냉매 과냉각을 이용한 열펌프 시스템의 성능 특성

노건상,손창효 한국수소및신에너지학회 2007 한국수소 및 신에너지학회논문집 Vol.18 No.4

In this paper, the performance characteristics of heat pump system using a new refrigerant subcooling system designed for the study, are introduced. The new heat pump system have the ice storage tank at the outlet of condenser. The experimental apparatus is a well-instrumented water/water heat pump which consisted of working fluid loop, coolant loop, and ice storage tank. The experiment parameters of subcooling ranged as the evaporating temperature from -5℃ to 8℃, the condensing temperature from 30℃ to 35℃. The test of the ice storage was carried out at evaporating temperature of -10℃ and the ice storage mode is Ice-On-Coil type. The working fluid was R-22 and the storage materials were city-water. The test results obtained were as follows; The refrigerant mass flow rate and compressor shaft power were unchanged by the degrees of subcooling, that is, they were independent of degrees of subcooling. The cooling capacity of the new heat pump system increase as the evaporating temperature and subcooling degrees increase and is higher by 25~30%, compared to the normal heat pump system. The COP of the new heat pump system increases as the degrees of subcooling and evaporating temperature increase and is higher by 28% than that of the normal heat pump system.

축냉시스템을 이용한 R410A 냉동시스템의 냉매과냉각 효과

이동원(Dong-Won Lee),주문창(Moon-Chang Joo),이상훈(Sang-Hoon Lee) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7

This study was experimentally performed to find the effects of refrigerant subcooling in the refrigeration system. A refrigerant subcooling refrigeration system consisted of a typical single compression refrigeration cycle, a subcooler, and a cold heat storage tank. The cold heat in the storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The performance of the refrigerant subcooling refrigeration system was measured by varying the degree of subcooling. In addition, the performance characteristics of the present system were compared with those of a conventional refrigeration system. The cooling capacity & COP of this system were higher than those of the conventional system due to the increase in the degree of subcooling. Typically, the refrigerant subcooling system showed superior performance to the conventional refrigeration system and would also contribute to load leveling.

축냉시스템을 이용한 냉매과냉각형 냉동시스템의 성능특성에 관한 실험적 연구

이은지(Eun-Ji Lee),이동원(Dong Won Lee),김용찬(Yong Chan Kim) 대한설비공학회 2010 설비공학 논문집 Vol.22 No.6

A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat exchange between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The performance of the refrigerant-subcooling refrigeration system was measured by varying the degree of subcooling. In addition, the performance characteristics of the present system were compared with those of a conventional refrigeration system. The mass flow rate of the present system was higher than that of the conventional system due to the increase in the degree of subcooling. Generally, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system.

축열조를 이용한 냉매과냉각시스템의 전력수요관리 효과에 대한 연구

이은지(Eun-Ji Lee),이동원(Dong Won Lee),김용찬(Yong Chan Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6

This study was experimentally performed to find the effects of refrigerant subcooled in the refrigeration system and to aim the efficient use of energy. A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat exchange between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The cooling capacity & COP of the present system were higher than that of the conventional system due to the increase in the degree of subcooling. Generally, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system and this system also contribute load leveling.

Enhanced boiling heat transfer on nanowire-forested surfaces under subcooling conditions

Lee, Donghwi,Kim, Beom Seok,Moon, Hokyu,Lee, Namkyu,Shin, Sangwoo,Cho, Hyung Hee Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.120 No.-

