교환기 설계를 위한 알고리즘을 개발하기 위해 수행되었다. 해석모델에 의해 히트파이프 열교환기의 열성능이 예측되었으며, 열교환기의 고온부와 저온부의 입력조건들에 따라 요구되는 열교환 성능이 획득될 수 있는 히트파이프 열 수가 예측될 수 있도록 알고리즘이 구성되었다. 해석모델은 열저항 접근에 의해 개발되었으며, 각 열에 배열된 히트파이프와 열매체에 대한 열저항-온도 관계가 정의되었다. 해석모델의 신뢰성은 문헌에서 공급된 실험결과에 의해 검증되었으며, 온도에 대한 상대오차는 평균적으로 5% 이내에 있었으나, 유용도에 대한 오차의 평균은 11.9%로 평가되었다. 히트파이프 열교환기의 성능모사를 위한 변수들로서 저온측 입구속도와 공통 벽의 위치가 채택되었으며, 각 열의 온도 분포, 유용도 및 압력강하에 기여하는 이들 변수들의 영향이 조사되었다. This study aimed to develop a mathematical model for predicting the heat exchange performance of a heat pipe heat exchanger and establish an algorithm for effective heat exchanger design. The thermal performance of the heat pipe heat exchanger was assessed using the analytical model, and an algorithm was formulated to estimate the number of heat pipe rows required to achieve the desired heat exchange performance based on the input conditions of the hot and cold sides of the heat exchanger. The analytical model was developed using the thermal resistance approach, defining thermal resistance-temperature relationships between the heat pipes arranged in each row and the heat transfer fluid. The reliability of the analytical model was validated against experimental results found in the literature. The relative error in temperature generally remained within 5, but the error in effectiveness reached up to 17.5%. Inlet velocity on the cold side and the location of the common wall were selected as variables for simulating the performance of the heat pipe heat exchanger. This allowed for an investigation into the effects of these variables on temperature distribution, utility, and pressure drop in each row.

히트파이프와 루프히트파이프의 성능향상에 관한 최신기술

정의국(Eui Guk Jung),권정훈(Cheong Hoon Kwon),부준홍(Joon Hong Boo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

This paper has dealt with the three latest technologies for performance improvement of heat pipe and loop heat pipe. First, a part of the liquid in the condenser is bypassed to the evaporator in order to reduce the interface flow resistance caused by the counter flow of liquid and vapor inside the heat pipe. By applying this technology, the maximum amount of heat transfer caused by dry-out of the heat pipe was increased, and the experimental results were introduced, which improved the heat transfer performance by reducing the thermal resistance. Second, a technique of bypassing a portion of the vapor generated from the evaporator to the liquid reservoir was introduced in order to overcome the operational limit of the loop heat pipe. Through the application of the vapor bypass technology, the temperature overshoot on the evaporator wall of the loop heat pipe could be eliminated, and the heat transfer performance could be improved at high heat load range. Third, a performance prediction model of the micro heat pipe was developed. In this study, a performance prediction model for micro heat pipe to which the augmented Young-Laplace equation is applied is presented. This mathematical model has the advantage of being able to predict the shape of the phase change interface created inside the micro heat pipe more precisely than the previous model. The three latest technologies mentioned above can be studied more popularly in the future and can contribute to the technological expansion of heat pipe and loop heat pipe.

가스내장 히트파이프의 냉시동특성과 성능에 관한 연구

홍성은,강환국 대한설비공학회 2006 설비공학 논문집 Vol.18 No.11

Considering heat pipe design principles in fabrication and operational performances, water is one of the most recommended working fluids to make mid to low temperature heat pipes. But the conventional water heat pipes might encounter the failure in a cold start-up operation when socked at a chilling temperature lower than the freezing point. If they are subjected to a heat supply for start-up at a temperature around -20℃, the rate of the vapor flow and the corresponding heat transfer from the evaporator to the condenser is so small that the vapor keeps to stick on the surface of the chilling condenser wall, forming an ice layer, resulting in a liquid deficiency in the evaporator. This kind of problems was resolved by Kang et al. in 2004 by adopting a gas loading heat pipe technology to the conventional water heat pipes. This study was conducted to examine a chilling start-up procedure of gas loading heat pipes by investigating the behaviors of heat pipe wall temperatures. And the thermal resistance of the gas loaded heat pipe that depends on the operating temperatures and heat loads was measured and examined.Two water heat pipes were designed and fabricated for the comparison of performances, one conventional and the other loaded with N2 gas. They were put on start-up test at a heat supply of 30W after having been socked at an initial temperature around -20℃. It was observed that the gas loaded one had succeeded in chilling start-up operation.

