• International Journal of Air-Conditioning and Refrigeration
• /
• 제12권1호
• /
• pp.1-9
• /
• 2004

The purpose of the present study is to examine the heat transport limitations in a screen mesh heat pipe for electronic cooling by theoretical analysis. Diameter of pipe was 6mm, and mesh numbers were 50, 100, 150, 200 and 250, and water was investigated as working fluid. According to the change of mesh number, wick layer, inclination and saturation temperature, the maximum heat transport limitations by capillary, entraintment, sonic and boiling were analyzed by a theoretical design method of heat pipe, including capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, etc. Based on the results, the capillary limitation in a small diameter of heat pipe is largely affected by mesh number and wick layer. Mesh number of 250 is desirable not to be used in pipe diameter of 6 mm, because capillary heat transport limitation decreases by the abrupt increase of liquid friction pressure due to the small liquid flow area. For the heat transport of 15 watt in 6mm diameter pipe, mesh number of 100 and one layer is an optimum wick condition, which thermal resistance is the smallest.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2003년도 춘계학술발표대회 요약집
• /
• pp.138.2-138.2
• /
• 2003

• 설비공학논문집
• /
• 제14권11호
• /
• pp.880-889
• /
• 2002

The purpose of the present study is to examine the factors affecting the heat transfer limitations of screen mesh heat pipe for electronic cooling by theoretical analysis. Diameter of pipe was 6 mm, and mesh numbers are 50, 100, 150, 200 and 250 and water was selected as a working fluid. According to the change of mesh number, wick layer, inclination and saturation temperature, capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, capillary limitation, entrainment limitation, sonic limitation and boiling limitation we analyzed by theoretical design method of a heat pipe. As some results, the capillary limitation in small diameter of heat pipe is largely affected by mesh number and wick layer.

• 설비공학논문집
• /
• 제11권3호
• /
• pp.313-320
• /
• 1999

A PFC(Perfluorocarbon) heat pipe has been used recently for cooling of GTO(gate turn off) thyristors or diodes in electric commuter trains. The present study was conducted to determine heat transport limitation of a PFC heat pipe which is one of the important parameters in heat pipes design. The variables such as tube diameter, fill charge ratio, internal surface structure and operating temperature were examined by way of experiment. Experimental data showed that the heat transport limitation of PFC heat pipe was considerably low and mostly dependent on tube diameter, with the value of 440~500W for d$o$/=22.23mm and 150~200W for d$o$=15.88mm. The other parameters had negligible effects, except for the case of small charge ratio less than 30%. Some correlations proposed by previous studies were in agreement with data from this study within 10~30%.

• 한국추진공학회지
• /
• 제24권3호
• /
• pp.59-70
• /
• 2020

본 논문에서는 기존 적층형 배관의 총 열전달 계수 경험식을 활용할 때 발생하는 한계점을 해결하고자, 외부 총 열전달 계수의 강제 대류 열전달 계수 항을 독립적으로 도출하는 간소화된 모델링을 제안하고, 이를 극저온 환경의 실험 결과로 확인하였다. 액체 산소 냉각 나선형 열교환기가 액체 질소와 열교환하는 실험 장치를 구성하고 열교환기의 열전달량을 계측하여, 외부 총 열전달 계수를 도출하였다. 측정된 외부 총 열전달 계수가 모델링으로 예측 곡선과 일치함을 확인하였다.

