• 한국태양에너지학회 논문집
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• 제21권1호
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• pp.83-91
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• 2001

The heat transfer experiment in a pilot scale latent heat storage tank as a solar energy storage system for the hot water supply was carried out. The latent heat storage tank was consisted of three parts; Outer shell for hot water from solar collector, PCM storage vessel in the middle of the tank and immersed coil in the PCM vessel for hot water recovery. The heat storage tank has the dimension of 115 cm in height and 32 cm outside diameter. Paraffin wax (m.p = 55.4C) and sodium acetate trihydrate (m.p = 58 C) were employed as the PCM this study. Experimental variables were inlet temperature and flow rate of the hot water for heat storage stage and cold water for heat recovery stage. Temperature profiles, heat transfer coefficient and the efficiency of heat storage $(Q/Q_{max})$ and heat recovery $(Q/Q_{max})$ were determined for the paraffin wax and inorganic salt respectively.

• 한국자동차공학회논문집
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• 제3권5호
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• pp.64-73
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• 1995

A numerical simulation of heat and fluid flow for predicting the effect of passage arrangement in automotive heat battery has been performed. The system is assumed to be a two-dimensional laminar flow and isothermal boundary is applied to the surface of the latent heat storage vessel. In the case of ideal heat battery the flow rate into each flow passage is evenly distributed. The various models are considered in the view of pressure drop and bulk temperature. The effects on the efficiency of the heat battery are examined by varying geometrical factors such as flow passage clearance, length of a inlet and outlet tank and the length of a latent heat storage vessel. The flow clearance is a very important -factor on the efficiency of a heat battery. As the flow passage clearance becomes narrow, the flow distribution becomes uniform and the bulk temperature increases, however the pressure drop is large. Therefore, optimal flow passage clearance has to be chosen. The present work can be used in optimizing heat battery efficiency.

• 설비공학논문집
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• 제6권2호
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• pp.110-119
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• 1994

Three dimensional characteristics of fluid flow and heat transfer have been studied numerically around the latent heat storage vessel which was applied to the practical ice-storage system. The result obtained indicates that the value of frictional coefficient decreases with decrease of baffle width. For the baffle spacing. $S/H_D=9.375$, baffle height. $H/H_D=0.5$ and various pressure drop, average Nusselt numbers in heat transfer surface are much dependent on the width of side baffle and middle baffle. that is. Nu_m decreases with decrease of the width of middle baffle when the width of side baffle is 4.375, where as the optimum condition of side baffle for $Nu_m$ exists in the range of 3.5< $B_1/H_D$ <4.375 at the width of middle baffle, $B_2/H_D=6.875$.

• 한국태양에너지학회 논문집
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• 제21권1호
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• pp.71-82
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• 2001

The heat transfer experiment in a latent heat storage tank as a solar energy storage system for the hot water supply was carried out. The latent heat storage tank was consisted of triple - tube type ; Outer shell for hot water from solar collector, PCM storage vessel in the middle of the tank and inside tube for hot water recovery. The heat storage tank has the dimension of 60 cm long and 34 cm outside diameter. Paraffin wax(m.p = 55.4C) and sodium acetate trihydrate(m.p = 58 C) were employed as the PCM this study. Experimental variables were inlet temperature and flow rate of the hot water for heat storage stage and cold water for heat recovery stage. Temperature profiles, heat transfer coefficient and the efficiency of heat storage$(Q/Q_{max})$ and heat recovery $(Q/Q_{max})$ were determined for the paraffin wax and inorganic salt respectively.

• 태양에너지
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• 제19권2호
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• pp.29-36
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• 1999

Heat transfer characteristics of a low temperature latent heat storage system during the heat storage stage was examined for the circular finned tubes using fatty acid which shows the big density difference during melting as phase change materials. The heat storage vessel has the dimension of 530 mm height, 74 mm inside diameter and inner heat transfer tube is 480 mm in height and 13.5 mm outside diameter. Hot water was employed as the heat transfer fluid. During the heat storage stage, it was found that both conduction and natural convection were the major heat transfer mechanism. It was also found that the effect of natural convection on the heat transfer was more significant for the unfinned tube system than that for the finned tube system. The experimentally determined overall heat transfer coefficients were in the range of $50{\sim}250W/m^2K$ and the correlation for natural convection heat transfer as a function of Nusselt and Rayleigh number was proposed.

