模擬 發生된 波浪에 의한 海底地盤의 應力變化에 關한 實驗的 硏究

학위논문(석사)--서울大學校 大學院 :農工學科 農業土木專攻,1995.Maste

응력장이 존재하는 박막 표면의 형태 변화를 위한 연속체 모델

학위논문(석사)--서울대학교 대학원 :재료공학부,2003.Maste

마이크로 구조 표면에서의 최소막비등 온도 증진: 실험 및 해석

DoctorWe investigated the minimum film-boiling temperature, TMFB, on microstructured surfaces using a quenching experiment conducted in saturation temperature water at atmospheric pressure. Firstly, two microstructured quench spheres, Brass and SUS316L (d = 10 mm), were prepared using a chemical etching and anodic oxidation method: Microstructured Surface in Brass (MS_Brass) and MS_SUS316L. Secondly, three types of CuO surface structured quench spheres (MS_CuO, Nanostructured Surface NS_CuO and Micro/Nanostructured Surface MNS_Brass/CuO) on brass (d = 15 mm), were prepared using a chemical etching and electrochemical deposition (ECD) method. Especially, a periodic CuO microstructure is obtained using ECD of 1 µm diameter particles forming unit-cell porous cones of average height L = 100 µm and base diameter D = 20 µm in MS_CuO. Surface parameters, including the contact angle, L, D, and chemical composition, were measured. TMFB increased only at MS_SUS316L, but not on MS_Brass. Also, significant increase in TMFB (> 600oC) is achieved with MS_CuO. These results attributed to local cooling (fin effect) by the microstructure causing liquid–solid contact. The increase in TMFB was affected by the surface microstructures, and was determined by characteristic variables of microstructure: thermal conductivity k, L, D and its shape. Based on fin theory, we analyzed that the dimensionless temperature difference θ* of microstructure depends on the hybrid Biot number, Bih = (mL)2 = hL2/(kD). Fin analysis predicts the cone tip cooling to the homogeneous nucleation temperature of water (~ 330oC), while the base temperature is at 600oC in MS_CuO: Bih = 3.6 with h = 800 W/(m2-K), L = 100 µm, D = 20 µm and = 0.5 W/(m-K). This causes liquid–solid contact during quenching and analysis suggests the fin effective thermal conductivity and geometric ratio L2/D are key to this liquid–solid contact. By including the temperature difference between the fin-base and the fin-tip in the model suggested by K.J. Baumeister and F.F. Simon (1973), we develop a model of TMFB on microstructured surfaces. This approach improves our understanding of the effects of microstructured surfaces in liquid-solid contact during quenching, and may contribute to the development of advanced high temperature cooling systems

Experimental study on enhancement of flow boiling CHF in a completely wetted tube over atmospheric pressure

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Quenching experiment with modified surface using Anodic Oxidation

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Visualization study of Leidenfrost droplet on hydrophilic and hydrophobic surface

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친-소수성 표면에서의 라이덴프로스트 (Leidenfrost) 기작에 대한 실험적 연구

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Heat Flux Partitioning Analysis of Pool Boiling Heat Transfer using Infrared Visualization

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MHF (MINIMUM HEAT FLUX) POINT ON ANODIZED ZIRCONIUM SURFACE DURING QUENCHING

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