Study of pressure drop characteristics and heat transfer performance in an internally finned tube

Abstract

Heat exchangers have numerous applications in power plants, industries, automobiles and electrical and electronic equipmemts. In the present work steady state turbulent flow heat transfer performance of circular tube having integral internal longitudinal fins was experimentally studied. This report describes new experimental data for turbulent fluid flow and heat transfer in a tube having internal fins. An experimental set up was designed and installed to study the heat transfer performance and pressure drop characteristics in the entrance region as well as in the fully developed region of the finned tube. The tube and fin assembly was cast from brass to avoid contact resistance. Air was used as the working fluid. The Reynolds number based on inside diameter ranged from 1.86 x 104 to 3.97 X 104 . The heat transfer test section was heated electrically by wrapping nichrome wire providing an ... uniform heat flux around the tube periphery over the entire length of the test section. Results exhibited high pressure gradient and high heat transfer coefficients in the entrance region, approaching the fully developed values away from the entrance section. Nusselt numbers of the finned tube were compared with those for an unfinned tube for both constant Reynolds number and constant pumping power. The enhancement of heat transfer rate due to integral fins was found to be very significant over the entire range of the flow rates studied in this experiment. Heat transfer coefficient based on inside diameter and nominal area of finned tube exceeded unfinned tube values by as much as 76.69%. The results of this study indicate that significant enhancement of heat transfer is possible by using internal fins with sacrificing less additional pumping power. These experimental results are expected to be very useful for the design of pipe-lines and heat exchanger tubes.