• 대한기계학회논문집B
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• 제21권1호
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• pp.24-35
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• 1997

Melting process inside in a vertical cylinder has been investigated numerically to observe heat transfer characteristics in the latent heat storage vessel applied to the thermal storage system. The time-dependent boundary fitted coordinate system was introduced to overcome the difficulty caused by the moving boundary. The present results are in good agreement with the available previous data when the initial subcooling effect of the solid phase is not considered. It is found that the melting is promoted by the natural convection, but is delayed by the initial subcooling effect of the solid phase.

• 해양환경안전학회지
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• 제21권5호
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• pp.577-582
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• 2015

본 논문은 육해상의 운송장치에 축냉시스템을 적용시키기 위한 기초 연구이다. 또한, 축냉재의 고액상변화에 대한 수치해석을 수행한 연구이다. 수치해석법으로는 유한차분법(Finite-Difference Method)을 이용하였으며, 1차원 비정상의 상태를 가정하여 계산하였다. 또한 용기는 직사각형의 구형용기로 가정하여 대칭의 조건을 이용하였다. 축냉을 목적으로 사용하는 열매체는 염화칼슘 수용액($CaCl_2$) 30wt%의 물성치를 사용하여 계산을 수행하였다. 계산에 영향을 미치는 요소로는 냉동고의 냉기 온도 및 냉기 유속이 있으며, 축냉재를 싸고 있는 용기는 플라스틱으로 가정하였다. 본 수치해석에서 경계층의 두께는 냉기의 속도 증가와 함께 얇게 되고 축열시간도 짧아지는 것을 확인할 수 있었다. 그리고 냉기의 유속이 빨라질수록 열전달이 촉진되어 축냉용기 전면부에서의 온도가 낮아짐을 알았다. 축냉용기의 후면부에서는 경계층이 두꺼워져 열전달이 전면부에 비해 작아짐을 알았다.

• 에너지공학
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• 제5권2호
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• pp.115-122
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• 1996

망초를 이용한 저온 잠열축열시스템에서 핀을 설치한 전열관에서 방열과정중의 열전달 특성을 살펴보았다. 잠열물질의 과냉각과 상분리를 방지하기위해 3.0 wt% $Na_2$B$_4$O$_{7}$10$H_2O$와 2.2 wt% acrylic acid sodium sulfate가 조핵제 및 증점제로 사용되었다. 축열조는 높이가 530 mm, 직경이 74 mm이고 열전달관은 높이가 480 mm, 직경이 13.5 mm인 이중관으로 되어있으며 열전달 유체로는 물을 사용하였다. 축열재로부터 열을 치수하는 방열과정에서 열회수율은 열전달 유체의 유입온도와 유량에 크게 의존하였다. 핀이 설치되지 않은 전열관과의 비교실험을 통하여 핀에 의한 열전달 촉진은 얇은 핀의 경우에는 열전달계수의 증가가 미미하였지만 두꺼운 핀을 사용한 경우에는 같은 조업조건에서 열전달계수가 약 60% 정도 증가하였다. 실험적으로 결정된 총괄 열전달계수는 핀이 없는 경우에는 약 150-260 w/$m^2$K이었고 두꺼운 핀을 사용한 전열관에서는 230-530 W/$m^2$K정도였다. 총괄 열전달계수의 크기와 핀에 의한 전열면적을 기준으로 한 핀의 효율은 두꺼운 핀의 경우에는 약 0.26, 얇은 핀의 경우에는 0.05 정도로 계산되었다.다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.375-375
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• 2006

The preparation methods are to be used as "melting method" and "absorption method", respectively. The reaction mixture in the reaction container was heating up the reaction mixture to $200^{\circ}C$ for 2 hour. The mixing time of lab scale preparation should be provided quit long, instead of the short working time in a compounder vessel. And The PP-PCM mixture in the reaction container was heating up the mixture around $60-80^{\circ}C$ for 2 hour. A melting method of frozen gel with 50/50 weight ratio of polypropylene-normal octadecane was prepared by adding PP chip and normal octadecane. An absorption method of frozen gel with 70/30 weight ratio of PP 4.8-normal n-octadecane was prepared by adding PP powder and normal octadecnae.