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김진홍,정낙규,김창오,박호진 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.2
The purpose of this study is to investigate the propriety of TMA clathrate as a cold storage medium. Particularly, this is to examine the extent of subcooling improvement when the additives are added to the TMA clathrate, because water used cold storage material has low phase change temperature and subcooling. This study has been analyzed and compared with TMA 30 wt% clathrate how phase change temperature, subcooling and specific heat in the various concentrations are changed. This results view to be improved phase change temperature and subcooling of TMA 30wt% as a cold storage medium, when it had some additive. Additionally, it is found that the additive must be controlled under available solution limit and study for new additive must be lasted to know its effect.
김진홍,정낙규,김창오 朝鮮大學校 機械技術硏究所 2006 機械技術硏究 Vol.9 No.1
This study aims to find out cooling characteristics of TMA(Tri-Methyl-Amine, (CH₃)₃N) 25wt%-clathrate compound with ethanol(CH₃CH₂0H) such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at -6∼-8℃, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as 3.8 ℃ according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is 0.9℃ and minimum supercooling is 0.8, 0.7℃ according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is 3.013∼3.048 kJ/kgK according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol. This can lead to shorten refrigerator operation time of low temperature thermal storage system and improve COP of refrigerator and efficiency of overall system. Therefore energy can be saved and efficiency can be improved much more.
저온잠열저장을 위한 TMA-물계 포접화합물의 냉각특성에 대한 연구
김진홍,정낙규,김창오 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.2
Clathrate compound is the material that host in hydrogen bond forms cage and guest is included into it and combined. Crystallization of hydrate is generated at higher temperature than that of ice from pure water. And physical properties according to temperature are stable and congruent melting phenomenon is occurred without phase separation. But clathrate compound still had supercooling problem occurred in the course of phase change and supercooling should be minimized because it affects efficiency of equipment very much. Therefore, various studies on additives to restrain this or heat storage methods are needed. In this study was investigated the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, (CH₃)₃N) of 20 ~ 25 wt% as a low temperature latent heat storage material. And ethanol(CH₃CH₃OH) was added and its cooling characteristics were studied experimentally to restrain supercooling of TMA-water clathrate compound.
TMA-물계 포접화합물의 첨가제에 의한 냉각특성 변화에 대한 연구
김진홍,정낙규,김창오 朝鮮大學校 機械技術硏究所 2005 機械技術硏究 Vol.8 No.2
This study is performed to investigate the supercooling improvement and cooling characteristics change of TMA 25 wt% clathrate compound by additives as a low temperature storage material at -6℃ heat source. The used additives are acetone 0.3 wt%, ethylene glycol 0.2 wt% and ethanol 0.5 wt%. The experimental results showde that the phase change temperature is decreased by 0.1~1.6℃ in case of TMA 25 wt% clathrate compound with additives. Also the degree of supercooling is improved by 7. 2℃ in case of ethanol 0.5 wt%. Additionally the specific heat is decreased and the rate of volume change is increased when additives is added TMA 25 wt% clathrate compound.
정낙규,김진홍,오율권,김창오,강승현 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.2
One of the ways to reduce abroad dependence for energy is to utilize solar energy when we are now confronted with not only insufficiency of natural resources but also the serious problems of environmental pollution. Therefore, full attention must now be paid to the development of solar energy system as alternative energy. To achieve this, solar hot water supply system was established at Chosun university, Gwang-ju, and experimental data were obtained based on meterological data and solar radiation. This study has been used the monthly mean values of the daily measurements obtained by data acquisition software Labview. This study shows Gwang-ju is a good region for the utilization of solar energy.
축냉재 포접화합물의 열물성에 관한 실험적 연구 : 충전량 변화 Variations of Charging Conditions
하옥남,김진홍,정낙규 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.1
본 연구에서는 축냉재로서 에너지의 합리적 이용을 위한 건물공조용 축냉시스템에 적용이 가능한 TMA-물계 포접화합물의 농도와 충전량의 변화에 따른 상변화온도, 비열 및 과냉도를 실험을 통하여 다음과 같은 결론을 얻었다. (1) 냉열원온도 -5。C에서 상변화온도는 5.4。C 이상으로서 적절함을 확인하였다. (2) 상변화온도는 충전량이 많을수록 높아지는 것을 확인하였다. 위의 실험결과로부터 TMA-포접화합물은 건물공조용 축냉재로서의 열물성을 갖는다고 판단된다. The objective of this paper is to investigate the thermal properties of TMA-clathrate compound applicable to cold storage system for residential air-conditioning in order to use energy reasonably. Especially, the test tube experiments are performed to compare and analyze the concentration of TMA-clathrate compound, the temperature of heat source, and the phase change temperature, specific heat and subcooling characteristics according to the variation of charge capacity. The result are summarized as follows:1) -5。C is proper as the temperature of heat source because the temperature of phase change is above 5.4。C, 2) the phase change temperature appears higher as the charge capacity is larger. Thus, it appears that TMA-clathrate compound has thermal properties as the cold storage medium for residential air-conditioning.
축냉재 포접화합물의 열물성에 관한 실험적 연구 (IV) : 온도 변화 Changing of Temperature
고광옥,임재경,김창오,김진홍,정낙규,하옥남 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.2
The objective of this paper is to investingate the thermal properties of TMA-clathrate applicable to cold storage system for building air-conditioning in order to use energy reasonably. Especially, the test tube experiments are performed by comparing and to analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of concentrations and temperature of heat source in TMA clathrate. The result are summarized as follows; 1) temperature of phase change is dropped as the temperature of heat source is lower 2) specific heat of TMA-clathrate is about 24~95 % of pure-water 3) subcooling is smalled as the temperature of heat source is lower. Thus, it apears that TMA-clathrate has thermal properties as the cold storage medium for residential air-conditioning