Estimation of Heat Transfer Characteristic on the Fin of Elliptic-Finned Tube Heat Exchangers with Experimental Data

• Main Authors: Yi-fan Lin, 林毅凡
• Other Authors: Han-taw Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/13223152199036233947

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 96 === The finite difference method in conjunction with the experimental temperature data and least-squares scheme is proposed to predict the average heat transfer coefficient and fin efficiency on a vertical elliptic fin of elliptic-finned tube heat exchangers for various air speeds and fin spacing. The heat transfer coefficient on this elliptic fin is assumed to be non-uniform. Thus the whole plate fin is divided into several sub-fin regions in order to predict the average heat transfer coefficient on the fin. The unknown heat transfer coefficient on each sub-fin region can be assumed to be constant. The results show that the average heat transfer coefficient and isothermal average heat transfer coefficient increase with increasing the fin spacing, and the fin efficiency decreases with increasing the fin spacing in natural convection. The average heat transfer coefficient and fin efficiency can approach their corresponding asymptotical value obtained from a single elliptic fin for the fin spacing above a certain value. The average heat transfer coefficient increases with increasing the air speed, and the fin efficiency decreases with increasing the air speed for various fin spacing in forced convection. The isothermal average heat transfer coefficient increases with increasing the fin spacing for a fixed air speed. It can also approach its corresponding asymptotical value obtained from a single elliptic fin for the fin spacing above a certain value. However, the effect of the fin spacing on the fin efficiency is very small. In order to evidence the reliability of the present inverse scheme, the present estimated results of the average heat transfer coefficient agree with the direction of the experiment results. Thus the reliability of the present inverse scheme is expected.