히트파이프와 핀을 활용한 2차 전지 실링 장비 냉각성능 평가

윤종성,우용건,윤린 한밭대학교 2011 한밭대학교 논문집 Vol.27 No.-

The study was done to decrease and to evenly disperse the heat transfer rate from the pouch-sealing unit to the cylinder part of the apparatus of manufacturing the battery for the electric vehicle. The pouch-sealing unit is made of the heating block having a cartridge heater, and the cylinder part is designed for moving the pouch-sealing unit. The heat transfer from the pouch-sealing unit to the cylinder deteriorate the performance of the cylinder working. The two different heat sinks made of aluminum fin, heat pipes, and the combination of heat sink and heat pipe were designed and tested for efficient cooling for the heating block. When the heat sink was applied to the system the temperatures of the heating block was lower by 21%, and for the combination of heat sink and heat pies the temperature decreased to 33%. 전자장 비 및 통신 기기의 고성능 및 고정 밀화 에 따른 고발열 로 인해 냉각장치 기술이 대두되고 있다. 최근 연구 에 따르면 반도체 접점의 냉각 온 도가 25℃ 에서 12℃ 5℃ 로 변하면 파손율은 거의 10 배 로 증가하고,접점의 온도 변화폭 이 심한 경우 는 일정한 온도조건 에서 작동하는 경우보다 수명 이 6 배 정도 짧아진다고 보고하였다. 이런 열 발생밀도의 증가로 냉각시스템 의 고성능화 가 필수 요건이 되었고,특히 이러한 상황에서 히트파 이프 및 히트 싱크 를 이용한 냉각장치 응용분야가 확대 되고 있는 상황이다. Hwang et al.은 히트파이프 를 PC CPU 의 냉각모듈 로 사용할 경우 기존 히트 싱크와 팬을 사용한 냉각모듈에 비해 무부하 시 7.3"(; (20%), 부하 시7.2"(;( 1 8.5%) 의 냉각성능 향상 이 있음을 보고하였다. 히트 파이프는 고효 율, 시스템의 소형화,무동력, 다양한 형상화 등의 장점 으로 인하여 최근에는 정보통신 산업 에 적용하기 위한 연구가 미국과 일본을 중심으로 매우 활발히 진행되고 있으며, 국내에서도 전자 부품 및 항공 우주분야의 냉각시스템의 고성능화에 히트파이프 기술을 이용 하는 업체들이 증가하면서 응용분야가 확대되고 있는 상황이다.

다공성 모델을 이용한 히트 파이프 열교환기의 열 성능 해석

이승재,김윤서,금교훈,강석경,신동환,이성혁,이정호,이형순 대한기계학회 2023 大韓機械學會論文集B Vol.47 No.12

히트 파이프 열교환기(HPHX)는 일반적인 열교환기와는 달리 히트 파이프를 사용하기 때문에 열을 효과적으로 전달할 수 있다. 하지만 열교환 효율을 높이기 위해 히트 파이프 외부에 얇은 핀(fin)을 추가하면, 이를 해석하기 위해 많은 격자가 필요하게 되고 높은 해석 비용으로 인해 정확도가 저하되게 된다. 본 연구에서는 full scale 전산 해석을 위해 히트 파이프의 외부 핀 영역을 porous media model 방식을 적용하였다. 이를 통해 HPHX에서 porous media model의 종류에 따른 열교환기에서의 열성능 및 효율 변화를 분석하였으며 이를 기반으로 작동 환경의 변화에 따른 열교환 성능 변화를 확인하였다. 본 연구의 결과는 HPHX 열교환기에 대해 porous media model을 활용한 전산 해석의 방법을 제공함으로써 열 및 유동 성능의 예측 정확도 향상에 기여할 수 있을 것으로 기대된다. Unlike conventional heat exchangers, HPHX employs heat pipes for more efficient heat transfer. However, augmenting heat exchange efficiency by adding thin fins to the heat pipe’s exterior necessitates intricate grid-based interpretation, resulting in diminished accuracy dur to the high computational costs involved. Here, we employed a porous media modeling approach to the external fin area of the heat pipe to conduct a thorough computational analysis of HPHX. Variations in heat transfer rate and effectiveness in the heat exchanger were extensively investigated based on different porous media modeling methods. These findings offer a methodological advancement in computational analysis for HPHX heat exchangers, enhancing the precision of predicting thermal and fluid performance.

