超音波 振動이 相變化 熱傳達 促進에 미치는 影響

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This study presents experimental and numerical works on the effect of ultrasonic vibrations on enhancement of Phase Change Heat Transfer. In order to investigate the melting process of a phase change material (PCM), the present study was applied experimental condition as following : one without ultrasonic vibrations (i.e., natural melting) and the other with ultrasonic vibrations. And a constant heat flux condition was considered and modified dimensionless number such as Ste* and Ra* were adopted. Also, heat flow phenomena were visually measured by a particle image velocimetry (PIV) and a thermal infrared camera with and without ultrasonic vibrations. Numerical work was applied to calculate the acoustic pressure in the liquid paraffin, instead of experimental measurement. For the numerical work, a coupled finite element-boundary element method (coupled FE-BEM) was applied.
The experimental results revealed the acoustic streaming could accelerate the melting process as much as 2.5 times, compared to the rate of the melting without ultrasonic vibration and was saved the total consumed electricity about 2.3 ~ 2.9 Wh. In addition, temperature and Nusselt number over time provided conclusive evidences which are the important roles of acoustic streaming on the melting phenomena of the phase change material. The numerical results of the profiles of acoustic pressure variation are consistent with those of augmentation of heat transfer. That is, the higher acoustic pressure distributions are, the higher augmentation ratio of heat transfer is near to ultrasonic transducers. In the end, it is concluded that acoustic pressure variations are closely related to the augmentation of heat transfer. This mechanism is believed to increase a coefficient of heat transfer
Alternative Title
Effect of Ultrasonic Vibrations on Enhancement of Phase Change Heat Transfer
Alternative Author(s)
Yoo, Sung-Lim
朝鮮大學校 敎育大學院
교육대학원 기술가정교육
Awarded Date
2005. 8
Table Of Contents
제 1 장 서론 = 1
1.1 연구배경 = 1
1.2 연구목적 및 내용 = 2
제 2 장 이론해석 = 4
2.1 해석모델 및 지배방정식 = 4
2.2 PIV의 기본개념과 알고리즘 = 7
2.3 적외선 열화상 카메라 열 해석방법 = 9
2.4 결합형 유한요소-경계요소법의 해석 = 11
제 3 장 실험장치 = 12
3.1 실험장치 구성 = 12
3.2 실험과정 = 16
3.3 수치해석 방법 및 절차 = 18
3.3.1 유한요소법에 의한 평판의 수치해석 = 18
3.3.2 경계요소법에 의한 수치해석 = 20
제 4 장 실험결과 = 22
4.1 히터표면의 온도분포 = 22
4.2 F。Ste*(무차원 시간)에 따른 고-액 경계면의 위치 = 24
4.3 열전달계수 측정 = 30
4.3.1 F。Ste*(무차원 시간)에 따른 열전달계수 = 30
4.3.2 τ((무차원 시간)에 따른 열전달계수의 예측 = 34
4.4 가시화를 통한 열전달 촉진 규명 = 36
4.5 자연용융과 초음파 가진 용융시의 소모 전력량 비교 = 40
4.6 매질내의 음압분포 측정 결과 = 41
제 5 장 결론 = 46
참고문헌 = 47
朝鮮大學校 敎育大學院
劉性林. (2005). 超音波 振動이 相變化 熱傳達 促進에 미치는 影響
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Education > Theses(Master)(교육대학원)
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