Experimental Studies on Passive Heat Transfer Method in a Horizontal Concentric Tube by Changing its Internal Surface Geometry

In the present Experimental study the heat transfer characteristics, friction factor and thermal enhancement factor of the horizontal concentric tube by changing its internal surface geometry was investigated. Experimentation were first conducted on smooth horizontal concentric tube and two different test section having different internal surface geometry i.e. by internal threading of pitches (p=1.78mm, p=3.57mm), under uniform wall heat flux condition. For experimentation purpose Reynolds number were varied in the range of 4000 to 9000. The tap water was used as a working fluid. The heat transfer characteristics, friction factor, thermal enhancement factor data obtained were compared with data obtained from smooth horizontal concentric tube under similar geometric and flow condition. The variation of heat transfer characteristics, friction factor, and thermal enhancement factor were determined and depicted graphically. The heat transfer rate for tube whose internal geometry was changed is found to be much higher compared with smooth horizontal concentric tube. So by changing the internal surface geometry the performance of smooth horizontal concentric tube was improved.