Heat Transfer Characteristics On Fin-Tube Air Heaters

• Main Authors: Sheng-Yao Ke, 柯盛耀
• Other Authors: Shih-Pin Liaw
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/30259547618134453223

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 98 === The objective of this study is to investigate the thermal characteristics of fin-tube air heaters by runing Dowtherm oil, water, steam and dry air respectively inside the tube. The Reynolds number, heat transfer convection coefficients inside and outside the tube are calculated, therefore the heat transfer area and the number of tubes are obtained by LMTD method. In addition, the layout of the tubes are studied accompanied withe the pressure drop required. The computer program “Excel” developed by Microsoft was used to handle this problem. The temperature dependent physical properties are inquired from the date base sheets. First of all, the energy balance was made according to the inlet/outlet temperature and mass flow rate of the fluids. The energy transfer between the hot and cold fluid must be met each other before the execution of the program. Through the variation in the input parameters the optimization work based on the minimum heat transfer area and acceptable head loss can be accessed. Different cases with the change in diameter, length, layout, and spacing of tubes are studied. Finally, the effect of variation on thickness, height and pitch of fins are also presented. Keywords : Fin-tube heat exchanger、fin、LMTDmethod.