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공냉식 증발기 팬의 동작 유·무에 대한 냉동시스템 성능분석
양형석(Hyung-Suk Yang),장우영(Woo-Young Jang) 산업기술교육훈련학회 2012 산업기술연구논문지 (JITR) Vol.17 No.1
This study is that by using gas compression type refrigeration trainer, analysed factor which affect to performance of refrigeration system between evaporator fan operating and not operating condition at the low temperature operating condition of low pressure side. At the evaporator fan operating condition, which is normal heat exchanging situation of refrigerant, analysing study result are high level conditions of condensing pressure, evaporating pressure, flash gas heat, and specially observed too high level of superheat. At the evaporator fan not operating condition, analysing research result are high level of refrigeration effect. coefficient of performance(COP), low level of compression work and wet compression work. By conducting this study, had result that refrigerator operating performance have been big affected by condition between evaporator fan operating and not operating at the air cooled refrigeration system.
양형석(Hyung-Suk Yang) 한국산업융합학회 2011 한국산업융합학회 논문집 Vol.14 No.3
This study analyzed facts affecting the performance of refrigeration systems after throttling actions, by changing the amount of refrigerant according to adjusting the opening of manual expansion valve to 80%, or 20% with vapor compressional refrigeration training equipment. At opening of 20%, the inlet and outlet temperature of compressor, subcooling and superheat, condenser heat, refrigeration effect, flash gas heat, coefficient of performance were higher, while at 80%, condensing pressure, evaporating pressure, compression work were higher, Thus, we could see changes in the amount of refrigerant affect the performance of the refrigeration system.
이중계자를 갖는 10 MW급 전초전도 동기 발전기의 교류손실 해석
박상호,이명희,이세연,양형석,김우석,이지광,최경달,Park, Sang Ho,Lee, Myeonghee,Lee, Seyeon,Yang, Hyung Suk,Kim, Woo-Seok,Lee, Ji-Kwang,Choi, Kyeongdal 한국전력공사 2020 KEPCO Journal on electric power and energy Vol.6 No.4
The superconducting synchronous generator is one of the breakthrough elements for direct-drive wind turbines because it is light and small. Normally the superconducting one has copper armature windings in the stator and superconducting field windings on the rotor. The high resistance of the armature can make large copper losses, comparing with the conventional generators with a gear box. One of the solutions for the large copper losses could be a fully superconducting generator. But the high magnetic fields from the superconducting field windings on the rotor also make high perpendicular magnetic fields on the superconducting tapes in the armature windings. We have proposed a fully superconducting synchronous generator with dual field windings. It could immensely decrease the circumferential component of the magnetic field from the field windings at the armature windings. In this paper, we conceptually designed 3 types of superconducting synchronous generators. The first one is the fully superconducting one with conventional structure, which has superconducting armature windings in the stator and superconducting field windings on the rotor. The second one is the one with dual superconducting field windings and superconducting armature windings between them. The last one is the same as the third one except the structure of the armature. If the concentrated armature windings are superconducting ones with cryostats, then they cannot be installed within the span of 2 poles. So, we adopted 3 phases windings within 4 poles system. It makes more AC losses but can be manufactured really.
조전욱(Cho, Jeon Wook),양형석(Yang, Hyung Suk),류철휘(Ryu, Cheol Hwi),김민지(Kim, Min Jee) 대한전기학회 2022 전기의 세계 Vol.71 No.1
본 특집에서는 우리나라에서 연구개발을 진행하고 있는 초전도전력기기 중 초전도케이블 시스템 및 초전도한류기에 대한 세계적 수준의 개발 성과 및 사업화 현황과 전망에 대하여 소개한다. In this special feature, the world-class development achievements and commercialization status and prospects for High Temperature Superconducting cable systems and High Temperature Superconducting current limiters are introduced among HTS power apparatus that are being research and development in Korea.
신동원(Dong Won Shin),김동락(Dong Lak Kim),양형석(Hyung Suk Yang),최연석(Yeon Suk Choi) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.1
액체질소 온도부근에서 작동하는 고온초전도 케이블 시스템을 개발하기 위해서는 고온초전도 케이블 시스템에 사용되는 극저온 절연재료의 정확한 열물성 자료가 필요하다. 금속재료와 달리, 비금속 계열의 재료는 열저항이 크기 때문에 정확한 열 유입량을 측정하기 위해서는 특별한 주의가 요구된다. 본 연구에서는 극저온 냉동기를 이용하여 30K부터 상온 사이에서 절연재료의 열전도도를 정확하게 측정할 수 있는 시스템을 개발하였다. 설계와 제작과정을 포함한 열전도도 측정 시스템을 자세하게 기술하였다. 또한 상온으로부터 침입하는 불가피한 열유입량을 최소화하기 위한 열전도도 측정 시스템의 최적화 과정을 소개한다. The thermal property of insulation material is essential in developing a high-temperature superconductor (HTS) power cable to be operated at around liquid-nitrogen temperature. Unlike metallic materials, nonmetallic materials have a high thermal resistance; therefore, accurate estimate of the heat flow is difficult in the case of nonmetallic materials. The aim of this study is to develop an instrument for precisely measuring the thermal conductivity of insulating materials over a temperature range of 30 K to approximately the room temperature by using a cryocooler. The details of the thermal-conductivity measurement system, including the design and fabrication processes, are described in this paper. In addition, the design optimization to minimize unavoidable heat leakage from room temperature is discussed.
신동원(Dong Won Shin),김동락(Dong Lak Kim),양형석(Hyung Suk Yang),최연석(Yeon Suk Choi) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5
액체질소 온도부근에서 작동하는 고온초선도 케이블 시스템을 개발하기 위해서는 고온초전도 케이블 시스템에 사용되는 극저온 절연재료의 정확한 열물성 자료가 필요하다. 금속재료와 달리, 비금속 계열의 재료는 열저항이 크기 때문에 정확한 열 유입량을 측정하기 위해서는 특별한 주의가 요구된다. 본 연구에서는 극저온 냉동기를 이용하여 30K 부터 상온 사이에서 절연재료의 열전도도를 정확하게 측정할 수 있는 시스템을 개발하였다. 설계와 제작과정을 포항한 열전도도 측정 시스템을 자세하게 기술 하였다. 또한 상온으로부터 침입하는 불가피한 열유입량을 최소화하기 위한 열전도도 측정 시스템의 최적화 과정을 소개한다. The thermal property of insulation material is essential to develop the high temperature superconductor (HTS) power cable operated around liquid nitrogen temperature. Unlike metallic material, nonmetallic material has a high thermal resistance, therefore special attention needs to be paid to estimate heat flow correctly. The objective of the present work is to develop a precise instrument for measuring the thermal conductivity of insulating materials over a temperature range from 30K to near room temperature using a cryocooler. The details of thermal conductivity measurement system including design and fabrication process is described in the paper. In addition, the design optimization to minimize unavoidable heat leakage from room temperature is presented.