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$Na_4P_2O_7{\cdot}10H_2O$의 축열방열시 열전달 특성에 관한 실험적 연구
이채문,임장순,Lee, C.M.,Yim, C.S. 한국태양에너지학회 1989 한국태양에너지학회 논문집 Vol.9 No.1
Sodium pyrophosphate that melting point is $79-80^{\circ}C$ have been Studied on heat storage and heat discharge. In heat storage process, sodium pyrophosphate was kept up initial temperature $50^{\circ}C,\;60^{\circ}C,\;70^{\circ}C$ which melt by heated water at temperature $85^{\circ}C,\;90^{\circ}C,\;95^{\circ}C$. In heat discharge process, initial temperature of sodium pyrophosphate was maintained at temperature $85^{\circ}C,\;90^{\circ}C,\;95^{\circ}C$ which varied cooling temperature $50^{\circ}C,\;60^{\circ}C,\;70^{\circ}C$. The experiment has been reached conclusions as follows. 1) Heat transfer properties of phase change material is controlled by conduction during heating and cooling process. 2) The temperature increased rapidly at initial stage and transient region increase slowly because of characteristic of latent heat. 3) The lower cooling water temperature is the less the time that get to thermal equivalent state take during discharge process. 4) The higher cooling water temperature is the less temperature difference between top and bottom in P.C.M during discharge process.
상변화 물질을 이용한 축열조에서 열전달현상에 관한 연구
이채문(C.M.Lee),임광순(C.S.Yim),M.Iqbal 한국태양에너지학회 1993 한국태양에너지학회 논문집 Vol.13 No.2·3
본 연구는 용융된 파라핀을 채운 수직원관 내의 상변화물질의 초기온도와 수직원관의 벽면온도를 변화시켰을때 관 내에서 일어나는 열전달현상을 다루었다. 자연대류의 효과는 초기과열된 액상영역 내에서 응고초기 짧은 시간에 걸쳐 일어났고, 그 후 전도열전달이 paraffin 전 영역을 지배하였다. 실험에서 관찰한 응고 형태는 상부표면에서 밀도 증가에 의한 수축공간이 발생하였으며, 그 공간의 크기는 냉각이 진행됨에 따라 증가하였다. 자연대류가 끝나자, 상경계면 상에서 수지상 결정과 mush-zone이 발견되었다. 액상 paraffin의 초기과열은 실험 전반부의 응고질량과 응고두께를 감소시키는 경향을 보였으며, 초기액상과열도와 벽면과냉도가 큰 경우에 크게 나타났다. This study investigated heat transfer phenomena during the freezing of an initially superheated or non-superheated liquid in a cooled cylinder tube. Numerical and experimental method were performed to obtain the temperature and velocity distribution, the shape of interface. Natural convection effects in the superheated liquid were confined and moderated a short freezing time. After natural convection ceases, heat conduction dominated in the whole paraffin, so Caystal and much-Zone were found out in PCM.<br/> Initial superheating of liquid tended to morderatly diminish the frozen layer thickness at shortfreezing times but little effect on the these quantities at longer times. On the amount of frozen mass, Iintial liquid superheating is less affected than tube wall subcooling.<br/> <br/>
저온공조용 잠열 축열조의 열전달 특성에 관한 실험적 연구
서인호(I.H.Seo),고재윤(J.Y.Koh),이채문(C.M.Lee),임장순(C.S.Yim) 한국태양에너지학회 2000 한국태양에너지학회 논문집 Vol.20 No.3
In this study, the basic data which were required for development of LHSS(latent heat storage system) were experimentally obtained. Experiments were carried out under the following conditions. The initial temperatures of P.C.M. which were used by parameter is 5℃, 9℃ and 14℃. The conditions of working fluid are -6℃, -4℃, and 65ℓ/min.. The pure water of which the freezing point is 0℃ was filled in the system, and the Ethylene glycol(brine) was circulated through the 10 vertical tubes as a secondary fluid in order to cool the P.C.M. down. The inlet temperature of the secondary fluid and the initial temperature of the water were varied to investigate the effects of the important design parameters. The phenomenons of temperature conversion of P.C.M. were appeared for the conductive heat transfer and free convective heat transfer by buoyancy force in this storage unit system. In order to find the effective water circulation path, we obtained P.C.M. temperature distributions of 5 parts in the storage tank during freezing process.