히트파이프와 용융염을 사용하는 태양열 축열조의 설계

이정륜(Jung Ryun Lee),부준홍(Joon Hong Boo) 한국태양에너지학회 2011 한국태양에너지학회 학술대회논문집 Vol.2011 No.4

Thermal design was conducted for a solar thermal storage system in a medium-temperature range between 200℃ and 400℃. The system was composed of heat pipes as heat carrier and molten salts as phase-change storage material. Each heat pipe penetrated through the storage system and had two heat-exchanging sections at both ends to interact with high- and low-temperature steams, while it exchanged heat with molten salts in the middle section. During a heat-storage mode, the heat pipes transferred heat from the hot steam at one side to the molten salts and it transferred heat from the molten salt to the cold steam at the other side during the heat-dissipating mode. A tube-bank type heat exchanger theory was applied to this design task to meet the required inlet and outlet temperatures of the steams depending on the operation modes. Several design variables were considered including the lengths of evaporator and condenser of a heat pipe, traverse and longitudinal pitches of the pipe, and the number of rows of the heat pipes for two different molten salt baths. An optimum design results were presented with discussion.

바이패스라인에 의한 히트파이프의 최대열전달 성능향상에 관한 연구

바트세이칸뭉크밧(Batsaikhan Munkhbat),세렌토르즈간프렙(Tserendorj Ganpurev),정의국(Eui Guk Jung) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

Dryout prevention is an important index of heat pipe performance. The balance between the capillary pressure supplied by the wick structure of a heat pipe and the flow resistance of the liquid returning to the evaporator determines the maximum heat transfer rate under which a steady state can be maintained. The maximum heat transfer rate is referred to as the capillary limit. If the heat pipe operates at a certain thermal load exceeding the capillary limit, then the onset of dryout in the wick structure occurs at the starting point of the evaporator and expands throughout the entire heat pipe over time. In this study, a bypass line for accelerating working fluid was first devised in order to improve the dryout prevention performance during heat pipe operation. The bypass line is designed so that a part of the working fluid can be bypassed without passing through the capillary structure by connecting the evaporator and the condenser. The liquid bypass line has the effect of increasing the maximum heat transfer rate of the heat pipe because it can increase the thermal load that can cause dryout by reducing the flow resistance of the working fluid on the phase change interface. Acetone was used as the working fluid. The effect of the bypass line on the heat transfer performance of the heat pipe was experimentally investigated. The maximum heat transfer rates of the heat pipe with and without the liquid bypass line were analyzed and compared at tilt angles of 0° to 20°. The results show that the maximum heat transfer rate was increased by approximately 35.5% using a horizontal arrangement.

히트파이프를 이용한 바닥복사패널의 난방특성 연구

한태수(Tae-Su Han),김용기(Yong-Ki Kim),이태원(Tae-Won Lee),전삼준(Sam-Joon Jun),문원국(Weon-Kook Moon) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

Most of the domestic buildings for residential purposes have used the radiant panel heating system, circulating hot water through the X-L pipe in the floor panel of the room. It was recently developed the radiant panel heating system using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal characteristics of this new heating method at the unit heating space that as heated by hot water from boiler through the coils installed in the floor heating panel, and which surrounded by outer space whose temperature of air be maintained constant. Flow rate, inlet and outlet temperatures of hot water and the heating time were yielded for various operating conditions and these results could be used for optimal design and efficient operation of the heating system as well as improvement of indoor air quality. We also found that the panel heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4~31% compared with the conventional panel heating system using X-L pipe.