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류진우(Jin Woo Yoo),정융(Yoong Jeong),김귀택(Gwi Taek Kim),송치우(Chi Woo Song),윤필현(Pil Hyun Yoon),사용철(Yong Cheol Sa),김민수(Min Soo Kim) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
In air heat pumps, frost naturally forms when the surface temperature of evaporator is lower than ice point. Judging the proper time of defrosting operation is one of the important task for air heat pump systems. Many different method were suggested previously but most of them are not cost-effective or realistic solution. In this study, a new method for determination of defrosting start time was suggested which calculates frost volume at evaporator. The frost volume was calculated with a dry bulb temperature and a humidity of outdoor air, evaporator temperature and degree of superheat (DSH). This method appropriately judge the start time of defrosting at the point within 15 minutes the system performance starts to decrease.
류진우(Jin Woo Yoo),최영욱(Young Uk Choi),강대훈(Dae Hoon Kang),김민수(Min Soo Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Steam generation heat pump system, increasing the efficiency of thermal energy usage during the industrial process, can combine with the energy storage system and heat energy network. Therefore, there are needs of study about the steam generation heat pump. In this study, the simulation of the steam generation heat pump system was conducted for the characteristics of high-temperature heat pump system performance. It was verified that the steam generation heat pump performance improved through the increase of the waste heat source temperature and heat exchanger size. Also steam generation rate tended to increase but COP tended to decrease through the refrigerant flow rate increases. The result is expected to be applicable in accordance with the characteristics of the various industrial processes and sites.
류진우(Jin Woo Yoo),강대훈(Dae Hoon Kang),김귀택(Gwi Taek Kim),김민수(Min Soo Kim) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11
The use of steam takes over one third of energy consumption in industrial sector. Using steam for processes in factory has many advantage such as quick heat transfer at constant temperature during processes because it utilizes latent heat. For conventional steam generation method, a boiler is commonly installed. However, a boiler has maximum possible efficiency of 100% while heat pump could generate more heat than received work. Introducing heat pumps can have strong effect on energy saving because of waste heat recovery. Most industrial processes which use steam generally have waste water after processes and thrown away after cooling process. However, the temperature of waste water is high thereby reusable as a heat source. In this study, a steam generation heat pump was designed and experiments were conducted to find out optimal charge amount of the system and the performance. In addition, steam generation rate at different heat source temperature was also presented.
수열원 열펌프에서 압축기 속도와 최적 냉매충전량의 관계에 관한 해석적 연구
류진우(Jin Woo Yoo),김동호(Dong Ho Kim),김민수(Min Soo Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Every heat pump system has its proper refrigerant charge amount. Once refrigerant is injected and sealed inside of a system, the amount is fixed in closed system. Therefore, it is very important to predict the charge amount of refrigerant that can yield the best performance. It is already proved that the optimal refrigerant charge amount depends on secondary fluid temperature conditions. However, there are only few studies that shows relationship between compressor speed and optimal refrigerant charge amount. In this study, a water-to-water heat pump system was numerically calculated in order to find how optimal refrigerant charge amount changes with different compressor speed at same temperature condition.
류진우(Jin Woo Yoo),김민수(Min Soo Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
In a heat pump system, refrigerant charge amount is fixed when it is first installed. Therefore, proper amount of refrigerant if required in order to operate system efficiently. However, the proper charge amount is not a fixed value. For different condition, such as secondary fluid temperature, the optimal charge amount maximizes system efficiency changes. For this reason, a method that controls refrigerant amount can improve overall efficiency of heat pump system. In this study, a charge amount control technique is newly suggested with simple control logic and numerically verified. The maximum COP value of this method is same as that of conventional system with optimal charge amount. With this technique, a heat pump system can be operated at its optimal charge amount condition.
극저온용 PCHE 내 프로판의 응축성능에 대한 실험적 연구
류진우(Jin Woo Yoo),남찬우(Chanwoo Nam),신정헌(Jeong-Heon Shin),김동호(Dong Ho Kim),윤석호(Seok Ho Yoon) 대한설비공학회 2020 대한설비공학회 학술발표대회논문집 Vol.2020 No.6
As the consumption of Liquified Natural Gas (LNG) increase, the demand for re-gasification facilities continues to be in demand. To regasify LNG, indirect method is preferred because direct method usually requires large -sized facilities. The indirect method uses the intermediate heating medium which has the advantage by utilizing the latent heat of the intermediate heating medium, the size of heat exchanger can be reduced. Among many cadidate for intermediate heating medium, the propane is suitable for low temperature region. For heat exchange process, a printed circuit heat exchanger (PCHE) can be applied to an environment of very low temperature such as LNG. PCHE is made by chemical etching a microchannel on a heat transfer plate and stacking multiple layers with diffusion bonding. In this study, an experiment was designed and conducted to figure out the condensation performance of propane in a PCHE under various mass flux and vapor quality conditions. Also a correlation for heat transfer coeffieient was derived and verify.