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휜-관 열교환기의 착.제상 거동에 대한 표면처리의 영향에 관한 실험적 연구
지성,이관수,Jhee, Sung,Lee, Kwan-Soo 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.8
The effect of heat exchanger surface treatment on the frosting/defrosting behavior in a fin-tube heat exchanger is investigated experimentally. It is found that the hydrophilic surface mainly influences on the frosting behavior, however, the hydrophobic surface gives some influence on the defrosting behavior. In view of frosting performance, surface-treated heat exchanger with either hydrophilic or hydrophobic characteristic shows a little improvement in the thermal performance than the aluminium heat exchanger with no surface treatment. The result reveals that the heat exchanger with hydrophobic surface treatment is more effective in view of the defrosting efficiency and time. The amounts of residual water on the surface-treated heat exchangers are shown to be smaller than those of the bare heat exchanger, therefore further improvements on the performance of re-operations are expected.
지성,이관수,여문수,Jhee, Sung,Lee, Kwan-Soo,Yeo, Moon-Su 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.9
This study presents a numerical model to predict the behavior of frost layer growth. The characteristics of the heat and mass transfer inside the frost layer are analyzed by coupling the air flow with the frost layer. The present model is validated by comparing with the several other analytical models. It has been known that most of the previous models cause considerable errors depending on the working conditions or correlations used in predicting the frost thickness growth, whereas the model in this work estimates the thickness of the frost layer more accurately within an error of 10% in comparison with the experimental data. Simulation results are presented for variations of heat and mass transfer during the frost formation and for the behavior of frost layer growth along the direction of air flow.
이관수,김용철,지성,Lee, Kwan-Soo,Kim, Yong-Chul,Jhee, Sung 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.8
This study has been performed experimentally to measure the frost properties over a cold flat plate in order to obtain the correlations of the frost properties with various environmental parameters. Correlations of the frost surface temperature, thickness, density, and thermal conductivity are presented along with the experimental results as a function of environmental parameters, distance from the leading edge of test plate, and time. These correlations can be used to predict the frost properties with a maximum error of 8% in the following ranges : air temperature 15∼25$\^{C}$, relative humidity 60∼80%, air velocity 1∼3m/s and cooling plate temperature -15∼-25$\^{C}$.
이관수,양동근,지성,Lee, Kwan-Soo,Yang, Dong-Keun,Jhee, Sung 대한설비공학회 2002 설비공학 논문집 Vol.14 No.3
The integral boundary layer equation for the air side and the diffusion equation for the frost layer are numerically analyzed in order to predict the behavior of frost layer growth. The thickness and density of the frost layer obtained from the present study agree well with those of previous numerical results and experimental data with a maximum error of 13%. The characteristics of heat and mass transfer within the frost layer and the frost layer growth along the flow direction are investigated by performing numerical analysis. The effects of operating conditions on the frost layer growth are also examined.
여러 종류의 재질을 이용한 평판상 착상 거동에 대한 실험적 연구
이장석(Jang-Seok Lee),지성(Sung Jhee),박진구(Jin-Koo Park),이관수(Kwan-Soo Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
An experimental study has been carried out to investigate the frosting behaviors of thermally conductive plastic(PBT based resin) resin by comparing with those of aluminum and some plastic(PTFE based resin) test specimens. It is found that the frosting behavior of plastic specimens with 1 mm thickness show similar trend with aluminum except PTFE. The properties of frost formed on the specimens are affected by both thermal conductivityand surface characteristics (hydrophilic/hydrophobic) of the materials. It can be said that the heat and mass transfer rate of plastic materials are almost equivalent with those of aluminum.