• 한국추진공학회지
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• 제23권4호
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• pp.28-34
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• 2019

본 연구에서는 터빈 냉각에 널리 사용되는 핀-휜 배열에 대한 연구를 진행하였다. 본 연구에서 원형 튜브 전방에 익형 와류발생기가 위치하며, 익형 단면 형상은 NACA-9410을 사용하였다. 본 논문에서는 와류 발생기가 있는 핀-휜 배열 유동의 전열 성능과 유동 특성을 수직인 방향으로 변화시키며 기존의 핀-휜 유동과 비교하였다. 레이놀즈수 영역은 6000, 10000 그리고 15000 세 가지를 계산하였다. 전산 해석은 상용 프로그램인 ANSYS v18.0 CFX, 난류 모델은 $k-{\omega}$ SST를 사용하였다. 결과적으로 전열 성능은 최대 5.8% 증가하였고 압력 손실은 1% 미만으로 증가하였다.

• 대한전자공학회논문지TC
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• 제46권12호
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• pp.44-51
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• 2009

핀 배열 안테나를 이용한 선형 위상 배열 안테나의 방사 특성을 일반적인 패치안테나를 이용한 선형 위상 배열 안테나와 방사 특성을 비교하였다. 핀 배열 안테나를 이용한 위상 배열 안테나는 단위 안테나간의 상호결합이 작게 발생하기 때문에 일반적인 패치안테나를 이용한 위상 배열 안테나의 성능보다 향상되었다. 핀 태열 안테나를 이용한 선형 위상 배열 안테나는 주빔의 방향에 따른 이득과 side lobe level 의 변화가 적은 우수한 방사 특성을 가진다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2738-2743
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• 2008

We conducted a study by computational simulation about the effects of frost thickness on the pressure drop and heat transfer characteristics as whole heat exchanger configuration changes. In order to perform the analysis for validation, we assumed that frost properties have constant values and the frost layers that are formed on the fin and tube surfaces are uniform. In order to find the constant thermal conductivity of frost layer, a variety of frost thermal conductivities are performed in our work and compared with the results by Lee et al. [4] and Yang et al. [5] proposed many experimental data about the 2-rows and 2-columns finned tube heat exchanger. The numerical results agreed well with the experimental data when frost conductivity is 0.07W/mK. After the validation had performed, we applied this procedure to the finned tube heat exchanger of domestic refrigeration and investigated the thermo-hydraulic characteristic of the heat exchanger affected by frost thickness according to the inlet velocities and temperatures of air considering the configuration change such as fin pitch.

• 설비공학논문집
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• 제17권10호
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• pp.930-937
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• 2005

The objective of this study is to investigate the heat transfer performance of flat plate finned-tube heat exchangers with large fin pitch. In this study, twenty-two heat exchangers were tested with a variation of fin pitch, number of tube row, and tube alignment. The heat transfer coefficient decreased with a reduction of the fin pitch and an increase of the number of tube row. The staggered tube alignment improved heat transfer performance more than $10\%$ compared to the inline tube alignment. A heat transfer correlation was developed from the measured data for flat plate finned-tubes with large fin pitch. The correlation yielded good predictions of the measured data with mean deviations of $3.6\%\;and\;6.4\%$ for the inline and staggered tube alignment, respectively.

• 설비공학논문집
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• 제15권2호
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• pp.132-136
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• 2003

For the study of performance evaluation on different shape heat exchangers that have the same energy consumption in a refrigerator, we make performance evaluation coefficient (PEC) which can distinguish performance of different shape heat exchangers. The results were reported in order to compare with for the dry frosting and wet frosting test as various definition of PECs. Results showed that PEC of dry frosting test is higher than that of wet frosting test because attached water droplet increases pressure drop of air-side then this decreases performance of heat exchanger.

• 대한기계학회논문집
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• 제18권9호
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• pp.2486-2493
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• 1994

Transient heat transfer characteristics in th radiant heating panel with heat diffusion fin were predicted by numerical analysis. Thermal behaviors of panel, such as temperature distributions in panel and convective and radiative heat fluxes in panel surface with advance of time, were obtained for several important parameters. The performance and thermal comfort of heating panel were studied and compared for various design conditions, such as pipe pitch, area ratio and thermal conductivity of optimal design of the new heating panels with heat diffusion fin. It was concluded that the efficient area ratio of heat diffusion fin is about 0.5, and the greater the thermal conductivity of fin is, the better the performance of panel is.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1267-1271
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• 2009

In the present study, performance characteristics on environment change of A/C applied fin-tube and PF heat exchangers were experimentally investigated. Capacity and COP changing an outlet air velocity, an indoor/outdoor temperature and a relative humidity were obtained. Air－enthalpy calorimeter was used. As the air velocity, indoor temperature and relative humidity increase, capacity and COP increase. PF A/C has smaller refrigerant weight than the fin-tube A/C. The performance of PF-2 A/C with the squarer fin was more excellent than that of PF-1 A/C with the triangler fin.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.408-413
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• 2008

This study presents comparison of the air side heat transfer and friction characteristics in a heating condition between Louver fin-tube heat exchangers and aluminum heat exchangers. Experiments are performed for the Louver fin-tube heat exchangers and aluminum heat exchangers using a calorimeter, which is designed based on air-enthalpy method described in ASHRAE standards. The air velocities its are varied from 0.7 to 1.6 m/s with 0.3 m/s interval. A study result shows that the heat transfer performances of aluminum heat exchangers are $40{\sim}80%$ higher than those of Louver fin-tube heat exchangers per unit volume, mass and heat transfer area.

• 설비공학논문집
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• 제19권1호
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• pp.28-35
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• 2007

In this study the seasonal performance of a residential air conditioning system having either a fin-and-tube condenser or a microchannel condenser is experimentally investigated. A commercially available 7 kW capacity residential air conditioning system having a fin-and-tube condenser served as the base system. The test results show that the system with a microchannel heat exchanger has a reduced refrigerant charge amount of 10%, the coefficient of performance is increased by 6% to 10%, and the SEER is increased by 7% as compared with those of the base system. Moreover, the condensing pressure of the system is decreased by 100 kPa and the pressure drop across the condenser is decreased by 84%. The microchannel heat exchanger enhances the SEER of the residential air conditioning system by providing better heat transfers at reduced pressure drops.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.156-156
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• 2012

본 연구에서는 organic 반도체 전자소자의 성능 향상을 위해 그래핀 전극과 hexagonal boron nitride(h-BN) 절연체를 이용한 높은 성능의 전자소자를 구현 하였다. 이를 위해 우리는 화학적 합성법으로 준비된 그래핀을 micro sacale pattern된 PDMS를 이용한 dry transfer 방법을 이용하였다.