混合對流在奈米流體填滿具有波形表面的空腔之研究

Study of mixed convection in wavy-wall cavities filled with nanofluid

何承英(Cheng-Ying He)

指導教授 ： 邱青煌

共同指導教授 ： 卓慶章(Ching-Chang Cho)

國立虎尾科技大學/工程學院/車輛工程系碩士班/碩士(2016年)

摘要

本文以數值模擬的方法研究填滿奈米流體的混合對流波形空腔之熱傳特性。在此研究中，工作流體假設為層流，空腔邊界條件設為上、下壁表面平坦絕熱且分別維持固定的速度往左、右方向拉動，而空腔左、右波形表面壁分別保持著固定的高、低溫。本研究主要探討改變流動參數、奈米流體濃度、空腔波振幅、高寬比、波數對於空腔熱傳效率之影響，並且透過等溫線、流線、熱線等方法探討空腔內部流場的變化。此外，藉由熱力學第二定律探討系統中的不可逆性，並且利用熵增最小化的方法，來評估此混合對流空腔能源運用之情形。

關鍵字

混合對流 ； 奈米流體 ； 空腔 ； 熱傳 ； 波形壁

並列摘要

A numerical investigation is performed into the mixed convection heat transfer characteristics of water based nanofluids confined within a lid-driven cavity. In the present study, the working fluid is assumed to be laminar flow, the boundary condition is assumed the upper and lower walls are both flat, insulated, and move horizontally, respectively. In addition, it is assumed that the left and right wavy-wall is maintained at high and low temperature, respectively. This study focuses on the respective effects of the dimensionless parameter, nanoparticle volume fraction, amplitude, aspect ratio and the waves number of the cavity. In addition, it investigates changes of the flow field inside the cavity through the streamline, heatline. Furthermore, it probes into the system irreversibility based on the second-law of thermodynamics, and uses entropy minimization method to assess the situation in this mixed convection cavity energy utilization.

並列關鍵字

Mixed convection ； Nanofluid ； Cavity ； Heat transfer ； wavy-wall

參考文獻

[1]S.U.S. Choi, J.A. Eastman,“Enhancing thermal conductivity of fluids with nanoparticles”, ASME International Mechanical Engineering Congress & Exposition, 1995.

[2]P. Selvakumar, S. Suresh, “Convective performance of CuO-water nanofluid in an electronic heat sink”, Thermal Fluid Sci. 40,pp. 57–63, 2012.

[3]A. Ijam, R. Saidur, “Nanofluid as a coolant for electronic devices cooling of electronic devices”, Therm. 32, pp.76–82, 2012.

[4]D.P. Kulkarni, D.K. Das, R.S. Vajjha, “Application of nanofluids in heating buildings and reducing pollution”, Appl Energy, 86,pp. 2566–257, 2009.

[5]Z. Wan, J. Deng, B. Li,Y. Xu, X. Wang, Y. Tang, “Thermal performance of a miniature loop heat pipe using water–copper nanofluid”, Appl Therm, 78,pp. 712–719, 2015.