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오승록 (서울과학기술대학교, 서울과학기술대학교 대학원)

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2022
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이 논문의 연구 히스토리 (2)

초록· 키워드

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본 연구에서는 수직형 마이크로채널 열교환기 내 이상유동 분배 특성을 유동가시화와 유량 측정을 통해 분석하였다. 또한 주입구의 수직 위치와 수를 변화시켜 그 영향을 파악하였다. 유동가시화를 위해 실제 열교환기를 모사하여 투명한 헤더에 15개의 마이크로채널 튜브를 삽입하여 시험부를 제작하였으며, 4개의 냉매 주입구를 배치하였다. 유량 분배 특성의 파악을 위해 각각의 채널로 흐르는 유량을 측정하여 채널 당 분배된 유량의 비율을 계산하였다.
실험은 HFE-7100을 작동 유체로 선정하여 25~75 kg/m2s의 질량 유속과 입구 건도 0~0.3의 영역에서 주입구의 수와 위치를 변경시켜 수행되었으며, 초고속 카메라를 통해 헤더 내 유동 양상을 촬영하였다. 각 실험 조건에 따른 채널 별 분배된 유량을 측정하였으며, 채널 당 유량비와 상대 표준 편차를 계산하여 유량의 균등한 분배 정도를 분석하였다.
실험 결과, 주입구의 위치가 높을수록 중력의 영향으로 인한 상 분리가 뚜렷하게 나타났으며, 하부에 포화 유체의 액상이 집중되는 양상을 보였다. 냉매 주입구가 헤더의 하단에 위치한 경우, 관성력의 영향으로 와류의 양상을 보이며 포화 유체 의 액상과 기상이 혼재된 이상영역이 발달하였으며, 전반적으로 균등한 분배 경향 을 보였다. 주입구가 상단에 위치하는 경우, 액상과 기상이 각각 헤더의 상부와 하부로 분리되어 유동하였으며 유체의 순환과 액막의 발달로 인해 헤더의 중간부 로는 유량이 거의 분배되지 않아 불균등한 분배 양상을 보였다.

목차

요약 ·································································································································· ⅰ
표목차 ······························································································································ ⅳ
그림목차 ·························································································································· ⅴ
기호설명 ·························································································································· ⅶ
I. 서 론 ······························································································································ 1
1.1 연구 배경 ··················································································································· 1
1.2 선행 연구 ··················································································································· 2
1.3 연구 개요 ··················································································································· 8
II. 실험 장치 ····················································································································· 9
2.1 시스템 구성··············································································································· 9
2.2 시험부 구성············································································································· 14
III. 실험 방법 ·················································································································· 18
3.1 기밀성 확인 시험··································································································· 18
3.2 에너지 밸런스 실험 ······························································································· 18
3.3 유동가시화 및 분배실험······················································································· 19
3.4 데이터 처리············································································································· 21
IV. 실험 결과 및 고찰 ··································································································· 23
4.1 유동 가시화 특성···································································································· 23
4.1.1 유동 가시화 특성(하단 주입구)········································································ 23
4.1.2 유동 가시화 특성(상단 주입구)········································································ 27
4.1.3 유동 가시화 특성(다수 주입구)········································································ 30
4.2 유량 분배 특성········································································································· 35
4.2.1 유량 분배 특성(상단 주입구)········································································· 35
4.2.2 유량 분배 특성(하단 주입구)·········································································· 37
4.2.3 유량 분배 특성(다수 주입구)·········································································· 38
4.2.4 유량 분배 특성(종합)························································································ 40
4.3 이상 유체의 분배 예측························································································· 42
4.3.1 선행 연구와의 비교 및 분배 예측 상관식·················································· 42
4.3.2 유량 분배비의 예측 및 고려사항 ·································································· 49
V. 결 론 ··························································································································· 51
참고문헌 ·························································································································· 52
영문초록(Abstract) ········································································································· 54
감사의글 ·························································································································· 55

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