• 대한설비공학회지:설비저널
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• 제10권1호
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• pp.12-21
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• 1981

The Enthalpy Model was verified in order to analyze two- dimensional phase change problems. By using the Enthalpy Model, interface locations, frozen fraction rates, heat flux distribution rut cooled surfaces, and surface-integrated heat flux were purely numerically calculated in rectangular thermal storage units, whose initial condition was saturated liquid and phase change material was cooled on its boundaries by convective heat transfer. The calculations were performed for various Stefan numbers and Biot numbers. The effect on those dimensionless numbers were explained.

• 한국가시화정보학회지
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• 제21권3호
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• pp.57-64
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• 2023

An open pulsating heat pipe operates continuously by inflow and outflow fluids through an open-type condenser. The open pulsating heat pipe is a device capable of obtaining the thrust due to the variation of internal pressure during phase change. Therefore, the open pulsating heat pipe is a suitable device to move fluids if the heat source such as waste heat exists. Many numerical studies have not been sufficiently conducted on the open pulsating heat pipe. In this study, the numerical analysis of the open pulsating heat pipe is performed according to the length of the condenser section. The OpenFOAM software is used to obtain the thrust and the flow visualization for the open pulsating heat pipe.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.962-971
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• 2004

This paper has dealt with thermo-physical properties of microencapsulated phase change material slurry as a latent heat storage material having a low melting point. The measured results of the thermo-physical properties of the test microencapsulated phase change material slurry, those are, density, specific heat, thermal conductivity and viscosity, were discussed for the temperature region of solid and liquid phases of the dispersion material (paraffin). The measurements of these properties of microencapsulated phase change material slurry have been carried out by using a specific-gravity meter, a water calorimeter, a differential scanning calorimeter(DSC), a transient hot wire method and rotating type viscometer, respectively. It was clarified that the additional properties law could be applied to the estimation of the density and specific heat of microencapsulated phase change material slurry and also the Euckens equation could be applied to the estimation of the thermal conductivity of this slurry.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.162-168
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• 2008

In this paper, we analyzed the heat transfer phenomenon and the reset current variation of PRAM device with thickness of phase change material using the 3-D finite element analysis tool. From the simulation, Joule's heat was generated at the contact surface of phase change material and bottom electrode of PRAM. As the thickness of phase change material was decreased, the reset current was highly increased. In case thickness of phase change material thin film was $200\;{\AA}$, heat increased through top electrode and reset current caused by phase transition highly increased. And as thermal conductivity of top electrode decreased, temperature of unit memory cell was increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1-6
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• 2003

The purpose of the present study is to investigate the capillary heat transportation limitation in heat pipe according to the change of screen mesh wick porosity. Diameter of pipe was 6 mm, and mesh numbers are 100, 150, 200 and 250 and water was selected as a working fluid. According to the change of wick porosity and mesh number, the capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, and capillary heat transportation limitation are analyzed by theoretical design method of a heat pipe. As some results, the capillary heat transportation limitation in screen mesh wick heat pipe is largely affected by wick porosity and mesh number.

• 한국표면공학회지
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• 제46권6호
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• pp.283-289
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• 2013

The experimental study for the temperature uniformity on the wafer using liquid-vapor phase heat transfer mechanism is performed. For the experiment, the heater plate which is consist of stainless steel container, working fluid and electrical heater is designed, manufactured and tested at the range of 600 to $850^{\circ}C$. The results showed that the phase change type heater plate was much more uniform and stable temperature on the heater plate surface and wafer than the uniform heat flux type heater plate at the atmospheric condition. Also, the results of 300 mm outer diameter of heater plate showed that the same temperature uniformity compared with 230 mm.

• 설비공학논문집
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• 제14권11호
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• pp.964-971
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• 2002

A numerical investigation of the constrained melting of phase change materials within spherical-like capsule is presented. A single-domain enthalpy formulation is used for simulation of the phase change phenomenon. The solution methodology is verified with the melting process inside an isothermal spherical capsule. Especially, the effect of capsule shape on the heat storage is emphasized. Two shape parameters are considered from the real capsule shape showing good characteristics of heat storage and the effect of these parameters is examined. Early during the melting process, the conduction mode of heat transfer is dominant. Thus the capsule shape with large surface area is desirable. However, the capsule shape with large surface area plays negative role on the strength of buoyancy-driven convection that becomes more important as melting continues.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.29-36
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• 2003

Exhaust manifolds suffer from serious temperature variation during the thermal fatigue test. The spatial distribution of temperature changes at each moment. Because transient flow can not be simulated during the long period of temperature change, the simulation can not be performed by conjugate heat transfer analysis. In this study, a new procedure for transient thermal analysis is established by decoupling fluid-solid analysis. The procedure consists of (1) transient CFD calculation (2 cycles), (2) mapping heat transfer coefficient to the inner surface of solid mesh as a boundary condition of heat conduction analysis and (3) transient heat conduction analysis in the long period (30 min). The realistic temperature change can be predicted by this procedure.

• 설비공학논문집
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• 제16권12호
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• pp.1183-1189
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• 2004

An experimental investigation is conducted to measure phase change temperature and supercooling when acetone is added to TMA 30 wt% clathrate during cooling process in heat source. Also rate of volume change is investigated when acetone is added to TMA 30 wt% clathrate during the cooling process in heat source -8$^{\circ}C$. The results show that phase change temperature is about 4.5～5.5$^{\circ}C$ when acetone is added to TMA 30 wt% clathrate during the cooling process for heat sink temperature of -6, -7$^{\circ}C$ and -8$^{\circ}C$. Supercooling is repressed about 2～1$0^{\circ}C$ when 0.08 wt% acetone is added to it and rate of volume change is decreased about 2.9% when 0.1 wt% acetone is added for the heat sink temperature of -8$^{\circ}C$.

• 환경영향평가
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• 제21권1호
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• pp.71-80
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• 2012

Against the backdrop of the clear impact of climate change, it has become essential to analyze the influence of climate change and relevant vulnerabilities. This research involved evaluating the impact of heat waves in Seoul, from among many local autonomous bodies that are responsible for implementing measures on adapting to climate change. To carry out the evaluation, the A1B scenario was used to forecast future temperature levels. Future climate scenario results were downscaled to $1km{\times}1km$ to result in the incorporation of regional characteristics. In assessing the influence of heat waves on people-especially the excess mortality-we analyzed critical temperature levels that affect excess mortality and came up with the excess mortality. Results of this evaluation on the impact of climate change and vulnerabilities indicate that the number of days on which the daily average temperature reaches $28.1^{\circ}C$-the critical temperature for excess mortality-in Seoul will sharply increase in the 2050s and 2090s. The highest level of impact will be in the month of August. The most affected areas in the summer will be Songpa-gu, Gangnam-gu, and Yeongdeungpo-gu. These areas have a high concentration of residences which means that heat island effects are one of the reasons for the high level of impact. The excess mortality from heat waves is expected to be at least five times the current figure in 2090. Adaptation plan needs to be made on drawing up long-term adaptation measures as well as implementing short-term measures to minimize or adapt the impact of climate change.