• 한국추진공학회지
• /
• 제8권4호
• /
• pp.16-25
• /
• 2004

구리분말 소결윅 히트파이프의 열수송 한계를 예측하는 이론적 해석을 수행하였다. 히트파이프의 직경은 8 mm이고 물을 작동유체로 사용하였다. 입자의 직경을 대표적인 5 가지로 분류하여 각각의 유효 모세관 반경($r_c$) 기공률($\varepsilon$), 투파율(K)을 토대로 작동온도와 윅 두에 그리고 경사각에 따른 모세관압력과 열수송 한계, 열저항을 분석하였다. 소결윅의 모세관한계는 입자 직경이 크고 윅 두께가 증가하며 작동온도가 높을수록 증가했다 기공률과 모세관 반경이 증가할수록 열수송 한계가 높아졌으며, 윅 두께가 증가함에 따라 열저항이 크게 상승하였다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2005년도 하계학술발표대회
• /
• pp.127-127
• /
• 2005

• 분석과학
• /
• 제28권4호
• /
• pp.270-277
• /
• 2015

비등점은 유기물의 물리화학적 성질을 특정하는데 있어 매우 근본적 요소 중 하나이다. 그러나 기존의 정량적 구조-물성 상관관계식들은 고에너지 물질 등과 같은 특정 물질 군에 대한 실험값들의 부족 등으로 인해 제한적인 응용성을 가지고 있었다. 본 연구에서는 서로 다른 출처로부터의 5,923개의 비등점 자료를 확보하였으며, 이에는 일반적 유기화합물과 더불어 특수목적을 가지는 분자들을 포함하였고, 이들 수집된 데이터 셋을 이용하여 새로운 비등점 예측모델을 개발하는데 사용하였다. 다양한 학습 방법을 이용하여 새로이 수집된 데이터 셋을 이용한 2차원 분자 표현자에 기반한 비등점 모델을 도출하였다. 개발된 예측모델의 적정성과 견고성을 확인하였고, 훈련 셋의 표현자에 기반한 비등점 예측모델의 적용구역을 도출하였다.

• 설비공학논문집
• /
• 제12권10호
• /
• pp.901-907
• /
• 2000

The conceptual determination of mixed-refrigerant (MR) for a closed Joule-Thomson cryocooler is described in this paper. The thermodynamic cycle design was mainly considered to develop a cryocooler by using a compressor of domestic air-conditioning unit. The target cooling performance of the designed cryocooler is 10 W around 70 K with less than 5 kJ/kg enthalpy rise. The systematic approach of choosing a proper refrigerant among 20 different kinds of mixture for such cryogenic temperature was introduced in detail. The main components of the cryocooler are compressor, evaporator, oil separator, after-cooler, counterflow heat exchanger, and J-T expansion device. Due to the limitation of the compressor operation range, the temperature after the compression was limited below $117^{\circ}C$ (390 K) and the temperature before compression was restricted above $5^{\circ}C$ (278 K). 20 atm of discharging pressure (high pressure) and less than 3 atm suction pressure (low pressure) were the design conditions. The inlet temperature of a counterflow heat exchanger in the high Pressure side was about 300 K. The proper composition of the mixed refrigerant for the designed J-T cryocooler is 15% mol of$ N_2, 30% mol of $CH_4,\; 30% mol\; of C^2H^ 6,\; 10%\; mol\; of\; C_3H_8\; and \;15%\; mol\; of\; i-C_4H_10$.

• 한국가시화정보학회지
• /
• 제18권3호
• /
• pp.61-68
• /
• 2020

Thermographic phosphor (TP) thermometry is a noncontact optical measurement method and has been applied in many fields such as combustion and heat transfer. However, due to the limitation of bonding technology and measurement method, most TP thermometry studies were conducted only on the air environment with water-soluble binders. In this paper, a temperature measurement technology in water using TP is proposed by coatings of manganese activated magnesium fluorogermanate (Mg4FGeO6:Mn4+, MFG) with Polydimethylsiloxane (PDMS). Four MFG-PDMS coatings with different thicknesses were prepared. The lifetime of MFG was not affected by the thickness of the coating as a result of the experiment and analysis of phosphor intensity using a photomultiplier tube. To measure the surface temperature field of an immerged body in water, a cylinder-type cartridge heater was coated with MFG doped PDMS. Transient surface temperature field was successfully measured even the initial temperature is higher than the boiling point of water.