• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.58-58
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• 2007

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.19-23
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• 2013

This study is concerned with air-conditioning system in use of thermoelectric device. It is introduced that the well designed structures for better cooling & heating performance with high efficiency. And also it is performed that the system performance test of four types trial products for the use of hybrid commercial vehicle. System performance is affected by many component parts, especially heat sink design & power control method. It is applied that dual extrusive fin tube with buffer zone for the effective radiating of circulating liquid in tube. And also it is applied that power supply method with constant-current system. It is attained that system cooling capacity is 1.2kW, COP is 0.95.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.234-235
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• 2005

In this experiment study, to acquire elementary data for explaining to generate frost layer in the fin - tube evaporator. the experiment condition is to supply air on 0.3m/s, 0.6m/s, 0.9m/s and inlet air temperature is 15$^{circ}C$, 20$^{circ}C$, 25$^{circ}C$ , supplied air relative humidity is 70%, 80, 90%. And brine temperature in the copper tube was kept -15$^{circ}C$ because, generally cooling temperature range is constantly -15$^{circ}C$ in the heat exchanger for air conditioning system. in conclusion, through this experiment, we did compare with frost layer and frost thickness in each condition and examine these data

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.166-171
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• 2005

In this experiment study, to acquire elementary data for explaining to generate frost layer in the fin - tube evaporator. the experiment condition is to supply air on 0.3m/s, 0.6m/s, 0.9m/s and inlet air temperature is kept constantly $20^{\circ}C$, supplied air relative humidity is 70%, 80, 90%. And brine temperature in the copper tube was kept $-15^{\circ}C$ because, generally cooling temperature range is constantly $-15^{\circ}C$ in the heat exchanger for air conditioning system. in conclusion, through this experiment, we did compare with frost layer and frost quantity in each condition and examine these data

• Journal of Energy Engineering
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• v.10 no.2
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• pp.166-175
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• 2001

핀-관 열교환기의 효율을 증대시키기 위하여는 열저항을 결정하는데 있어서 중요한 역할을 하는 공기측 열전달 특성의 향상이 필요하다. 본 연구에서는 슬릿핀과 같은 핀 형상의 개선으로 인한 높은 압력손실을 감소시키기 위하여 타원관형 열교환기를 고려하였으며 이를 자체 개발한 3차원 비압축성 Navier-Stokes 코드를 이용하여 공기측 성능을 해석하였다. 이 코드는 시간항에 스칼라 내재적 근사분해법(scalar implicit approximate factorization)절차, 공간항에 유한체적법과 2차의 풍상차분법을 사용한다. 핀 형상이 평판핀인 타원관에 대하여 세장비가 0.3, 0.5, 0.75인 경우와 핀 형상이 슬릿핀이고 세장비가 0.5인 타원관에 대하여 공기측 유동을 해석하였으며 이를 원관의 성능과 비교하였다. 평판핀의 경우, 압력강하량은 원관과 비교하여 세장비가 작아질수록 감소하는 것을 볼 수 있었으며, 열전달 계수는 고려한 유입속도 범위에서 원관을 기준으로 약 5%이하의 변화로 거의 동일하게 유지되는 것을 볼 수 있었다. 슬릿핀의 경우 역시 문제되는 높은 압력강하량은 타원관을 도입함으로써 효과적으로 낮출 수 있음을 볼 수 있었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.1017-1024
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• 2006

In this work, pool boiling heat transfer coefficients (HTCs) of five hydrocarbon refrigerants of propylene, propane, isobutane, butane and dimethylether (DME) were measured at the liquid temperature of $7^{\circ}C$ on a 26 fpi low fin tube, Turbo-B, and Thermoexcel-E tubes. All data were taken from 80 to $10kW/m^2$ in the decreasing order of heat flux. The data of hydrocarbon refrigerants showed a typical trend that nucleate boiling HTCs obtained on enhanced tubes also increase with the vapor pressure. Fluids with lower reduced pressure such as DME, isobutane, and butane took more advantage of the heat transfer enhancement mechanism of enhanced tubes than those enhancement ratios of $2.3\sim9.4$ among the tubes tested due to its sub-channels and re-entrant cavities.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.596-600
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• 2008

An experimental study has been conducted on the free convection heat transfer for the 7 kinds of circular finned tube heat exchangers. Empirical correlation was suggested at the range of 3,500$D_o$/$D_i$<3.0, 0.19<$P_f$/$D_i$<0.34. The 92% of experimental data agreed with the correlation within 10%.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.4
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• pp.163-168
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• 2007

The feature of six existing condensation heat transfer correlations for microfin tubes were evaluated with the consideration of vapor quality, mass flux, geometries, and various refrigerants. The Kosky and Staub [15] and the Jaster and Kosky [16] correlations for smooth tube were used for the evaluation of the heat transfer enhancement factor (EF). For the prediction of zeotropic mixtures, most correlations show discrepancy with previous measurements. The Yu and Koyama [4] and the Shikazono et al. [8] correlations do not consider spiral angle effect. The Han and Lee [10] correlation shows fin height growth deteriorates heat transfer. Experimental verification to develop reliable condensation heat transfer correlation for microfin tubes is still needed with the consideration of geometrical effects and working conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.9
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• pp.825-834
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• 2000

A heat exchanger analysis is performed to investigate the heating characteristics of cryogenic nitrogen by ambient air for the purpose of cryogenic automotive propulsion. The heat exchanger is a concentric triple-passage for supercritical nitrogen, and the radial fins are attached on the outermost tube for the crossflow of ambient air. The temperature distribution is calculated for the nitrogen along the passage, including the real gas properties of nitrogen, the fluid convections and the conductions through the tube walls and the fins. Since the wall temperature of the outer (ambient side) tube is very low in most cases, a heavy frost can be formed on the surface, affecting the heat exchange performance. By the method of the similarity between the heat and the mass transfer of moist air, the frost growth and the time-dependent effectiveness of the heat exchanger are calculated for various operating conditions. It is concluded that the frost formation can augment the heating of nitrogen during the initial period because of the latent heat, then gradually degrades the heat exchange because of the increased thermal resistance. Practical design issues are discussed for the flow rate of nitrogen, the velocity and humidity of ambient air, and the sizes of the fin.

• Journal of Ocean Engineering and Technology
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• v.24 no.5
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• pp.22-30
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• 2010

The fuel tank of a ship is filled with heavy fuel oil (HFO) that has a very high viscosity. In order to inject the HFO into the engine easily, heating coils are usually installed inside the fuel tank to heat the HFO and lower its viscosity. Currently, several different types of heating coils are used, e.g., fin-type, bare-type, drum-type, and shell-and-tube-type. It is well known that the shell-and-tube-type heating coil has good performance and high efficiency. In this study, experiments were conducted to determine the heat transfer efficiencies of three different shell-and-tube-type heating coils. Heat transfer efficiency was evaluated by using FLUENT 6.3.26 software. Also, structural safety was assessed by using ANSYS.simulation software.