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학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
논문 기본 정보
- 자료유형
- 학위논문
- 저자정보
- 지도교수
- 엄용균
- 발행연도
- 2017
- 저작권
- 안동대학교 논문은 저작권에 의해 보호받습니다.
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초록· 키워드
오류제보하기
The impingement of circular liquid jets is one of a convenient method of surface cooling. The impinging jet has a wide range of applications such as cooling of aircraft parts, steel manufacturing process, grocery dryness, clothing dryness and in film/paper manufacturing process. The heat transfer of liquid jets impingement on high temperature upward plate were analyzed in earlier studies. The heat transfer phenomenon when liquid jets impinges to the low temperature (T<100℃) plate were not investigated.
Hence, the present study investigates a heat transfer phenomenon when a single round jet impinges upwardly on a circular plate with low temperature. The experimental investigation is performed for jet flow rates 3.6L/min, 4.6L/min and 5.6L/min, a jet fluid temperature of 24℃, isothermal condition 60℃, 70℃ and 80℃, H/D=1, 3 and 8 with a single round jet diameter 4mm, 6mm, and 8mm.
Results :
After circular jet impinges on the circular plate, its direction changes. For the constant flow rate, hydraulic jump increases from the circular plate as the diameter of nozzle decreases and the wall jet flows to the downstream. However, under the same flow rate and same nozzle diameter, the position of the hydraulic jump was almost the same.
For isothermal condition, nozzle diameter, H/D conditions, the nozzle flow rate increases which in turn increasing the effect of heat transfer. In all cases, the maximum heat transfer effect is found to occur at the stagnation point of the circular jet.
When keeping the isothermal condition, nozzle flow, and H/D constant, decreasing the diameter ratio(Dr), the local heat transfer coefficient(hr) and average heat transfer coefficient(havg) increases in all the regions.
Similarly, for the case of constant isothermal condition, nozzle diameter, and nozzle flow, the variation in the H/D dose not influence the heat transfer effect.
For the case of constant nozzle diameter, nozzle flow, and H/D, the heat transfer effect is negligible when the isothermal condition varies.
From the experimental results, we decided to derive the correlation equation of Nur, Prr and Rer at H/D=1 as follows.
Hence, the present study investigates a heat transfer phenomenon when a single round jet impinges upwardly on a circular plate with low temperature. The experimental investigation is performed for jet flow rates 3.6L/min, 4.6L/min and 5.6L/min, a jet fluid temperature of 24℃, isothermal condition 60℃, 70℃ and 80℃, H/D=1, 3 and 8 with a single round jet diameter 4mm, 6mm, and 8mm.
Results :
After circular jet impinges on the circular plate, its direction changes. For the constant flow rate, hydraulic jump increases from the circular plate as the diameter of nozzle decreases and the wall jet flows to the downstream. However, under the same flow rate and same nozzle diameter, the position of the hydraulic jump was almost the same.
For isothermal condition, nozzle diameter, H/D conditions, the nozzle flow rate increases which in turn increasing the effect of heat transfer. In all cases, the maximum heat transfer effect is found to occur at the stagnation point of the circular jet.
When keeping the isothermal condition, nozzle flow, and H/D constant, decreasing the diameter ratio(Dr), the local heat transfer coefficient(hr) and average heat transfer coefficient(havg) increases in all the regions.
Similarly, for the case of constant isothermal condition, nozzle diameter, and nozzle flow, the variation in the H/D dose not influence the heat transfer effect.
For the case of constant nozzle diameter, nozzle flow, and H/D, the heat transfer effect is negligible when the isothermal condition varies.
From the experimental results, we decided to derive the correlation equation of Nur, Prr and Rer at H/D=1 as follows.
목차
제 1 장 서론 11.1 연구의 배경 및 목적 1제 2 장 본 론 82.1 연구 내용 82.2 실험 장치 92.2.1 열전대 보정 122.2.2 원형시편의 가열면, 냉각면 온도측정을 위한 T/C설치 세부구조 142.2.3 표면조도 측정 172.2.4 원형시편 등온조건 형성을 위한 등온수 공급장치 182.2.5 충돌제트 노즐(Nozzle)과 노즐의 설치방법 192.3 실험 방법 222.3.1 실험 조건 222.3.2 원형등온면의 국소대류열전달계수()의 계산 242.3.3 실험결과 국소대류열전달계수()와 열전달 상관관계식 25제 3 장 결과 및 고찰 263.1 등온평판에서 원형노즐 충돌제트에 의한 수력도약(Hydraulic jump) 현상 263.2 등온조건(T)이 일정할 때, 노즐유량(G)이 국소대류열전달계수()에 미치는 영향 313.3 노즐유량(G)이 일정할 때, 직경비()가 국소대류열전달계수()에 미치는 영향 393.4 노즐유량(G)이 일정할 때, 무차원간극비(H/D)가 국소대류열전달계수()에 미치는 영향 443.5 직경비()가 가열원형평판의 평균대류열전달계수()의 상관관계 583.6 상관관계식 61제 4 장 결 론 65참고문헌 68Abstract 72감사의 글 74
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