• 한국자동차공학회논문집
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• 제4권3호
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• pp.187-198
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• 1996

In this study, the performance of an automobile heat storage system using PCM is numerically simulated. For the analysis of system performance. The phase-change of the PCM and the transient forced convective heat transfer for the HTF are considered simultaneously as a conjugate problem. The phase-change behavior is effectively analyzed using a concept of thermal resistance. From the correlations of phase change rate and heat transfer due to the variations of flow rate of HTF around PCM, the automobile heat storage system performance is predicted. The present results amy be used as the fundamental information for the design of automobile heat storage system.

• 대한기계학회논문집B
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• 제29권7호
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• pp.814-819
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• 2005

The phase change heat transfer has been applied to the processes of machines as well as of manufacturing. The cycle in a heat exchanger includes the phase change phenomena of coolant for air conditioning, the solidification in casting process makes use of the characteristics of phase change of metal, and the welding also proceeds with melting and solidification. To predict the phase change processes, the experimental and numerical approaches are available. In the case of numerical analysis, the Enthalpy method is most widely applied to the phase change problem, comparing to the other numerical methods, i.e. the Equivalent Specific Heat method and the Temperature Recovery method. It's because that the Enthalpy method is accurate and straightforward. The Enthalpy method does not include any correction step while the correction of final temperature field is inevitable in the Equivalent Specific Heat method and the Temperature Recovery method. When the temperature field is to be used in the calculation, however, there must be converting process from enthalpy to temperature in the calculation scheme of Enthalpy method. In this study, an improved method for the Equivalent Specific Heat method is introduced whose method dose not include the correction steps and takes temperature as an independent variable so that the converting between enthalpy and temperature does not need any more. The improved method is applied to the solidification process of pure metal to see the differences of conventional and improved methods.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.618-623
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• 2004

This paper has dealt with the heat storage characteristics of gel type micro size latent heat storage material slurry. The heat release operation to the gel type micro size latent heat storage material slurry was carried out using hot air bubbles by direct contact heat exchange. This experiment was carried out using phase change material of n-paraffin so the heat release amount is higher than cold water system. The parameters of this experiment were concentration of latent heat phase change material, height of heat release bath and inlet velocity of hot air. The main results obtained are as follows : (1) The effect of concentration of latent heat phase change material dispersed with water is very affective to the direct contact heat exchange between hot air and gel type micro size latent heat storage material slurry. (2) It is clarified that the most effective concentration of latent heat phase change material dispersed with water exists around 20mass% at this type of direct heat exchange model experiment.

• 설비공학논문집
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• 제18권6호
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• pp.518-525
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• 2006

The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase-change material and water mixture slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration, heat flux, and the slurry velocity. The experimental results revealed that the increase of tube wall temperature of latent microcapsule slurry was lower than that of water caused by the heat absorption of fusion.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.193-198
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• 2005

The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase change material and water mixed slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration, heat flux, and the slurry velocity. The experimental results revealed that the increase of tube wall temperature of latent microcapsule slurry was lower than that of water caused by the heat absorption of fusion.

• 대기
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• 제25권3호
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• pp.483-499
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• 2015

This study examined the impact of change of land-use and meteorological condition due to urbanization on heat environment in Seoul metropolitan area over a decade (2000 and 2009) using Weather Research and Forecasting (WRF)-Urban Canopy Model (UCM). The numerical simulations consist of three sets: meteorological conditions of (1) October 2000 with land-use data in 2000 (base simulation), (2) October 2009 with land-use data in 2000 (meteorological condition change effect) and (3) October 2009 with land-use data in 2009 (both the effects of land-use and meteorological condition change). According to the experiment results, the change of land-use and meteorological condition by urbanization over a decade showed different contribution to the change of heat environment in Seoul metropolitan area. There was about $1^{\circ}C$ increase in near-surface (2 m) temperature over all of the analyzed stations due to meteorological condition change. In stations where the land-use type changed into urban, large temperature increase at nighttime was observed by combined effects of meteorological condition and land-use changes (maximum $4.23^{\circ}C$). Urban heat island (UHI) over $3^{\circ}C$ (temperature difference between Seoul and Okcheon) increased 5.24% due to the meteorological condition change and 26.61% due to the land-use change. That is, land-use change turned out to be contributing to the strengthening of UHI more than the meteorological condition change. Moreover, the land-use change plays a major role in the increase of sensible heat flux and decrease of latent heat flux.

• 한국해안·해양공학회논문집
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• 제20권1호
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• pp.62-72
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• 2008

본 연구에서는 흐름에 수직한 방향으로 급격한 수심 변화가 존재하는 해역에서 점열원에 의한 열오염 분포를 예측할 수 있는 해석 모델을 개발하였다. 개발된 모델을 이용하여 열오염 분포에 있어 수심 변화와 흐름효과를 검토하였다. 계산 결과 흐름에 수직한 방향으로 수심 변화가 존재할 경우 수평 확산 플럭스의 증감으로 인해 수심 변화 경계를 가로지르는 열의 이동이 증가하거나 감소하는 것으로 나타났다. 조류와 동시에 잔차류 성분을 포함할 경우에는 이류에 의한 열오염 수송 효과가 증가하여 수심 변화 경계를 가로지르는 수평 확산은 상대적으로 감소하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.22-24
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• 2004

The land use has changed rapidly since 1960s in accordance with urbanization in Seoul Metropolitan Region. As a result, the urban microclimate has undergone changes as well. This study aims to recognize trend of the urban heat island change which is caused by land use change during urbanization in large city. Thermal data of Landsat TM images in 1987 and 1999 were for land surface temperature change detection in the study.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.23-29
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• 2002

Solid-liquid phase change (i.e. melting or solidification) occurs in a number of situations of practical interest. Some common examples include the melting of edible oil, metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, due to the practical importance of the subject, there have been a large number of experimental and numerical studies of problems involving phase change during the past few decades. Also, this study presented the effective way to enhance phase change heat transfer.

• Journal of Advanced Marine Engineering and Technology
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• 제28권8호
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• pp.1225-1238
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• 2004

The present study has been performed for obtaining the melting heat transfer enhancement characteristics of water mixture slurries of plural microcapsules having different diameters encapsulated with solid-liquid phase change material(PCM) flowing in a pipe heated under a constant wall heat flux condition. In the turbulent flow region, the friction factor of the present PCM slurry was to be lower than that of only water flow due to the drag reducing effect of the PCM slurry. The heat transfer coefficient of the PCM slurry flow in the pipe was increased by both effects of latent heat involved in phase change process and microconvection around plural microcapsules with different diameters. The experimental results revealed that the average heat transfer coefficient of the PCM slurry flow was about 2～2.8 times greater than that of a single phase of water.