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염한길,박성제,홍용주,고준석,인세환,김효봉,Yeom, Hankil,Park, Seoung-Je,Hong, Hong-Ju,Ko, Junseok,In, Sehwan,Kim, Hyo-Bong 대한기계학회 2015 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.3 No.4
국내 사용되고 있는 적외선 검출기 냉각용 스털링 극저온 냉동기는 상당부분 수입에 의존하고 있으며, 높은 대당 가격, 제한적인 수명 및 내구성 부족으로 지속적인 극저온 냉동기 수요가 발생하고 있다. 그런데 적외선 검출기용 극저온 냉동기 기술은 국방, 우주관련 기술로 선진국의 기술이전이나 공동 개발이 매우 제한적이다. 본 연구를 통해 개발하고자 하는 맥동관 극저온 냉동기는 저온구동부의 기계적 피스톤을 가스피스톤으로 대체하고, 압축방식을 선형압축방식으로 바꿈으로써 낮은 진동, 높은 수명 및 내구성을 확보할 수 있다. 이를 통해 맥동관 냉동기의 기술수준을 선진국에 근접시키고, 독자적인 냉각형 적외선 검출기 설계 및 제작기술에 대한 기술을 확보하고자 한다. Most of the Stirling cryocoolers used for infrared detector cooling in domestic is imported. Because the cooler has a high price, short life and poor durability, demand for the coolers continues steadily. However, the cooler is highly related to defense and space technology, technology transfer or co-development with the countries having experties in cooler design is very limited. The pulse tube cooler to be developed in this study is such that the mechanical piston in low temperature actuating part is replaced by the gas piston and linear compressor is adopted, which results in low vibration, long life and better durability. It is expected that development of the pulse tube cooler will not only improve our technology to the level of advanced countries, but also enhance the skills in designing and manufacturing of the infrared detector.
미세 채널에서 R123/R134a 혼합 냉매의 유동 비등 열전달에 대한 실험적 연구
인세환(Sehwan In),정상권(Sangkwon Jeong) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
This paper describes flow boiling heat transfer of a R123/R134a mixture (mole fraction of R123, 0.746) in the micro-channel of 0.19 ㎜ ID. The experiment was performed at mass velocities from 314 to 470 ㎏/㎡-s, heat fluxes from 10 to 20 ㎾/㎡, vapor qualities from 0.2 to 0.85 and the saturation pressure of 360 ㎪. The flow boiling heat transfer characteristics of the mixture were similar to those of a single component, R123 which had indicated both mass velocity and heat flux effects in the previous experiment for the identical micro-channel. The heat transfer coefficients were compared with the correlation established from the flow boiling experiment of a single component, R123. The reduction of heat transfer coefficients by a mass diffusion effect was found from the comparison. The reduction rate, moreover, was compared with the mixture correction factor of macro-channels.
홍용주(Yong-Ju Hong),인세환(Sehwan In),염한길(Han-Kil Yeom),김희선(Heesun Kim),김혜림(Hye-Rim Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
The Superconducting Fault Current Limiter (SFCL) is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of HTS(High Temperature Superconductor) modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics of HTS modules. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen should be designed well with a cryocooler and circulation devices. The pressure of the cryostat for the SFCL should be pressurized to reduce the generation of nitrogen vapor in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype SFCL, which consist of a 4 kW stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat, to verify the design of the cooling method and the electric performance of the SFCL. The normal operation condition of the SFCL is 71 K and 500 kPa.
미세 채널에서 R123/R134a/R22 혼합 냉매의 유동 비등 열전달에 대한 실험적 연구
박인명(Inmyong Park),인세환(Sehwan In),정상권(Sangkwon Jeong) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
This paper describes the flow boiling heat transfer of R123/R134a/R22 mixture in a single round micro-channel with 0.19 ㎜ ID. The flow boiling heat transfer coefficients were measured for ternary mixture (R123/R134a/R22 mole fraction: 0.19/0.62/0.19) at various experimental conditions: mass velocities (314, 392, 470 ㎏/㎡-s), heat fluxes (10, 15, 20 ㎾/㎡) and vapor qualities (0.2 - 0.8). The heat transfer characteristics of the R123/R134a /R22 mixture are similar to those of the R123/R134a mixture (mole fraction: 0.5/0.5) observed in the previous flow boiling experiment which indicates that the major heat transfer mechanism in the micro-channel is dominated by evaporation of thin liquid film around the elongated bubbles. The large reduction of heat transfer coefficients compared with pure refrigerant is observed in micro-channel flow boiling by mass transfer effect of mixed refrigerant.
염한길(Hankil Yeom),홍용주(Yong-Ju Hong),고준석(Junseok Ko),김효봉(Hyobong Kim),고득용(Deuk-Yong Koh),박성제(Seong-Je Park),인세환(Sehwan In),김혜림(Hye-Rim Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The SFCL (Superconducting Fault Current Limiter) must be cooled to below the critical temperature of HTS(High Temperature Superconductor) modules. In general, they are submerged in sub-cooled liquid nitrogen because of their thermal stability. To cool and maintain the target temperature and pressure the cryostat should be designed well with a cryocooler and a circulation devices. There are two operation modes in SFCL. One is the standby mode, there exist steady heat load due to heat invasion through current lead, heat invasion from surroundings and heat generation by AC loss. Their heat loads are removed by the cryocooler. Another is the quench mode, when the HTS modules are quenched with the event of high current, it instantaneously generates large amount of heat. This heat is removed by the liquid nitrogen’s latent heat of evaporation, so the generated nitrogen gas should be exhausted from the cryostat. In this paper, we designed the cryostat and cooling method for the stable operation of the SFCL. To achieve this objective sizing and structural analysis of the cryostat, and design the cooling method as cool in sub-cooled liquid nitrogen.