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용량 가변 및 유량변화에 따른 지열원 물대물 열펌프 유닛의 충전량 변화에 따른 성능 특성
조찬용(Cho, Chan-Yong),최종민(Choi, Jong-Min) 한국신재생에너지학회 2011 신재생에너지 Vol.7 No.4
The objective of this study is to investigate the effects of the refrigerant charge amount on the performance of a water-to-water ground source heat pump with a variation of compressor speed and the secondary fluid flow rate. The water-to-water ground source heat pump was tested by varying refrigerant charge amount from -40% to 20% of full charge. Compressor speed was changed from 30 Hz to 75 Hz and the secondary fluid flow rate was adjusted from 6 LPM to 14 LPM. For all test conditions, EWTs of an indoor heat exchanger and an outdoor heat exchanger were maintained at standard conditions of ISO 13256-2. The slope of the COP with the variation of charge amount is much steeper at undercharged conditions than that at overcharged conditions. For all compressor speed, the variation of the system performance according to charge amounts showed the similar trends. However, the optimum charge amount of the system increased a little with an increment of compressor speed. When the secondary fluid flow rate decreased, the system was optimized at higher refrigerant charge amount conditions.
무인기용 레큐퍼레이터 소재의 용접부에 대한 고온 피로수명 예측
이상래(Sang-rae Lee),조찬용(Chan-yong Cho),김재훈(Jae-hoon Kim) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5
본 논문은 경량 및 고효율 레큐퍼레이터를 구성하는 전열판의 용접부에 대한 실험적 연구이다. 특히 해당 용접부에 대한 수명을 알아내기 위해 고온환경에서 피로특성을 실험을 통하여 알아내기로 하였다. 실험은 레큐퍼레이터의 소재로 주로 선정되는 두가지 재질에 대해(STS347, AL20-25+nb) 실시하였으며, 시편은 실제 제작에 사용되는 방법과 ASTM에서 권고하는 규격을 준용하여 제작하였다. 그리고 상온과 고온에서 해당 시료의 기계적 특성을 평가하고자, 기계적 물성치를 시험하는 MTS-810 과고온환경을 부여하기 위한 고온로를 이용하였다. 시험은 각 시편에 대해 상온 및 고온 환경에서 인장시험을 실시하였으며, 나타난 인장강도의 50%, 40%, 30%, 20% 그리고 10% 에 해당하는 하중을 응력비 0.1 로 설정하여 피로시험을 시행하였다. 마지막으로 실험을 통해 나타난 피로수명 특성을 레큐퍼레이터의 운전조건에서 발생하는 하중에 따르는 응력과 비교하여 무인기 시스템이 요구하는 운전시간에 대비하여 해당 용접부들의 수명을 평가하였다. This paper is an experimental study on the welding part of the heat transfer plate which constitutes the lightweight and high efficiency recuperator. Especially, in order to find out the service life of the welded part, the fatigue characteristics were determined through experiments. Experiments were carried out on two materials (STS347, AL20-25 + nb), which are mainly selected as the material of the recuperator, and the specimens were manufactured using the methods used for actual fabrication and the standards recommended by ASTM. To evaluate the mechanical properties of the specimens at room and high temperature, MTS-810 was used to test the mechanical properties and a high-temperature furnace was used to give a high temperature environment. The tensile test was carried out at room and high temperature for each specimen. The fatigue test was carried out by setting the load ratio corresponding to 50%, 40%, 30%, 20% and 10% of the tensile strength at the stress ratio of 0.1. Finally, the fatigue life characteristics obtained by the experiment were compared with the stresses due to the load generated in the operating conditions of the recuperator, and the lifetime of the welds was evaluated in preparation for the operation time required by the UAV.
지중 순환수 유량 변화에 따른 지열원 히트펌프 시스템의 성능 특성 연구
이준엽(Jun Yub Lee),정진택(Jin Taek Chung),조찬용(Chan Yong Cho),최종민(Jong Min Choi) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
The aim of this study is to investigate the influence of the secondary fluid flow rate through GLHX on a GSHP system with vertical single U-tube type GLHXs. The COP of a GSHP system with large flow rate was lower than that with small flow rate due to large power consumption of ground loop circulating pump. It is suggested that the heat pump unit with high COP and low flow rate through the GLHX has to be selected in order to enhance the performance of the system and reduce the length of GLHX.