<P><B>Abstract</B></P> <P>In boiling heat transfer, the emerging issues are the improvement of both the critical heat flux (CHF) and the thermal stability. Nanowire-forested (NF) surfaces and subcooled environments are favorable for improving CHF as well as the thermal stability owing to their distinctive morphology and consequential convection expedition, respectively. In this study, the improvement of CHF and temperature uniformity/stability are evaluated on NF surfaces immersed in de-ionized water with subcooling from 0 to 30 K using a resistance temperature detector (RTD) sensor with five measuring points. NF surfaces catalyze dispersed, confined and fast bubble ebullitions under subcooling conditions, resulting in the delayed bubble coalescences. This lead to the enhancement of CHF accompanying stabilized spatial/temporal temperature variations. We demonstrate that NF surfaces applying 30 K subcooled condition not only significantly improve the thermal stability by reducing spatial/temporal temperature variations to less than 1/5 but also enhance CHF by 4.3 folds, compared to the plain surfaces under the saturated condition. These remarkable enhancements show that NF surfaces can be effective solutions to secure the thermal stability under vigorous boiling conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Boiling experiment is conducted on nanowire-forested (NF) surfaces under subcooling. </LI> <LI> Boiling performance is evaluated using a resistance temperature detector (RTD) sensor. </LI> <LI> NF surfaces improve critical heat flux (CHF) by 4.3 folds under 30 K subcooling. </LI> <LI> Spatial/temporal temperature variations reduced to 1/5 on 30 K subcooled NF surfaces. </LI> <LI> Enhanced boiling heat transfer is analyzed by bubble images on subcooled NF surfaces. </LI> </UL> </P>

축열조를 이용한 냉매과냉각 시스템의 전력수요관리 효과에 대한 연구

김정배(Jeongbae Kim),이은지(Eun-Ji Lee),이동원(Dong Won Lee) 대한설비공학회 2010 설비공학 논문집 Vol.22 No.12

This study was experimentally performed to find the effects of refrigerant subcooling in the refrigeration system and to propose how to get the efficient use of energy. A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat transfer between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The cooling capacity and COP of this system were higher than those of the conventional system due to the increase in the degree of subcooling. Typically, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system and would also contribute to load leveling.

Performance simulation of CO2 transcritical cooling system with mechanical subcooling cycle for automobile air conditioning

Sun-Ik Na,Minsung Kim,김민수 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9

In newly produced vehicles, the low global warming potential (GWP) refrigerant must be charged instead of conventional high GWP media according to the environmental regulations. For these needs, the CO 2 cooling system is re-attracted as green technology in the automobile field. However, the conventional CO 2 system has the drawback that it sharply declines the cooling capacity and coefficient of performance (COP) when the hot ambient conditions. To enhance the COP of a CO 2 air conditioner, the mechanical subcooling cycle is introduced in this study. But the subcooling cycle requires installing additional heat exchangers. In the automobile application which has limited install space, the design of heat exchangers should be considered for adopting the subcooling cycle. Thus, in this study, numerical models were built to predict the COP by changing the heat exchangers. In addition, an optimal method is used to determine the maximum COP. The results show that the COP improves when applying the subcooling cycle, and the maximum COP is determined based on the thermodynamic states at the outlets of the gas cooler and the subcooler. Meanwhile, the refrigerant types do not substantially affect the COP. While the COP is improved with the use of larger heat exchangers and fans, the rate of improvement gradually decreases. In the optimum efficiency calculation, the power consumption of fans should be considered, and the proper heat exchanger and fan should be designed accordingly.

에탄올을 첨가한 TMA 포접화합물의 냉각특성에 대한 연구

김창오,정용우,박호진,김진흥,정낙규 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

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.

첨가제를 첨가한 TMA-포접화합물의 상변화에 관한 실험적 연구

김진흥,정낙규,김창오,박호진,강승현,김광일 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 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 surfactants are added to the TMA clathrate, because water used cold storage material has low phase change temperature and subcooling. this study has been analysed and compared with TMA 30wt% 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 TMA30wt% as a cold storage medium, when it had some surfactant. Additionally, it is that surfactant must be controlled under available solution limit and study for new additive must be lasted to know its effect.

계면활성제를 첨가한 TMA-포접화합물의 상변화에 관한 실험적 연구

김창오,정낙규,김진흥,오율권 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.1

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 surfactants 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 30wt% 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 TMA30wt% as a cold storage medium, when it had some surfactant. Additionally, it is that surfactant must be controlled under available solution limit and study for new additive must be lasted to know its effect.