Thermodynamic Second Law Analysis of Film Condensation from Vapor Flowing Slowly Inside a Semi-Ellipsoid

• Main Authors: Tzung-You Wu, 吳宗祐
• Other Authors: Sheng-An Yang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/66598261824406068086

碩士 === 國立高雄應用科技大學 === 模具工程系 === 97 === The present paper aims to perform the entropy generation analysis of film condensation from saturated vapor flowing slowly inside an isothermal vertical semi-ellipsoid. Previous literature shows that the condensation heat transfer performance of the elliptical tube with vertical major axis is better then that of circular tube. Thus, it is worth investigating the condensation heat transfer and thermodynamics second law analysis for vapor flowing inside a vertical semi-ellipsoid. The dependent working parameters of the local and average entropy generation caused by heat transfer and film flow friction are found to be Brinkman, Rayleigh, Bond, and geometric parameters. Based on Adrian Bejan entropy generation minimization technique, the result shows that local entropy generation rate increases with eccentricity, Brinkman, Rayleigh parameters, but decreases with the increase of surface tension. Furthermore, the heat transfer irreversibility dominates over the friction irreversibility in the upper half of a Semi-Ellipsoid. With the advantages of more time and cost savings for using CFD-Computational Fluid Dynamics to understand the system, VOF method is used to simulate two-phase flow problem and to verify the feasibility of numerical simulation compared with the solution of theoretical analysis. In the future, the present result can be used as a reference for the design of heat pipe and the condenser.